Effect of a lung recruitment strategy lung gas function during general anaesthesia

A major contributor to postoperative pulmonary complications after major surgery is collapse (atelectasis) in poorly ventilated lung segments during and after general anaesthesia (GA). Atelectasis arises from the reduced muscle tone caused by nearly all anaesthetics,and the non-physiological pattern of distribution of ventilation that characterizes controlled mechanical positive pressure ventilation (CMV), and occurs early in the course of anaesthesia. Strategies to reduce lung atelectasis and postoperative pulmonary complications include the use of positive end-expiratory pressure (PEEP) and lung recruitment manoeuvres. Recently, Maquet Critical Care AB (Sweden) have released a new functionality on their Flow-i anaesthesia machine which allows targeted lung recruitment using a stepped increase in PEEP and lung inflation pressures. The system simultaneously monitors airway pressures and dynamic lung compliance, The latter is used to identify the optimal level of PEEP to minimize lung atelectasis, where measured dynamic lung compliance (Cdyn) is maximal. We wish to measure the effectiveness of this new technology on improving lung function and gas exchange in patients under GA for elective surgery.