Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - an observational study in 29 countries

Abstract

Background: Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients.

Objectives: To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs.

Design: This was a prospective international 1-week observational study using the 'Assess Respiratory Risk in Surgical Patients in Catalonia risk score' (ARISCAT score) for PPC for risk stratification.

Patients and setting: Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries.

Main outcome measures: The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes.

Results: A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure.

Conclusion: The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.

Trial registration: The study was registered at Clinicaltrials.gov, number NCT01601223.

Fig. 1

Flow chart: Data collection and selection of centres and patients. Two centres used the optional randomisation program to reduce the number of patients: one centre reduced the patient numbers by 50% (excluding 75 patients) and another centre by 75% (excluding 307 patients). ARISCAT, Assess Respiratory Risk in Surgical Patients in Catalonia; IRB, institutional review board.

Fig. 2

Ventilation parameters in patients at increased vs. patients at low risk of PPCs. (a) Cumulative frequency distribution of tidal volume; (b) cumulative frequency distribution of positive end-expiratory pressure; (c) cumulative distribution of peak pressure; (d) cumulative distribution of driving pressure. PBW, predicted body weight; PEEP, positive end-expiratory pressure; PPC, postoperative pulmonary complications; V_T, tidal volume.

Fig. 3

Scatterplots showing distribution of (a) tidal volume with positive end-expiratory pressure combinations; (b) tidal volume with peak pressure; (c) tidal volume with driving pressure; (d) tidal volume with respiratory rate in patients at increased vs. patients at low risk of PPCs. bpm, breaths per minute; PBW, predicted body weight; PEEP, positive end-expiratory pressure; PPC, postoperative pulmonary complications; V_T, tidal volume.

Fig. 4

Outcome in patients at increased vs. patients at low risk of PPCs. (a) Probability of development of PPCs; (b) probability of hospital discharge; and (c) probability of in-hospital mortality. PPC, postoperative pulmonary complications.

Fig. 5

Outcome in patients at low, moderate, and high risk of PPCs: (a) probability of development of PPCs; (b) probability of hospital discharge; and (c) probability of in-hospital mortality. PPC, postoperative pulmonary complications.