Intra-operative adherence to lung-protective ventilation: a prospective observational study

BACKGROUND Lung-protective ventilation in patients with acute respiratory distress syndrome improves mortality. Adopting this strategy in the perioperative period has been shown to reduce lung inflammation and postoperative pulmonary and non-pulmonary sepsis complications in patients undergoing major abdominal surgery. We conducted a prospective observational study into the intra-operative ventilation practice across the West Midlands to assess the use of lung-protective ventilation. METHODS Data was collected from all adult ventilated patients undergoing surgery across 14 hospital trusts in the West Midlands over a 2-day period in November 2013. Data collected included surgical specialty, patient's biometric data, duration of procedure, grade of anesthetist, and ventilatory parameters. Lung-protective ventilation was defined as the delivery of a tidal volume between 6 and 8 ml/kg/predicted body weight, a peak pressure of less than 30 cmH2O, and the use of positive end expiratory pressure of 6-8 cmH2O. Categorical data are presented descriptively, while non-parametric data are displayed as medians with statistical tests from Mann-Whitney U tests or Kruskal-Wallis tests for independent samples while paired samples are represented by Wilcoxon signed rank tests. RESULTS Four hundred six patients with a median age of 56 years (16-91) were included. The majority of operations (78 %) were elective procedures with the principal anesthetist being a consultant. The commonest surgical specialties were general (29 %), trauma and orthopedic (19 %), and ENT (17 %). Volume-controlled ventilation was the preferred ventilation strategy in 70 % of cases. No patients were ventilated using lung-protective ventilation. Overall peak airway pressure (pPeak) was low (median 20 cmH2O (inter-quartile range [IQR] 10-43 cmH2O)) with median delivered tidal volumes of 8.4 ml/kg/predicted body weight (PBW) (IQR 3.5-14.5 ml/kg/PBW). The median positive end expiratory pressure (PEEP) was only 4 cmH2O (0-5 cmH2O) with PEEP not used in 152 cases. CONCLUSIONS Perioperative lung protection ventilation can improve patient outcomes from major surgery. This large prospective study demonstrates that within the West Midlands lung-protective ventilation during the perioperative period is uncommon, especially in relation to the use of PEEP, and that perhaps further trials are required to promote wider adoption of practice.