Lung Ultrasonography for the Assessment of Perioperative Atelectasis

Lung ultrasound on first postoperative day predicts out-of-hospital pulmonary complications following video-assisted thoracic surgery: A prospective cohort study

BACKGROUND

The integration of enhanced recovery after surgery (ERAS) protocols into the peri-operative management of video-assisted thoracic surgery (VATS) has facilitated rapid patient recovery, enabling discharge within 48 h. However, postoperative pulmonary complications (PPCs) postdischarge pose significant concerns for patient welfare. Despite the established utility of lung ultrasound (LUS) in diagnosing the causes of dyspnoea, the effectiveness of quantitative LUS in predicting PPCs after VATS remains uncertain.

OBJECTIVES

To determine whether quantitative LUS performed 24 h after surgery can identify patients with a higher risk of developing PPCs within 30 days after discharge from hospital.

DESIGN

Single-centre prospective cohort study.

SETTING

Academic tertiary care medical centre.

PATIENTS

Adults scheduled for elective VATS under general anaesthesia from November 2022 to January 2023.

MAIN OUTCOME MEASURES

This primary aim was to verify the association between lung ultrasound score (LUSS) on postoperative day 1 (POD1) and PPCs. The secondary aim was to identify other relevant peri-operative factors closely related to PPCs and establish a model capable of predicting the risk of PPCs in patients undergoing fast-track VATS.

RESULTS

Of the 200 recruited patients, 182 completed the LUS examination and 30-day follow-up. Of these, 66 (36.2%) developed various types of PPCs. These patients had a higher LUSS on POD 1 ( P  < 0.001), and more subpleural consolidation areas compared to those without PPCs ( P  < 0.001). Receiver-operating characteristics (ROC) analysis identified the optimal LUSS cut-off value at 6 points for predicting the occurrence of PPCs, with an area under the curve (AUC) of 0.838 (95% CI, 0.768 to 0.909). Patients with PPCs had higher rates of immune system diseases and ARISCAT score, longer hospital stay and procalcitonin levels, increased frequency of lobar resection, longer durations of surgical and mechanical ventilation, and greater incidence of unplanned hospital readmissions within 30 days postdischarge, compared with those without PPCs (all P  < 0.001). Multivariable logistic regression analysis indicated that the comorbidity of immune system disease, along with postoperative 24 h LUSS, were independent risk factor for PPCs within 30 days after VATS.

CONCLUSION

LUSS on POD 1 emerged as an independent risk factor for PPCs in fast-track VATS patients and reliably predicted the occurrence of PPCs within 30 days of hospital discharge.

TRIAL REGISTRATION

ClinicalTrials. gov No. ChiCTR2200065865.

Effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) ventilation strategy on postoperative atelectasis in patients undergoing laparoscopic surgery as assessed by ultrasonography: study protocol for a prospective randomized controlled trial

BACKGROUND

Ventilator-induced lung injury caused by mechanical ventilation under general anesthesia as well as CO2 pneumoperitoneum and special positions for laparoscopy may increase the risk of postoperative pulmonary complications (PPCs). Lung protective ventilation under general anesthesia is advised by the guidelines to lower the risk of PPCs in surgical patients. However, there is considerable controversy about the optimal level of positive end-expiratory pressure (PEEP) and how to set it. Driving pressure reflects the overall respiratory stress and high driving pressure is an independent risk factor for PPCs. The purpose of this study is to explore whether driving pressure-guided individualized PEEP ventilation can lower the incidence of postoperative atelectasis by improving respiratory mechanics during laparoscopic surgery consequently lowering the incidence of PPCs compared with the traditional fixed PEEP ventilation strategy.

METHODS

The study will be a single-center, prospective, randomized controlled clinical study. A total of 106 adult patients with medium-to-high-risk PPCs undergoing laparoscopic surgery for more than 2 h will be randomly assigned in a 1:1 ratio to receive an individualized PEEP guided by minimum driving pressure (group D) or a fixed PEEP of 5 cmH2O (group C). Patients in group C will maintain a PEEP of 5 cmH2O throughout the whole process, and patients in group D will be administered individualized PEEP after the start of pneumoperitoneum to achieve minimum driving pressure until the end of the operation. The primary outcome is the LUS score at 24 h postoperatively. The secondary outcomes are the LUS scores at other time points, intraoperative respiratory mechanics and oxygenation index, incidence and specific types of PPCs at 7 days postoperatively.

DISCUSSION

This study will better evaluate the effect of individualized PEEP application guided by driving pressure on the incidence of postoperative atelectasis based on ultrasound assessment consequently the incidence of PPCs in patients undergoing prolonged laparoscopic surgery. The results may provide a clinical evidence for optimizing perioperative lung protection strategies.

TRIAL REGISTRATION

www.chictr.org.cn ChiCTR2300079041. Registered on December 25, 2023.

Evaluation of perioperative lung ultrasound scores in robotic radical prostatectomy: prospective observational study

Robotic major abdominal surgeries are popular worldwide, yet very few clinical studies have investigated the effects of robotic surgery setup on respiratory outcomes. In this prospective observational study, it is aimed to demonstrate the change in ultrasonographic condition of the lungs throughout the robotic surgery and its relation with respiratory outcomes. Robotic radical prostatectomy patients without any preexisting lung or cardiac pathology were enrolled in the study. Lung ultrasound score (LUS) was chosen to evaluate lungs perioperatively in three different time points that is as follows: 5 min after intubation (T1), before extubation (T2), and 30 min after extubation (T3). Blood gas analyses were made at the same time points. Primary outcome was the change of LUS comparing T3 versus T1. Secondary outcomes included intraoperative change of LUS, severe postoperative pulmonary complication incidence, unplanned intensive care unit (ICU) admission incidence, comparison of oxygenation via PaO2 and PaO2/FiO2, and sensitivity/specificity of LUS for determining ICU admission. Total 48 patients were analyzed. T3 LUS was significantly higher than T1 LUS, and T2 was the highest amongst (15.5 [6, 25] vs 8.5 [4, 20] vs 20.5 [13, 30], respectively, p < 0.01). Pre-extubation LUS were significantly higher in patients who were admitted to ICU comparing who were not (23.5 [17, 30] vs 20 [13, 27], p = 0.03). PaO2/FiO2 ratio did not change among the groups significantly (p = 0.14). ROC curve of T2LUS showed 67% sensitivity and 85% specificity with a cut-off value of 22.5 for ICU admission (AUC 0.73 [0.516, 0.937], p = 0.04). LUS significantly worsened in robotic prostatectomy throughout the surgery, yet clinical deoxygenation or severe PPC were not observed. On the other hand, pre-extubation LUS may be used to determine possible ICU admission for the patients.Clinical trial registry: This study was prospectively registered at Clinicaltrials.gov (NCT05528159).

Individual FiO2 guided by SPO2 prevents hyperoxia and reduces postoperative atelectasis in colorectal surgery: A randomized controlled trial

STUDY OBJECTIVE

To determine whether individualized fraction of inspired oxygen (iFiO2) improves pulmonary atelectasis after elective laparoscopic colorectal surgery relative to 60 % FiO2.

DESIGN

This was a single-center, prospective, randomized study.

SETTING

This study was conducted in a single tertiary care hospital in China.

PATIENTS

A total of 84 eligible inpatients who underwent elective laparoscopic colorectal surgery between August 2021 and May 2022 were included in the study.

INTERVENTIONS

The patients were randomly assigned to receive either a fixed fraction of inspiration oxygen (fFiO2 group) or individualized FiO2 based on physiological SpO2 (iFiO2 group).

MEASUREMENTS

The primary outcome was the lung ultrasound score (LUS) at 30 min after extubation. Secondary outcomes included the length of hospital stay, admission to the intensive care unit, the length of post-anesthetic care unit stay, the ratio of lung capacity on the third day after surgery compared with before surgery, the incidence of nausea and vomiting, and surgical site infections after surgery. Additionally, the airway plate pressure, airway peak pressure, pulmonary dynamic compliance, PaO2, oxygenation index, alveolar-arterial oxygen tension gradient (A-aDO2), and pulmonary shunt fraction (Qs/Qt) were considered.

MAIN RESULTS

The LUS was significantly lowered in the iFiO2 group (5 [4, 7]) compared with the fFiO2 group (8 [4, 10]) (P = 0.03). Based on the criterion for determining atelectasis, 25 patients (62.5 %) in the fFiO2 group experienced significant atelectasis compared with 15 patients (37.5 %) in the iFiO2 group (P = 0.025). At the end of surgery, PaO2, A-aDO2, and Qs/Qt were significantly reduced in patients in the iFiO2 group compared with those in the fFiO2 group.

CONCLUSIONS

The use of iFiO2 during operation significantly reduces the LUS and pulmonary atelectasis in patients undergoing laparoscopic colorectal surgery under general anesthesia.

CLINICAL TRIAL REGISTRATION

ChiCTRT2100049615.

Mapping Trends and Hotspots Regarding the Use of Lung Ultrasound in the Field of Anesthesiology: A Bibliometric Analysis of Global Research

Purpose

Lung ultrasound (LUS) is increasingly utilized in the field of anesthesiology due to its focused, quick application and the advantage of not exposing patients to ionizing radiation. This study aims to analyze the status and trends in this area from a macroscopic perspective.

Methods

A bibliometric analysis was conducted using the Web of Science (WoS) Core Collection. The analysis and visualization were performed using WoS, Excel, VOSviewer, and CiteSpace. Parameters such as publications, countries, institutions, journals, and keywords were analyzed.

Results

A total of 133 articles published over the last 10 years were analyzed to clarify the current status and future trends on the use of LUS in anesthesiology. The number of publications increased markedly from May 1, 2014, to April 30, 2024. China is the highest productive country, while the USA had the highest number of citations. In the institution, Seoul National University in South Korea published the most articles and had the highest number of citations. Kim Jin-Tae emerged as the most prolific and influential author. BMC Anesthesiology and the Journal of Cardiothoracic and Vascular Anesthesia were identified as the most popular journals in the field. Keywords such as "atelectasis", "mechanical ventilation", and "pulmonary complications" were closely related to the use of LUS in anesthesiology.

Conclusion

This study provides a comprehensive analysis of research on the use of LUS in anesthesiology, highlighting the growing interest in LUS and its relevance to pulmonary complications.

Effects of ultrasound-guided recruitment manoeuvres on postoperative pulmonary complications in laparoscopic bariatric surgery patients: study protocol for a randomised clinical trial

BACKGROUND

Lung ultrasound-guided alveolar recruitment manoeuvres (RMs) may reduce the lung ultrasound score. However, whether the use of this strategy can reduce the incidence of postoperative pulmonary complications (PPCs) in the adult obese population has not yet been tested.

METHODS/DESIGN

This is a single-centre, two-arm, prospective, randomised controlled trial. A total number of 476 obese patients scheduled for bariatric surgeries will be enrolled. They will be randomly assigned to receive either lung ultrasound-guided RMs (intervention group) or conventional RMs (control group) intraoperatively. The occurrence of PPCs will be recorded as the primary outcome.

DISCUSSION

To the best of our knowledge, this is the first trial to test the effect of lung ultrasound-guided RMs on PPCs. The results of this trial will support the anaesthesiologists in choosing a potentially more efficient method to perform RMs for bariatric surgery patients.

TRIAL REGISTRATION

www.chictr.org.cn ChiCTR2400080203. Registered on 23 January 2024.

Ultrasound-guided deep versus superficial continuous serratus anterior plane block for pain management in patients with multiple rib fractures: A prospective randomized double-blind clinical trial

Background

Efficient analgesia is the cornerstone in multiple rib fractures (MRFs) management. The serratus anterior plane block (SAPB) shows promising outcomes. However, it is still provocative whether the superficial or deep approach is more effective in the SAPB procedure. We hypothesized that the deep approach of ultrasound (US)-guided continuous SAPB could be superior for MRFs pain management.

Methods

Sixty-two adult patients having unilateral MRFs, were randomized into two groups to receive continuous superficial SAPB (group S, n = 31) or continuous deep SAPB (group D, n = 31). As a primary outcome, we compared pain numeric rating scale (NRS), while total analgesic consumption, incentive spirometer volume (IS-V), lung ultrasound score (LUSS), basal and 24-h serum beta-endorphin (BE) levels, and any adverse events were secondary outcomes.

Results

There was a significant reduction in NRS in favor of group D when compared to group S at 30 minutes (P = 0.001) until 12 hours (P = 0.029); total analgesic consumption was significantly lower in group D (P = 0.005). A significant increase in the median IS-V in group D compared to group S at 90 minutes (P = 0.02) and 12h postblock (P = 0.004) LUSS was significantly lower in D group at 90 min, 12 h, and 24 h (P = 0.04, 0.001, 0.031). No significant differences as regards serum BE levels. No adverse events were noted.

Conclusion

Either superficial or deep continuous SAPB can be used safely and effectively in managing pain related to MRFs. Notably, the deep approach offered superior analgesia and improved deep breathing compared to the superficial.

Lung ultrasound in neonates and children with cardiac diseases with focus on post cardiac surgical period: time for systematic use-an expert opinion report by the Association for European Paediatric and Congenital Cardiology Imaging Working Group

Background

Despite lung ultrasound (LUS) gaining consensus for the diagnosis of pulmonary complication in paediatric acute care setting and in adult cardiology, its use in paediatric cardiology remains limited.

Aim

The aim of the present investigation is to provide an expert opinion on the applications of LUS in neonates and children with congenital heart disease, with a special focus on the post-surgical period.

Methods and Results

A complete guide for identification of landmarks and major signs (A and B lines) and their characteristics is provided. Diagnostic criteria, tips, and tricks for the diagnosis, and differential diagnosis of common pulmonary diseases such as pleural effusion, pneumonia, and consolidation are provided. To perform diagnosis of pneumothorax is illustrated. Applications of LUS for evaluation of hemidiaphragm motility and for a comprehensive assessment of retrosternal area are also discussed. The use of LUS for guidance of minor, common interventional procedures such as lung recruitment and drainage insertion is also described. The report also highlights current gaps of knowledge, including the difficulty for quantitative estimation of pleural effusion and atelectasis, and future prospective.

Conclusion

There is sufficient evidence to support a systematic use of LUS for the diagnosis and follow-up of neonates and children with cardiac disease especially those undergoing paediatric cardiac surgery. LUS is an easy, accurate, fast, cheap, and radiation-free tool that should become a routine in daily practice.

Ultrasonographic modeling of lung and diaphragm mechanics: clinical trial of a novel non-invasive method to evaluate pre-operative pulmonary function

Background

Pre-operative pulmonary function testing (PFT) plays a key role in predicting postoperative complications or functional impairment. However, PFT requires the subject and examiner to cooperate and the results are influenced by both technical and personal factors. In contrast, the use of ultrasound (US) for structural and functional assessments of the lungs and diaphragm is on the rise, as it requires minimal patient cooperation. Dyspnea is mainly caused by lung or pleural lesions but may also be caused by weak respiratory muscles. As the diaphragm is a primary respiratory muscle, combining lung ultrasonography (LUS) with diaphragm ultrasound (DUS) may enable a more comprehensive assessement of pulmonary function. This study aims to introduce a novel approach for assessing pulmonary function using a mathematical model based on LUS and DUS.

Methods

This prospective study was performed at the First Affiliated Hospital of Nanchang University between June 2021 and December 2021, 208 patients were recruited and underwent PFT, LUS, and DUS examinations. An experienced physician, blinded to the clinical history and PFT results, performed LUS and DUS and explored the correlations between a mathematical model (ultrasonographic modeling score (U-score)) using LUS combined with DUS and pulmonary function parameters. Univariate, multivariate, and logistic regression analyses were also performed.

Results

According to the univariate and multivariable analysis, diaphragm thickness fraction in deep breathing (D-DTF) (odds ratio (OR), 0.88; 95% confidence interval (CI) [0.83-0.94]; P < 0.001), and LUS score (OR, 1.44; 95% CI [1.16-1.80]; P < 0.001) were each independently associated with pulmonary function. According to the logistics equation, a U-score of -0.126 × D-DTF + 0.368 × LUS score was produced. The U-score showed a more significant negative correlation with forced expiratory volume in the first second/forced vital capacity (FEV1/FVC) (r = -0.605, P < 0.001) than the LUS or DUS indices alone. The U-score (area under the curve (AUC) = 0.971) was greater than the other indices for assessing pulmonary function.

Conclusions

With validation, the U-score through both lung and diaphragm ultrasound measurements may assist in estimating pulmonary function. This approach facilitates the assessment of pulmonary function in patients who may be unable to reliably participate in PFT.

Perioperative Lung Ultrasound Findings in Elective Intra-Abdominal Surgery: Associations with Postoperative Pulmonary Complications

Background: For patients undergoing abdominal surgery, postoperative pulmonary complications (PPCs) are a major source of morbidity and mortality. The use of point-of-care ultrasonography (POCUS), and specifically POCUS of the lungs, has seen many advancements in recent years. Objectives: We hypothesize that perioperative lung ultrasonography can be used as a predictor for PPCs. Methods: In a Single, 1000 beds, trauma level I medical center, patients presenting for elective intra-abdominal surgery with no severe pulmonary or cardiac diseases were evaluated preoperatively with a standardized 12-point lung ultrasound exam. A second identical exam was performed after surgery in the post-anesthesia care unit. PPCs were also documented. All lung ultrasound exams were presented to a blinded researcher and a lung ultrasound score (LUS) was calculated. Statistical analysis comparing pre- and postoperative LUS and PPC scores were performed. Results: A total of 61 patients were evaluated. The pre-surgery median LUS was 0 (in the range of 0-6) and the post-surgery median LUS was 3 (in the range of 0-14). The pre- to postsurgical LUS delta was 3.4 (standard deviation of 3.3). A postoperative LUS of 6 or more was defined as "high." A High LUS did not correlate with prolonged post-anesthesia care unit or hospital stay, prolonged oxygen support, or number of desaturation events. Conclusion: For elective abdominal surgery in relatively healthy patients, preoperative LUS usually begins at a normal level and becomes worse after general anesthesia. However, this difference in LUS is not significantly associated with clinically relevant postoperative pulmonary complications such as prolonged oxygen therapy, pneumonia, and noninvasive or invasive mechanical ventilation. Trial registration: Clinicaltrials.gov identifier: NCT05502926. Summary: This paper explores the use of point-of-care ultrasonography as a predictor for postoperative pulmonary complications. The findings suggest that while the lung ultrasound score worsens with general anesthesia, the differences are not significantly associated with postoperative pulmonary complications.

Effect of ultrasound-guided individualized positive end-expiratory pressure on the severity of postoperative atelectasis in elderly patients: a randomized controlled study

Postoperative pulmonary complications (PPCs) are common in patients undergoing general anesthesia, with atelectasis being a key contributor that increases postoperative mortality and prolongs hospitalization. Our research hypothesis is that ultrasound-guided individualized PEEP titration can reduce postoperative atelectasis. This single-center randomized controlled trial recruited elderly patients for laparoscopic surgery. Patients were randomly assigned to two group: the study group (individualized PEEP groups, PEEP Ind group) and the control group (Fixed PEEP group, PEEP 5 group). All patients in these two groups received volume-controlled ventilation during general anesthesia. Patients in the study group were given ultrasound-guided PEEP, while those in the control group were given a fixed 5 cmH2O PEEP. Bedside ultrasound assessed lung ventilation. The primary outcome was the severity of atelectasis within seven days post-surgery. Eighty-nine patients scheduled for elective laparoscopic radical surgery for colorectal cancer were enrolled in our study. Lung ultrasound scores (LUSs) in the study group during postoperative seven days was significantly decreased compared with that in the control group (P < 0.05). The severity of postoperative atelectasis in the study group was significantly improved. The incidence of PPCs during postoperative 7 days in the study group was significantly less than that in the control group (48.6% vs. 77.8%; RR = 0.625; CI = 0.430-0.909; P = 0.01). In elderly patients undergoing laparoscopic radical resection, lung ultrasound-guided individualized PEEP can alleviate the severity of postoperative atelectasis.Clinical trial number and registry URL: No. ChiCTR2200062979 ( https://www.chictr.org.cn ).

The effects of laryngeal mask versus endotracheal tube on atelectasis after general anesthesia induction assessed by lung ultrasound: A randomized controlled trial

STUDY OBJECTIVE

This study aims to evaluate the impact of Supreme™ laryngeal masks versus endotracheal tubes on atelectasis during general anesthesia using lung ultrasound (LUS), and provide evidence for respiratory management.

DESIGN

A single-center, double-blind, randomized controlled trial was conducted.

SETTING

The study was conducted in both the operating room and the post-anesthesia care unit, with follow-up assessments performed in the ward.

PATIENTS

Enrollment included 180 cases undergoing non-laparoscopic surgeries in gynecology, urology, and orthopedic limb surgeries.

INTERVENTIONS

Patients were randomly assigned 1:1 to the endotracheal intubation or laryngeal mask group.

MEASUREMENTS

LUS scores were recorded across 12 lung regions at baseline, 15 min after airway establishment, at the end of surgery, and 30 min following airway removal. Outcome measures encompassed the oxygenation index, dynamic lung compliance, incidence of postoperative pulmonary complications, throat pain, and other postoperative complications assessed at 24 and 48 h postoperatively. The primary outcome focused on the LUS score in all 12 lung regions at 15 min after airway establishment.

MAIN RESULTS

Intention-to-treat analysis of 177 subjects revealed endotracheal intubation led to significantly higher LUS scores at 15 min {P < 0.001, mean difference 4.15 ± 0.60, 95% CI [2.97, 5.33]}, end of surgery (P < 0.001, mean difference 3.37 ± 0.68, 95% CI [2.02, 4.72]), and 30 min post-removal (P < 0.001, mean difference 2.63 ± 0.48, 95% CI [1.68, 3.58]). No major complications occurred in the two groups.

CONCLUSIONS

Compared to endotracheal intubation, laryngeal masks effectively reduce atelectasis formation and progression in gynecological, urological non-laparoscopic, and orthopedic limb surgeries. However, caution is warranted when generalizing these findings to surgeries with a higher risk of laryngeal mask leakage or obese patients. Additionally, the efficacy of laryngeal masks in reducing postoperative atelectasis remains uncertain when comprehensive monitoring of muscle relaxation and reversal therapy is employed.

Effect of visual lung recruitment manoeuvres guided by trans-oesophageal lung ultrasound on atelectasis after thoracoscopic lobectomy: a randomised, single-blind, prospective study

BACKGROUND

Although the incidence of postoperative atelectasis could be reduced using lung recruitment manoeuvres, it remains high. We hypothesised that intraoperative visual lung recruitment guided by trans-oesophageal lung ultrasound would be more effective than the conventional method for managing postoperative atelectasis.

METHODS

In this randomised, controlled, prospective study, 84 patients undergoing thoracoscopic lobectomy were recruited from Affiliated Chengdu Fifth People's Hospital (teaching hospital) in China. Patients were grouped into trans-oesophageal lung ultrasound-guided (Group G, n = 42) and control (Group C, n = 42) groups.

METHODS

Lung recruitment was performed after anaesthesia induction, before chest closure and before the endotracheal tube extubation. In Group C, recruitment pressure was controlled at 30 cm H2O for 10 s (performed thrice); in Group G, the pressure was controlled at 30 cm H2O (performed thrice), and the tidal volume did not exceed 20 ml kg-1 until no atelectasis was detected by trans-oesophageal ultrasound. The primary outcome was lung ultrasound scores measured at the post anaesthesia care unit 30 min after extubation. The secondary outcomes included the oxygenation index (30 min after extubation) and the incidence of atelectasis (30 min after extubation and 3 days after surgery).

RESULTS

The final analysis included 79 patients. The lung ultrasound score was significantly higher in the control group than in the ultrasound-guided group 30 min after extubation (Group C vs. Group G, 8.6 ± 2.6 vs. 6.5 ± 2.0, P < 0.001). No significant difference in the oxygenation indexes 30 min after extubation was observed between the groups (P = 0.074); however, the incidence of atelectasis 30 min after extubation significantly differed between the two groups (Group C vs. Group G, 57% vs. 33%, P = 0.031). The incidence of atelectasis 3 days after surgery did not significantly differ between the two groups (Group C vs. Group G, 45% vs. 28%, P = 0.122).

CONCLUSIONS

Lung recruitment guided by trans-oesophageal lung ultrasound can reduce lung ultrasound scores and the incidence of atelectasis at the post anaesthesia care unit 30 min after extubation. However, it does not significantly reduce the incidence of atelectasis 3 days after surgery. TRIAL REGISTRATION: Registration number: ChiCTR2200062509. Registered on 10 /8/ 2022.

A comparison of the effects of lung protective ventilation and conventional ventilation on the occurrence of atelectasis during laparoscopic surgery in young infants: a randomized controlled trial

Objective

This study utilized lung ultrasound to investigate whether lung protective ventilation reduces pulmonary atelectasis and improves intraoperative oxygenation in infants undergoing laparoscopic surgery.

Methods

Eighty young infants (aged 1-6 months) who received general anesthesia for more than 2 h during laparoscopic surgery were randomized into the lung protective ventilation group (LPV group) and the conventional ventilation group (control group). The LPV group received mechanical ventilation starting at 6 mL/kg tidal volume, 5 cmH2O PEEP, 60% inspired oxygen fraction, and half-hourly alveolar recruitment maneuvers. Control group ventilation began with 8-10 mL/kg tidal volume, 0 cmH2O PEEP, and 60% inspired oxygen fraction. Lung ultrasound was conducted five times-T1 (5 min post-intubation), T2 (5 min post-pneumoperitoneum), T3 (at the end of surgery), T4 (post-extubation), and T5 (prior to discharge from the PACU)-for each infant. Simultaneous arterial blood gas analysis was performed at T1, T2, T3, and T4.

Results

Statistically significant differences were observed in pulmonary atelectasis incidence, lung ultrasound scores, and the PaO2, PaCO2, PaO2/FiO2 ratios at T2, T3, and T4. However, at T5, no statistically significant differences were noted in terms of lung ultrasound scores (4.30 ± 1.87 vs. 5.00 ± 2.43, 95% CI: -1.67 to 0.27, p = 0.153) or the incidence of pulmonary atelectasis (32.5% vs. 47.5%, p = 0.171).

Conclusion

In infants aged 1-6 months, lung protective ventilation during laparoscopy under general anesthesia significantly reduced the incidence of pulmonary atelectasis and enhanced intraoperative oxygenation and dynamic lung compliance compared to conventional ventilation. However, these benefits did not persist; no differences were observed in lung ultrasound scores or the incidence of pulmonary atelectasis at PACU discharge.

Clinical trial registration

http://www.chictr.org.cn/, identifier: ChiCTR2200058653.

Evaluation of oxygen administration in cesarean section under spinal anesthesia via lung ultrasound and the oxygen reserve index

BACKGROUND

Respiratory functions may be impaired in cesarean section (C/S) delivery performed under spinal anesthesia (SA) and oxygen supplementation may be required. Therefore, we conducted a randomized controlled study aimed to evaluate the effects of different oxygen administrations in pregnant women on the lungs during C/S under SA using ultrasound and oxygen reserve index (ORI).

METHODS

We conducted a randomized, controlled, single-center study from May 1, 2021, to March 31, 2022. A total of 90 patients scheduled for C/S under SA were randomly divided into 3 groups. Following the SA, patients in group 0 were treated with room air, in Group 3 were administered 3 L/min O₂ with a nasal cannula (NC), in Group 6 were administered 6 L/min O₂ with a simple face mask. In addition to routine monitoring, ORI values were measured. Lung aeration was evaluated through the modified lung ultrasound score (LUS) before the procedure (T0), at minute 0 (T1), 20 (T2), and hour 6 (T3) after the procedure, and ∆LUS values were recorded.

RESULTS

After SA, the ORI values of Group 3 were higher than Group 0 at all times (p < 0.05), while the intraoperative 1st minute and the 10th, 25th and 40th minutes after delivery (p = 0.001, p = 0.027, p = 0.001, p = 0.019) was higher than Group 6. When the LUS values of each group were compared with the T0 values a decrease was observed in Group 3 and Group 6 (p < 0.001, p = 0.016). While ∆LUS values were always higher in Group 3 than in Group 0, they were higher only in T1 and T2 in Group 6.

CONCLUSION

We determined that it would be appropriate to prefer 3 L/min supplemental oxygen therapy with NC in C/S to be performed under SA.

Ultrasound-guided versus conventional lung recruitment manoeuvres in thoracic surgery: a randomised controlled study

Lung recruitment manoeuvres (RMs) during mechanical ventilation may reduce atelectasis, however, the optimal recruitment strategy for patients undergoing thoracic surgery remains unknown. Our study was designed to investigate whether ultrasound-guided lung RMs is superior to conventional RMs in reducing perioperative atelectasis during thoracic surgery with one-lung ventilation. We conducted a randomised controlled clinical trial from August 2022 to September 2022. Sixty patients scheduled for video-assisted thoracoscopic surgery (VATS) under general anaesthesia were enrolled. Subjects were randomly divided into the ultrasound-guided RMs group (manual inflation guided by lung ultrasound) or conventional RMs group (manual inflation with 30 cmH2O pressure). Lung ultrasound were performed at three predefined time points (1 min after anaesthetic induction; after RMs at the end of surgery; before discharge from postanesthesia care unit [PACU]). The primary outcome was lung ultrasound score before discharge from the PACU after extubation. In the early postoperative period, lung aeration deteriorated in both groups even after lung RMs. However, ultrasound-guided lung RMs had significantly lower lung ultrasound scores when compared with conventional RMs in bilateral lungs (2.0 [0.8-4.0] vs. 8.0 [3.8-10.3], P < 0.01) at the end of surgery, which remained before patients discharged from the PACU. Accordingly, the lower incidence of atelectasis was found in ultrasound-guided RMs group than in conventional RMs group (7% vs. 53%; P < 0.01) at the end of surgery. Ultrasound-guided RMs is superior to conventional RMs in improving lung aeration and reducing the incidence of lung atelectasis at early postoperative period in patients undergoing VATS. The study protocol was approved by the Institutional Review Board of the Fudan University Shanghai Cancer Center (No. 220,825,810; date of approval: August 5, 2022) and registered on Chinese Clinical Trial Registry (registration number: ChiCTR2200062761).

Effects of Different Extubation Strategies on Atelectasis in Older Adults after Major Abdominal Surgery: A Prospective Randomized Controlled Trial

BACKGROUND

Older patients are particularly vulnerable to age-related respiratory changes. This prospective randomized controlled trial studied the effects of high and low fractions of inspired oxygen (FiO2) with the recruitment maneuver (RM) during extubation on lung atelectasis postoperatively in older patients undergoing major abdominal surgery.

METHODS

We randomized a total of 126 patients aged >60 years who underwent both elective and emergency major abdominal surgeries and met the inclusion criteria into three groups (H, HR, and LR) using computer-generated block randomization. Group H received high FiO2 (1), Group HR received high FiO2 (1) with RM followed by a positive end-expiratory pressure of 5 cm H2O, and Group LR received low FiO2 (0.4) with RM followed by a positive end-expiratory pressure of 5 cm H2O 10 minutes before extubation. Oxygenation and atelectasis were measured using the arterial partial pressure of oxygen (PaO2)/FiO2 ratios and lung ultrasound score. Postoperative pulmonary complications were recorded up to 24 hours postoperatively.

RESULTS

The mean PaO2/FiO2 at 30 minutes post-extubation was significantly higher in Groups LR and HR compared to that in Group H (390.71±29.55, 381.97±24.97, and 355.37±31.70; p<0.001). In the immediate postoperative period, the median lung ultrasound score was higher in Group H than that in Groups LR and HR (6 [5-7], 3 [3-5], and 3.5 [2.25-4.75]; p<0.001). The incidence of oxygen desaturation and oxygen requirements was higher in Group H during the postoperative period.

CONCLUSION

The RM before extubation is beneficial in reducing atelectasis and postoperative pulmonary complications, irrespective of the FiO2 concentration used in older adults undergoing major abdominal surgeries. (Trail registration number: Reference No. CTRI/2022/04/042115; date of CTRI registration 25/02/2022; and date of enrolment of the first research participant 05/05/2022).

Comparison of lung aeration loss in open abdominal oncologic surgeries after ventilation with electrical impedance tomography-guided PEEP versus conventional PEEP: a pilot feasibility study

BACKGROUND

Existing literature lacks high-quality evidence regarding the ideal intraoperative positive end-expiratory pressure (PEEP) to minimize postoperative pulmonary complications (PPCs). We hypothesized that applying individualized PEEP derived from electrical impedance tomography would reduce the severity of postoperative lung aeration loss, deterioration in oxygenation, and PPC incidence.

METHODS

A pilot feasibility study was conducted on 36 patients who underwent open abdominal oncologic surgery. The patients were randomized to receive individualized PEEP or conventional PEEP at 4 cmH2O. The primary outcome was the impact of individualized PEEP on changes in the modified lung ultrasound score (MLUS) derived from preoperative and postoperative lung ultrasonography. A higher MLUS indicated greater lung aeration loss. The secondary outcomes were the PaO2/FiO2 ratio and PPC incidence.

RESULTS

A significant increase in the postoperative MLUS (12.0 ± 3.6 vs 7.9 ± 2.1, P < 0.001) and a significant difference between the postoperative and preoperative MLUS values (7.0 ± 3.3 vs 3.0 ± 1.6, P < 0.001) were found in the conventional PEEP group, indicating increased lung aeration loss. In the conventional PEEP group, the intraoperative PaO2/FiO2 ratios were significantly lower but not the postoperative ratios. The PPC incidence was not significantly different between the groups. Post-hoc analysis showed the increase in lung aeration loss and deterioration of intraoperative oxygenation correlated with the deviation from the individualized PEEP.

CONCLUSIONS

Individualized PEEP appears to protect against lung aeration loss and intraoperative oxygenation deterioration. The advantage was greater in patients whose individualized PEEP deviated more from the conventional PEEP.

Adjustment of positive end-expiratory pressure to body mass index during mechanical ventilation in general anesthesia: BodyVent, a randomized controlled trial

BACKGROUND

In patients requiring general anesthesia, lung-protective ventilation can prevent postoperative pulmonary complications, which are associated with higher morbidity, mortality, and prolonged hospital stay. Application of positive end-expiratory pressure (PEEP) is one component of lung-protective ventilation. The correct strategy for setting adequate PEEP, however, remains controversial. PEEP settings that lead to a lower pressure difference between end-inspiratory plateau pressure and end-expiratory pressure ("driving pressure," ΔP) may reduce the risk of postoperative pulmonary complications. Preliminary data suggests that the PEEP required to prevent both end-inspiratory overdistension and end-expiratory alveolar collapse, thereby reducing ΔP, correlates positively with the body mass index (BMI) of patients, with PEEP values corresponding to approximately 1/3 of patient's respective BMI. Thus, we hypothesize that adjusting PEEP according to patient BMI reduces ΔP and may result in less postoperative pulmonary complications.

METHODS

Patients undergoing general anesthesia and endotracheal intubation with volume-controlled ventilation with a tidal volume of 7 ml per kg predicted body weight will be randomized and assigned to either an intervention group with PEEP adjusted according to BMI or a control group with a standardized PEEP of 5 mbar. Pre- and postoperatively, lung ultrasound will be performed to determine the lung aeration score, and hemodynamic and respiratory vital signs will be recorded for subsequent evaluation. The primary outcome is the difference in ΔP as a surrogate parameter for lung-protective ventilation. Secondary outcomes include change in lung aeration score, intraoperative occurrence of hemodynamic and respiratory events, oxygen requirements and postoperative pulmonary complications.

DISCUSSION

The study results will show whether an intraoperative ventilation strategy with PEEP adjustment based on BMI has the potential of reducing the risk for postoperative pulmonary complications as an easy-to-implement intervention that does not require lengthy ventilator maneuvers nor additional equipment.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS), DRKS00031336. Registered 21st February 2023.

TRIAL STATUS

The study protocol was approved by the ethics committee of the Christian-Albrechts-Universität Kiel, Germany, on 1st February 2023. Recruitment began in March 2023 and is expected to end in September 2023.

Restoration of Pulmonary Compliance after Laparoscopic Gynecologic Surgery Using a Recruitment Maneuver

BACKGROUND/OBJECTIVES

This study aimed to investigate the hypothesis that an alveolar recruitment maneuver can restore lung compliance to initial values after laparoscopic gynecological surgery.

METHODS

A total of 31 patients who underwent laparoscopic gynecological surgery were enrolled. Protective mechanical ventilation was applied, and the radial artery was catheterized in all patients. An alveolar recruitment maneuver (incremental and decremental positive end-expiratory pressure) was applied ten minutes after the release of pneumoperitoneum. The respiratory mechanics and blood gas results were recorded at eight different time points: after induction of anesthesia (T1), in the lithotomy position (T2), in the Trendelenburg position (T3), 10 and 90 min after insufflation of carbon dioxide (T4 and T5), in the supine position (T6), after desufflation (T7), and 10 min after an alveolar recruitment maneuver at the end of surgery (T8).

RESULTS

Pneumoperitoneum and the Trendelenburg position caused a decline of 15 units in compliance (T7 vs. T1; p < 0.05) compared to baseline. After the alveolar recruitment maneuver, compliance increased by 17.5% compared with the mean value of compliance at time T1 (T8 vs. T1; p < 0.05). The recruitment maneuver had favorable results in patients with low initial compliance (41.5 mL/cmH2O, IQR: 9.75 mL/cmH2O), high Body Mass Index 30.32 kg/m2 (IQR: 1.05 kg/m2), and high initial plateau airway pressure (16.5 cmH2O, IQR: 0.75 cmH2O).

CONCLUSIONS

Lung compliance does not return to initial values after performing laparoscopic gynecological procedures. However, after the release of pneumoperitoneum, an alveolar recruitment maneuver is beneficial as it improves compliance and gas exchange.

The application value of lung ultrasound scoring in assessing disease severity: Evaluation of small-scale outbreaks of COVID-19

PURPOSE

This study explored the use of transthoracic lung ultrasound for evaluating COVID-19 patients, compared it with computed tomography (CT), and examined its effectiveness using 8 and 12 lung regions.

METHODS

A total of 100 patients with COVID-19 and 40 healthy volunteers were assessed using 12 regions (bilateral upper/lower regions of the anterior/lateral/posterior chest) and simplified 8 zones (bilateral upper/lower regions of the anterior/lateral chest) transthoracic lung ultrasound. The relationships between ultrasound, CT, and clinical indicators were analyzed to evaluate the diagnostic value of ultrasound scores in COVID-19.

RESULTS

Increased disease severity correlated with increased 8- and 12-zone ultrasound and CT scores (all p < 0.05). The modified 8-zone method strongly correlated with the 12-zone method (Pearson's r = 0.908, p < 0.05). The 8- and 12-zone methods correlated with CT scoring (correlation = 0.568 and 0.635, respectively; p < 0.05). The intragroup correlation coefficients of the 8-zone, 12-zone, and CT scoring methods were highly consistent (intragroup correlation coefficient = 0.718, p < 0.01). The 8-zone ultrasound score correlated negatively with oxygen saturation (rs  = 0.306, p < 0.05) and Ca (rs  = 0.224, p < 0.05) and positively with IL-6 (rs  = 0.0.335, p < 0.05), erythrocyte sedimentation rate (rs  = 0.327, p < 0.05), alanine aminotransferase (rs  = 0.230, p < 0.05), and aspartate aminotransferase (rs  = 0.251, p < 0.05). The 12-zone scoring method correlated negatively with oxygen saturation (rs  = 0.338, p < 0.05) and Ca (rs  = 0.245, p < 0.05) and positively with IL-6 (rs  = 0.354, p < 0.05) and erythrocyte sedimentation rate (rs  = 0.495, p < 0.05).

CONCLUSION

Lung ultrasound scores represent the clinical severity and have high clinical value for diagnosing COVID-19 pneumonia. The 8-zone scoring method can improve examination efficiency and reduce secondary injuries caused by patient movement.

Lung Ultrasound Score on Postoperative Day 1 Is Predictive of the Occurrence of Pulmonary Complications after Major Abdominal Surgery: A Multicenter Prospective Observational Study

BACKGROUND

Postoperative pulmonary complications after major abdominal surgery are frequent and carry high morbidity and mortality. Early identification of patients at risk of pulmonary complications by lung ultrasound may allow the implementation of preemptive strategies. The authors hypothesized that lung ultrasound score would be associated with pulmonary postoperative complications. The main objective of the study was to evaluate the performance of lung ultrasound score on postoperative day 1 in predicting pulmonary complications after major abdominal surgery. Secondary objectives included the evaluation of other related measures for their potential prediction accuracy.

METHODS

A total of 149 patients scheduled for major abdominal surgery were enrolled in a bicenter observational study. Lung ultrasound score was performed before the surgery and on days 1, 4, and 7 after surgery. Pulmonary complications occurring before postoperative day 10 were recorded.

RESULTS

Lung ultrasound score on postoperative day 1 was higher in patients developing pulmonary complications before day 10 (median, 13; interquartile range, 8.25 to 18; vs. median, 10; interquartile range, 6.5 to 12; Mann-Whitney P = 0.002). The area under the curve for predicting postoperative pulmonary complications before day 10 was 0.65 (95% CI, 0.55 to 0.75; P = 0.003). Lung ultrasound score greater than 12 had a sensitivity of 0.54 (95% CI, 0.40 to 0.67), specificity of 0.77 (95% CI, 0.67 to 0.85), and negative predictive value of 0.74 (95% CI, 0.65 to 0.83). Lung ultrasound score greater than 17 had sensitivity of 0.33 (95% CI, 0.21 to 0.47), specificity of 0.95 (95% CI, 0.88 to 0.98), and positive predictive value of 0.78 (95% CI, 0.56 to 0.93). Anterolateral lung ultrasound score and composite scores using lung ultrasound score and other patient characteristics showed similar predictive accuracies.

CONCLUSIONS

An elevated lung ultrasound score on postoperative day 1 is associated with the occurrence of pulmonary complications within the first 10 days after major abdominal surgery.

EDITOR’S PERSPECTIVE

Effect of ultrasound-guided transversus abdominis plane block in reducing atelectasis after laparoscopic surgery in children: A randomized clinical trial

Background

Atelectasis is a commonly observed postoperative complication of general anesthesia in children. Pulmonary protective ventilation strategies have been reported to have a beneficial effect on postoperative atelectasis in children. Therefore, the present study aimed to evaluate the efficacy of the ultrasound-guided transversus abdominis plane (TAP) block technique in preventing the incidence of postoperative atelectasis in children.

Materials and methods

This study enrolled 100 consecutive children undergoing elective laparoscopic bilateral hernia repair and randomly divided them into the control and TAP groups. Conventional lung-protective ventilation was initiated in both groups after the induction of general anesthesia. The children in the TAP group received an ultrasound-guided TAP block with 0.3 mL/kg of 0.5% ropivacaine after the induction of anesthesia.

Results

Anesthesia-induced atelectasis was observed in 24% and 84% of patients in the TAP (n = 50) and control (n = 50) groups, respectively, before discharge from the post-anesthetic care unit (T3; PACU) (odds ratio [OR], 0.062; 95% confidence interval [CI], 0.019-0.179; P < 0.001). No significant difference was observed between the control and TAP groups in terms of the lung ultrasonography (LUS) scores 5 min after endotracheal intubation (T1). However, the LUS scores were lower in the TAP group than those in the control group at the end of surgery (T2, P < 0.01) and before discharge from the PACU (T3, P < 0.001). Moreover, the ace, legs, activity, cry and consolability (FLACC) pain scores in the TAP group were lower than those in the control group at each postoperative time point.

Conclusion

Ultrasound-guided TAP block effectively reduced the incidence of postoperative atelectasis and alleviated pain in children undergoing laparoscopic surgery.

Randomized Controlled Trial Investigating the Impact of High-Flow Nasal Cannula Oxygen Therapy on Patients Undergoing Robotic-Assisted Laparoscopic Rectal Cancer Surgery, with a Post-Extubation Atelectasis as a Complication

Background

Utilizing high-flow nasal cannula (HFNC) oxygen therapy may prevent the collapse of alveoli and improve overall alveolar ventilation. In this study, we aimed to investigate the impact of HFNC on postoperative atelectasis in individuals undergoing robotic-assisted laparoscopic surgery.

Methods

Patients undergoing robotic-assisted laparoscopic surgery for rectal cancer were randomly assigned to the control or HFNC groups. After the surgical procedure was complete and the trachea was extubated, both groups underwent an initial lung ultrasound (LUS) scan. In the post-anesthesia care unit (PACU), the control group received conventional nasal cannula oxygen therapy, while the HFNC group received high-flow nasal cannula oxygen therapy. A second LUS scan was conducted before the patient was transferred to the ward. The primary outcome measured was the total LUS score at the time of PACU discharge.

Results

In the HFNC group (n = 39), the LUS score and the incidence of atelectasis at PACU discharge were significantly lower compared to the control group (n = 39) [(5 vs 10, P < 0.001), (48.72% vs 82.05%, P = 0.002)]. None of the patients in the HFNC group experienced hypoxemia in the PACU, whereas six patients in the control group did (P = 0.03). Additionally, the minimum SpO2 value in the PACU was notably higher in the HFNC group compared to the control group [99 vs 97, P < 0.001].

Conclusion

Based on the results, HFNC improves the extent of postoperative atelectasis and decreases the occurrence of atelectasis in individuals undergoing robotic-assisted laparoscopic surgery for rectal cancer.

Positive end-expiratory pressure during one-lung ventilation for preventing atelectasis after video-assisted thoracoscopic surgery: a triple-arm, randomized controlled trial

BACKGROUND

There is little evidence regarding the benefits of lung-protective ventilation in patients undergoing one-lung ventilation for thoracic surgery. This study aimed to determine the optimal level of positive end-expiratory pressure (PEEP) during one-lung ventilation for minimizing postoperative atelectasis through lung ultrasonography.

METHODS

A total of 142 adult patients scheduled for video-assisted thoracoscopic surgery at Seoul National University Hospital between May 2019 and February 2020 were enrolled in this study. Patients were randomly assigned to different groups: 1) PEEP 3 cmH2O group; 2) PEEP 6 cmH2O group; and 3) PEEP 9 cmH2O group during one-lung ventilation. The lung ultrasound score was used to evaluate lung aeration using ultrasonography 1 hour after surgery.

RESULTS

The 1-hour post-surgery lung ultrasound scores were 8.1±2.5, 6.8±2.6, and 5.9±2.6 in the PEEP 3, 6, and 9 cmH2O groups, respectively (P<0.001). The PEEP 3 cmH2O group showed significantly higher lung ultrasound scores than the PEEP 6 (adjusted P=0.034) and 9 cmH2O groups (adjusted P<0.001). The PaO2/FiO2 ratio measured at 10 minutes after the end of one-lung ventilation was significantly lower in the PEEP 3 cmH2O group (392 [331 to 469]) than the PEEP 6 cmH2O (458 [384 to 530], adjusted P=0.018) or PEEP 9 cmH2O groups (454 [374 to 522], adjusted P=0.016).

CONCLUSIONS

Although the optimal level of PEEP during one-lung ventilation was not determined, the application of higher PEEP can prevent aeration loss in the ventilated lung after video-assisted thoracoscopic surgery under one-lung ventilation.

Evaluation of the Effect of Pressure-Controlled Ventilation-Volume Guaranteed Mode vs. Volume-Controlled Ventilation Mode on Atelectasis in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Clinical Trial

Background and Objectives: Laparoscopic surgery, which results in less bleeding, less postoperative pain, and better cosmetic results, may affect the lung dynamics via the pneumoperitoneum. After laparoscopic surgery, atelectasis develops. The primary aim of the present study is to demonstrate the effects of two different ventilation modes on the development of atelectasis using lung ultrasound, and the secondary outcomes include the plateau pressure, peak inspiratory pressure, and compliance differences between the groups. Materials and Methods: In this study, 62 participants aged 18-75 years undergoing laparoscopic cholecystectomy were enrolled. The patients were randomly assigned into two groups: the volume-controlled ventilation (VCV) group (group V) or the pressure-controlled-volume guaranteed ventilation (PCV-VG) group (group PV). The lung ultrasound score (LUS) was obtained thrice: prior to induction (T1), upon the patient's initial arrival in the recovery room (T2), and just before departing the recovery unit (T3). The hemodynamic data and mechanical ventilation parameters were recorded at different times intraoperatively. Results: The LUS score was similar between the groups at all the times. The change in the LUS score of the right lower anterior chest was statistically higher in the VCV group than the PCV group. The peak inspiratory pressure (PIP) was found to be statistically higher in the V group than the PV group five minutes after induction (T5) (20.84 ± 4.32 p = 0.021). The plateau pressure was found to be higher in the V group than the PV group at all times (after induction (Tind) 17.29 ± 5.53 p = 0.004, (T5) 17.77 ± 4.89 p = 0.001, after pneumoperitoneum (TPP) 19.71 ± 4.28 p = 0.002). Compliance was found to be statistically higher in the PV group than the V group at all times ((Tind) 48.87 ± 15.37 p = 0.011, (T5) 47.94 ± 13.71 p = 0.043, (TPP) 35.65 ± 6.90 p = 0.004). Before and after the pneumoperitoneum, the compliance was determined to be lower in the V group than the PV group, respectively (40.68 ± 13.91 p = 0.043, 30.77 ± 5.73 p = 0.004). Conclusions: LUS score was similar between groups at all times. The PCV-VG mode was superior to the VCV mode in providing optimal ventilatory pressures and maintaining high dynamic compliance in patients undergoing laparoscopic abdominal surgery.

Lung ultrasound for evaluating perioperative atelectasis and aeration in the post-anesthesia care unit

PURPOSE

Lung ultrasound is widely accepted as a reliable, noninvasive tool for evaluating lung status at the bedside. We assessed the impact of perioperative variables on atelectasis and lung aeration using lung ultrasound, and their correlation with postoperative oxygenation in patients undergoing general anesthesia.

METHODS

This prospective observational study evaluated 93 consecutive patients scheduled to undergo elective non-cardiothoracic surgery under general anesthesia. Lung ultrasound was performed 5 min after admission to the post-anesthesia care unit (PACU). Twelve pulmonary quadrants were selected for each ultrasound examination. The lung ultrasound scores and atelectasis status were calculated. The oxygenation assessment was obtained by arterial blood gas analysis before discharge from the PACU.

RESULTS

Thirty-two patients (34%) had atelectasis in at least one of the 12 evaluated segments, whereas 12 patients (13%) had atelectasis in at least three segments. The proportion of B-lines (≥ 3) and atelectasis in the inferolateral and posterior regions was significantly higher than in other regions. Patients with lung ultrasound scores ≥ 5 had a higher body mass index and lower PaO2 before discharge from the PACU than those with scores < 5. Patients with atelectasis had higher body mass indices and lung ultrasound scores. The presence of ≥ 2 regions of atelectasis was associated with lower PaO2. Using multivariate analysis, body mass index, intraoperative body position, and sex independently correlated with lung ultrasound scores. Age and lung ultrasound scores independently correlated with hypoxemia.

CONCLUSION

Lung ultrasound enables early postoperative evaluation of atelectasis and lung aeration, which are closely associated with postoperative oxygenation.

Minimizing Lung Injury During Laparoscopy in Head-Down Tilt: A Physiological Cohort Study

BACKGROUND

Increased intra-abdominal pressure during laparoscopy induces atelectasis. Positive end-expiratory pressure (PEEP) can alleviate atelectasis but may cause hyperinflation. Cyclic opening of collapsed alveoli and hyperinflation can lead to ventilator-induced lung injury and postoperative pulmonary complications. We aimed to study the effect of PEEP on atelectasis, lung stress, and hyperinflation during laparoscopy in the head-down (Trendelenburg) position.

METHODS

An open-label, repeated-measures, interventional, physiological cohort trial was designed. All participants were recruited from a single tertiary Belgian university hospital. Twenty-three nonobese patients scheduled for laparoscopy in the Trendelenburg position were recruited.We applied a decremental PEEP protocol: 15 (high), 10 and 5 (low) cm H 2 O. Atelectasis was studied with the lung ultrasound score, the end-expiratory transpulmonary pressure, the arterial oxygen partial pressure to fraction of inspired oxygen concentration (P ao2 /Fi o2 ) ratio, and the dynamic respiratory system compliance. Global hyperinflation was evaluated by dead space volume, and regional ventilation was evaluated by lung ultrasound. Lung stress was estimated using the transpulmonary driving pressure and dynamic compliance. Data are reported as medians (25th-75th percentile).

RESULTS

At 15, 10, and 5 cm H 2 O PEEP, the respective measurements were: lung ultrasound scores (%) 11 (0-22), 27 (11-39), and 53 (42-61) ( P < .001); end-expiratory transpulmonary pressures (cm H 2 O) 0.9 (-0.6 to 1.7), -0.3 (-2.0 to 0.7), and -1.9 (-4.6 to -0.9) ( P < .001); P ao2 /Fi o2 ratios (mm Hg) 471 (435-538), 458 (410-537), and 431 (358-492) ( P < .001); dynamic respiratory system compliances (mL/cm H 2 O) 32 (26-36), 30 (25-34), and 27 (22-30) ( P < .001); driving pressures (cm H 2 O) 8.2 (7.5-9.5), 9.3 (8.5-11.1), and 11.0 (10.3-12.2) ( P < .001); and alveolar dead space ventilation fractions (%) 10 (9-12), 10 (9-12), and 9 (8-12) ( P = .23). The lung ultrasound score was similar between apical and basal lung regions at each PEEP level ( P = .76, .37, and .76, respectively).

CONCLUSIONS

Higher PEEP levels during laparoscopy in the head-down position facilitate lung-protective ventilation. Atelectasis and lung stress are reduced in the absence of global alveolar hyperinflation.

Effect of a pre-emptive 2-hour session of high-flow nasal oxygen on postoperative oxygenation after major gynaecologic surgery: a randomised clinical trial

BACKGROUND

We aimed at determining whether a 2-h session of high-flow nasal oxygen (HFNO) immediately after extubation improves oxygen exchange after major gynaecological surgery in the Trendelenburg position in adult female patients.

METHODS

In this single-centre, open-label, randomised trial, patients who underwent major gynaecological surgery were randomised to HFNO or conventional oxygen treatment with a Venturi mask. The primary outcome was the Pao2/FiO2 ratio after 2 h of treatment. Secondary outcomes included lung ultrasound score, diaphragm thickening fraction, dyspnoea, ventilatory frequency, Paco2, the percentage of patients with impaired gas exchange (Pao2/FiO2 ≤40 kPa) after 2 h of treatment, and postoperative pulmonary complications at 30 days.

RESULTS

A total of 83 patients were included (42 in the HFNO group and 41 in the conventional treatment group). After 2 h of treatment, median (inter-quartile range) Pao2/FiO2 was 52.9 (47.9-65.2) kPa in the HFNO group and 45.7 (36.4 -55.9) kPa in the conventional treatment group (mean difference 8.7 kPa [95% CI: 3.4 to 13.9], P=0.003). The lung ultrasound score was lower in the HFNO group than in the conventional treatment group (9 [6-10] vs 12 [10-14], P<0.001), mostly because of the difference of the score in dorsal areas (7 [6-8] vs 10 [9-10], P<0.001). The percentage of patients with impaired gas exchange was lower in the HFNO group than in the conventional treatment group (5% vs 37%, P<0.001). All other secondary outcomes were not different between groups.

CONCLUSIONS

In patients who underwent major gynaecological surgery, a pre-emptive 2-h session of HFNO after extubation improved postoperative oxygen exchange and reduced atelectasis compared with a conventional oxygen treatment strategy.

CLINICAL TRIAL REGISTRATION

NCT04566419.

Effect of individualized PEEP titration by ultrasonography on perioperative pulmonary protection and postoperative cognitive function in patients with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the effect of the individualized positive end-expiratory pressure (PEEP) lung protection ventilation strategy by combining driving pressure (ΔP) and pulmonary ultrasound (LUS)-based titration on lung function and postoperative cognitive function in patients with chronic obstructive pulmonary disease (COPD) during laparoscopic surgery.

METHODS

A total of 108 patients with COPD undergoing laparoscopic gastrointestinal surgery under general anesthesia were included in this study. They were randomly divided into three groups (n = 36): traditional volume ventilation group (Group C), fixed PEEP 5 cmH₂O group (Group P), and ΔP combined with LUS-based PEEP titration in the resuscitation room group (Group T). All three groups were given volume ventilation mode, I:E = 1:2; In group C, VT was 10 mL/kg and PEEP was 0 cmH₂O; In groups P and T, VT was 6 mL/kg and PEEP was 5 cmH₂O; After mechanical ventilation for 15 min in Group T, ΔP in combination with LUS was used to titrate PEEP. The oxygenation index (PaO2/FiO2), airway platform pressure (Pplat), dynamic lung compliance (Cdyn), Montreal Cognitive Assessment (MoCA), and venous interleukin-6(IL-6) were recorded at the corresponding time points, and the final PEEP value in Group T was recorded.

RESULTS

The final PEEP value of Group T was (6.4 ± 1.2) cmH₂O; Compared with groups C and P: PaO₂/FiO₂ and Cdyn in Group T were significantly increased (P < 0.05) and value of IL-6 was significantly decreased (P < 0.05) at the corresponding time points. Compared with group C, the MoCA score on day 7 after surgery in Group T was significantly higher (P < 0.05).

CONCLUSION

Compared with the traditional ventilation strategy, the individualized ΔP combined with LUS-based PEEP titration in patients with COPD during the perioperative period of laparoscopic surgery can play a better role in lung protection and can improve postoperative cognitive function.

A preoperative ultrasound-based protocol for optimisation of fluid therapy to prevent early intraoperative hypotension: a randomised controlled study

BACKGROUND

Intraoperative hypotension is a risk factor for postoperative complications. Preoperative dehydration is a major contributor, although it is difficult to estimate its severity. Point-of-care ultrasound offers several potential methods, including measurements of the inferior vena cava. The addition of lung ultrasound may offer a safety limit. We aimed to evaluate whether the implication of an ultrasound-based preoperative fluid therapy protocol can decrease the incidence of early intraoperative hypotension.

METHODS

Randomised controlled study in a tertiary university department involves elective surgical patients of ASA 2-3 class, scheduled for elective major abdominal surgery under general anaesthesia with intubation. We randomised 40-40 patients; 38-38 were available for analysis. Conventional fluid therapy was ordered on routine preoperative visits. Ultrasound-based protocol evaluated the collapsibility index of inferior vena cava and lung ultrasound profiles. Scans were performed twice: 2 h and 30 min before surgery. A high collapsibility index (≥ 40%) indicated a standardised fluid bolus, while the anterior B-profile of the lung ultrasound contraindicated further fluid. The primary outcome was the incidence of postinduction and early intraoperative (0-10 min) hypotension (MAP < 65 mmHg and/or ≥ 30% of decrease from baseline). Secondary endpoints were postoperative lactate level, urine output and lung ultrasound score at 24 h.

RESULTS

The absolute criterion of postinduction hypotension was fulfilled in 12 patients in the conventional group (31.6%) and 3 in the ultrasound-based group (7.9%) (p = 0.0246). Based on composite criteria of absolute and/or relative hypotension, we observed 17 (44.7%) and 7 (18.4%) cases, respectively (p = 0.0136). The incidence of early intraoperative hypotension was also lower: HR for absolute hypotension was 2.10 (95% CI 1.00-4.42) in the conventional group (p = 0.0387). Secondary outcome measures were similar in the study groups.

CONCLUSION

We implemented a safe and effective point-of-care ultrasound-based preoperative fluid replacement protocol into perioperative care.

TRIAL REGISTRATION

The study was registered to ClinicalTrials.gov on 10/12/2021, registration number: NCT05171608 (registered prospectively on 10/12/2021).

Lung Ultrasound to Determine the Effect of Lower vs. Higher PEEP on Lung Aeration in Patients without ARDS-A Substudy of a Randomized Clinical Trial

BACKGROUND

Ventilation with lower positive end-expiratory pressure (PEEP) may cause loss of lung aeration in critically ill invasively ventilated patients. This study investigated whether a systematic lung ultrasound (LUS) scoring system can detect such changes in lung aeration in a study comparing lower versus higher PEEP in invasively ventilated patients without acute respiratory distress syndrome (ARDS).

METHODS

Single center substudy of a national, multicenter, randomized clinical trial comparing lower versus higher PEEP ventilation strategy. Fifty-seven patients underwent a systematic 12-region LUS examination within 12 h and between 24 to 48 h after start of invasive ventilation, according to randomization. The primary endpoint was a change in the global LUS aeration score, where a higher value indicates a greater impairment in lung aeration.

RESULTS

Thirty-three and twenty-four patients received ventilation with lower PEEP (median PEEP 1 (0-5) cm H₂O) or higher PEEP (median PEEP 8 (8-8) cm H₂O), respectively. Median global LUS aeration scores within 12 h and between 24 and 48 h were 8 (4 to 14) and 9 (4 to 12) (difference 1 (-2 to 3)) in the lower PEEP group, and 7 (2-11) and 6 (1-12) (difference 0 (-2 to 3)) in the higher PEEP group. Neither differences in changes over time nor differences in absolute scores reached statistical significance.

CONCLUSIONS

In this substudy of a randomized clinical trial comparing lower PEEP versus higher PEEP in patients without ARDS, LUS was unable to detect changes in lung aeration.

Effect of Lung Compliance-Based Optimum Pressure Versus Fixed Positive End-Expiratory Pressure on Lung Atelectasis Assessed by Modified Lung Ultrasound Score in Laparoscopic Gynecological Surgery: A Prospective Randomized Controlled Trial

BACKGROUND

 Lung protective ventilation during the intraoperative period is now well established. However, the additional role of positive end-expiratory pressure (PEEP) during the intraoperative period remains uncertain in major laparoscopic gynecological surgery. The authors hypothesized that compliance-based optimum PEEP titration reduces postoperative lung atelectasis and improves outcomes.

METHODS

 Patients undergoing major laparoscopic pelvic gynecological surgeries with healthy lungs were randomized to the fixed PEEP group (PEEP 5 cm H₂O and recruitment maneuver {RM}) and optimum PEEP group (compliance-based PEEP and RM). Lung ultrasound and arterial blood gas analysis were performed at four time points. Modified lung ultrasound scoring was done, and the same was used as means of assessing lung aeration and the amount of lung atelectasis. Postoperative supplemental oxygen requirement and duration were also assessed and compared.

RESULTS

Lung ultrasound score (LUS) 30 minutes after extubation in fixed (Group F) and optimum (Group O) PEEP groups were median (interquartile range {IQR}) 3 (2-3) versus 1 (1-2), p=0.0001. Ventilatory parameters between Group F and Group O after lung recruitment were tidal volume (mean 357 mL {SD: 35} versus 362 mL {SD: 22}, p=0.46), PEEP (median, 5 cm H₂O {IQR: 5-5} versus median 16 cm H₂O {IQR: 14-18}), peak airway pressure (median 26 cm H₂O {IQR: 24-28} versus median 30 cm H₂O {IQR: 28-32} p<0.0001), plateau pressure (median 22 cm H₂O {IQR: 20-24} versus median 26 cm H₂O {IQR: 24-28} p<0.0001), static compliance (32.07±8.36 mL cm H₂O-1 versus 39.58±8.99 mL cm H₂O-1, p=0.0002). The number of patients requiring postoperative oxygen therapy to maintain SpO₂ >94% after extubation in postanesthesia care unit (PACU) was statistically significantly greater in group F (39/41 {95%} versus 30/41 {73%}, p=0.007). Median (IQR) duration of oxygenation therapy in the first 24 hours of the postoperative period between Group F and Group O differed with statistical significance, with the median (IQR) values being 25 (20-30) minutes versus 10 (0-15) minutes (p<0.0001).

CONCLUSIONS

 The modified lung ultrasound score significantly differed intraoperatively between the two groups, with lower scores in the optimum PEEP group. This has reflected improved postoperative outcomes in optimum PEEP group patients, with fewer patients requiring postoperative oxygen supplementation and reduced supplemental oxygen requirement duration.

Effect of driving pressure on early postoperative lung gas distribution in supratentorial craniotomy: a randomized controlled trial

BACKGROUND

Neurosurgical patients represent a high-risk population for postoperative pulmonary complications (PPCs). A lower intraoperative driving pressure (DP) is related to a reduction in postoperative pulmonary complications. We hypothesized that driving pressure-guided ventilation during supratentorial craniotomy might lead to a more homogeneous gas distribution in the lung postoperatively.

METHODS

This was a randomized trial conducted between June 2020 and July 2021 at Beijing Tiantan Hospital. Fifty-three patients undergoing supratentorial craniotomy were randomly divided into the titration group or control group at a ratio of 1 to 1. The control group received 5 cmH₂O PEEP, and the titration group received individualized PEEP targeting the lowest DP. The primary outcome was the global inhomogeneity index (GI) immediately after extubation obtained by electrical impedance tomography (EIT). The secondary outcomes were lung ultrasonography scores (LUSs), respiratory system compliance, the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO₂/FiO₂) and PPCs within 3 days postoperatively.

RESULTS

Fifty-one patients were included in the analysis. The median (IQR [range]) DP in the titration group versus the control group was 10 (9-12 [7-13]) cmH₂O vs. 11 (10-12 [7-13]) cmH₂O, respectively (P = 0.040). The GI tract did not differ between groups immediately after extubation (P = 0.080). The LUS_S was significantly lower in the titration group than in the control group immediately after tracheal extubation (1 [0-3] vs. 3 [1-6], P = 0.045). The compliance in the titration group was higher than that in the control group at 1 h after intubation (48 [42-54] vs. 41 [37-46] ml·cmH₂O^-1, P = 0.011) and at the end of surgery (46 [42-51] vs. 41 [37-44] ml·cmH₂O^-1, P = 0.029). The PaO₂/FiO₂ ratio was not significantly different between groups in terms of the ventilation protocol (P = 0.117). At the 3-day follow-up, no postoperative pulmonary complications occurred in either group.

CONCLUSIONS

Driving pressure-guided ventilation during supratentorial craniotomy did not contribute to postoperative homogeneous aeration, but it may lead to improved respiratory compliance and lower lung ultrasonography scores.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT04421976.

Emerging Applications of Extracardiac Ultrasound in Critically Ill Cardiac Patients

Point-of-care ultrasound has evolved as an invaluable diagnostic modality and procedural guidance tool in the care of critically ill cardiac patients. Beyond focused cardiac ultrasound, additional extracardiac ultrasound modalities may provide important information at the bedside. In addition to new uses of existing modalities, such as pulsed-wave Doppler ultrasound, the development of new applications is fostered by the implementation of additional features in mid-range ultrasound machines commonly acquired for intensive care units, such as tissue elastography, speckle tracking, and contrast-enhanced ultrasound quantification software. This review explores several areas in which ultrasound imaging technology may transform care in the future. First, we review how lung ultrasound in mechanically ventilated patients can enable the personalization of ventilator parameters and help to liberate them from mechanical ventilation. Second, we review the role of venous Doppler in the assessment of organ congestion and how tissue elastography may complement this application. Finally, we explore how contrast-enhanced ultrasound could be used to assess changes in organ perfusion.

Lung ultrasound score-based assessment of postoperative atelectasis in obese patients according to inspired oxygen concentration: A prospective, randomized-controlled study

BACKGROUND

According to a recent meta-analysis, in patients with a body mass index (BMI) ≥ 30, a high fraction of inhaled oxygen (FiO2) did not increase postoperative atelectasis. However, a high FiO2 generally increases the risk of postoperative atelectasis. Therefore, this study aimed to evaluate the effect of FiO2 on the development of atelectasis in obese patients using the modified lung ultrasound score (LUSS).

METHODS

Patients were assigned to 4 groups: BMI ≥ 30: group A (n = 21) and group B (n = 20) and normal BMI: group C (n = 22) and group D (n = 21). Groups A and C were administered 100% O2 during preinduction and emergence and 50% O2 during anesthesia. Groups B and D received 40% O2 for anesthesia. The modified LUSS was assessed before and 20 min after arrival to the postanesthesia care unit (PACU).

RESULTS

The difference between the modified LUSS preinduction and PACU was significantly higher in group A with a BMI ≥ 30 (P = .006); however, there was an insignificant difference between groups C and D in the normal BMI group (P = .076).

CONCLUSION

High FiO2 had a greater effect on the development of atelectasis in obese patients than did low FiO2; however, in normal-weight individuals, FiO2 did not have a significant effect on postoperative atelectasis.

Effect of recruitment manoeuvres under lung ultrasound-guidance and positive end-expiratory pressure on postoperative atelectasis and hypoxemia in major open upper abdominal surgery: A randomized controlled trial

Background

Postoperative pulmonary complications (PPCs) especially atelectasis and hypoxemia are common during abdominal surgery. Studies on the effect of either recruitment manoeuvres (RMs) or positive end-expiratory pressure (PEEP) on PPCs are controversial. The objective of this study is to evaluate the effect of perioperative lung ultrasound (LUS)-guided RMs combined with PEEP on the reduction of postoperative atelectasis and hypoxemia in major open upper abdominal surgery.

Methods

In this randomized controlled trial, 122 adult patients undergoing major open upper abdominal surgery were allocated into three groups: control (C) group (n = 42); PEEP (P) group (n = 40); RMs combined with PEEP (RP) group (n = 40). All patients were scheduled for general anaesthesia using the lung-protective ventilation (LPV) strategy. The levels of PEEP in the three groups were 0 cmH₂O, 5 cmH₂O and 5 cmH₂O. LUS examination was carried out at 3 predetermined time points in each group: 5 min after intubation (T₁), at the end of surgery (T₂) and 15 min after extubation (T₃). Patients with atelectasis on the sonogram in the RP group received LUS-guided RMs at point T₂. LUS scores were used to estimate the severity of aeration loss. The P/F ratio (PaO₂/FiO₂) at 15min after extubation was used to assess the incidence of postoperative hypoxemia. Primary outcomes were the incidences of postoperative atelectasis and hypoxemia (PaO₂/FiO₂ < 300 mmHg). The secondary outcome was the distribution of LUS scores in each lung area.

Results

From July 2021 to December 2021, 122 consecutive patients were enrolled. No typical atelectasis was observed 5 min after intubation. The incidence of atelectasis was 52.4%, 50.0% and 42.5% in the C group, P group and RP group at the end of surgery, respectively. The rate of atelectasis in the C group, P group and RP group (after RMs) was 52.4%, 50.0% and 17.5%, respectively, 15 min after extubation (P < 0.01). The frequency of postoperative hypoxemia was 27.5%, 15.0% and 5.0% in the C group, P group and RP group, respectively (P < 0.017). The increased LUS scores mainly occurred in the superoposterior and inferoposterior quadrants at the end of surgery. Only in the RP group demonstrated a decreased LUS score in the posteriorquadrants after extubation.

Conclusions

In patients undergoing major open upper abdominal surgery, an intraoperative mechanical ventilation strategy without PEEP or with PEEP alone did not reduce PPCs. However, PEEP of 5 cmH₂O combined with LUS-guided RMs proved feasible and beneficial to decrease the occurrence of postoperative atelectasis and hypoxemia in major open upper abdominal surgeries.

Effect of electrical impedance-guided PEEP in reducing pulmonary complications after craniotomy: study protocol for a randomized controlled trial

Objective

The purpose of this study is to explore whether electrical impedance tomography (EIT)-guided individualized positive end-expiratory pressure (PEEP) can reduce the incidence of pulmonary complications within 1 week following a craniotomy compared with a single PEEP (PEEP = 6 cmH₂O) from dura suturing to extubation.

Methods

A randomized controlled trial will be conducted at the Second Affiliated Hospital of Soochou University. Five hundred forty patients undergoing a craniotomy in the supine position will be randomly allocated into the P6 (PEEP = 6 cmH₂O) or Pi (individualized PEEP) group. Both groups of patients will receive a lung recruitment maneuver before suturing the dura. Then, the P6 group will receive 6 cmH₂O PEEP, and the Pi group will receive EIT-guided individualized PEEP. The incidence and severity score of pulmonary complications within 1 week following surgery, the lung ultrasound score (LUS), regional cerebral oxygen saturation (rScO₂), and PaO₂/FiO₂ before anesthesia (T0), 10 min after extubation (T1), 24 h after extubation (T2), and 72 h after extubation (T3) will be compared between the two groups. The duration of surgery and anesthesia, the level and duration of PEEP during surgery, the volume of liquid intake and output during surgery, and the postoperative ICU and hospital stays will be recorded. The main outcome of this study will be the incidence of pulmonary complications within 1 week after surgery.

Discussion

The purposes of this study are to determine whether EIT-guided individualized PEEP from the beginning of dura suturing to extubation reduces the incidence of pulmonary complications within 1 week after a craniotomy compared with a single constant PEEP and to evaluate the length of ICU and hospital stays. If our results are positive, this study will show that EIT-guided individualized PEEP is better than a single constant PEEP and can further improve the prognosis of neurosurgical patients and reduce hospitalization costs, which will promote the wide application of individualized PEEP in clinical anesthesia.

Trial registration

Chinese Clinical Trial Registry CHiCTR2100051200. Registered on 15 September 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06751-6.

A structured narrative review of clinical and experimental studies of the use of different positive end-expiratory pressure levels during thoracic surgery

OBJECTIVES

This study aimed to present a review on the general effects of different positive end-expiratory pressure (PEEP) levels during thoracic surgery by qualitatively categorizing the effects into detrimental, beneficial, and inconclusive.

DATA SOURCE

Literature search of Pubmed, CNKI, and Wanfang was made to find relative articles about PEEP levels during thoracic surgery. We used the following keywords as one-lung ventilation, PEEP, and thoracic surgery.

RESULTS

We divide the non-individualized PEEP value into five grades, that is, less than 5, 5, 5-10, 10, and more than 10 cmH₂ O, among which 5 cmH₂ O is the most commonly used in clinic at present to maintain alveolar dilatation and reduce the shunt fraction and the occurrence of atelectasis, whereas individualized PEEP, adjusted by test titration or imaging method to adapt to patients' personal characteristics, can effectively ameliorate intraoperative oxygenation and obtain optimal pulmonary compliance and better indexes relating to respiratory mechanics.

CONCLUSIONS

Available data suggest that PEEP might play an important role in one-lung ventilation, the understanding of which will help in exploring a simple and economical method to set the appropriate PEEP level.

The effects of laryngeal mask airway versus endotracheal tube on atelectasis in patients undergoing general anesthesia assessed by lung ultrasound: A protocol for a prospective, randomized controlled trial

Background

The incidence of atelectasis is high in patients undergoing general anesthesia. This may cause oxygenation impairment and further contribute to postoperative pulmonary complications (PPCs). As important airway management devices for general anesthesia, few studies have compared the effects of laryngeal mask airway (LMA) and endotracheal tube (ETT) on atelectasis. Additionally, lung ultrasound has been increasingly used for bedside atelectasis diagnosis. For the above considerations, this trial is designed to compare the effects of LMA and ETT on atelectasis assessed by lung ultrasound scores, further providing more powerful clinical evidence for perioperative respiratory management of non-laparoscopic elective lower abdominal surgery under general anesthesia.

Methods

This is a prospective, single-center, single-blind, randomized controlled trial. From July 2021 to July 2022, 180 patients undergoing elective non-laparoscopic lower abdominal surgery under general anesthesia will be recruited and randomly divided into the ETT and LMA groups at a ratio of 1:1. The primary outcome is the total atelectasis LUS of 12 lung regions 15 min after the establishment of the artificial airway. The total atelectasis LUS at the end of surgery and 30 min after extubation, oxygenation index, postoperative airway complications, PPCs, and length of stay will be analyzed as secondary indicators.

Trial registration

ClinicalTrials.gov identifier: ChiCTR1900020818. Registered on January 20, 2019. Registered with the name of “Laryngeal mask airway versus endotracheal tube for atelectasis.” URL: https://www.chictr.org.cn/showproj.aspx?proj=35143.

Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial

Background

The majority of patients may experience atelectasis under general anesthesia, and the Trendelenburg position and pneumoperitoneum can aggravate atelectasis during laparoscopic surgery, which promotes postoperative pulmonary complications. Lung recruitment manoeuvres have been proven to reduce perioperative atelectasis, but it remains controversial which method is optimal. Ultrasonic imaging can be conducive to confirming the effect of lung recruitment manoeuvres. The purpose of our study was to assess the effects of ultrasound-guided alveolar recruitment manoeuvres by ultrasonography on reducing perioperative atelectasis and to check whether the effects of recruitment manoeuvres under ultrasound guidance (visual and semiquantitative) on atelectasis are superior to sustained inflation recruitment manoeuvres (classical and widely used) in laparoscopic gynaecological surgery.

Methods

In this randomized, controlled, double-blinded study, women undergoing laparoscopic gynecological surgery were enrolled. Patients were randomly assigned to receive either lung ultrasound-guided alveolar recruitment manoeuvres (UD group), sustained inflation alveolar recruitment manoeuvres (SI group), or no RMs (C group) using a computer-generated table of random numbers. Lung ultrasonography was performed at four predefined time points. The primary outcome was the difference in lung ultrasound score (LUS) among groups at the end of surgery.

Results

Lung ultrasound scores in the UD group were significantly lower than those in both the SI group and the C group immediately after the end of surgery (7.67 ± 1.15 versus 9.70 ± 102, difference, -2.03 [95% confidence interval, -2.77 to -1.29], P < 0.001; 7.67 ± 1.15 versus 11.73 ± 1.96, difference, -4.07 [95% confidence interval, -4.81 to -3.33], P < 0.001;, respectively). The intergroup differences were sustained until 30 min after tracheal extubation (9.33 ± 0.96 versus 11.13 ± 0.97, difference, -1.80 [95% confidence interval, -2.42 to -1.18], P < 0.001; 9.33 ± 0.96 versus 10.77 ± 1.57, difference, -1.43 [95% confidence interval, -2.05 to -0.82], P < 0.001;, respectively). The SI group had a significantly lower LUS than the C group at the end of surgery (9.70 ± 1.02 versus 11.73 ± 1.96, difference, -2.03 [95% confidence interval, -2.77 to -1.29] P < 0.001), but the benefit did not persist 30 min after tracheal extubation.

Conclusions

During general anesthesia, ultrasound-guided recruitment manoeuvres can reduce perioperative aeration loss and improve oxygenation. Furthermore, these effects of ultrasound-guided recruitment manoeuvres on atelectasis are superior to sustained inflation recruitment manoeuvres.

Trial registration

Chictr.org.cn, ChiCTR2100042731, Registered 27 January 2021, www.chictr.org.cn.

Effects of Driving Pressure-Guided Ventilation on Postoperative Pulmonary Complications in Prone-Positioned Patients Undergoing Spinal Surgery: A Randomized Controlled Clinical Trial

BACKGROUND

Prolonged spinal surgery in the prone position may lead to postoperative pulmonary complications (PPCs). We aimed to compare the effects of driving pressure-guided ventilation versus conventional protective ventilation on postoperative pulmonary complications in patients undergoing spinal surgery in the prone position. We hypothesized that driving pressure-guided ventilation would be associated with a decreased incidence of PPC.

METHODS

We enrolled 78 patients into this single-center, double-blind, randomized controlled trial. The driving pressure (DP) group (n = 40) received a tidal volume of 6 ml/kg of predicted body weight, individualized positive end-expiratory pressure (PEEP) which produced the lowest driving pressure (plateau pressure-PEEP), and a recruitment maneuver. The protective ventilation (PV) group (n = 38) received the same tidal volume and recruitment maneuver but with a fixed PEEP of 5 cm H₂O. Our primary outcome was postoperative pulmonary complications based on Lung Ultrasound Scores (LUS) at the end of the surgery and the simplified Clinical Pulmonary Infection Score (sCPIS) on postoperative days (POD) 1 and 3.

RESULTS

DP patients had lower LUS and POD1 sCPIS than the PV group (p < 0.01). DP patients had lower driving pressure during the surgery than PV patients (p < 0.01). Perioperative arterial blood gases and hemodynamic parameters were comparable between the two groups (p > 0.05). The visual pain score (VAS) in postoperative days, drainage, and lengths of stay (LOS) were also similar between the two groups (p > 0.05).

CONCLUSIONS

Driving pressure-guided ventilation during spinal surgery with a prolonged prone patient position may reduce the incidence of early postoperative pulmonary complications, compared with conventional protective ventilation.

Effect of sigh in lateral position on postoperative atelectasis in adults assessed by lung ultrasound: a randomized, controlled trial

Background

Postoperative atelectasis occurs in 90% of patients receiving general anesthesia. Recruitment maneuvers (RMs) are not always effective and frequently associated with barotrauma and hemodynamic instability. It is reported that many natural physiological behaviors interrupted under general anesthesia could prevent atelectasis and restore lung aeration. This study aimed to find out whether a combined physiological recruitment maneuver (CPRM), sigh in lateral position, could reduce postoperative atelectasis using lung ultrasound (LUS).

Methods

We conducted a prospective, randomized, controlled trial in adults with open abdominal surgery under general anesthesia lasting for 2 h or longer. Subjects were randomly allocated to either control group (C-group) or CPRM-group and received volume-controlled ventilation with the same ventilator settings. Patients in CPRM group was ventilated in sequential lateral position, with the addition of periodic sighs to recruit the lung. LUS scores, dynamic compliance (Cdyn), the partial pressure of arterial oxygen (PaO₂) and fraction of inspired oxygen (FiO₂) ratio (PaO₂/FiO₂), and other explanatory variables were acquired from each patient before and after recruitment.

Results

Seventy patients were included in the analysis. Before recruitment, there was no significant difference in LUS scores, Cdyn and PaO₂/FiO₂ between CPRM-group and C-group. After recruitment, LUS scores in CPRM-group decreased significantly compared with C-group (6.00 [5.00, 7.00] vs. 8.00 [7.00, 9.00], p = 4.463e-11 < 0.05), while PaO₂/FiO₂ and Cdyn in CPRM-group increased significantly compared with C-group respectively (377.92 (93.73) vs. 309.19 (92.98), p = 0.008 < 0.05, and 52.00 [47.00, 60.00] vs. 47.70 [41.00, 59.50], p = 6.325e-07 < 0.05). No hemodynamic instability, detectable barotrauma or position-related complications were encountered.

Conclusions

Sigh in lateral position can effectively reduce postoperative atelectasis even without causing severe side effects. Further large-scale studies are necessary to evaluate it’s long-term effects on pulmonary complications and hospital length of stay.

Trial registration

ChiCTR1900024379. Registered 8 July 2019, 

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01748-9.

The effect of ultrasound-guided lung recruitment maneuvers on atelectasis in lung-healthy patients undergoing laparoscopic gynecologic surgery: a randomized controlled trial

BACKGROUND

Atelectasis is the primary cause of hypoxemia during general anesthesia. This study aimed to evaluate the impact of the combination of recruitment maneuvers (RM) and positive end-expiratory pressure (PEEP) on the incidence of atelectasis in adult women undergoing gynecologic laparoscopic surgery using pulmonary ultrasound.

METHODS

In this study, 42 patients with healthy lungs undergoing laparoscopic gynecologic surgery were randomly divided into the recruitment maneuver group (RM group; 6 cm H₂O PEEP and RM) or the control group (C group; 6 cm H₂O PEEP and no RM), 21 patients in each group. Volume-controlled ventilation was used in all selected patients, with a tidal volume of 6-8 mL·kg^-1 of ideal body weight. When atelectasis was detected, patients in the RM group received ultrasound-guided RM, while those in the C group received no intervention. The incidence and severity of atelectasis were determined using lung ultrasound scores.

RESULTS

A total of 41 patients were investigated. The incidence of atelectasis was lower in the RM group (40%) than in the C group (80%) 15 min after arrival in the post-anesthesia care unit (PACU). Meanwhile, lung ultrasound scores (LUSs) were lower in the RM group compared to the C group. In addition, the differences in the LUS between the two groups were mainly due to the differences in lung ultrasound scores in the posterior regions. However, this difference did not persist after 24 h of surgery.

CONCLUSIONS

In conclusion, the combination of RM and PEEP could reduce the incidence of atelectasis in patients with healthy lungs 15 min after arrival at the PACU; however, it disappeared within 24 h after surgery.

TRIAL REGISTRATION

(Prospectively registered): ChiCTR2000033529 . Registered on 4/6/2020.

Use of point-of-care ultrasound in the diagnosis and treatment of pulmonary oedema in an infant

This case demonstrates the value of perioperative point-of-care ultrasound for rapid bedside evaluation and treatment of pulmonary oedema in an infant. A nine-week-old male infant undergoing cleft lip repair received significant intravenous fluid resuscitation for intraoperative hypotension. After uneventful extubation, he developed increased work of breathing and a gradual decline in oxygen saturation despite supplemental oxygen by way of a facemask. Lung point-of-care ultrasound revealed confluent B-lines in multiple lung fields, consistent with pulmonary oedema, likely from fluid overload. He was treated with furosemide resulting in clinical improvement within 30 minutes.