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

Abstract

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 H 2 O 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 H 2 O. 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 SpO 2 Յ92% 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.

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“…There was no significant difference in preoperative BMI or STOP-Bang scores of obese patients between the two groups, which suggests that the risk of suffering respiratory depression in both groups was similar. With reference to previous studies, 19,26 oxygen desaturation in our study was defined as SpO 2 <92% for ≥10 sec, and apnea was defined as an absence of respiratory effort ≥10 sec. We defined hypoxemia for SpO2<92% for ≥10 s to exclude the interference of the plethysmographic pulse waveform.…”

Effects of Protective Mechanical Ventilation With Different PEEP Levels on Alveolar Damage and Inflammation in a Model of Open Abdominal Surgery: A Randomized Study in Obese Versus Non-obese Rats

“…The PEEP levels tested in the present study (2 and 6 cmH 2 O) represented a two-fold increase compared with humans (4 and 12 cmH 2 O), due to differences in transpulmonary pressures between humans and rats (Caironi et al, 2011). These PEEP levels were previously tested in clinical studies (Nestler et al, 2017;Pereira et al, 2018;Bluth et al, 2019).…”

“…A multicenter, international randomized controlled trial (PROBESE) compared the effects of two different levels of intraoperative PEEP (4 cmH 2 O versus 12 cmH 2 O) during protective low-V T ventilation in obese patients and observed no differences in PPCs (Bluth et al, 2019). Taking into account species differences, the PEEP levels used in our study and in PROBESE are comparable, but comparison between these two studies is unwarranted, since laparoscopy and recruitment maneuvers were performed in most patients.…”

“…In an animal model of open abdominal surgery, both low-V T and moderate to high-PEEP and RMs resulted in lower driving pressure, mechanical power, and lung damage (Maia et al, 2017). The PROBESE trial (Bluth et al, 2019) compared high-PEEP and RM versus low-PEEP at low V T and found no significant differences in PPCs.…”

Protective ventilation from ICU to operating room: state of art and new horizons

“…In another study, the PROVHILO trial (2014) demonstrated that a strategy consisting of a high level of PEEP combined with RM during open abdominal surgery does not protect against PPC; the authors conclude that the perioperative protective ventilation strategy should include low V T and low PEEP without RM [88]. The recent multicenter PROBESE trial (2019) also demonstrated that setting a high PEEP of 12 cmH 2 O and using RM in obese patients (body mass index > 35 kg/m 2 ) is not associated with any reduction of PPC compared to a low level of PEEP (4 cmH 2 O) [89]. The rationale for higher intraoperative PEEP and RM in thoracic surgery with one-lung ventilation is being explored in the ongoing PROTHOR trial (NCT02963025) [90].…”