How to preoxygenate in operative room: healthy subjects and situations "at risk"

The comparison of preoxygenation methods before endotracheal intubation: a network meta-analysis of randomized trials

Background

Preoxygenation before endotracheal intubation (ETI) maintains asphyxiated oxygenation and reduces the risk of hypoxia-induced adverse events. Previous studies have compared various preoxygenation methods. However, network meta-analyses (NMAs) of the combined comparison of preoxygenation methods is still lacking.

Methods

We searched for studies published in PubMed, Embase, Web of Science, Scopus, and the Cochrane Library. Review Manager version 5.3 was used to evaluate the risk of bias. The primary outcome of this meta-analysis was low oxygen saturation (SpO2) during ETI. The secondary outcomes included SpO2 <80%, SpO2 <90%, and apnea time during ETI. NMA was performed using R 4.1.2 software gemtc packages in RStudio.

Results

A total of 15 randomized controlled trials were included in this study. Regarding the lowest SpO2, the noninvasive ventilation (NIV) with high-flow nasal cannula (HFNC) group performed better than the other groups. For SpO2 <80%, the NIV group (0.8603467) performed better than the HFNC (0.1373533) and conventional oxygen therapy (COT, 0.0023) groups, according to the surface under the cumulative ranking curve results. For SpO2 <90%, the NIV group (0.60932667) performed better than the HFNC (0.37888667) and COT (0.01178667) groups. With regard to apnea time, the HFNC group was superior to the COT group (mean difference: -50.05; 95% confidence interval: -90.01, -10.09; P = 0.01).

Conclusion

Network analysis revealed that NIV for preoxygenation achieved higher SpO2 levels than HFNC and COT and offered a more significant advantage in maintaining patient oxygenation during ETI. Patients experienced a longer apnea time after HFNC preoxygenation. The combination of NIV with HFNC proved to be significantly superior to other methods. Given the scarcity of such studies, further research is needed to evaluate its effectiveness.

Systematic review registration

identifier CRD42022346013.

Gastric insufflation and surgical view according to mask ventilation method for laparoscopic cholecystectomy: a randomized controlled study

BACKGROUND

Proper mask ventilation is important to prevent air inflow into the stomach during induction of general anesthesia, and it is difficult to send airflow only through the trachea without gastric inflation. Changes in gastric insufflation according to mask ventilation during anesthesia induction were compared.

METHODS

In this prospective, randomized, single-blind study, 230 patients were analyzed to a facemask-ventilated group (Ventilation group) or no-ventilation group (Apnea group) during anesthesia induction. After loss of consciousness, pressure-controlled ventilation at an inspiratory pressure of 15 cmH2O was performed for two minutes with a two-handed mask-hold technique for Ventilation group. For Apnea group, only the facemask was fitted to the face for one minute with no ventilation. Next, endotracheal intubation was performed. The gastric cross-sectional area (CSA, cm2) was measured using ultrasound before and after induction. After pneumoperitoneum with carbon dioxide, gastric insufflation of the surgical view was graded by the surgeon for each group.

RESULTS

Increase of postinduction antral CSA on ultrasound were not significantly different between Ventilation group and Apnea group (0.04 ± 0.3 and 0.02 ± 0.28, p-value = 0.225). Additionally, there were no significant differences between the two groups in surgical grade according to surgeon's judgement.

CONCLUSIONS

Pressure-controlled ventilation at an inspiratory pressure of 15 cmH2O for two minutes did not increase gastric antral CSA and insufflation of stomach by laparoscopic view.

TRIAL REGISTRATION

http://cris.nih.go.kr (KCT0003620) on 13/3/2019.

A quasi-experimental study of fresh oxygen flow on patients' oxygen reserve during mask-assisted ventilation under general anesthesia induction

Background

To compare the effect of different amounts of fresh oxygen flow on oxygen reserve in patients undergoing general anesthesia.

Methods

Seventy-two patients were enrolled in this quasi-experimental study. Patients were randomly divided into experimental groups with a fresh oxygen flow of 1 L/min, 2 L/min, 4 L/min, and 8 L/min (denoted as G1, G2, G3, and G4, respectively) for 2 min of mask-assisted ventilation. Safe apnea time (SAT) was the primary endpoint; SAT was defined as the time from the cessation of ventilation to the time the patient's pulse oxygen saturation (SpO2) decreased to 90%. Ventilation indicators such as end-tidal oxygen concentration (EtO2), end-tidal carbon dioxide partial pressure (EtCO2), SpO2, and carbon dioxide (CO2) elimination amount, during mask-assisted ventilation, were the secondary endpoints.

Results

The SAT of G1, G2, G3, and G4 were 305.1 ± 97.0 s, 315 ± 112.5 s, 381.3 ± 118.6 s, and 359 ± 104.4 s, respectively (p > 0.05). The EtO2 after 2 min of mask-assisted ventilation in groups G1, G2, G3, and G4 were 69.7 ± 8.8%, 75.2 ± 5.0%, 82.5 ± 3.3%, and 86.8 ± 1.5%, respectively (p < 0.05). Also, there was a moderate positive correlation between the fresh oxygen flow and EtO2 (correlation coefficient r = 0.52, 95% CI 0.31-0.67, p < 0.0001). The CO2 elimination in the G1 and G2 groups was greater than that in the G4 group (p < 0.05). There was no significant difference in other indicators among the groups (all p > 0.05).

Conclusion

The amount of fresh oxygen flow during mask-assisted ventilation was positively correlated with EtO2. Also, even though there was no significant difference, the patients' oxygen reserves increased with the increase in fresh oxygen flow.

High Frequency Jet Ventilation or Mechanical Ventilation for Panendoscopy for Cervicofacial Cancer: A Retrospective Study

Introduction-the upper airway panendoscopy, performed under general anesthesia, is mandatory for the diagnosis of cervicofacial cancer. It is a challenging procedure because the anesthesiologist and the surgeon have to share the airway space together. There is no consensus about the ventilation strategy to adopt. Transtracheal high frequency jet ventilation (HFJV) is the traditional method in our institution. However, the COVID-19 pandemic forced us to change our practices because HFJV is a high risk for viral dissemination. Tracheal intubation and mechanical ventilation were recommended for all patients. Our retrospective study compares the two ventilation strategies for panendoscopy: high frequency jet ventilation (HFJV) and mechanical ventilation with orotracheal intubation (MVOI). Methods-we reviewed all panendoscopies performed before the pandemic in January and February 2020 (HFJV) and during the pandemic in April and May 2020 (MVOI). Minor patients, patients with a tracheotomy before or after, were excluded. We performed a multivariate analysis adjusted on unbalanced parameters between the two groups to compare the risk of desaturation. Results-we included 182 patients: 81 patients in the HFJV group and 80 in the MVOI group. After adjustments based on BMI, tumor localization, history of cervicofacial cancer surgery, and use of muscle relaxants, the patients from the HFJV group showed significantly less desaturation than the intubation group (9.9% vs. 17.5%, OR_a = 0.18, p = 0.047). Conclusion-HFJV limited the incidence of desaturation during upper airway panendoscopies in comparison to oral intubation.

Preoxygenation with standard facemask combining apnoeic oxygenation using high flow nasal cannula versuss standard facemask alone in patients with and without obesity: the OPTIMASK international study

BACKGROUND

Combining oxygen facemask with apnoeic oxygenation using high-flow-nasal-oxygen (HFNO) for preoxygenation in the operating room has not been studied against standard oxygen facemask alone. We hypothesized that facemask-alone would be associated with lower levels of lowest end-tidal oxygen (EtO2) within 2 min after intubation in comparison with facemask combined with HFNO.

METHODS

In an international prospective before-after multicentre study, we included adult patients intubated in the operating room from September 2022 to December 2022. In the before period, preoxygenation was performed with facemask-alone, which was removed during laryngoscopy. In the after period, facemask combined with HFNO was used for preoxygenation and HFNO for apnoeic oxygenation during laryngoscopy. HFNO was maintained throughout intubation. The primary outcome was the lowest EtO2 within 2 min after intubation. The secondary outcome was SpO2 ≤ 95% within 2 min after intubation. Subgroup analyses were performed in patients without and with obesity. This study was registered 10 August 2022 with ClinicalTrials.gov, number NCT05495841.

RESULTS

A total of 450 intubations were evaluated, 233 with facemask-alone and 217 with facemask combined with HFNO. In all patients, the lowest EtO2 within 2 min after intubation was significantly lower with facemask-alone than with facemask combined with HFNO, 89 (85-92)% vs 91 (88-93)%, respectively (mean difference - 2.20(- 3.21 to - 1.18), p < 0.001). In patients with obesity, similar results were found [87(82-91)% vs 90(88-92)%, p = 0.004]; as in patients without obesity [90(86-92)% vs 91(89-93)%, p = 0.001)]. SpO2 ≤ 95% was more frequent with facemask-alone (14/232, 6%) than with facemask combined with HFNO (2/215, 1%, p = 0.004). No severe adverse events were recorded.

CONCLUSIONS

Combining facemask with HFNO for preoxygenation and apnoeic oxygenation was associated with increased levels of lowest EtO2 within 2 min after intubation and less desaturation.

How to improve intubation in the intensive care unit. Update on knowledge and devices

Tracheal intubation in the critically ill is associated with serious complications, mainly cardiovascular collapse and severe hypoxemia. In this narrative review, we present an update of interventions aiming to decrease these complications. MACOCHA is a simple score that helps to identify patients at risk of difficult intubation in the intensive care unit (ICU). Preoxygenation combining the use of inspiratory support and positive end-expiratory pressure should remain the standard method for preoxygenation of hypoxemic patients. Apneic oxygenation using high-flow nasal oxygen may be supplemented, to prevent further hypoxemia during tracheal intubation. Face mask ventilation after rapid sequence induction may also be used to prevent hypoxemia, in selected patients without high-risk of aspiration. Hemodynamic optimization and management are essential before, during and after the intubation procedure. All these elements can be integrated in a bundle. An airway management algorithm should be adopted in each ICU and adapted to the needs, situation and expertise of each operator. Videolaryngoscopes should be used by experienced operators.

Positive end-expiratory pressure individualization guided by continuous end-expiratory lung volume monitoring during laparoscopic surgery

To determine whether end-expiratory lung volume measured with volumetric capnography (EELV_CO2) can individualize positive end-expiratory pressure (PEEP) setting during laparoscopic surgery. We studied patients undergoing laparoscopic surgery subjected to Fowler (F-group; n = 20) or Trendelenburg (T-group; n = 20) positions. EELV_CO2 was measured at 0° supine (baseline), during capnoperitoneum (CP) at 0° supine, during CP with Fowler (head up + 20°) or Trendelenburg (head down - 30°) positions and after CP back to 0° supine. PEEP was adjusted to preserve baseline EELV_CO2 during and after CP. Baseline EELV_CO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELV_CO2 decreased from baseline values in F-group [median and IQR 2079 (768) to 1545 (725) mL; p = 0.0001] and in T-group [2164 (789) to 1870 (940) mL; p = 0.0001]. Change in body position maintained EELV_CO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH₂O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH₂O in T-group (p = 0.0001) were necessary to reach baseline EELV_CO2 values. EELV_CO2 increased close to baseline with PEEP in the F-group [1984 (600) mL; p = 0.073] and in the T-group [2175 (703) mL; p = 0.167]. After capnoperitoneum and back to 0° supine, PEEP needed to maintain EELV_CO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH₂O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH₂O; p = 0.006]. Those new PEEP values gave EELV_CO2 similar to baseline in the F-group [2039 (980) mL; p = 0.370] and in the T-group [2150 (715) mL; p = 0.881]. Breath-by-breath noninvasive EELV_CO2 detected changes in lung volume induced by capnoperitoneum and body position and was useful to individualize the level of PEEP during laparoscopy.Trial registry: Clinicaltrials.gov NCT03693352. Protocol started 1st October 2018.

Continuous positive airway pressure to reduce the risk of early peripheral oxygen desaturation after onset of apnoea in children: A double-blind randomised controlled trial

Continuous positive airway pressure (CPAP) during anaesthesia induction improves oxygen saturation (SpO₂) outcomes in adults subjected to airway manipulation, and could similarly support oxygenation in children. We evaluated whether CPAP ventilation and passive CPAP oxygenation in children would defer a SpO₂ decrease to 95% after apnoea onset compared to the regular technique in which no positive airway pressure is applied. In this double-blind, parallel, randomised controlled clinical trial, 68 children aged 2–6 years with ASA I–II who underwent surgery under general anaesthesia were divided into CPAP and control groups (n = 34 in each group). The intervention was CPAP ventilation and passive CPAP oxygenation using an anaesthesia workstation. The primary outcome was the elapsed time until SpO₂ decreased to 95% during a follow-up period of 300 s from apnoea onset (T1). We also recorded the time required to regain baseline levels from an SpO₂ of 95% aided by positive pressure ventilation (T2). The median T1 was 278 s (95% confidence interval [CI]: 188–368) in the CPAP group and 124 s (95% CI: 92–157) in the control group (median difference: 154 s; 95% CI: 58–249; p = 0.002). There were 17 (50%) and 32 (94.1%) primary events in the CPAP and control groups, respectively. The hazard ratio was 0.26 (95% CI: 0.14–0.48; p<0.001). The median for T2 was 21 s (95% CI: 13–29) and 29 s (95% CI: 22–36) in the CPAP and control groups, respectively (median difference: 8 s; 95% CI: -3 to 19; p = 0.142). SpO₂ was significantly higher in the CPAP group than in the control group throughout the consecutive measures between 60 and 210 s (with p ranging from 0.047 to <0.001). Thus, in the age groups examined, CPAP ventilation and passive CPAP oxygenation deferred SpO₂ decrease after apnoea onset compared to the regular technique with no positive airway pressure.

ORi™: a new indicator of oxygenation

In the perioperative period, hypoxemia and hyperoxia are crucial factors that require attention, because they greatly affect patient prognoses. The pulse oximeter has been the only noninvasive monitor that can be used as a reference of oxygenation in current anesthetic management; however, in recent years, a new monitoring method that uses the oxygen reserve index (ORi™) has been developed by Masimo Corp. ORi is an index that reflects the state of moderate hyperoxia (partial pressure of arterial oxygen [PaO2] between 100 and 200 mmHg) using a non-unit scale between 0.00 and 1.00. ORi monitoring performed together with percutaneous oxygen saturation (SpO2) measurements may become an important technique in the field of anesthetic management, for measuring oxygenation reserve capacity. By measuring ORi, it is possible to predict hypoxemia and to detect hyperoxia at an early stage. In this review, we summarize the method of ORi, cautions for its use, and suitable cases for its use. In the near future, the monitoring of oxygen concentrations using ORi may become increasingly common for the management of respiratory function before, after, and during surgery.

Impact of body mass index on early and mid-term outcomes after surgery for acute Stanford type A aortic dissection

Background

Obesity is dramatically increasing worldwide, and more obese patients may develop aortic dissection and present for surgical repair. The study aims to analyse the impact of body mass index (BMI) on surgical outcomes in patients with acute Stanford type A aortic dissection (ATAAD).

Methods

From January 2017 to June 2019, the clinical data of 268 ATAAD patients in a single centre were retrospectively reviewed. They were divided into three groups based on the BMI: normal weight (BMI 18.5 to < 25 kg/m², n = 110), overweight (BMI 25 to < 30 kg/m², n = 114) and obese (BMI ≥30 kg/m², n = 44).

Results

There was no statistical difference among the three groups in terms of the composite adverse events including 30-day mortality, stroke, paraplegia, renal failure, hepatic failure, reintubation or tracheotomy and low cardiac output syndrome (20.9% vs 21.9% vs 18.2% for normal, overweight and obese, respectively; P = 0.882). No significant difference was found in the mid-term survival among the three groups. The proportion of prolonged ventilation was highest in the obese group followed by the overweight and normal groups (59.1% vs 45.6% vs 34.5%, respectively; P = 0.017). Multivariable logistic regression analysis suggested that BMI was not associated with the composite adverse events, while BMI ≥30 kg/m² was an independent risk factor for prolonged ventilation (OR 2.261; 95% CI 1.056–4.838; P = 0.036).

Conclusions

BMI had no effect on the early major adverse outcomes and mid-term survival after surgery for ATAAD. Satisfactory surgical outcomes can be obtained in patients with ATAAD at all weights.

Management of Intraoperative Mechanical Ventilation to Prevent Postoperative Complications after General Anesthesia: A Narrative Review

Mechanical ventilation (MV) is still necessary in many surgical procedures; nonetheless, intraoperative MV is not free from harmful effects. Protective ventilation strategies, which include the combination of low tidal volume and adequate positive end expiratory pressure (PEEP) levels, are usually adopted to minimize the ventilation-induced lung injury and to avoid post-operative pulmonary complications (PPCs). Even so, volutrauma and atelectrauma may co-exist at different levels of tidal volume and PEEP, and therefore, the physiological response to the MV settings should be monitored in each patient. A personalized perioperative approach is gaining relevance in the field of intraoperative MV; in particular, many efforts have been made to individualize PEEP, giving more emphasis on physiological and functional status to the whole body. In this review, we summarized the latest findings about the optimization of PEEP and intraoperative MV in different surgical settings. Starting from a physiological point of view, we described how to approach the individualized MV and monitor the effects of MV on lung function.

Perioperative Noninvasive Ventilation After Adult or Pediatric Surgery: A Comprehensive Review

Postoperative pulmonary complications and acute respiratory failure are among the leading causes of adverse postoperative outcomes. Noninvasive ventilation may safely and effectively prevent acute respiratory failure in high-risk patients after cardiothoracic surgery and after abdominal surgery. Moreover, noninvasive ventilation can be used to treat postoperative hypoxemia, particularly after abdominal surgery. Noninvasive ventilation also can be helpful to prevent or manage intraoperative acute respiratory failure during non-general anesthesia, primarily in patients with poor respiratory function. Finally, noninvasive ventilation is superior to standard preoxygenation in delaying desaturation during intubation in morbidly obese and in critically ill hypoxemic patients. The few available studies in children suggest that noninvasive ventilation could be safe and valuable in treating hypoxemic or hypercapnic acute respiratory failure after cardiac surgery; on the other hand, it could be dangerous after tracheoesophageal correction.

The Effect of Bariatric Surgery Volume on General Surgery Outcomes for Morbidly Obese Patients

INTRODUCTION

Bariatric surgery performed at high volume centers decreases length of stay, cost, and morbidity and mortality. The effect of a high volume of bariatric surgery procedures on outcomes may extend not just to bariatric surgery but to any general surgical procedure in morbidly obese patients. We hypothesized that patients with morbid obesity (body mass index >40 kg/m²) undergoing common, nonbariatric general surgery would have decreased morbidity and mortality at centers performing high volumes of bariatric surgery.

METHODS

The 2016 National Inpatient Sample (NIS) was used to identify the number of laparoscopic gastric bypass and sleeve gastrectomy performed at each hospital. Hospitals were classified as high volume bariatric hospitals (HVBH) ≥10 reported cases (50 actual)/year or low volume bariatric hospitals (LVBH) <10 reported cases (50 actual)/year, as NIS reports a 20% sample of actual cases. Patients with morbid obesity undergoing laparoscopic or open appendectomy, cholecystectomy, or ventral hernia repair were included for analysis. Propensity scores were developed based on available demographics, comorbidities, and hospital procedure volume. Postoperative complications during the index hospital admission, determined by ICD-10 code, were compared using inverse propensity weights. Differences were considered significant with a p value of <0.05.

RESULTS

The total number of general surgery patient cases analyzed was 14,028 from 2,482 hospitals, representing 70,140 admissions. The cohort of patients undergoing operations treated at HVBH were younger (p=0.03) with higher rates of COPD (p=0.04). Patients at LVBH had higher rates of nicotine dependence (p=0.0001) and obstructive sleep apnea (p < 0.001). On propensity-weighted analysis adjusting for preoperative comorbidities and hospital procedure volume, there were significantly higher rates of multiple postprocedure complications at LVBH, specifically, postprocedure respiratory failure for patients undergoing elective laparoscopic cholecystectomy, elective ventral hernia repair with mesh and appendectomy.

CONCLUSION

Patients with morbid obesity may have an advantage in having general surgery procedures at HVBH. HVBH may have a volume-outcomes relationship where the hospital and staff familiarity with the management principles required to minimize the postoperative risk associated with morbid obesity and improve patient outcomes.

[Pregnant patients wirsth major trauma in the resuscitation room : Special (patho)physiological and therapeutic aspects]

BACKGROUND

Severely injured pregnant women are rarely encountered even in major trauma centers; at the same time high expectations are set for the best possible outcome of mother and child.

OBJECTIVE

Summary of the main pathophysiological aspects of pregnancy and essential therapeutic implications for emergency room treatment from the perspective of anesthetists.

METHODOLOGY

Selective literature analysis with a focus on primary physiological literature and the synthesis of pregnancy-adapted recommendations of related guidelines.

RESULTS

The essential physiological adaptations to pregnancy and their implications for acute care are presented.

CONCLUSION

Teamwork, structured decision making as well as airway management and goal-oriented hemodynamic treatment are the foundations for a good outcome of mother and child.

[Preoperative risk and perioperative management of obese patients]

The obese patient is at an increased risk of perioperative complications. Most importantly, these include difficult access to the airways (intubation, difficult or impossible ventilation), and post-extubation respiratory distress secondary to the development of atelectasis or obstruction of the airways, sometimes associated with the use of morphine derivatives. The association of obstructive sleep apnea syndrome (OSA) with obesity is very common, and induces a high risk of peri- and postoperative complications. Preoperative OSA screening is crucial in the obese patient, as well as its specific management: use of continuous positive pre, per and postoperative pressure. For any obese patient, the implementation of protocols for mask ventilation and/or difficult intubation and the use of protective ventilation, morphine-sparing strategies and a semi-seated positioning throughout the care, is recommended, combined with close monitoring postoperatively. The dosage of anesthetic drugs should be based on the theoretical ideal weight and then titrated, rather than dosed to the total weight. Monitoring of neuromuscular blocking should be used where appropriate, as well as monitoring of the depth of anesthesia. The occurrence of intraoperative recall is indeed more frequent in the obese patient than in the non-obese patient. Appropriate prophylaxis against venous thromboembolic disease and early mobilization are recommended, as thromboembolic disease is increased in the obese patient. The use of non-invasive ventilation to prevent the occurrence of acute post-operative respiratory failure and for its treatment is particularly effective in obese patients. In case of admission to ICU, an individualized ventilatory management based on pathophysiology and careful monitoring should be initiated.

Perioperative anaesthetic management of patients with or at risk of acute distress respiratory syndrome undergoing emergency surgery

Patients undergoing emergency surgery may present with the acute respiratory distress syndrome (ARDS) or develop this syndrome postoperatively. The incidence of ARDS in the postoperative period is relatively low, but the impact of ARDS on patient outcomes and healthcare costs is relevant Aakre et.al (Mayo Clin Proc 89:181-9, 2014).The development of ARDS as a postoperative pulmonary complication (PPC) is associated with prolonged hospitalisation, longer duration of mechanical ventilation, increased intensive care unit length of stay and high morbidity and mortality Ball et.al (Curr Opin Crit Care 22:379-85, 2016). In order to mitigate the risk of ARDS after surgery, the anaesthetic management and protective mechanical ventilation strategies play an important role. In particular, a careful integration of general anaesthesia with neuraxial or locoregional techniques might promote faster recovery and reduce opioid consumption. In addition, the use of low tidal volume, minimising plateau pressure and titrating a low-moderate PEEP level based on the patient's need can improve outcome and reduce intraoperative adverse events. Moreover, perioperative management of ARDS patients includes specific anaesthesia and ventilator settings, hemodynamic monitoring, moderately restrictive fluid administration and pain control.The aim of this review is to provide an overview and evidence- and opinion-based recommendations concerning the management of patients at risk of and with ARDS who undergo emergency surgical procedures.

Controversies when using mechanical ventilation in obese patients with and without acute distress respiratory syndrome

INTRODUCTION

As the prevalence of obesity increases, so does the number of obese patients undergoing surgical procedures and being admitted into intensive care units. Obesity per se is associated with reduced lung volume. The combination of general anaesthesia and supine positioning involved in most surgeries causes further reductions in lung volumes, thus resulting in alveolar collapse, decreased lung compliance, increased airway resistance, and hypoxemia. These complications can be amplified by common obesity-related comorbidities. In otherwise healthy obese patients, mechanical ventilation strategies should be optimised to prevent lung damage; in those with acute distress respiratory syndrome (ARDS), strategies should seek to mitigate further lung damage. Areas covered: This review discusses non-invasive and invasive mechanical ventilation strategies for surgical and critically ill adult obese patients with and without ARDS and proposes practical clinical insights to be implemented at bedside both in the operating theatre and in intensive care units. Expert opinion: Large multicentre trials on respiratory management of obese patients are required. Although the indication of lung protective ventilation with low tidal volume is apparently translated to obese patients, optimal PEEP level and recruitment manoeuvres remain controversial. The use of non-invasive respiratory support after extubation must be considered in individual cases.

Comparison of preoxygenation efficiency with Intersurgical Economy and Intersurgical QuadraLite anaesthetic face masks

BACKGROUND

Sufficient preoxygenation prevents arterial oxygen desaturation prior to intubation. An optimally sealed facemask is necessary for fast preoxygenation. The study was aimed at comparing the efficiency of preoxygenation using two different face masks.

MATERIALS AND METHODS

In 2018, a prospective study was conducted. Patients were classified into two groups: group A - Intersurgical Economy face masks, group B - Intersurgical QuadraLite masks. The circuit was flushed with 100% O2 for 30s, preoxygenation started with flow of 8l/min, FiO2100. The patients were asked to breathe deeply. Fentanyl (1-2 mcg/kg) was administered to increase mask toleration. End-tidal oxygen concentration (EtO2) ≥90% was the goal. EtO2 was monitored after 30, 60, 90, 120, 180, 210, 240, 270 and 300 seconds. Data was analyzed using the Independent-Samples T-test and the Mann-Whitney-U test.

RESULTS

Twelve patients were enrolled in group A and 19 in group B. Differences in sex, age, BMI and Mallampati class in the groups were statistically insignificant (p = 0.13, 0.39, 0.65, 0.43 respectively). Patients assigned to ASA I - 25.8% (n = 8->2/6), ASA II - 71.0 % (n = 22->10/12), ASA III - 3.2% (n = 1->0/1), p = 0.64. The success rate of preoxygenation to EtO290 within 5 min was statistically significantly different in the groups, with 33.3% in group A and 94.7% in group B (p < 0.01). Mean time to EtO290 was 228.3 ± 104.0/164.4 ± 84.3. Mean EtO2 after: 30s - 56.0 ± 13.5/69.3 ± 11.2 (p < 0.01); 60s - 63.8 ± 15.3/76.1 ± 11.7 (p = 0.02), 90s - 67.8 ± 17.7/80.7 ± 10.1 (p = 0.03); 120s-69.6 ± 18.2/83.4 ± 10.0 (p = 0.03), 150s-71.1 ± 19.0/87.1 ± 6.5 (p = 0.01); 180s - 72.9 ± 16.8/88.5 ± 5.3 (p = 0.01), 210s - 72.6 ± 18.0/89.2 ± 5.1 (p < 0.01); 240s - 74.17 ± 15.4/90.0 ± 4.3 (p < 0.01), 270s-76.3 ± 16.3/90.2 ± 3.6; 300s - 77.8 ± 14.6/90.2 ± 1.5 (p < 0.01).

CONCLUSIONS

Preoxygenation was significantly more efficient and faster with Intersurgical QuadraLite face masks.

Impact of the driving pressure on mortality in obese and non-obese ARDS patients: a retrospective study of 362 cases

PURPOSE

The relation between driving pressure (plateau pressure-positive end-expiratory pressure) and mortality has never been studied in obese ARDS patients. The main objective of this study was to evaluate the relationship between 90-day mortality and driving pressure in an ARDS population ventilated in the intensive care unit (ICU) according to obesity status.

METHODS

We conducted a retrospective single-center study of prospectively collected data of all ARDS patients admitted consecutively to a mixed medical-surgical adult ICU from January 2009 to May 2017. Plateau pressure, compliance of the respiratory system (Crs) and driving pressure of the respiratory system within 24 h of ARDS diagnosis were compared between survivors and non-survivors at day 90 and between obese (body mass index ≥ 30 kg/m2) and non-obese patients. Cox proportional hazard modeling was used for mortality at day 90.

RESULTS

Three hundred sixty-two ARDS patients were included, 262 (72%) non-obese and 100 (28%) obese patients. Mortality rate at day 90 was respectively 47% (95% CI, 40-53) in the non-obese and 46% (95% CI, 36-56) in the obese patients. Driving pressure at day 1 in the non-obese patients was significantly lower in survivors at day 90 (11.9 ± 4.2 cmH2O) than in non-survivors (15.2 ± 5.2 cmH2O, p < 0.001). Contrarily, in obese patients, driving pressure at day 1 was not significantly different between survivors (13.7 ± 4.5 cmH2O) and non-survivors (13.2 ± 5.1 cmH2O, p = 0.41) at day 90. After three multivariate Cox analyses, plateau pressure [HR = 1.04 (95% CI 1.01-1.07) for each point of increase], Crs [HR = 0.97 (95% CI 0.96-0.99) for each point of increase] and driving pressure [HR = 1.07 (95% CI 1.04-1.10) for each point of increase], respectively, were independently associated with 90-day mortality in non-obese patients, but not in obese patients.

CONCLUSIONS

Contrary to non-obese ARDS patients, driving pressure was not associated with mortality in obese ARDS patients.

Optimizing education in difficult airway management: meeting the challenge

PURPOSE OF REVIEW

The last 2 decades have seen a vast change in the science and technology of airway management. As a result, there is an increasing need to equip anesthesiologists with the new knowledge and skills for the safe management of a difficult airway.

RECENT FINDINGS

In addition to knowledge and expertise, human factors and nontechnical skills (NTS), including situational awareness, communication and team work, play an important role during difficult airway management and contribute to the outcome. Didactic sessions are useful to impart knowledge. Self-learning, interactive discussions, simulation and debriefing are important tools for teaching and training in difficult airway management. Manikin training and simulation enable development of technical as well as NTS without subjecting patients to risk and allow multiple training sessions of relatively uncommon scenarios. Guidelines are useful teaching tools, whereas cognitive tools such as the Vortex approach may be useful during a difficult airway.

SUMMARY

There is need for research on difficult airway management and optimized training methods. Research is also required to determine the barriers to adoption of guidelines and strategies to ensure widespread dissemination and implementation of guidelines and best practices for difficult airway management.

The ABCDs of Managing Morbidly Obese Patients in Intensive Care Units

More than one-third of the US adult population and 17% of the youth are now obese, and obesity is associated with more than $147 billion a year in health care costs. Critical care nurses should understand the physiological differences and practice guidelines for patients with a body mass index greater than 30. The ABCD approach encompasses key clinical concepts in the management of critically ill obese and morbidly obese patients, including management of airways and breathing, minimizing nurses' back and other injuries, increasing awareness of bias, circulation problems, risks of decubitus ulcers and other skin breakdown, differences in drug calculations and metabolism, limitations in diagnostic equipment and imaging, diet and nutritional recommendations, and concerns with durable medical equipment.

Efficiency and Efficacy of Two Techniques of Preoxygenation during Modified Rapid Sequence Intubation

Background:

Apneic mass movement of oxygen by applying continuous positive airway pressure (CPAP) is possible only when the airway is kept patent which helps to reduce the rate of desaturation.

Aims:

The aim of this study was to check the efficiency of preoxygenation and apneic oxygenation by assessing the drop in partial pressure of arterial oxygen (PaO₂) during apnea with and without keeping an oropharyngeal airway to maintain the patency of airway.

Settings and Design:

This prospective observational study was conducted at a tertiary care center.

Materials and Methods:

Sixty patients undergoing robotic and laparoscopic-assisted surgeries requiring modified rapid sequence intubation were recruited for the study. In Group A, CPAP was not applied during preoxygenation and oropharyngeal airway was not used, but oxygen was administered at 5 L/min during the apnea. In Group B, CPAP of 5 cmH₂O was maintained during preoxygenation and after induction an oropharyngeal airway was inserted. Patients in both the groups were induced and paralyzed following standardized anesthesia protocol.

Statistical Analysis Used:

Chi-square test, independent t-test, and ANCOVA were used as applicable.

Results:

Group B showed significantly higher mean PaO₂ levels after preoxygenation (525.3 ± 42.5 vs. 500.8 ± 51) and at 90 s of apnea (494.8 ± 42.6 vs. 368.6 ± 98.4) as compared to Group A. The fall in PaO₂ was significantly lower in Group B. The rise in partial pressure of arterial carbon dioxide was comparable in both groups.

Conclusion:

Preoxygenation with CPAP of 5 cmH₂O followed by apneic oxygenation with CPAP keeping the airway patent with an oropharyngeal airway results in significantly higher PaO₂ after preoxygenation and slower reduction in PaO₂ during apnea.

Effects of Preoxygenation with Tidal Volume Breathing Followed by Apneic Oxygenation with and without Continuous Positive Airway Pressure on Duration of Safe Apnea Time and Arterial Blood Gases

Background:

Application of continuous positive airway pressure (CPAP) helps to recruit collapsed areas of the lung, which improves the oxygen reserve.

Aim of the Study:

To compare the time to desaturate to 90% during apnea following preoxygenation and apneic ventilation with tidal volume breathing for 3 min with and without the application of CPAP.

Settings and Design:

This prospective randomized study was conducted in a tertiary care institution.

Subjects and Methods:

Twenty adult surgical patients were allocated into two groups. Group C patients were preoxygenated with 100% oxygen with CPAP of 20 cm H₂O for 3 min. Group P patients were preoxygenated for 3 min without CPAP. In Group C, apneic oxygenation was initiated following induction and neuromuscular blockade with CPAP of 20 cm H₂O. In Group P, no CPAP was applied. The study was terminated when the patient desaturated to 90%.

Statistical Analysis Used:

Chi-square test and Mann–Whitney test.

Results:

Group C had a significantly longer apnea time as compared to Group P (816.00 ± 30.98 vs. 348.00 ± 122.64 s). Three patients in Group P desaturated to <90% by 3 min and the remaining soon after 6 min. No patient in Group C desaturated till 12 min of apnea. PaO₂ was significantly higher in Group C at 3 and 6 min of apnea. At 3 and 6 min, Group P had significantly lower saturation as compared to Group C.

Conclusion:

Preoxygenation with CPAP significantly delayed desaturation during apnea with significantly higher arterial partial pressure of oxygen as compared to preoxygenation without CPAP.

Comparison of Arterial Oxygenation and Acid-Base Balance with the use of Transnasal Humidified Rapid-insufflation Ventilatory Exchange versus Tidal Volume Breathing with Continuous Positive Airway Pressure for Preoxygenation and Apneic Ventilation

Background:

Preoxygenation and apneic ventilation prolong apnea time without desaturation.

Aims:

The primary objective of this study is to compare arterial oxygenation during the periods of apnea following preoxygenation and apneic ventilation with tidal volume breathing for 3 min with continuous positive airway pressure (CPAP) versus with transnasal humidified rapid-insufflation ventilatory exchange (THRIVE).

Settings and Designs:

This prospective randomized study was conducted in 20 adult patients at a tertiary care institution.

Subjects and Methods:

Group C patients (n = 10) were preoxygenated with 100% oxygen using a face mask at a rate of 6 L/min for 3 min with CPAP of 15 cm of H₂O. In Group H, oxygen was administered using THRIVE at 30 L/min for 3 min. Apneic ventilation was given in Group C with 10 L/min oxygen with CPAP of 15 cm H₂O and in Group H with THRIVE at 60 L/min. The endpoint was desaturation to 90% or maximum duration of 12 min.

Statistical Analysis Used:

Chi-square test and Mann–Whitney test.

Results:

Both groups tolerated apnea for 12 min without desaturation. PaO₂ in Group C was significantly higher than Group H from 3 min of apnea to 12 min. The PaCO₂ was significantly lower in Group C from 6 min. The pH was comparable in both groups except at 12 min with Group H having significantly lower pH.

Conclusion:

Tidal volume breathing with CPAP resulted in significantly higher arterial oxygen levels than THRIVE, though both modalities were equally effective in prolonging apnea time without desaturation up to 12 min. Group C showed an added advantage of lower PaCO₂ with less acidemia.

Effectiveness of transnasal humidified rapid-insufflation ventilatory exchange versus traditional preoxygenation followed by apnoeic oxygenation in delaying desaturation during apnoea: A preliminary study

Background and Aims:

Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) during apnoea has shown to delay desaturation. The primary objective was to compare time to desaturate to <90% during apnoea with THRIVE versus traditional preoxygenation followed by apnoeic oxygenation.

Methods:

This prospective, randomised, single-blinded study was conducted in 10 adult patients presenting for direct laryngoscopy under general anaesthesia without endotracheal intubation. Group P patients were preoxygenated with 100% oxygen, and in Group H, high-flow humidified oxygen was delivered using nasal cannula for 3 min. After induction and neuromuscular blockade, time to desaturate to 90%, while receiving apnoeic oxygenation, was noted. Chi-square test and Mann–Whitney tests were used.

Results:

Group H had a significantly longer apnoea time as compared to Group P (796.00 ± 43.36 vs. 444.00 ± 52.56 s). All patients in Group H continued to have nearly 100% saturation even at 12 min of apnoea. However, in Group P, 80% of patients desaturated to <90% after 6 min of apnoea. Baseline blood gases, that following preoxygenation and at 3 min of apnoea time were comparable in both groups. At 6 min, Group H had a significantly higher PaO₂ (295.20 ± 122.26 vs. 135.00 ± 116.78) and PaCO₂ (69.46 ± 7.15 vs. 59.00 ± 4.64). Group H continued to have a PaO₂ of >200 mmHg even at 12 min of apnoea with a significant rise in PaCO₂ along with fall in pH after 6 min.

Conclusion:

During apnoeic periods time to desaturate to <90% was significantly prolonged with use of THRIVE.

Prevention and care of respiratory failure in obese patients

With the increase in the global prevalence of obesity, there is a parallel rise in the proportion of obese patients admitted to intensive care units, referred for major surgery or requiring long-term non-invasive ventilation (NIV) at home for chronic respiratory failure. We describe the physiological effect of obesity on the respiratory system mainly in terms of respiratory mechanics, respiratory drive, and patency of the upper airways. Particular attention is given to the prevention and the clinical management of respiratory failure in obese patients with a main focus on invasive and NIV in intensive care during the perioperative period and long-term use of NIV on return home. We also address other aspects of care of obese patients, including antibiotic dosing and catheter-related infections.

WHO Needs High FIO2?

World Health Organization and the United States Center for Disease Control have recently recommended the use of 0.8 FIO₂ in all adult surgical patients undergoing general anaesthesia, to prevent surgical site infections. This recommendation has arisen several discussions: As a matter of fact, there are numerous studies with different results about the effect of FIO₂ on surgical site infection. Moreover, the clinical effects of FIO₂ are not limited to infection control. We asked some prominent authors about their comments regarding the recent recommendations.

Mechanical ventilation in obese ICU patients: from intubation to extubation

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2017. Other selected articles can be found online at http://ccforum.com/series/annualupdate2017. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Low-positive pressure ventilation improves non-hypoxaemic apnoea tolerance during ear, nose and throat pan-endoscopy: A randomised controlled trial

BACKGROUND

It has been suggested that oxygenation using pressure support ventilation (PSV) before general anaesthesia can reduce the duration of non-hypoxaemic apnoea.

OBJECTIVE

The objective was to determine whether or not pre-oxygenation with PSV increases the duration of non-hypoxaemic apnoea in non-obese patients during pan-endoscopy.

DESIGN

A randomised, controlled trial.

SETTING

Amiens University Hospital, France.

PATIENTS

Fifty patients scheduled for ENT pan-endoscopy with a BMI lower than 35  kg  m(-2).

INTERVENTION

Patients scheduled for pan-endoscopy were enrolled to receive either 100% oxygen at neutral pressure (the control group) or 100% oxygen with positive-pressure ventilation (a positive inspiratory pressure of 4  cmH2O and a positive end-expiratory pressure of 4  cmH2O; the PSV group) during spontaneous ventilation with a face mask. The goal of pre-oxygenation was to obtain an end-tidal oxygen concentration of more than 90% prior to induction of anaesthesia.

MAIN OUTCOME MEASURES

The primary efficacy criterion was the duration of non-hypoxaemic apnoea (i.e. before the peripheral capillary oxygen saturation fell to 90%). Secondary outcomes were duration of pre-oxygenation, pre-oxygenation failure and tolerance.

RESULTS

The mean (interquartile range) duration of non-hypoxaemic apnoea was longer in the PSV group [598 (447 to 717) s] than in the control group [310 (217 to 451) s] (P < 0.001). Oxygenation time was shorter in the PSV group [190 (159 to 225) s] than in the control group [245 (151 to 435) s] (P = 0.037). Pre-oxygenation was unsuccessful (i.e. end-tidal oxygen concentration was < 90%) in 20% of the patients in the control group but none in the PSV group. The intergroup difference in the duration of pan-endoscopy was not significant. Tolerance was good or very good in all patients.

CONCLUSION

Our results show that pre-oxygenation with PSV is associated with a longer duration of non-hypoxaemic apnoea and a lower frequency of manual reventilation during ENT pan-endoscopy. CLINICALTRIALS.

GOV REGISTRATION NUMBER

NCT02167334.

Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial

PURPOSE

High-flow nasal cannula oxygen (HFNC) has the potential to provide apnoeic oxygenation. We decided to assess in a proof-of-concept study whether the addition of HFNC to non-invasive ventilation (NIV) could reduce oxygen desaturation during intubation, compared with NIV alone for preoxygenation, in severely hypoxaemic intensive care unit (ICU) patients with respiratory failure.

METHODS

We conducted a randomised, controlled, single-centre trial with assessor-blinded outcome assessment in patients admitted to the ICU. Hypoxaemic patients requiring orotracheal intubation for respiratory failure were randomised to receive preoxygenation using HFNC [flow = 60 L/min, fraction of inspired oxygen (FiO2) = 100 %] combined with NIV (pressure support = 10 cmH2O, positive end-expiratory pressure = 5 cmH2O, FiO2 = 100 %) in the intervention group or NIV alone in the reference group prior to intubation. The primary outcome was the lowest oxygen saturation (SpO2) during the intubation procedure. Secondary outcomes were intubation-related complications and ICU mortality.

RESULTS

Between July 2015 and February 2016, we randomly assigned 25 and 24 patients to the intervention and reference groups, respectively. In both groups the main reasons for respiratory failure were pneumonia and ARDS. During the intubation procedure, the lowest SpO2 values were significantly higher in the intervention group than in the reference group [100 (95-100) % vs. 96 (92-99) %, p = 0.029]. After exclusion of two patients from analysis for protocol violation, no (0 %) patients in the intervention group and five (21 %) patients in the reference group had SpO2 below 80 % (p = 0.050). We recorded no significant difference between the groups in intubation-related complications or ICU mortality.

CONCLUSIONS

A novel strategy for preoxygenation in hypoxaemic patients, adding HFNC for apnoeic oxygenation to NIV prior to orotracheal intubation, may be more effective in reducing the severity of oxygen desaturation than the reference method using NIV alone.

All India Difficult Airway Association 2016 guidelines for the management of unanticipated difficult tracheal intubation in adults

The All India Difficult Airway Association (AIDAA) guidelines for management of the unanticipated difficult airway in adults provide a structured, stepwise approach to manage unanticipated difficulty during tracheal intubation in adults. They have been developed based on the available evidence; wherever robust evidence was lacking, or to suit the needs and situation in India, recommendations were arrived at by consensus opinion of airway experts, incorporating the responses to a questionnaire sent to members of the AIDAA and the Indian Society of Anaesthesiologists. We recommend optimum pre-oxygenation and nasal insufflation of 15 L/min oxygen during apnoea in all patients, and calling for help if the initial attempt at intubation is unsuccessful. Transnasal humidified rapid insufflations of oxygen at 70 L/min (transnasal humidified rapid insufflation ventilatory exchange) should be used when available. We recommend no more than three attempts at tracheal intubation and two attempts at supraglottic airway device (SAD) insertion if intubation fails, provided oxygen saturation remains ≥ 95%. Intubation should be confirmed by capnography. Blind tracheal intubation through the SAD is not recommended. If SAD insertion fails, one final attempt at mask ventilation should be tried after ensuring neuromuscular blockade using the optimal technique for mask ventilation. Failure to intubate the trachea as well as an inability to ventilate the lungs by face mask and SAD constitutes 'complete ventilation failure', and emergency cricothyroidotomy should be performed. Patient counselling, documentation and standard reporting of the airway difficulty using a 'difficult airway alert form' must be done. In addition, the AIDAA provides suggestions for the contents of a difficult airway cart.

Apneic oxygenation is associated with a reduction in the incidence of hypoxemia during the RSI of patients with intracranial hemorrhage in the emergency department

Critically ill patients undergoing emergent intubation are at risk of oxygen desaturation during the management of their airway. Patients with intracranial hemorrhage (ICH) are particularly susceptible to the detrimental effects of hypoxemia. Apneic oxygenation (AP OX) may be able to reduce the occurrence of oxygen desaturation during the emergent intubation of these patients. We sought to assess the effect AP OX on oxygen desaturation during the rapid sequence intubation (RSI) of patients with ICH in the emergency department (ED). We prospectively collected data on all patients intubated in an urban academic ED over the 2-year period from July 1, 2013 to June 30, 2015. Following each intubation, the operator completed a standardized continuous quality improvement (CQI) data form, which included information on patient, operator and intubation characteristics. Operators recorded data on the use of AP OX, the oxygen flow rate used for AP OX, and the starting and lowest saturations during intubation. Adult patients with ICH who underwent RSI by emergency medicine (EM) residents were included in the analyses. The primary outcome variable was any oxygen saturation <90 % during the intubation. We performed a backward stepwise multivariate logistic regression analysis to identify variables associated with oxygen desaturation. The primary independent variable of interest was the use of AP OX during the intubation. Inclusion criteria for the study was met by 127 patients. AP OX was used in 72 patients (AP OX group) and was not used in 55 patients (NO AP OX group). The incidence of desaturation was 5/72 (7 %) in the AP OX group and was 16/55 (29 %) in the NO AP OX group. In the multivariate logistic regression analysis the use of AP OX was associated with a reduced odds of desaturation (aOR 0.13; 95 % CI 0.03-0.53). Patients with ICH who received AP OX during RSI in the ED were seven times less likely to have an oxygen saturation of <90 % during the intubation compared to patients who did not receive AP OX. AP OX is a simple intervention that may minimize the risk of oxygen desaturation during the RSI of patients with ICH.

New method of preoxygenation for orotracheal intubation in patients with hypoxaemic acute respiratory failure in the intensive care unit, non-invasive ventilation combined with apnoeic oxygenation by high flow nasal oxygen: the randomised OPTINIV study protocol

INTRODUCTION

Tracheal intubation in the intensive care unit (ICU) is associated with severe life-threatening complications including severe hypoxaemia. Preoxygenation before intubation has been recommended in order to decrease such complications. Non-invasive ventilation (NIV)-assisted preoxygenation allows increased oxygen saturation during the intubation procedure, by applying a positive end-expiratory pressure (PEEP) to prevent alveolar derecruitment. However, the NIV mask has to be taken off after preoxygenation to allow the passage of the tube through the mouth. The patient with hypoxaemia does not receive oxygen during this period, at risk of major hypoxaemia. High-flow nasal cannula oxygen therapy (HFNC) has a potential for apnoeic oxygenation during the apnoea period following the preoxygenation with NIV. Whether application of HFNC combined with NIV is more effective at reducing oxygen desaturation during the intubation procedure compared with NIV alone for preoxygenation in patients with hypoxaemia in the ICU with acute respiratory failure remains to be established.

METHODS AND ANALYSIS

The HFNC combined to NIV for decreasing oxygen desaturation during the intubation procedure in patients with hypoxaemia in the ICU (OPTINIV) trial is an investigator-initiated monocentre randomised controlled two-arm trial with assessor-blinded outcome assessment. The OPTINIV trial randomises 50 patients with hypoxaemia requiring orotracheal intubation for acute respiratory failure to receive NIV (pressure support=10, PEEP=5, fractional inspired oxygen (FiO2)=100%) combined with HFNC (flow=60 L/min, FiO2=100%, interventional group) or NIV alone (reference group) for preoxygenation. The primary outcome is lowest oxygen saturation during the intubation procedure. Secondary outcomes are intubation-related complications, quality of preoxygenation and ICU mortality.

ETHICS AND DISSEMINATION

The study project has been approved by the appropriate ethics committee (CPP Sud-Méditerranée). Informed consent is required. If combined application of HFNC and NIV for preoxygenation of patients with hypoxaemia in the ICU proves superior to NIV preoxygenation, its use will become standard practice, thereby decreasing hypoxaemia during the intubation procedure and potential complications related to intubation.

TRIAL REGISTRATION NUMBER

NCT02530957.

The Physiologically Difficult Airway

Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation.