Risk factors for PPCs in laparoscopic non-robotic vs. laparoscopic robotic abdominal surgery (LapRas): rationale and protocol for a patient-level analysis of LAS VEGAS and AVATaR.

INTRODUCTION: Postoperative pulmonary complications (PPCs) vary amongst different surgical techniques. We aim to compare the incidence of PPCs after laparoscopic non-robotic versus laparoscopic robotic abdominal surgery. METHODS AND ANALYSIS: LapRas (Risk Factors for PPCs in Laparoscopic Non-robotic vs Laparoscopic robotic abdominal surgery) incorporates harmonized data from 2 observational studies on abdominal surgery patients and PPCs: 'Local ASsessment of VEntilatory management during General Anaesthesia for Surgery' (LAS VEGAS), and 'Assessment of Ventilation during general AnesThesia for Robotic surgery' (AVATaR). The primary endpoint is the occurrence of one or more PPCs in the first five postoperative days. Secondary endpoints include the occurrence of each individual PPC, hospital length of stay and in-hospital mortality. Logistic regression models will be used to identify risk factors for PPCs in laparoscopic non-robotic versus laparoscopic robotic abdominal surgery. We will investigate whether differences in the occurrence of PPCs between the two groups are driven by differences in duration of anesthesia and/or the intensity of mechanical ventilation. ETHICS AND DISSEMINATION: This analysis will address a clinically relevant research question comparing laparoscopic and robotic assisted surgery. No additional ethical committee approval is required for this metanalysis. Data will be shared with the scientific community by abstracts and original articles submitted to peer-reviewed journals. REGISTRATION: The registration of this post-hoc analysis is pending; individual studies that were merged into the used database were registered at clinicaltrials.gov: LAS VEGAS with identifier NCT01601223, AVATaR with identifier NCT02989415.

Epidemiology, ventilation management and outcome in patients receiving intensive care after non-thoracic surgery - Insights from the LAS VEGAS study.

INTRODUCTION AND OBJECTIVES: Information about epidemiology, ventilation management and outcome in postoperative intensive care unit (ICU) patients remains scarce. The objective was to test whether postoperative ventilation differs from that in the operation room. MATERIAL AND METHODS: This was a substudy of the worldwide observational LAS VEGAS study, including patients undergoing non-thoracic surgeries. Of 146 study sites participating in the LAS VEGAS study, 117 (80%) sites reported on the postoperative ICU course, including ventilation and complications. The coprimary outcomes were two key elements of ventilator management, i.e., tidal volume (VT) and positive end-expiratory pressure (PEEP). Secondary outcomes included the proportion of patients receiving low VT ventilation (LTVV, defined as ventilation with a median VT < 8.0 ml/kg PBW), and the proportion of patients developing postoperative pulmonary complications (PPC), including ARDS, pneumothorax, pneumonia and need for escalation of ventilatory support, ICU and hospital length of stay, and mortality at day 28. RESULTS: Of 653 patients who were admitted to the ICU after surgery, 274 (42%) patients received invasive postoperative ventilation. Median postoperative VT was 8.4 [7.3-9.8] ml/kg predicted body weight (PBW), PEEP was 5 [5-5] cm H2O, statistically significant but not meaningfully different from median intraoperative VT (8.1 [7.3-8.9] ml/kg PBW; P < 0.001) and PEEP (4 [2-5] cm H2O; P < 0.001). The proportion of patients receiving LTVV after surgery was 41%. The PPC rate was 10%. Length of stay in ICU and hospital was independent of development of a PPC, but hospital mortality was higher in patients who developed a PPC (24 versus 4%; P < 0.001). CONCLUSIONS: In this observational study of patients undergoing non-thoracic surgeries, postoperative ventilation was not meaningfully different from that in the operating room. Like in the operating room, there is room for improved use of LTVV. Development of PPC is associated with mortality.

Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) With Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients: A Randomized Clinical Trial.

Importance: An intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain. Objective: To determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP. Design, Setting, and Participants: Randomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018. Interventions: Patients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight. Main Outcomes and Measures: The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute). Results: Among 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P = .23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P < .001). Conclusions and Relevance: Among obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications. Trial Registration: ClinicalTrials.gov Identifier: NCT02148692.

Association between night-time surgery and occurrence of intraoperative adverse events and postoperative pulmonary complications.

BACKGROUND: The aim of this post hoc analysis of a large cohort study was to evaluate the association between night-time surgery and the occurrence of intraoperative adverse events (AEs) and postoperative pulmonary complications (PPCs). METHODS: LAS VEGAS (Local Assessment of Ventilatory Management During General Anesthesia for Surgery) was a prospective international 1-week study that enrolled adult patients undergoing surgical procedures with general anaesthesia and mechanical ventilation in 146 hospitals across 29 countries. Surgeries were defined as occurring during 'daytime' when induction of anaesthesia was between 8:00 AM and 7:59 PM, and as 'night-time' when induction was between 8:00 PM and 7:59 AM. RESULTS: Of 9861 included patients, 555 (5.6%) underwent surgery during night-time. The proportion of patients who developed intraoperative AEs was higher during night-time surgery in unmatched (43.6% vs 34.1%; P<0.001) and propensity-matched analyses (43.7% vs 36.8%; P=0.029). PPCs also occurred more often in patients who underwent night-time surgery (14% vs 10%; P=0.004) in an unmatched cohort analysis, although not in a propensity-matched analysis (13.8% vs 11.8%; P=0.39). In a multivariable regression model, including patient characteristics and types of surgery and anaesthesia, night-time surgery was independently associated with a higher incidence of intraoperative AEs (odds ratio: 1.44; 95% confidence interval: 1.09-1.90; P=0.01), but not with a higher incidence of PPCs (odds ratio: 1.32; 95% confidence interval: 0.89-1.90; P=0.15). CONCLUSIONS: Intraoperative adverse events and postoperative pulmonary complications occurred more often in patients undergoing night-time surgery. Imbalances in patients' clinical characteristics, types of surgery, and intraoperative management at night-time partially explained the higher incidence of postoperative pulmonary complications, but not the higher incidence of adverse events. CLINICAL TRIAL REGISTRATION: NCT01601223.

Intraoperative ventilation settings and their associations with postoperative pulmonary complications in obese patients.

BACKGROUND: There is limited information concerning the current practice of intraoperative mechanical ventilation in obese patients, and the optimal ventilator settings for these patients are debated. We investigated intraoperative ventilation parameters and their associations with the development of postoperative pulmonary complications (PPCs) in obese patients. METHODS: We performed a secondary analysis of the international multicentre Local ASsessment of VEntilatory management during General Anesthesia for Surgery' (LAS VEGAS) study, restricted to obese patients, with a predefined composite outcome of PPCs as primary end-point. RESULTS: We analysed 2012 obese patients from 135 hospitals across 29 countries in Europe, North America, North Africa, and the Middle East. Tidal volume was 8.8 [25th-75th percentiles: 7.8-9.9] ml kg-1 predicted body weight, PEEP was 4 [1-5] cm H2O, and recruitment manoeuvres were performed in 7.7% of patients. PPCs occurred in 11.7% of patients and were independently associated with age (P<0.001), body mass index ≥40 kg m-2 (P=0.033), obstructive sleep apnoea (P=0.002), duration of anaesthesia (P<0.001), peak airway pressure (P<0.001), use of rescue recruitment manoeuvres (P<0.05) and routine recruitment manoeuvres performed by bag squeezing (P=0.021). PPCs were associated with an increased length of hospital stay (P<0.001). CONCLUSIONS: Obese patients are frequently ventilated with high tidal volume and low PEEP, and seldom receive recruitment manoeuvres. PPCs increase hospital stay, and are associated with preoperative conditions, duration of anaesthesia and intraoperative ventilation settings. Randomised trials are warranted to clarify the role of different ventilatory parameters in obese patients. CLINICAL TRIAL REGISTRATION: NCT01601223.

Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE): study protocol for a randomized controlled trial.

BACKGROUND: Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise hemodynamics, and the effects on PPCs are uncertain. We hypothesized that intraoperative mechanical ventilation using high PEEP with periodic recruitment maneuvers, as compared with low PEEP without recruitment maneuvers, prevents PPCs in obese patients. METHODS/DESIGN: The PRotective Ventilation with Higher versus Lower PEEP during General Anesthesia for Surgery in OBESE Patients (PROBESE) study is a multicenter, two-arm, international randomized controlled trial. In total, 2013 obese patients with body mass index ≥35 kg/m2 scheduled for at least 2 h of surgery under general anesthesia and at intermediate to high risk for PPCs will be included. Patients are ventilated intraoperatively with a low tidal volume of 7 ml/kg (predicted body weight) and randomly assigned to PEEP of 12 cmH2O with lung recruitment maneuvers (high PEEP) or PEEP of 4 cmH2O without recruitment maneuvers (low PEEP). The occurrence of PPCs will be recorded as collapsed composite of single adverse pulmonary events and represents the primary endpoint. DISCUSSION: To our knowledge, the PROBESE trial is the first multicenter, international randomized controlled trial to compare the effects of two different levels of intraoperative PEEP during protective low tidal volume ventilation on PPCs in obese patients. The results of the PROBESE trial will support anesthesiologists in their decision to choose a certain PEEP level during general anesthesia for surgery in obese patients in an attempt to prevent PPCs. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02148692. Registered on 23 May 2014; last updated 7 June 2016.

Positive end-expiratory pressure following coronary artery bypass grafting.

BACKGROUND: Cardiac surgery-related pulmonary complications include alterations in lung mechanics and anomalies in gas exchange. Higher levels of positive end-expiratory pressure (PEEP) have been suggested to benefit cardiac surgical patients. We compared respiratory compliance, arterial oxygenation and time till tracheal extubation in 2 cohorts of patients weaned from mechanical ventilation with different levels of PEEP after elective and uncomplicated coronary artery bypass grafting (CABG). We hypothesized that higher PEEP levels improve pulmonary compliance and gas exchange in the first hours of weaning from mechanical ventilation, but not to shorten time till tracheal extubation. METHODS: Secondary retrospective analysis of 2 randomized controlled trials: in the first trial patients were weaned with PEEP levels of 10 cmH2O for the first 4 hours followed by PEEP levels of 5 cmH2O until tracheal extubation (high PEEP, HP); and the second trial patients were weaned with PEEP levels of 5 cmH2O during the entire weaning phase (low PEEP, LP). The primary endpoint was pulmonary compliance. Secondary endpoints included arterial oxygenation, duration of mechanical ventilation and postoperative pulmonary complications. RESULTS: The analysis included 121 patients; 60 HP patients and 61 LP patients. Baseline characteristics were similar. Compared to LP patients, HP patients had a better pulmonary compliance, 47.2±14.1 versus 42.7±10.2 ml/cmH2O (P<0.05), and higher levels of PaO2, 18.5±6.6 (138.75±49.5) versus 16.7±5.4 (125.25±40.5) kPa (mmHg) (P<0.05). Patients in the HP group were less frequent in need of supplementary oxygen after ICU discharge. These differences remained present during the entire weaning phase, even after reduction of PEEP. However, HP patients had a longer time till tracheal extubation, 16.9±6.1 versus 10.5±5.0 hours (P<0.001). HP patients had longer durations of postoperative infusion of propofol, 4.9 (2.6-7.4) versus 3.5 (1.8-5.8) hours (P<0.05). There were no differences in use of inotropes. Cumulative fluid balances were slightly higher in HP patients. CONCLUSION: Use of higher PEEP levels after elective uncomplicated CABG improves pulmonary compliance and oxygenation but seems to be associated with a delay in tracheal extubation.