The Effect of Pressure Changes During Mechanical Insufflation-Exsufflation on Respiratory and Airway Physiology

BACKGROUND

Respiratory muscle weakness can impair cough function, leading to lower respiratory tract infections. These infections are an important contributor to morbidity and mortality in patients with neuromuscular disease. Mechanical insufflation-exsufflation (MIE) is used to augment cough function in these patients. Although MIE is widely used, there are few data to advise on the optimal technique. Since the introduction of MIE, the recommended pressures to be delivered have increased. There are concerns regarding the use of higher pressures and their potential to cause lung derecruitment and upper airway closure.

RESEARCH QUESTION

What is the impact of high-pressure MIE (HP-MIE) on lung recruitment, respiratory drive, upper airway flow, and patient comfort, compared with low-pressure MIE (LP-MIE), in patients with respiratory muscle weakness?

STUDY DESIGN AND METHODS

Clinically stable patients using domiciliary MIE with respiratory muscle weakness secondary to Duchenne muscle dystrophy, spinal cord injury, or long-term tracheostomy ventilation received LP-MIE (30/-30 cm H2O) and HP-MIE (60/-60 cm H2O) in a random sequence. Lung recruitment, neural respiratory drive, and cough peak expiratory flow were measured throughout, and patients reported comfort and breathlessness following each intervention.

RESULTS

A total of 29 patients (10 with Duchenne muscle dystrophy, eight with spinal cord injury, and 11 with long-term tracheostomy ventilation) were included in this study. HP-MIE augmented cough peak expiratory flow compared with LP-MIE (mean cough peak expiratory flow HP-MIE 228 ± 81 L/min vs LP-MIE 179 ± 67 L/min; P = .0001) without any significant change in lung recruitment, neural respiratory drive, or patient-reported breathlessness. However, in patients with more pronounced respiratory muscle weakness, HP-MIE resulted in an increased rate of upper airway closure and patient discomfort that may have an impact on clinical efficacy.

INTERPRETATION

HP-MIE did not lead to lung derecruitment or breathlessness compared with LP-MIE. However, it was poorly tolerated in individuals with advanced respiratory muscle weakness. HP-MIE generates more upper airway closure than LP-MIE, which may be missed if cough peak expiratory flow is used as the sole titration target.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT02753959; URL: www.

CLINICALTRIALS

gov.

Pilot observational cohort study to determine whether waveform and flow traces from mechanical insufflation-exsufflation (MI-E) can be used to identify laryngeal responses to MI-E and thus optimise treatment algorithms in neuromuscular patients in a tertiary centre: a protocol description

INTRODUCTION

Patients with neuromuscular disease often have a weak and ineffective cough due to respiratory muscle weakness. One treatment option is mechanical insufflation-exsufflation (MI-E), also known as cough assist, which is known to increase cough strength. However, some patients have a laryngeal response to MI-E, which can make the treatment ineffective. Currently, the only method for assessing this is via nasal endoscopy while using MI-E. Some MI-E devices have onboard secure data (SD) cards, which allow the visualisation of waveforms. We hypothesise that the waveforms can be used to identify laryngeal responses to the MI-E.

METHODS AND ANALYSIS

Participants will complete baseline assessments of spirometry, peak cough flow and sniff nasal inspiratory pressure. A nasal endoscope will be used to visualise the larynx during simultaneous MI-E via a mask with a drilled hole. MI-E will be delivered by an experienced physiotherapist. Four cycles of MI-E at a range of prescriptions will be delivered. MI-E waveforms will be downloaded into Care Orchestrator Essence software (Philips, Murraysville). Data will be collected prospectively and reviewed in a descriptive context, providing trends and potential rationales describing the waveforms in comparison to the nasal endoscope videos.

ETHICS AND DISSEMINATION

This protocol has been reviewed by the East of England-Cambridge Central Research Ethics Committee, who have granted a favourable ethical opinion. The study opened to recruitment in January 2022 and aims to publish trial results in June 2024.

TRIAL REGISTRATION NUMBER

NCT05189600.

Transnasal Humidified Rapid Insufflation Ventilatory Exchange in Endoscopic Esophageal Surgery

OBJECTIVES

Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) describes apneic oxygenation using humidified high flow nasal-cannula oxygen. Although it has been described as a sole mode of oxygenation in endoscopic laryngotracheal surgery, its use in endoscopic esophageal surgery under general anesthesia with neuromuscular paralysis has not previously been described. The objective of this study is to assess the safety and efficacy of THRIVE in esophagology.

METHODS

We conducted a retrospective review of adult patients undergoing esophageal procedures under general anesthesia who were oxygenated using THRIVE at two academic institutions. Demographic, clinical, and anesthesiologic data were collected and analyzed.

RESULTS

14 cases performed from March 2021 to March 2022 met inclusion criteria. 13/14 (92.9%) of patients were able to maintain oxygenation throughout the entirety of their procedure. The mean apneic time was 17.9 minutes with a maximum of 32 minutes. One patient required "rescue" intubation due to failure to maintain oxygenation. Excluding the sole THRIVE failure, the median SpO2 at the conclusion of surgery was 99% (range 94-100%). A linear regression model yielded an increase in EtCO2 of 0.95 mmHg/min or 0.127 kPa/min. SpO2 was negatively associated with both tobacco pack-year smoking history (R2 = 0.343, P = .014) and BMI (R2 = 0.238, P = .038).

CONCLUSION

THRIVE is a feasible, safe, and efficacious means of apneic oxygenation for patients undergoing esophageal endoscopic surgery under general anesthesia with neuromuscular paralysis, which may be particularly beneficial in patients with airway stenosis, as post-intubation changes can have severe clinical implications for this patient population. Obese patients and tobacco smokers may be at increased risk of oxygen desaturation when using THRIVE.

Impact of Standard Versus Low Pneumoperitoneum Pressure on Peritoneal Environment in Laparoscopic Cholecystectomy. Randomized Clinical Trial

BACKGROUND

High CO 2 pneumoperitoneum pressure during laparoscopy adversely affects the peritoneal environment. This study hypothesized that low pneumoperitoneum pressure may be linked to less peritoneal damage and possibly to better clinical outcomes.

MATERIALS AND METHODS

One hundred patients undergoing scheduled laparoscopic cholecystectomy were randomized 1:1 to low or to standard pneumoperitoneum pressure. Peritoneal biopsies were performed at baseline time and 1 hour after peritoneum insufflation in all patients. The primary outcome was peritoneal remodeling biomarkers and apoptotic index. Secondary outcomes included biomarker differences at the studied times and some clinical variables such as length of hospital stay, and quality and safety issues related to the procedure.

RESULTS

Peritoneal IL6 after 1 hour of surgery was significantly higher in the standard than in the low-pressure group (4.26±1.34 vs. 3.24±1.21; P =0.001). On the contrary, levels of connective tissue growth factor and plasminogen activator inhibitor-I were higher in the low-pressure group (0.89±0.61 vs. 0.61±0.84; P =0.025, and 0.74±0.89 vs. 0.24±1.15; P =0.028, respectively). Regarding apoptotic index, similar levels were found in both groups and were 44.0±10.9 and 42.5±17.8 in low and standard pressure groups, respectively. None of the secondary outcomes showed differences between the 2 groups.

CONCLUSIONS

Peritoneal inflammation after laparoscopic cholecystectomy is higher when surgery is performed under standard pressure. Adhesion formation seems to be less in this group. The majority of patients undergoing surgery under low pressure were operated under optimal workspace conditions, regardless of the surgeon's expertise.

Airway Clearance Strategies and Secretion Management in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a rare, neurodegenerative motor neuron disease that affects voluntary muscle movement. Often, difficulty in coughing, breathing, and swallowing are sequela associated with the condition, and the presence of bulbar muscle predominant weakness results in deleterious effects on airway clearance and secretion management. This narrative review will provide practical guidance for clinicians treating this population. Cough insufficiency in this population typically manifests as a prolonged, slow, weak cough effort that impedes the clearability of secretions and airway protection. Dystussia and dysphagia frequently occur simultaneously in bulbar dysfunction, subsequently impacting respiratory health. Measures of respiratory strength should be obtained and monitored every 3-6 months, preferably in a multidisciplinary clinic setting. Cough augmentation, whether manual or mechanical techniques, should be sought as early in the disease progression as possible to adequately control secretions in the proximal airways. This airway clearance strategy can aid in the prevention and treatment of respiratory tract infections (RTIs), which can pose a significant clinical hurdle to those with ALS. The use of mechanical insufflation-exsufflation may be complicated by severe bulbar dysfunction rendering this technique ineffective. Though peripheral airway clearance strategies, such as high-frequency chest-wall compression, have the advantage of being less impacted by bulbar dysfunction, it is only recommended this modality be used in conjunction with, versus in lieu of, proximal strategies. Salivary secretion management includes the use of anticholinergics, botulinum toxin, and radiation therapy depending on severity and desire for relief.

The role of warmed-humidified carbon dioxide insufflation in colorectal surgery: A systematic review and meta-analysis

BACKGROUND

Maintenance of normothermia is a crucial part of enhanced recovery after colorectal surgery. Dry-cold carbon dioxide (CO2 ) traditionally used for insufflation in laparoscopic surgery and negative pressure operating theatres has been associated with intraoperative hypothermia. Studies suggest that use of warmed-humidified CO2 may promote normothermia. However, due to a scarcity of high-quality studies demonstrating a proven benefit on intraoperative core body temperature, its use in colorectal surgery remains limited. Therefore, the aim of this review was to evaluate the effects of warmed-humidified CO2 compared to traditional dry-cold CO2 , or ambient air in operating theatres, during colorectal surgery.

METHODS

A search of Medline, EMBASE, and CENTRAL was performed. Randomised controlled trials (RCTs) that compared patients receiving warmed-humidified CO2 with either dry-cold CO2 insufflation in laparoscopic procedures or no insufflation during open surgery were included. The primary outcome was change in intraoperative core body temperature. Secondary outcomes included length of stay, operating time, return of gastrointestinal function, wound infection, and postoperative pain. A pairwise meta-analysis was performed using inverse variance random effects.

RESULTS

Among the six RCTs included, 208 patients received warmed-humidified CO2 (42.3% female, mean age: 65.8 years) and 210 patients received either dry-cold CO2 in laparoscopic procedures or no gas insufflation during open procedures (46.2% female, mean age: 66.1 years). No significant difference was found for change in intraoperative core body temperature (MD = 0.01, 95% CI: -0.1, 0.11, p = 0.90, very low certainty). Patients in the warmed-humidified CO2 group had significantly higher pain scores on postoperative day 1 (MD = 1.61, 95% CI: 0.91, 2.31, p < 0.05, very low certainty). No significant differences were found in any of the other secondary outcomes studied.

CONCLUSION

Patients undergoing colorectal surgery receiving warmed-humidified CO2 do not experience any clinically meaningful difference in core body temperature change compared to their counterparts receiving dry-cold CO2 insufflation or no insufflation. However, patients may report greater pain scores on postoperative day 1 with warmed-humidified CO2 . There is likely no clinically important difference between warmed-humidified CO2 and dry-cold CO2 for patients undergoing colorectal surgery. Patient, clinician, and institution factors should be considered when deciding between these two insufflation modalities.

Comparison of a Valveless Trocar System and Conventional Insufflation in Pediatric Urologic Surgery

Background: Conventional operative insufflation uses a one-way trocar to handle instruments while maintaining pneumoperitoneum. In 2007, the AirSeal® valveless trocar insufflation system was introduced, which maintains stable pneumoperitoneum while continuously evacuating smoke. Although this device has been validated in adult patients, it has not been extensively validated in the pediatric population. Materials and Methods: A retrospective cohort study of pediatric urology patients aged 0 to 21 who underwent laparoscopic pyeloplasty between March 2016 and October 2021 was performed. Intraoperative physiologic parameters, procedure characteristics, postoperative outcomes, and demographics of each patient in whom either AirSeal insufflation system (AIS) or conventional insufflation system (CIS) was utilized were obtained from hospital records. Data were compared across the AIS and CIS cohorts. The primary outcomes were intraoperative anesthetic and physiologic parameters, including end tidal carbon dioxide, oxygen saturation, body temperature, positive inspiratory pressure, systolic blood pressure, and heart rate. Results: There were no significant differences in the anesthetic and physiologic parameters in the AIS and CIS groups. In addition, no differences in demographics, procedural characteristics, or complication rates were found between the cohorts. Conclusion: The AirSeal valveless trocar insufflation system demonstrates comparable intraoperative anesthetic and physiologic outcomes compared to conventional one-way valve insufflation in pediatric laparoscopic pyeloplasty. Certain surgeon-related qualitative metrics are underappreciated in this study, however, including improved visualization with vigorous suctioning and pressure maintenance with frequent instrument exchanges. Surgeon experience may mask the benefits of these characteristics as it pertains to quantitative surgical outcomes such as estimated blood loss, operative time, and perioperative complications.

Escape of surgical smoke particles, comparing conventional and valveless trocar systems

BACKGROUND

During minimal access surgery, surgical smoke is produced which can potentially be inhaled by the surgical team, leading to several health risks. This smoke can escape from the abdominal cavity into the operating room due to trocar leakage. The trocars and insufflator that are used during surgery influence gas leakage. Therefore, this study compares particle escape from a valveless (Conmed AirSeal iFS), and a conventional (Karl Storz Endoflator) system.

MATERIALS AND METHODS

Using an in vitro model, a conventional and a valveless trocar system were compared. A protocol that simulated various surgical phases was defined to assess the surgical conditions and particle leakage. Insufflation pressures and instrument diameters were varied as these are known to affect gas leakage.

RESULTS

The conventional trocar leaked during two distinct phases. Removal of the obturator caused a sudden release of particles. During instrument insertion, an average of 211 (IQR 111) particles per second escaped when using the 5 mm diameter instrument. With the 10 mm instrument, 50 (IQR 13) particles per second were measured. With the conventional trocar, a higher abdominal pressure increased particle leakage. The valveless trocar demonstrated a continuously high particle release during all phases. After the obturator was removed, particle escape increased sharply. Particle escape decreased to 1276 (IQR 580) particles per second for the 5 mm instrument insertion, and 1084 (IQR 630) particles per second for 10 mm instrument insertion. With the valveless trocar system, a higher insufflation pressure lowered particle escape.

CONCLUSIONS

This study shows that a valveless trocar system releases more particles into the operating room environment than a conventional trocar. During instrument insertion, the leakage through the valveless system is 6 to 20 times higher than the conventional system. With a valveless trocar, leakage decreases with increasing pressure. With both trocar types leakage depends on instrument diameter.

Mechanical insufflation-exsufflation for invasively ventilated critically ill patients-A focus group study

INTRODUCTION

Mechanical Insufflation-Exsufflation (MI-E) is used as an airway clearance intervention in primary care (home ventilation), long-term care (prolonged rehabilitation after intensive care, neuromuscular diseases, and spinal cord injury), and increasingly in acute care in intensive care units (ICU).

AIM

We sought to develop in-depth understanding of factors influencing decision-making processes of health care professionals regarding initiation, escalation, de-escalation, and discontinuation of MI-E for invasively ventilated patients including perceived barriers and facilitators to use.

METHODS

We conducted focus groups (3 in the Netherlands; 1 with participants from four European countries) with clinicians representing the ICU interprofessional team and with variable experience of MI-E. The semi-structured interview guide was informed by the Theoretical Domains Framework (TDF). Two researchers independently coded data for directed content analysis using codes developed from the TDF.

RESULTS

A purposive sample of 35 health care professionals participated. Experience varied from infrequent to several years of frequent MI-E use in different patient populations. We identified four main themes: (1) knowledge; (2) beliefs; (3) clinical decision-making; and (4) future adoption.

CONCLUSION

Interprofessional knowledge and expertise of MI-E in invasively ventilated patients is limited due to minimal available evidence and adoption. Participants believed MI-E a potentially useful intervention for airway clearance and inclusion in weaning protocols when more evidence is available.

RELEVANCE TO CLINICAL PRACTICE

This focus group study provides an overview of current practice, knowledge and expertise, and barriers and facilitators to using MI-E in mechanically ventilated patients. From these data, it is evident there is a need to develop further clinical expertise and evidence of efficacy to further understand the role of MI-E as an airway clearance technique for ventilated patients.

Outcome of Water Exchange and Air Insufflation Colonoscopy Performed by Supervised Trainee and Their Assessment of the Training Experience

GOALS

The hypotheses that supervised trainees would provide a more favorable assessment of the learning experience and could achieve superior results with water exchange (WE) compared with air insufflation were tested.

BACKGROUND

WE decreased pain, increased cecal intubation rate (CIR), and polyp detection rate (PDR).

STUDY

In a prospective pilot observational study, the trainees were taught WE in unsedated and WE and air insufflation in alternating order in sedated veterans. Trainee scores and procedural outcomes were tracked.

RESULTS

83 air insufflation and 119 WE cases were included. Trainee evaluations of the respective methods were scored based on a 5-point scale [1 (strongly agree) to 5 (strongly disagree, with lower scores being more favorable]. Evaluation scores [mean (SD)] were as follows: my colonoscopy experience was better than expected: WE 2.02 (1.00) versus air insufflation 2.43 (1.19), P =0.0087; I was confident with my technical skills using this method: WE 2.76 (0.91) versus air insufflation 2.85 (0.87), P =0.4822. Insertion time was 40 (21) min for WE and 30 (20) min for air insufflation ( P =0.0008). CIR were 95% (WE, unsedated); 99% (WE, overall), and 89% (air insufflation, overall). WE showed significantly higher CIR (99% vs. 89%, P =0.0031) and PDR (54% vs. 32%, P =0.0447).

CONCLUSIONS

The long air insufflation insertion time indicated the trainees were inexperienced. The significantly longer WE insertion time confirmed that learning WE required extra time. This pilot study revealed that supervised trainees reported more favorable learning experience with WE and equivalent confidence in technical skills scores. They completed both unsedated and sedated colonoscopy in over 89% of cases achieved significantly higher CIR and PDR with WE than air insufflation. It appeared that trainee education in WE might be an acceptable alternative to augment air insufflation to meet the challenges of training posed by traditional air insufflation colonoscopy.

Safety and Utility of Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) for Laser Laryngeal Surgery

OBJECTIVE

Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) is gaining acceptance as a safe method for apneic ventilation and oxygenation during laryngeal procedures, but remains controversial during laser laryngeal surgery (LLS) due to the theoretical risk of airway fire. This study describes our experience with THRIVE during LLS.

STUDY DESIGN

Retrospective cohort study.

SETTING

Stanford University Hospital, October 15, 2015 to June 1, 2021.

METHODS

Retrospective chart review of patients ≥18 years who underwent LLS involving the CO2 or KTP laser with THRIVE as the primary mode of oxygenation.

RESULTS

A total of 172 cases were identified. 20.9% were obese (BMI ≥ 30). Most common operative indication was subglottic stenosis. The CO2 laser was used in 79.1% of cases. Median lowest intraoperative SpO2 was 96%. 44.7% cases were solely under THRIVE while 16.3% required a single intubation and 19.2% required multiple intubations. Mean apnea time for THRIVE only cases was 32.1 minutes and in cases requiring at least one intubation 24.0 minutes (p < .001). Mean apnea time was significantly lower for patients who were obese (p < .001) or had a diagnosis of hypertension (p = .016). Obese patients and patients with hypertension were 2.03 and 1.43 times more likely to require intraoperative intubation, respectively. There were no intraoperative complications or fires since the institution of our LLS safety protocol.

CONCLUSION

By eliminating the fuel component of the fire triangle, THRIVE can be safely used for continuous delivery of high FiO2 during LLS, provided adherence to institutional THRIVE-LLS protocols.

Effect of mechanical insufflation-exsufflation for ineffective cough on weaning duration in diseases of the peripheral or central nervous system (MEDINE): study protocol for a randomised controlled trial in a neurological weaning centre

INTRODUCTION

Patients with neurological or neurosurgical disease can suffer from impaired cough, which may result in life-threatening retention of tracheobronchial secretions, atelectasis, pneumonia and finally death. Due to a lack of alternatives and pathophysiological plausibility, the application of mechanical insufflation-exsufflation (MI-E) has already become international standard care in neuromuscular disease and spinal cord injury although a lack of evidence for efficacy. High-quality studies to support the use of MI-E in neurological and neurosurgical patients during weaning from mechanical ventilation are missing. The goal of this exploratory study is to display the effect size of MI-E intervention on the duration of mechanical ventilation and additional outcomes.

METHODS AND ANALYSIS

One hundred adult patients with a cough deficiency or retention of secretion admitted to a neurological intensive care unit (ICU) are planned to be recruited for this randomised controlled trial. Patients are randomised 1:1 to receive either MI-E or best standard care. Observation will take place until discharge from the hospital, death or end of the study period. The primary endpoint of this trial is the duration of mechanical ventilation from randomisation until successful weaning. The outcome will be analysed with Kaplan-Meier estimation and competing risks analyses. Secondary endpoint is the proportion of patients with successful weaning. Further outcomes will include the incidence of hospital-acquired pneumonia, mortality, decannulation rate, length of stay on the ICU and the total score of the Glasgow Coma Scale.

ETHICS AND DISSEMINATION

The study was approved by the Medical Ethics Committee of the University of Oldenburg. The findings of this study will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

DRKS00020981.

A novel method for assessment of airway opening pressure without the need for low-flow insufflation

BACKGROUND

Airway opening pressure (AOP) detection and measurement are essential for assessing respiratory mechanics and adapting ventilation. We propose a novel approach for AOP assessment during volume assist control ventilation at a usual constant-flow rate of 60 L/min.

OBJECTIVES

To validate the conductive pressure (Pcond) method, which compare the Pcond-defined on the airway pressure waveform as the difference between the airway pressure level at which an abrupt change in slope occurs at the beginning of insufflation and PEEP-to resistive pressure for AOP detection and measurement, and to compare its respiratory and hemodynamic tolerance to the standard low-flow insufflation method.

METHODS

The proof-of-concept of the Pcond method was assessed on mechanical (lung simulator) and physiological (cadavers) bench models. Its diagnostic performance was evaluated in 213 patients, using the standard low-flow insufflation method as a reference. In 45 patients, the respiratory and hemodynamic tolerance of the Pcond method was compared with the standard low-flow method.

MEASUREMENTS AND MAIN RESULTS

Bench assessments validated the Pcond method proof-of-concept. Sensitivity and specificity of the Pcond method for AOP detection were 93% and 91%, respectively. AOP obtained by Pcond and standard low-flow methods strongly correlated (r = 0.84, p < 0.001). Changes in SpO2 were significantly lower during Pcond than during standard method (p < 0.001).

CONCLUSION

Determination of Pcond during constant-flow assist control ventilation may permit to easily and safely detect and measure AOP.

Effect of transnasal humidified rapid-insufflation ventilatory exchange on gastric insufflation during anaesthesia induction: A randomised controlled trial and multivariate analysis

BACKGROUND

Mask ventilation during anaesthesia induction is generally used to provide adequate oxygenation but improper mask ventilation can result in gastric insufflation. It has been reported that oxygen administered by transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) during anaesthesia induction can maintain oxygenation but its effect on gastric insufflation is unknown.

OBJECTIVES

The primary aim of this study was to evaluate whether THRIVE provided adequate oxygenation without gastric insufflation. The secondary aim was to explore the change in cross-sectional area of the antrum (CSAa) during anaesthesia induction. Other potential risk factors of gastric insufflation were also explored.

DESIGN

A prospective, randomised, double-blind study.

SETTING

Single centre, Department of Anaesthesiology, 1 st Affiliated Hospital, Wenzhou Medical University, China, from May 2022 to September 2022.

PATIENTS

A total of 210 patients (age >18 years, ASA classification I to III) scheduled to undergo general anaesthesia were enrolled.

INTERVENTIONS

For induction of general anaesthesia, patients were randomised into two groups: THRIVE and pressure-controlled facemask ventilation (PCFV). The THRIVE group received high-flow nasal oxygen with no additional ventilation. The PCFV group had pressure-controlled positive pressure ventilation from the anaesthesia machine via a tight fitting facemask. Gastric insufflation was detected using real-time ultrasonography. The CSAa was measured from ultrasonography images obtained before anaesthesia induction and at 0, 1, 2 and 3 min after loss of consciousness.

MAIN OUTCOME MEASURES

The incidence of gastric insufflation during the period from loss of consciousness until intubation.

RESULTS

The THRIVE group had a lower incidence of gastric insufflation during anaesthesia induction than the PCFV group (13.0 vs. 35.3%, odds ratio (OR) = 0.27, 95% confidence interval (CI), 0.14 to 0.56, P  < 0.001). Increase in the CSA after anaesthesia induction was significantly correlated with gastric insufflation (OR = 5.35, 95% CI, 2.90 to 9.89, P  < 0.001). Multivariate logistic regression analysis showed that advancing age (OR = 1.04, 95% CI, 1.01 to 1.07), obstructive sleep apnoea syndrome (OR = 2.43, 95% CI, 1.24 to 4.76), higher Mallampati score (OR = 2.66, 95% CI, 1.21 to 5.85) and PCFV (OR = 4.78, 95% CI, 2.06 to 11.06) were important independent risk factors for gastric insufflation.

CONCLUSION

During anaesthesia induction, the THRIVE technique provided adequate oxygenation with a reduced incidence of gastric insufflation. PCFV, advancing age, obstructive sleep apnoea syndrome and the Mallampati score were found to be independent risk factors for gastric insufflation during anaesthesia induction.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR200059555.

Evidence for Beneficial Effect of Daily Use of Mechanical Insufflation-Exsufflation in Patients With Neuromuscular Diseases

BACKGROUND

Daily application of mechanical insufflation-exsufflation (MI-E) is used increasingly in patients with neuromuscular diseases (NMDs) to prevent pulmonary congestion and thereby respiratory tract infections, although its beneficial effect remains uncertain. We, therefore, conducted a systematic review, registered in PROSPERO (CRD42020158278), to compile available evidence for daily MI-E use in subjects with NMDs and stable respiratory condition.

METHODS

We performed a systematic comprehensive search of MEDLINE, Embase, CINAHL, and Web of Science up to December 23, 2021. We excluded articles studying the effect of MI-E in case of acute respiratory failure or infections and studies comparing different MI-E devices and settings. Studied outcomes were prevalence and severity of respiratory infections, lung function, respiratory characteristics, and patient satisfaction. We performed a meta-analysis using DerSimonian-Laird random effects model and assessed methodological quality by using the Alberta Heritage Foundation for Medical Research tool.

RESULTS

A total of 3,374 records were screened, of which 25 were included, studying 608 subjects. One randomized controlled trial (RCT) found a trend toward reduced duration of respiratory infections compared to air stacking (AS) that was not statistically significant. Long-term effects on pulmonary function tests (PFT) results were reported in one RCT and one retrospective study, with mixed results regarding vital capacity. Most studies compared PFT results before and immediately after MI-E use. Meta-analysis showed an overall beneficial effect of MI-E on cough peak flow (CPF) compared to unassisted CPF (mean difference 91.6 L/min [95% CI 28.3-155.0], P < .001). Subject satisfaction was high, though possibly influenced by major bias.

CONCLUSIONS

There is limited evidence available to support beneficial effects of daily use of MI-E in clinically stable subjects with NMDs, with the possible exception of increased CPF immediately after MI-E application. Lack of longitudinal studies preclude conclusions regarding long-term effects. The very limited data comparing MI-E to AS preclude comparisons.

Impact of pneumoperitoneum pressure during laparoscopic hysterectomy: A randomized controlled trial

OBJECTIVE

Minimally invasive hysterectomy is a commonly performed gynecologic procedure with associated postoperative pain managed with opioid medications. Uncontrolled postoperative pain leads to increased opioid use/abuse, longer hospital stays, increase in healthcare visits, and may negatively affect patient satisfaction. Current data suggests that reduced pneumoperitoneum insufflation pressure during laparoscopic surgery may impact postoperative pain. Given the current opioid epidemic, surgeons are proactively finding ways to reduce postoperative pain. It is unclear how reduced pneumoperitoneum pressure impacts the surgeon. We investigated the impact of reduced pneumoperitoneum insufflation pressure on surgeon satisfaction.

STUDY DESIGN

This was a pilot, double-blinded, randomized controlled trial from March 2020 to July 2021 comparing pneumoperitoneum pressure of 15 mmHg to reduced pressures of 12 mmHg and 10 mmHg during laparoscopic hysterectomy.

RESULTS

A total of 40 patients were randomized (13 - 15 mmHg, 13 - 12 mmHg, and 14 - 10 mmHg). The primary outcome was surgeon satisfaction. Secondary outcomes included patient satisfaction, operative time, blood loss, postoperative pain, opioid usage, and discharge timing. There were no differences in baseline demographics or perioperative characteristics. Surgeon satisfaction was negatively impacted with lower pneumoperitoneum pressures greatest with 10 mmHg, including overall satisfaction (p =.01), overall effect of the pneumoperitoneum (p =.04), and quality of visualization (p =.01). There was an apparent although not statistically significant difference in operative time (p =.06) and blood loss (p =.054). There was no difference in patient satisfaction, postoperative pain scores, opioid usage, or time to discharge.

CONCLUSION(S)

Reduced pneumoperitoneum insufflation pressure during laparoscopic hysterectomy negatively impacted surgeon satisfaction with a trend towards longer operative times and greater blood loss, and did not positively impact patient satisfaction, postoperative pain, opioid demand, or discharge timing.

Distribution of surgical smoke particles within a simulated laparoscopic cavity utilizing an AirSeal® system

An exploratory study was performed to determine the distribution of surgical smoke particulate matter (SSPM) and evacuation times within an AirSeal® System and a traditional insufflation access system in various simulated surgical scenarios. Identified trends showed statistical significance when setting the AirSeal® System to Low smoke evacuation that it reduces the percentage of particulate matter at the Access Port opening. Additionally, it was observed that when utilising a laparoscopic tool a similar trend in particle distributions were seen between either insufflation and access system at the opening of the Access Port and trocar. Evacuation times for SSPM removal within the AirSeal® System showed an overall average to ≥95% reduction of 5.64 min within the surgical cavity, 3.69 min at the Access Port opening, and 3.61 min within the smoke evacuation line. The overall average for the traditional insufflation and access system was 9.38 min within the surgical cavity and 6.06 min at the trocar opening. Results showed that when using the traditional system compared to the AirSeal® System, it resulted in a percent change increase in evacuation times of 66.31% within the surgical cavity and 64.23% at the trocar opening.

Effects of Mechanical Insufflation-Exsufflation With Different Pressure Settings on Respiratory Mucus Displacement During Invasive Ventilation

BACKGROUND

Mechanical insufflation-exsufflation (MI-E) has been proposed as a potential strategy to generate high expiratory flows and simulate cough in the critically ill. However, efficacy and safety of MI-E during invasive mechanical ventilation are still to be fully elucidated. This study in intubated and mechanically ventilated pigs aimed to evaluate the effects of 8 combinations of insufflation-exsufflation pressures during MI-E on mucus displacement, respiratory flows, as well as respiratory mechanics and hemodynamics.

METHODS

Six healthy Landrace-Large White female pigs were orotracheally intubated, anesthetized, and invasively ventilated for up to 72 h. Eight combinations of insufflation-exsufflation pressures (+40/-40, +40/-50, +40/-60, +40/-70, +50/-40, +50/-50, +50/-60, +50/-70 cm H₂O) were applied in a randomized order. The MI-E device was set to automatic mode, medium inspiratory flow, and an inspiratory-expiratory time 3 and 2 s, respectively, with a 1-s pause between cycles. We performed 4 series of 5 insufflation-exsufflation cycles for each combination of pressures. Velocity and direction of movement of a mucus simulant containing radio-opaque markers were assessed through sequential lateral fluoroscopic images of the trachea. We also evaluated respiratory flows, respiratory mechanics, and hemodynamics before, during, and after each combination of pressures.

RESULTS

In 3 of the animals, experiments were conducted twice; and for the remaining 3, they were conducted once. In comparison to baseline mucus movement (2.85 ± 2.06 mm/min), all insufflation-exsufflation pressure combinations significantly increased mucus velocity (P = .01). Particularly, +40/-70 cm H₂O was the most effective combination, increasing mucus movement velocity by up to 4.8-fold (P < .001). Insufflation pressure of +50 cm H₂O resulted in higher peak inspiratory flows (P = .004) and inspiratory transpulmonary pressure (P < .001) than +40 cm H₂O.

CONCLUSIONS

MI-E appeared to be an efficient strategy to improve mucus displacement during invasive ventilation, particularly when set at +40/-70 cm H₂O. No safety concerns were identified although a transient significant increase of transpulmonary pressure was observed.

Waveforms Analysis in Patients With Amyotrophic Lateral Sclerosis for Enhanced Efficacy of Mechanically Assisted Coughing

BACKGROUND

Effectiveness of mechanical assisted coughing with insufflation-exsufflation (MI-E) in amyotrophic lateral sclerosis (ALS) depends largely on severity of bulbar dysfunction, which can generate different upper-airway responses. The aim of the study was to evaluate the use of graphs generated by MI-E in ALS to detect airway obstruction and set parameters to achieve an effective mechanically assisted coughing.

METHODS

This was a prospective study enrolling patients with ALS. Several sessions with MI-E were applied, administering different insufflation-exsufflation (± 20, ± 30, ± 40, ± 50 cm H₂O) levels in each session. The graphs produced were recorded and analyzed, and the results were used to select the parameters resulting in more effective MI-E.

RESULTS

Sixty-nine subjects with ALS were included, yielding a total of 351 analyzed records. A pattern of obstruction during insufflation was detected in 34 subjects (50.7%) and of upper-airway collapse during exsufflation in 18 subjects (26%). The variable associated with obstruction during insufflation was bulbar upper motor neuron dysfunction (odds ratio 7.19 [95% CI 2.32-22.29], P = .001), whereas bulbar lower motor neuron dysfunction was related to upper-airway collapse during exsufflation (odds ratio 0.32 [95% CI 0.11-0.98], P = .046). After parameters were adjusted, in 68 subjects (98.55%) an effective MI-E was achieved. The only variable that predicted absence of alterations in the graphs was Norris bulbar score (odds ratio 0.87 [95% CI 0.78-0.96], P = .007).

CONCLUSIONS

Analysis of graphics generated by applying MI-E in ALS was an effective method to detect upper-airway responses and select optimal set parameters. Obstruction during insufflation is related to bulbar upper motor neuron dysfunction and collapse during exsufflation to bulbar lower motor neuron dysfunction.

A novel method for monitoring abdominal compliance to optimize insufflation pressure during laparoscopy

BACKGROUND

Abdominal compliance describes the ease of expansion of the abdominal cavity. Several studies highlighted the importance of monitoring abdominal compliance (Cab) during the creation of laparoscopic workspace to individualize the insufflation pressure. The lack of validated clinical monitoring tools for abdominal compliance prevents accurate tailoring of insufflation pressure. Oscillometry, also known as the forced oscillation technique (FOT), is currently used to measure respiratory mechanics and has the potential to be adapted for monitoring abdominal compliance. This study aimed to define, develop and evaluate a novel approach which can monitor abdominal compliance during laparoscopy using endoscopic oscillometry.

MATERIALS AND METHODS

Endoscopic oscillometry was evaluated in a porcine model for laparoscopy. A custom-built insufflator was developed for applying an oscillatory pressure signal superimposed onto a mean intra-abdominal pressure. This insufflator was used to measure the abdominal compliance at insufflation pressures ranging from 5 to 20 hPa (3.75 to 15 mmHg). The measurements were compared to the static abdominal compliance, which was measured simultaneously with computed tomography imaging.

RESULTS

Endoscopic oscillometry recordings and CT images were obtained in 10 subjects, resulting in 76 measurement pairs for analysis. The measured dynamic Cab ranged between 0.0216 and 0.261 L/hPa while the static Cab based on the CT imaging ranged between 0.0318 and 0.364 L/hPa. The correlation showed a polynomial relation and the adjusted R-squared was 97.1%.

CONCLUSIONS

Endoscopic oscillometry can be used to monitor changes in abdominal compliance during laparoscopic surgery, which was demonstrated in this study with a comparison with CT imaging in a porcine laparoscopy model. Use of this technology to personalize the insufflation pressure could reduce the risk of applying excessive pressure and limit the drawbacks of insufflation.

Single versus continuous sustained inflations during chest compressions and physiological-based cord clamping in asystolic lambs

BACKGROUND

The feasibility and benefits of continuous sustained inflations (SIs) during chest compressions (CCs) during delayed cord clamping (physiological-based cord clamping; PBCC) are not known. We aimed to determine whether continuous SIs during CCs would reduce the time to return of spontaneous circulation (ROSC) and improve post-asphyxial blood pressures and flows in asystolic newborn lambs.

METHODS

Fetal sheep were surgically instrumented immediately prior to delivery at ~139 days' gestation and asphyxia induced until lambs reached asystole. Lambs were randomised to either immediate cord clamping (ICC) or PBCC. Lambs then received a single SI (SIsing; 30 s at 30 cmH2O) followed by intermittent positive pressure ventilation, or continuous SIs (SIcont: 30 s duration with 1 s break). We thus examined 4 groups: ICC +SIsing, ICC +SIcont, PBCC +SIsing, and PBCC +SIcont. Chest compressions and epinephrine administration followed international guidelines. PBCC lambs underwent cord clamping 10 min after ROSC. Physiological and oxygenation variables were measured throughout.

RESULTS

The time taken to achieve ROSC was not different between groups (mean (SD) 4.3±2.9 min). Mean and diastolic blood pressure was higher during chest compressions in PBCC lambs compared with ICC lambs, but no effect of SIs was observed. SIcont significantly reduced pulmonary blood flow, diastolic blood pressure and oxygenation after ROSC compared with SIsing.

CONCLUSION

We found no significant benefit of SIcont over SIsing during CPR on the time to ROSC or on post-ROSC haemodynamics, but did demonstrate the feasibility of continuous SIs during advanced CPR on an intact umbilical cord. Longer-term studies are recommended before this technique is used routinely in clinical practice.

Translation from manual to automatic endoscopic insufflation enhanced by a pressure limiter

BACKGROUND

Optimal visualization and safety have always been essential in performing any type of endoscopic surgery. However, the safety of automatic gastrointestinal (GI) insufflation has yet to be thoroughly studied, especially when combined with manual insufflation. The current study aimed to verify whether the pressure limiter could lower GI endoluminal pressure during endoscopic procedures and affect the behavioral patterns of endoscopists.

METHODS

A preclinical blinded trial was conducted on endoscopists who had no knowledge regarding the presence of the pressure limiter that prevents a GI endoluminal pressure above 25 mmHg. Endoscopists in group A performed esophageal endoscopic submucosal dissection (ESD) with our insufflation device equipped with the pressure limiter, whereas those in group B performed the same procedure without the pressure limiter. During all procedures, endoluminal pressure was continuously monitored. The primary endpoint of the current study was to measure the endoluminal pressure with or without the pressure limiter during esophageal ESD, while the secondary endpoint was to evaluate the effect of the pressure limiter on intraesophageal pressure and perioperative outcomes during esophageal ESD. A questionnaire survey was conducted after each session.

RESULTS

A total of 79 endoscopists were included in this randomized control study. Group A had significantly lower endoluminal pressure than group B (10.6 ± 4.61 vs. 16.25 ± 7.51 mmHg, respectively; p < 0.05). Although two pigs in group B died from tension pneumothorax, none in group A died. Evaluation of lumen expansion, ease of aspiration, and visual field reproducibility were poorer in group A than in group B, although all fell within the acceptable range. Subjective evaluation of usability was divided into two categories, Excellent/Good and Poor/Bad, with no significant differences in any of the items.

CONCLUSIONS

This preclinical study showed that endoscopic treatment with an automatic insufflation system could be performed at lower endoluminal pressure with a pressure limiter, which had no adverse effects on the endoscopist's feels on endoscopic procedures with the device.

The Use of Mechanical Insufflation-Exsufflation in Invasively Ventilated Critically Ill Adults

Mechanical insufflation-exsufflation (MI-E) is traditionally used in the neuromuscular population. There is growing interest of MI-E use in invasively ventilated critically ill adults. We aimed to map current evidence on MI-E use in invasively ventilated critically ill adults. Two authors independently searched electronic databases MEDLINE, Embase, and CINAHL via the Ovid platform; PROSPERO; Cochrane Library; ISI Web of Science; and International Clinical Trials Registry Platform between January 1990-April 2021. Inclusion criteria were (1) adult critically ill invasively ventilated subjects, (2) use of MI-E, (3) study design with original data, and (4) published from 1990 onward. Data were extracted by 2 authors independently using a bespoke extraction form. We used Mixed Methods Appraisal Tool to appraise risk of bias. Theoretical Domains Framework was used to interpret qualitative data. Of 3,090 citations identified, 28 citations were taken forward for data extraction. Main indications for MI-E use during invasive ventilation were presence of secretions and mucus plugging (13/28, 46%). Perceived contraindications related to use of high levels of positive pressure (18/28, 68%). Protocolized MI-E settings with a pressure of ±40 cm H₂O were most commonly used, with detail on timing, flow, and frequency of prescription infrequently reported. Various outcomes were re-intubation rate, wet sputum weight, and pulmonary mechanics. Only 3 studies reported the occurrence of adverse events. From qualitative data, the main barrier to MI-E use in this subject group was lack of knowledge and skills. We concluded that there is little consistency in how MI-E is used and reported, and therefore, recommendations about best practices are not possible.

VOLUMETRIC CAPNOGRAPHY FOR RESPIRATORY MONITORING OF PATIENTS DURING ROUTINE COLONOSCOPY WITH ROOM-AIR AND CARBON DIOXIDE INSUFFLATION

BACKGROUND

Capnography and carbon dioxide (CO2) insufflation during gastrointestinal endoscopy under sedation are associated with safety and comfort improvements, respectively. Capnography can provide early detection of apnea and hypoxemia, whereas CO2 insufflation causes lower periprocedural discomfort. This is the first study to report the application of volumetric capnography in colonoscopy.

OBJECTIVE

This study aimed to evaluate the use of volumetric capnography with room air (RA) and CO2 insufflation during routine colonoscopy.

METHODS

In this prospective cohort study, 101 patients who underwent routine colonoscopy under sedation with volumetric capnography monitoring were included. Insufflation with RA was used to distend the intestinal lumen in group 1 (n=51), while group 2 (n=50) used CO2 insufflation. The primary endpoints were episodes of hypoxia, alveolar hypoventilation, and end-tidal CO2 (EtCO2). The secondary endpoints were tidal volume per minute, consumption of sedation medications, and post-procedure pain using the Gloucester modified pain scale.

RESULTS

The number of episodes of hypoxia (SpO2<90%) was similar between the groups: four episodes in Group 1 and two episodes in Group 2. The duration of hypoxia was significantly longer in group 2 (P=0.02). Hypoalveolar ventilation (EtCO2) occurred more frequently in Group 2 than in Group 1 (27 vs 18 episodes, P=0.05). Regarding EtCO2, Group 2 showed higher values in cecal evaluation (28.94±4.68 mmHg vs 26.65±6.12 mmHg, P=0.04). Regarding tidal volume per minute, Group 2 had significantly lower values at the cecal interval compared to Group 1 (2027.53±2818.89 vs 970.88±1840.25 L/min, P=0.009). No episodes of hypercapnia (EtCO2 > 60 mmHg) occurred during the study. There was no difference in the consumption of sedation medications between the groups. Immediately after colonoscopy, Group 2 reported significantly less pain than Group 1 (P=0.05).

CONCLUSION

In our study, volumetric capnography during colonoscopy was feasible and effective for monitoring ventilatory parameters and detecting respiratory complications. CO2 insufflation was safe and associated with less pain immediately after colonoscopy.

Eustachian tube insufflation with thermal water: Effectiveness in the treatment of pediatric otitis media with effusion

PURPOSE

Otitis media with effusion (OME) is the most common ear disease in childhood. The hearing loss associated with OME impacts on children's language development and behavior. Eustachian tube insufflation are among possible treatments for OME, but data regarding their effectiveness are scarce. The aim of this investigation was to analyze the effect of inhalatory thermal therapy and Eustachian tube insufflation in a consecutive cohort of pediatric patients with OME.

MATERIALS AND METHODS

Seventy-four pediatric patients referred for OME to the thermal medical center "La Contea" (Battaglia Terme, Padova, Italy) were considered. Data from tympanometry and pure tone audiometry performed immediately before (T0), at the end of treatment (T1) and at a follow-up control (T2) were analyzed.

RESULTS

Data from 148 ears were available. The pressure values of tympanometry significantly improved from T0 to T1 (p = 0.0001), and further improvement was recorded at T2, when 60.8% of patients had normal tympanograms. A significant gain of the air-conduction threshold in the T0-T2 interval was observed (p = 0.0001). At otoscopy, a significant reduction of tympanic membranes with fluid or air-fluid levels presence (p < 0.00001) and a significant increase of normal tympanic membranes (p = 0.0001) were found.

CONCLUSION

Eustachian tube insufflation represented a well-tolerated and effective treatment in children with OME. Further investigations should deepen these results in randomized, double-blind settings, possibly with long-term follow-up periods. A quality-of-life and cost-effectiveness evaluation of this treatment approach for pediatric OME could be helpful for public health decision-making.

Use of mechanical insufflation exsufflation and manual techniques in an intubated adult with COVID-19 positioned in prone-A case study

BACKGROUND AND PURPOSE

The therapeutic benefits of prone positioning have been described over the last 50 years culminating in a systematic review supporting this management strategy for patients with severe hypoxaemic respiratory failure. Early work detailing treatment approaches for COVID-19 have advocated the use of prone positioning. Limited data exists regarding physiotherapy intervention in patients with COVID-19 owing to the recent emergence of this novel disease. Despite the acknowledged beneficial effects of physiotherapy on secretion clearance and lung recruitment in the general critical care population, there is a lack of evidence pertaining to physiotherapeutic intervention for acutely unwell intubated adults in prone lying.

METHODS

This case study report follows the CARE case report guidelines. One patient with COVID-19 pneumonitis who underwent physiotherapy intervention in prone lying is discussed. Informed consent was gained from next of kin for data to be published.

RESULTS

Treatment techniques including mechanical insufflation-exsufflation in prone were feasible and well tolerated by this patient with only transient adverse effects noted. Treatment techniques assisted with secretion clearance.

DISCUSSION

Further work on safety, feasibility, and efficacy of physiotherapy intervention in patients with and without COVID-19 in prone will contribute to the evidence base on this subject.

Warm humidified CO2 insufflation improves pericardial integrity for cardiac surgery: a randomized control study

BACKGROUND

Flooding the surgical field with dry cold CO<inf>2</inf> during open-chamber cardiac surgery has been used to mitigate air entrainment into the systemic circulation. However, exposing epithelial surfaces to cold, dry gas causes tissue desiccation. This randomized controlled study was designed to investigate whether the use of humidified warm CO<inf>2</inf> insufflation into the cardiac cavity could reduce pericardial tissue damage and the incidence of micro-emboli when compared to dry cold CO<inf>2</inf> insufflation.

METHODS

Forty adult patients requiring elective open-chamber cardiac surgery were randomized to have either dry cold CO<inf>2</inf> insufflation via a standard catheter or humidified warm CO<inf>2</inf> insufflation via the HumiGard device (Fisher & Paykel Healthcare, Panmure, Auckland, New Zealand). The primary endpoint was biopsied pericardial tissue damage, assessed using electron microscopy. We assessed the percentage of microvilli and mesothelial damage, using a damage severity score (DSS) system. We compared the proportion of patients who had less damage, defined as DSS<2. Secondary endpoints included the severity of micro-emboli, by visual assessment of bubble load on transesophageal echocardiogram; lowest near infrared spectroscopy; total de-airing time; highest cardio-pulmonary bypass sweep speed; hospital length of stay and complications.

RESULTS

A higher proportion of patients in the humidified warm CO<inf>2</inf> group displayed conserved microvilli (47% vs. 11%, P=0.03) and preserved mesothelium (42% vs. 5%, P=0.02) compared to the control group. There were no differences in the secondary outcomes.

CONCLUSIONS

Humidified warm CO<inf>2</inf> insufflation significantly reduced pericardial epithelial damage when compared to dry cold CO<inf>2</inf> insufflation in open-chamber cardiac surgery. Further studies are warranted to investigate its potential clinical benefits.

Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery

BACKGROUND

This is the second update of a Cochrane Review first published in 2013 and last updated in 2017. Laparoscopic surgery is now widely performed to treat various abdominal diseases. Currently, carbon dioxide is the most frequently used gas for insufflation of the abdominal cavity (pneumoperitoneum). Although carbon dioxide meets most of the requirements for pneumoperitoneum, the absorption of carbon dioxide may be associated with adverse events. Therefore, other gases have been introduced as alternatives to carbon dioxide for establishing pneumoperitoneum.

OBJECTIVES

To assess the safety, benefits, and harms of different gases (e.g. carbon dioxide, helium, argon, nitrogen, nitrous oxide, and room air) used for establishing pneumoperitoneum in participants undergoing laparoscopic abdominal or gynaecological pelvic surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, four other databases, and three trials registers on 15 October 2021 together with reference checking, citation searching, and contact with study authors to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different gases for establishing pneumoperitoneum in participants (irrespective of age, sex, or race) undergoing laparoscopic abdominal or gynaecological pelvic surgery under general anaesthesia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 10 RCTs, randomising 583 participants, comparing different gases for establishing pneumoperitoneum: nitrous oxide (four trials), helium (five trials), or room air (one trial) was compared to carbon dioxide. All the RCTs were single-centre studies. Four RCTs were conducted in the USA; two in Australia; one in China; one in Finland; one in Iran; and one in the Netherlands. The mean age of the participants ranged from 27.6 years to 49.0 years. Four trials randomised participants to nitrous oxide pneumoperitoneum (132 participants) or carbon dioxide pneumoperitoneum (128 participants). None of the trials was at low risk of bias. The evidence is very uncertain about the effects of nitrous oxide pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto odds ratio (OR) 2.62, 95% CI 0.78 to 8.85; 3 studies, 204 participants; very low-certainty evidence), or surgical morbidity (Peto OR 1.01, 95% CI 0.14 to 7.31; 3 studies, 207 participants; very low-certainty evidence). There were no serious adverse events related to either nitrous oxide or carbon dioxide pneumoperitoneum (4 studies, 260 participants; very low-certainty evidence). Four trials randomised participants to helium pneumoperitoneum (69 participants) or carbon dioxide pneumoperitoneum (75 participants) and one trial involving 33 participants did not state the number of participants in each group. None of the trials was at low risk of bias. The evidence is very uncertain about the effects of helium pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto OR 1.66, 95% CI 0.28 to 9.72; 3 studies, 128 participants; very low-certainty evidence), or surgical morbidity (5 studies, 177 participants; very low-certainty evidence). There were three serious adverse events (subcutaneous emphysema) related to helium pneumoperitoneum (3 studies, 128 participants; very low-certainty evidence). One trial randomised participants to room air pneumoperitoneum (70 participants) or carbon dioxide pneumoperitoneum (76 participants). The trial was at high risk of bias. There were no cardiopulmonary complications, serious adverse events, or deaths observed related to either room air or carbon dioxide pneumoperitoneum.    AUTHORS' CONCLUSIONS: The evidence is very uncertain about the effects of nitrous oxide, helium, and room air pneumoperitoneum compared to carbon dioxide pneumoperitoneum on any of the primary outcomes, including cardiopulmonary complications, surgical morbidity, and serious adverse events. The safety of nitrous oxide, helium, and room air pneumoperitoneum has yet to be established, especially in people with high anaesthetic risk.

Transient End-Tidal Carbon Dioxide Elevation During Pediatric Upper Endoscopy With Carbon Dioxide Insufflation: Is It True Hypercapnia?

BACKGROUND

Endoscopic insufflation, long performed using air, is being replaced by carbon dioxide (CO2) at many pediatric centers, despite limited published data on its use in children. We have previously demonstrated that CO2 use during esophagogastroduodenoscopy (EGD) in non-intubated children is associated with transient elevations of end-tidal CO2 (EtCO2). This observation raised concerns about possible CO2 inhalation and systemic absorption. Here, we investigate this concern by concurrently measuring both EtCO2 and transcutaneous CO2 (tCO2) during upper endoscopic procedures in children.

AIM

To determine if elevations in EtCO2 levels seen in non-intubated children undergoing CO2 insufflation during EGD are associated with elevated systemic CO2 levels.

METHODS

Double-blinded, prospective, randomized clinical trial. Children were randomized 1:1 to receive either CO2 or air for endoscopic insufflation. EtCO2 was sampled with a CO2-sampling nasal cannula and tCO2 was monitored using the Radiometer transcutaneous monitoring device.

RESULTS

Fifty nine patients were enrolled; 30 patients in the CO2 insufflation group and 29 in the air group. All patients underwent a procedure involving an EGD. Transient elevations in EtCO2 (defined as >60 mmHg) were observed only in the CO2 insufflation group. This contrasted with the similar elevations of tCO2 between the CO2 and air insufflation groups. None of these events were of clinically significant magnitude or duration.

CONCLUSION

This study demonstrates that the observed transient elevations in EtCO2 seen during EGD in non-intubated children receiving CO2 insufflation are most likely measurements of eructated CO2 without evidence of excessive systemic absorption of CO2.

Cough augmentation techniques for people with chronic neuromuscular disorders

BACKGROUND

People with neuromuscular disorders may have a weak, ineffective cough predisposing them to respiratory complications. Cough augmentation techniques aim to improve cough effectiveness and mucous clearance, reduce the frequency and duration of respiratory infections requiring hospital admission, and improve quality of life.

OBJECTIVES

To determine the efficacy and safety of cough augmentation techniques in adults and children with chronic neuromuscular disorders.

SEARCH METHODS

On 13 April 2020, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and ClinicalTrials.gov for randomised controlled trials (RCTs), quasi-RCTs, and randomised cross-over trials.

SELECTION CRITERIA

We included trials of cough augmentation techniques compared to no treatment, alternative techniques, or combinations thereof, in adults and children with chronic neuromuscular disorders.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility, extracted data, and assessed risk of bias. The primary outcomes were the number and duration of unscheduled hospitalisations for acute respiratory exacerbations. We assessed the certainty of evidence using GRADE.

MAIN RESULTS

The review included 11 studies involving 287 adults and children, aged three to 73 years. Inadequately reported cross-over studies and the limited additional information provided by authors severely restricted the number of analyses that could be performed. Studies compared manually assisted cough, mechanical insufflation, manual and mechanical breathstacking, mechanical insufflation-exsufflation, glossopharyngeal breathing, and combination techniques to unassisted cough and alternative or sham interventions. None of the included studies reported on the primary outcomes of this review (number and duration of unscheduled hospital admissions) or listed 'adverse events' as primary or secondary outcome measures. The evidence suggests that a range of cough augmentation techniques may increase peak cough flow compared to unassisted cough (199 participants, 8 RCTs), but the evidence is very uncertain. There may be little to no difference in peak cough flow outcomes between alternative cough augmentation techniques (216 participants, 9 RCTs). There was insufficient evidence to determine the effect of interventions on measures of gaseous exchange, pulmonary function, quality of life, general function, or participant preference and satisfaction.

AUTHORS' CONCLUSIONS

We are very uncertain about the safety and efficacy of cough augmentation techniques in adults and children with chronic neuromuscular disorders and further studies are needed.

Insufflation pressure above 25 mm Hg confers no additional benefit over lower pressure insufflation during posterior retroperitoneoscopic adrenalectomy: a retrospective multi-centre propensity score-matched analysis

BACKGROUND

Insufflation pressures of or in excess of 25 mm Hg CO2 are routinely used during posterior retroperitoneoscopic adrenalectomy (PRA) in most centres. A critical analysis of the surgical literature provides limited evidence to support this strategy.

OBJECTIVE

To determine whether high pressure (≥ 25 mm Hg) compared with lower pressure (< 25 mm Hg) retroperitoneoscopy reduces operating time and complications.

METHODS

A multi-centre retrospective cohort study was performed using data collected over a period of almost one decade (1st November 2008 until 1st February 2018) from surgical centres in Germany. A total of 1032 patients with benign adrenal tumours were identified. We compared patients undergoing PRA with insufflation pressures of < 25 mm Hg (G20 group) versus ≥ 25 mm Hg (G25 group). A propensity score matching analysis was performed using BMI, tumour size and surgeon's experience as independent variables. The main outcomes were (1) the incidence of perioperative complications and (2) the length of operating time.

RESULTS

The baseline patient characteristics were similar in both groups, with the exception of tumour size, BMI and surgeon's experience in PRA. After propensity score matching, perioperative outcomes, especially perioperative complications (3.7% vs. 5.5% in G20 and G25, respectively; p = 0.335) and operation duration (47 min vs. 45 min in G20 and G25, respectively; p = 0.673), did not significantly differ between the groups.

CONCLUSION

Neither patient safety nor operative success was compromised when PRA was performed with insufflation pressures below 25 mm Hg. Prospective studies are required to determine whether an optimal insufflation pressure exists that maximizes patient safety and minimizes the risks of post-surgical complications. Nevertheless, our results call for a careful re-evaluation of the routine use of high insufflation pressures during PRA. In the absence of prospective data, commencing PRA with lower insufflation pressures, with the option of increasing insufflation pressures to counter intraoperative bleeding or exposition difficulties, may represent a reasonable strategy.

Stop the leak!: Mitigating potential exposure of aerosolized COVID-19 during laparoscopic surgery

BACKGROUND

Viral particles have been shown to aerosolize into insufflated gas during laparoscopic surgery. In the operating room, this potentially exposes personnel to aerosolized viruses as well as carcinogens. In light of circumstances surrounding COVID-19 and a concern for the safety of healthcare professionals, our study seeks to quantify the volumes of gas leaked from dynamic interactions between laparoscopic instruments and the trocar port to better understand potential exposure to surgically aerosolized particles.

METHODS

A custom setup was constructed to simulate an insufflated laparoscopic surgical cavity. Two surgical instrument use scenarios were examined to observe and quantify opportunities for insufflation gas leakage. Both scenarios considered multiple configurations of instrument and trocar port sizes/dimensions: (1) the full insertion and full removal of a laparoscopic instrument from the port and (2) the movement of the scope within the port, recognized as "dynamic interaction", which occurs nearly 100% of the time over the course of any procedure.

RESULTS

For a 5 mm instrument in a 5 mm trocar, the average volume of gas leaked during dynamic interaction and full insertion/removal scenarios were 43.67 and 25.97 mL of gas, respectively. Volume of gas leaked for a 5 mm instrument in a 12 mm port averaged 41.32 mL and 29.47 for dynamic interaction vs. instrument insertion and removal. Similar patterns were shown with a 10 mm instrument in 12 mm port, with 55.68 mL for the dynamic interaction and 58.59 for the instrument insertion/removal.

CONCLUSIONS

Dynamic interactions and insertion/removal events between laparoscopic instruments and ports appear to contribute to consistent leakage of insufflated gas into the OR. Any measures possible taken to reduce OR gas leakage should be considered in light of the current COVID-19 pandemic. Minimizing laparoscope and instrument removal and replacement would be one strategy to mitigate gas leakage during laparoscopic surgery.

The usefulness and utilization of a detachable steel wire-rimmed retractor (KN retractor) for endoscopic thyroid and parathyroid surgery

PURPOSE

In endoscopic surgery, surgeons occasionally encounter difficulties due to visual field obstruction by muscles or blood vessels. In these situations, specialized instruments that can effectively retract these obstructions are required. Recently, we developed a new detachable wire-rimmed retractor (KN retractor) for narrow-space surgery.

METHODS

We evaluated the utility of this KN retractor in 15 patients with thyroid and parathyroid disease. Of those, five patients with papillary thyroid cancer had gasless endoscopic hemithyroidectomy with central node dissection, five underwent endoscopic total thyroidectomy for Graves' disease, and the remaining five received endoscopic parathyroidectomy with gas insufflation.

RESULTS

Surgeons were able to perform meticulous operations in a satisfactory visual field supported by the KN retractor. In all patients, the strap muscles were preserved without cutting. The average operating time was 149, 154, and 81 min in patients who underwent hemithyroidectomy with central node dissection, total thyroidectomy, and parathyroidectomy, respectively. Gas insufflation was successfully completed in all cases while maintaining sufficient airtightness.

CONCLUSIONS

The KN retractor is suitable for both the gasless lifting method and gas insufflation surgery in a narrow space. We believe that the KN retractor is a new device that will greatly improve the safety and shorten the operation time in endoscopic surgery.

Intra-abdominal pressure during endoscopic full-thickness resection comparing manual and automatic control insufflation: a block-randomized porcine study

BACKGROUND AND STUDY AIMS

An automatic carbon dioxide (CO2) insufflating system (SPACE) was developed to stabilize intra-lumenal pressure (ILP) during endoscopic interventions. This study investigated whether SPACE could improve the control and monitoring of extra-lumenal intra-abdominal pressure (IAP) after establishing a perforation during endoscopic full-thickness resection (EFTR) of the gastric wall in porcine models.

MATERIALS AND METHODS

After first establishing the optimal preset pressure for gastric EFTR in four pigs, we compared IAP dynamics during EFTR between manual insufflation and SPACE using a block-randomized study (n = 10). IAP was percutaneously monitored and plotted on a timeline graph every 5 s. The maximal IAP and the area under the IAP curve exceeding 10 mmHg (AUC≥10 mmHg) were compared between groups, with the agreement between IAP and endolumenally monitored ILP also analyzed for animals in the SPACE group.

RESULTS

In the first study, 8 mmHg was identified as the most preferable preset pressure after establishment of the perforation. In the randomized study, the mean maximal IAP in the SPACE group was significantly lower than that in the manual insufflation group (11.0 ± 2.0 mmHg vs. 17.0 ± 3.5 mmHg; P = 0.03). The mean AUC≥10 mmHg was also significantly smaller in the SPACE group. Bland-Altman analysis demonstrated agreement between IAP and ILP within a range of ± 1.0 mmHg.

CONCLUSIONS

SPACE could be used to control and safely monitor IAP during gastric EFTR by measuring ILP during perforation of the gastric wall.

Effect of different carbon dioxide (CO2) insufflation for laparoscopic colorectal surgery in elderly patients: A randomized controlled trial

BACKGROUND

Evidence suggests that dry CO2 insufflation during laparoscopic colorectal surgery results in greater structural injury to the peritoneum and longer hospital stay than the use of warm, humidified CO2. We aimed to test the hypothesis that warm, humidified CO2 insufflation could reduce postoperative pain and improve recovery in laparoscopic colorectal surgery.

METHODS

One hundred fifty elderly patients undergoing laparoscopic colorectal surgery under general anesthesia from May 2017 to October 2018 were randomly divided into 3 groups. The primary outcomes were resting pain, cough pain, and consumption of sufentanil at 2, 4, 6, 12, 24, and 48 hours postoperatively. Quality of visual image, hemodynamic changes, esophageal temperature, mean skin temperature, mean body temperature, recovery time, days to first flatus and solid food intake, shivering, incidence of postoperative ileus, length of hospital stay, surgical site infections, patients and surgeon satisfaction scores, adverse events, prothrombin time, activated partial thromboplastin time, and thrombin time were recorded.

RESULTS

Group CE patients were associated with significantly higher early postoperative cough pain and sufentanil consumption than the other 2 groups (P < .05). Compared with group CE, patients in both groups WH and CF had significantly reduced intraoperative hypothermia, recovery time of PACU, days to first flatus and solid food intake, and length of hospital stay, while the satisfaction scores of both patients and surgeon were significantly higher (P < .05). Prothrombin time, activated partial thromboplastin time, and thrombin time were significantly higher in group CE from 60 minutes after pneumoperitoneum to the end of pneumoperitoneum than the other 2 groups (P < .05). The number of patients with a shivering grade of 0 was significantly lower and grade of 3 was significantly higher in group CE than in the other 2 groups (P < .05).

CONCLUSION

Use of either warm, humidified CO2 insufflations or 20°C, 0% relative humidity CO2 combined with forced-air warmer set to 38°C during insufflations can both reduce intraoperative hypothermia, dysfunction of coagulation, early postoperative cough pain, sufentanil consumption, days to first flatus, solid food intake, and length of hospital stay.

Peak Cough Flow Fails to Detect Upper Airway Collapse During Negative Pressure Titration for Cough-Assist

OBJECTIVE

To study the ability of peak cough flow (PCF) and effective cough volume, defined as the volume exsufflated >3 L/s, to detect upper airway collapse during mechanical insufflation-exsufflation (MI-E) titration in neuromuscular patients.

DESIGN

Prospective observational study.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Patients (N=27) with neuromuscular disease causing significant impairment of chest wall and/or diaphragmatic movement.

INTERVENTIONS

The lowest insufflation pressure producing the highest inspiratory capacity was used. Exsufflation pressure was decreased from -20 cm H₂O to -60/-70 cm H₂O, in 10-cm H₂O decrements, until upper airway collapse was detected using the reference standard of flow-volume curve analysis (after PCF, abrupt flattening or flow decrease vs previous less negative exsufflation pressure).

MAIN OUTCOME MEASURES

PCF and effective cough volume profiles during expiration with MI-E.

RESULTS

Upper airway collapse occurred in 10 patients during titration. Effective cough volume increased with decreasing expiratory pressure then decreased upon upper airway collapse occurrence. PCF continued to increase after upper airway collapse occurrence. In 5 other patients, upper airway collapse occurred at the initial -20 cm H₂O exsufflation pressure, and during titration, PCF increased and effective cough volume remained unchanged at <200 mL. PCF had 0% sensitivity for upper airway collapse, whereas effective cough volume had 100% sensitivity and specificity.

CONCLUSION

Of 27 patients, 15 experienced upper airway collapse during MI-E titration. Upper airway collapse was associated with an effective cough volume decrease or plateau and with increasing PCF. Accordingly, effective cough volume, but not PCF, can detect upper airway collapse.

Clinical effects of warmed humidified carbon dioxide insufflation in infants undergoing major laparoscopic surgery

PURPOSE

Some studies have reported that warmed humidified carbon dioxide (CO2) insufflation in adult laparoscopic surgery could reduce pain and improve the core body temperature (CBT). However, similar studies are lacking in infants. Thus, this study aimed to investigate the clinical effects of warmed, humidified CO2 insufflation in pediatric patients undergoing major laparoscopic surgeries.

METHODS

From January 2015 to December 2017, infants who underwent major laparoscopic surgeries in Ningbo Women and Children's Hospital were randomized to Group A (standard CO2 insufflation) or Group B (warmed humidified CO2 insufflation, 35°C, 95% relative humidity). Change in CBT at the end of surgery was the primary outcome. Secondary outcomes included surgery time, intraoperative blood loss, oxygen saturation (SO2), and Face, Legs, Activity, Cry and Consolability (FLACC) scale. These variables were compared between the 2 groups.

RESULTS

Sixty-three infants (38 females, 25 males) were included; 30 patients were in Group A and 33 in Group B. The diseases treated with the laparoscopic approach included congenital megacolon, congenital diaphragmatic hernia, and intestinal malrotation. No deaths were noted. CBT was significantly higher in Group B at the end of surgery (P = .021). The occurrence of postoperative shivering (P = .02), hypothermia (P = .032), bowel movement (P = .044), and hospital stay (P = .038) was significantly different between the 2 groups; Group B had less shivering and hypothermia occurrence after surgery. Moreover, Group B demonstrated a more rapid postoperative recovery of bowel movement and shortened hospital stay than Group A. There was no statistical difference in operative time (P = .162), intraoperative blood loss (P = .541), SO2 (P = .59), and FLACC scale (P = .65) between the 2 groups.

CONCLUSION

The use of warmed humidified CO2 insufflation in infants undergoing major laparoscopic surgery was helpful for maintaining normothermia and was associated with several positive postoperative outcomes, including less shivering and hypothermia, faster recovery of bowel movement, and shortened hospital stay.

Effects of a multifaceted individualized pneumoperitoneum strategy in elderly patients undergoing laparoscopic colorectal surgery: A retrospective study

BACKGROUND

Laparoscopic colorectal surgery may adversely affect respiration, circulation, and acid-base balance in elderly patients, owing to the relatively long duration of CO2 absorption. We conducted this retrospective study to determine the safety and efficacy of warmed, humidified CO2 pneumoperitoneum in elderly patients undergoing laparoscopic colorectal surgery.

METHODS

We enrolled 245 patients between January 2016 and August 2018.The experimental group (warming and humidification group [WH]) received warmed (37°C), humidified (98%) insufflation of CO2, and the control group (cold, dry CO2/control group [CD]) received standard CO2 (19°C, 0%). All other aspects of patient care were standardized. Intraoperative hemodynamic data, arterial blood pH, and lactic acid levels were recorded. We also recorded intra-abdominal pressure, incidence of shivering 1 hour after surgery, satisfaction scores of patients and surgeons 24 hours after surgery, times to first flatus/defecation, first bowel movement, and tolerance of semiliquid food, discharge time, and incidence of vomiting, diarrhea, and surgical site infections.

RESULTS

Compared with the WH group, heart rate and mean arterial pressure were significantly higher from T3 to T8 (P < .05), lactic acid levels were significantly higher from T4 to T9 (P < .05), and recovery time in the post-anesthesia care unit (PACU) was significantly longer in the CD group (P < .05). Patient and surgeon satisfaction scores were significantly higher in the WH group than the CD group (P < .05). In addition, the times to first flatus/defecation and bowel movement were significantly longer in the CD group (P < .05). No significant differences were noted between the groups in the time to tolerance of semiliquid food and time of discharge (P > .05). The incidence of vomiting, diarrhea, and shivering was significantly lower in the WH group (P < .05). The number of patients with a shivering grade of 0 was significantly higher in the WH group, whereas the number with a shivering grade of 3 was significantly higher in the CD group (P < .05).

CONCLUSION

Warmed, humidified insufflation of CO2 in elderly patients undergoing laparoscopic colorectal surgery could stabilize hemodynamics, and reduce lactic acid levels, recovery time in the PACU, and the incidence of acute gastrointestinal injury-related symptoms.

Heated humidified carbon dioxide for partial uterine insufflation in fetoscopic myelomeningocele repair: insights from animal model

Linked Comment: Ultrasound Obstet Gynecol 2018; 53: 340-347.

Transnasal Humidified Rapid Insufflation Ventilatory Exchange in children requiring emergent intubation (Kids THRIVE): a protocol for a randomised controlled trial

INTRODUCTION

Emergency intubation of children with abnormal respiratory or cardiac physiology is a high-risk procedure and associated with a high incidence of adverse events including hypoxemia. Successful emergency intubation is dependent on inter-related patient and operator factors. Preoxygenation has been used to maximise oxygen reserves in the patient and to prolong the safe apnoeic time during the intubation phase. Transnasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) prolongs the safe apnoeic window for a safe intubation during elective intubation. We designed a clinical trial to test the hypothesis that THRIVE reduces the frequency of adverse and hypoxemic events during emergency intubation in children and to test the hypothesis that this treatment is cost-effective compared with standard care.

METHODS AND ANALYSIS

The Kids THRIVE trial is a multicentre randomised controlled trial performed in participating emergency departments and paediatric intensive care units. 960 infants and children aged 0-16 years requiring emergency intubation for all reasons will be enrolled and allocated to THRIVE or control in a 1:1 allocation with stratification by site, age (<1, 1-7 and >7 years) and operator (junior and senior). Children allocated to THRIVE will receive weight appropriate transnasal flow rates with 100% oxygen, whereas children in the control arm will not receive any transnasal oxygen insufflation. The primary outcomes are defined as follows: (1) hypoxemic event during the intubation phase defined as SpO₂ <90% (patient-dependent variable) and (2) first intubation attempt success without hypoxemia (operator-dependent variable). Analyses will be conducted on an intention-to-treat basis.

ETHICS AND DISSEMINATION

Ethics approval for the protocol and consent process has been obtained (HREC/16/QRCH/81). The trial has been actively recruiting since May 2017. The study findings will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ACTRN12617000147381.

Interventions to reduce shoulder pain following gynaecological laparoscopic procedures

BACKGROUND

Laparoscopy is a common procedure used to diagnose and treat various gynaecological conditions. Shoulder-tip pain (STP) as a result of the laparoscopy occurs in up to 80% of women, with potential for significant morbidity, delayed discharge and readmission. Interventions at the time of gynaecological laparoscopy have been developed in an attempt to reduce the incidence and severity of STP.

OBJECTIVES

To determine the effectiveness and safety of methods for reducing the incidence and severity of shoulder-tip pain (STP) following gynaecological laparoscopy.

SEARCH METHODS

We searched the following databases: Cochrane Gynaecology and Fertility (CGF) Specialised Register, the Cochrane Central Register of Studies Online (CRSO), MEDLINE, Embase, PsycINFO and CINAHL from inception to 8 August 2018. We also searched the reference lists of relevant articles and registers of ongoing trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions used during or immediately after gynaecological laparoscopy to reduce the incidence or severity of STP.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcomes: incidence or severity of STP and adverse events of the interventions; secondary outcomes: analgesia usage, delay in discharge, readmission rates, quality-of-life scores and healthcare costs.

MAIN RESULTS

We included 32 studies (3284 women). Laparoscopic procedures in these studies varied from diagnostic procedures to complex operations. The quality of the evidence ranged from very low to moderate. The main limitations were risk of bias, imprecision and inconsistency.Specific technique versus "standard" technique for releasing the pneumoperitoneumUse of a specific technique of releasing the pneumoperitoneum (pulmonary recruitment manoeuvre, extended assisted ventilation or actively aspirating intra-abdominal gas) reduced the severity of STP at 24 hours (standardised mean difference (SMD) -0.66, 95% confidence interval (CI) -0.82 to -0.50; 5 RCTs; 670 participants; I² = 0%, low-quality evidence) and reduced analgesia usage (SMD -0.53, 95% CI -0.70 to -0.35; 4 RCTs; 570 participants; I² = 91%, low-quality evidence). There appeared to be little or no difference in the incidence of STP at 24 hours (odds ratio (OR) 0.87, 95% CI 0.41 to 1.82; 1 RCT; 118 participants; low-quality evidence).No adverse events occurred in the only study assessing this outcome.Fluid instillation versus no fluid instillationFluid instillation is probably associated with a reduction in STP incidence (OR 0.38, 95% CI 0.22 to 0.66; 2 RCTs; 220 participants; I² = 0%, moderate-quality evidence) and severity (mean difference (MD) (0 to 10 visual analogue scale (VAS) scale) -2.27, 95% CI -3.06 to -1.48; 2 RCTs; 220 participants; I² = 29%, moderate-quality evidence) at 24 hours, and may reduce analgesia usage (MD -12.02, 95% CI -23.97 to -0.06; 2 RCTs; 205 participants, low-quality evidence).No study measured adverse events.Intraperitoneal drain versus no intraperitoneal drainUsing an intraperitoneal drain may reduce the incidence of STP at 24 hours (OR 0.30, 95% CI 0.20 to 0.46; 3 RCTs; 417 participants; I² = 90%, low-quality evidence) and may reduce analgesia use within 48 hours post-operatively (SMD -1.84, 95% CI -2.14 to -1.54; 2 RCTs; 253 participants; I² = 90%). We are uncertain whether it reduces the severity of STP at 24 hours, as the evidence was very low quality (MD (0 to 10 VAS scale) -1.85, 95% CI -2.15 to -1.55; 3 RCTs; 320 participants; I² = 70%).No study measured adverse events.Subdiaphragmatic intraperitoneal local anaesthetic versus control (no fluid instillation, normal saline or Ringer's lactate)There is probably little or no difference between the groups in incidence of STP (OR 0.72, 95% CI 0.42 to 1.23; 4 RCTs; 336 participants; I² = 0%; moderate-quality evidence) and there may be no difference in STP severity (MD -1.13, 95% CI -2.52 to 0.26; 1 RCT; 50 participants; low-quality evidence), both measured at 24 hours. However, the intervention may reduce post-operative analgesia use (SMD-0.57, 95% CI -0.94 to -0.21; 2 RCTs; 129 participants; I² = 51%, low-quality evidence).No adverse events occurred in any study.Local anaesthetic into peritoneal cavity (not subdiaphragmatic) versus normal salineLocal anaesthetic into the peritoneal cavity may reduce the incidence of STP at 4 to 8 hours post-operatively (OR 0.23, 95% CI 0.06 to 0.93; 2 RCTs; 157 participants; I² = 56%; low-quality evidence). Our other outcomes of interest were not assessed.Warmed, or warmed and humidified CO₂ versus unwarmed and unhumidified CO₂There may be no difference between these interventions in incidence of STP at 24 to 48 hours (OR 0.81 95% CI 0.45 to 1.49; 2 RCTs; 194 participants; I² = 12%; low-quality evidence) or in analgesia usage within 48 hours (MD -4.97 mg morphine, 95% CI -11.25 to 1.31; 1 RCT; 95 participants; low-quality evidence); there is probably little or no difference in STP severity at 24 hours (MD (0 to 10 VAS scale) 0.11, 95% CI -0.75 to 0.97; 2 RCTs; 157 participants; I² = 50%; moderate-quality evidence).No study measured adverse events.Gasless laparoscopy versus CO₂ insufflationGasless laparoscopy may be associated with increased severity of STP within 72 hours post-operatively when compared with standard treatment (MD 3.8 (0 to 30 VAS scale), 95% CI 0.76 to 6.84; 1 RCT; 54 participants, low-quality evidence), and there may be no difference in the risk of adverse events (OR 2.56, 95% CI 0.25 to 26.28; 1 RCT; 54 participants; low-quality evidence).No study measured the incidence of STP.

AUTHORS' CONCLUSIONS

There is low to moderate-quality evidence that the following interventions are associated with a reduction in the incidence or severity, or both, of STP, or a reduction in analgesia requirements for women undergoing gynaecological laparoscopy: a specific technique for releasing the pneumoperitoneum; intraperitoneal fluid instillation; an intraperitoneal drain; and local anaesthetic applied to the peritoneal cavity (not subdiaphragmatic).There is low to moderate-quality evidence that subdiaphragmatic intraperitoneal local anaesthetic and warmed and humidified insufflating gas may not make a difference to the incidence or severity of STP.There is low-quality evidence that gasless laparoscopy may increase the severity of STP, compared with standard treatment.Few studies reported data on adverse events. Some potentially useful interventions have not been studied by RCTs of gynaecological laparoscopy.

Spiroergometric measurements under increased inspiratory oxygen concentration (FIO2)-Putting the Haldane transformation to the test

Spiroergometric measurements of persons who require oxygen insufflation due to illness can be performed under conditions of increased inspiratory oxygen concentration (FIO2). This increase in FIO2, however, often leads to errors in the calculation of oxygen consumption ([Formula: see text]). These inconsistencies are due to the application of the Haldane Transformation (HT), an otherwise indispensable correction factor in the calculation of [Formula: see text] that becomes inaccurate at higher FIO2 concentrations. A possible solution to this problem could be the use of the 'Eschenbacher transformation' (ET) as an alternative correction factor. This study examines the concentration of FIO2 at which the HT and the ET are valid, providing plausible data of oxygen consumption corresponding to the wattage achieved during cycle ergometry. Ten healthy volunteers underwent spiroergometric testing under standard conditions (FIO2 = 20.9%), as well as at FIO2 = 40% and 80%. When compared with the predicted values of [Formula: see text], as calculated according to Wasserman et al. (2012), the data obtained show that both the HT and ET are valid under normal conditions and at an increased FIO2 of 40%. At FIO2 concentrations of 80%, however, the [Formula: see text] values provided by the HT begin to lose plausibility, whereas the ET continues to provide credible results. We conclude that the use of the ET in place of the HT in spiroergometric measurements with increased FIO2 allows a reliable evaluation of stress tests in patients requiring high doses of supplemental oxygen.

Water exchange versus air insufflation for colonoscopy: A meta-analysis

BACKGROUND/AIMS

To compare water exchange (WE) method with conventional air insufflation (AI) method for colonoscopy, evaluating the technical quality, screening efficacy, and patients' acceptance.

MATERIALS AND METHODS

Electronic databases were systematically searched for randomized controlled trials comparing WE colonoscopy with AI colonoscopy. The pooled data of procedure-associated and patient-related outcomes were assessed, using the weighted mean difference (WMD) with 95% confidence interval (CI) for continuous variables and relative risk (RR) with 95% CI for dichotomous variables, respectively.

RESULTS

A total of 13 studies involving 7056 patients were included. The cecum intubation rate was similar between WE and AI methods (RR = 1.01, 95% CI = 0.99-1.02,P = 0.37); however, a significantly longer cecum intubation time was shown in WE group (WMD = 1.56, 95% CI = 0.75-2.37,P = 0.002). Compared with AI, WE was associated with a higher risk of adenoma detection rate (ADR) (RR = 1.28, 95% CI = 1.18-1.38,P < 0.00001) and polyp detection rate (PDR) (RR = 1.30, 95% CI = 1.21-1.39,P < 0.00001). Patients in WE group experienced significantly less maximum pain score (WMD = -1.99, 95% CI = -2.68 to -1.30,P < 0.00001) and less requested on-demand sedation (RR = 0.58, 95% CI = 0.44-0.77,P = 0.0002). Likewise, they also experienced less abdominal compression (RR = 0.62, 95% CI = 0.51-0.74,P < 0.00001) and reposition (RR = 0.74, 95% CI = 0.63-0.86,P = 0.0001). Moreover, patients' willingness to repeat colonoscopy was significantly greater for WE (RR = 1.14, 95% CI = 1.07-1.21,P < 0.0001).

CONCLUSION

This meta-analysis confirmed that WE method could significantly increase ADR/PDR and improve patients' acceptance of colonoscopy, while reducing the degree of pain and minimize the need for on-demand sedation and adjunct maneuvers, despite requiring more cecal intubation time.

Low-dose spectral insufflation computed tomography protocol preoperatively optimized for T stage esophageal cancer - preliminary research experience

AIM

To evaluate the T stage of esophageal squamous cell carcinoma (ESCC) using preoperative low-dose esophageal insufflation computed tomography (EICT).

METHODS

One hundred and twenty ESCC patients confirmed by surgery or esophagoscopy were divided into three groups. Groups B and C were injected with 300 mgI/kg contrast medium for automatic spectral imaging assist (GSI assist), while group A underwent a conventional 120 kVp computed tomography (CT) scan with a 450 mgI/kg contrast medium injection. EICT was performed in group C. Group A was reconstructed with filtered back projection, and groups B and C were reconstructed with 50% adaptive statistical iterative reconstruction. The contrast-to-noise ratio of lesion-to-mediastinal adipose tissue and the radiation dose were measured. Specific imaging features were observed, and T stage ESCCs were evaluated.

RESULTS

The sensitivity and accuracy of the T1/2 stage were higher in group C than in groups A and B (sensitivity: 43.75% vs 31.82% and 33.33%; accuracy: 54.29% vs 46.67% and 52.50%, respectively). With regard to the T3 stage, the sensitivity and specificity in group C were higher than those in groups A and B (sensitivity: 56.25% vs 41.17% and 44.44%; specificity: 73.68% vs 67.86% and 63.64%, respectively). The diagnostic sensitivity, specificity and accuracy of the T4 stage were similar among all groups. There were no significant differences in volume CT dose index [(5.91 ± 2.57) mGy vs (3.24 ± 1.20) vs (3.65 ± 1.77) mGy], dose-length product [(167.10 ± 99.08) mGy•cm vs (113.24 ± 54.46) mGy•cm vs (117.98 ± 32.32) mGy•cm] and effective dose [(2.52 ± 1.39) vs (1.63 ± 0.76) vs (1.73 ± 0.44) mSv] among the groups (P > 0.05). However, groups B and C received similar effective doses but lower iodine loads than group A [(300 vs 450) mgI/kg].

CONCLUSION

EICT combined with GSI assist allows differential diagnosis between the T1/2 and T3 stages. The ability to differentially diagnose the T3 and T4 stages of medullary ESCC can be improved by quantitatively and qualitatively analyzing the adipose tissue in front of the vertebral body.

Fetal blood-gas values during fetoscopic myelomeningocele repair performed under carbon dioxide insufflation

Fetoscopic myelomeningocele (MMC) repair is performed using intrauterine carbon dioxide (CO₂ ) insufflation. Sheep experiments have shown that CO₂ insufflation is associated with significant fetal acidemia; however, corresponding data for human pregnancy are not available. We performed umbilical venous cord blood sampling in three patients during fetoscopic MMC repair at 25 + 1, 25 + 3 and 24 + 0 weeks' gestation, respectively. Fetal venous pH at the beginning of CO₂ insufflation was 7.36, 7.46 and 7.37, respectively in the three fetuses, and repeat values were 7.28, 7.35 and 7.36 after 181, 159 and 149 min, respectively. The partial pressure of oxygen and CO₂ was maintained in the normal range during these times, and pH decrease was less in Patient 3 who received humidified CO₂ insufflation. Our observations suggest that, in contrast to sheep experiments, CO₂ insufflation during fetoscopic myelomeningocele repair does not cause acidemia in human fetuses. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prevention of laparoscopic surgery induced hypothermia with warmed humidified insufflation: Is the experimental combination of a warming blanket synergistic?

INTRODUCTION

Maintaining normothermia during anesthesia is imperative to provide quality patient care and to prevent adverse outcomes. Prolonged laparoscopic procedures have been identified as a potential risk factor for hypothermia, due to continuous insufflation of cold and dry carbon dioxide. Perioperative hypothermia is associated with increased hospital cost and many complications including; impaired drug metabolism, impaired immune function, cardiac morbidity, shivering, coagulopathy.

METHODS

In this experimental study, four pigs underwent four interventions each, resulting in 16 total trials. Using standardized general anesthesia in a randomized Latin-square sequence the four interventions include: 1. Control group without an administered pneumoperitoneum, 2. Administered standard pneumoperitoneum using 21°C insufflated gas and under-body forced-air warming, 3. Administered pneumoperitoneum with insufflation of warmed/humidified carbon dioxide, 4. Administered pneumoperitoneum with insufflation of warmed/humidified carbon dioxide and under-body forced-air warming. The primary outcome was distal esophageal temperature change 4 hours after trocar insertion.

RESULTS

Four hours after trocar insertion, pigs in the control group lost 2.1 ± 0.4°C; pigs with warmed and humidified insufflation lost 1.8 ± 0.4°C; pigs with forced-air warming group lost 1.3 ± 0.9°C; and pigs exposed to a combination of warmed and humidified insufflation with forced-air warming increased by 0.3 ± 0.2°C.

CONCLUSION

This experimental animal study provides evidence that a combination of warmed and humidified insufflation of carbon dioxide (CO2) in conjunction with forced-air warming is an effective strategy in the prevention of perioperative hypothermia. Further clinical trials investigating humans are therefore indicated.