Postoperative Atelectasis Prevention by Application of PEEP and Pressure Support Ventilation: a Prospective Randomized Controlled Trial

General anaesthesia is known to promote lung collapse (atelectasis) which will persist in the postoperative period. Inflating the lung to a pressure of 40 cmH2O, called a vital capacity manoeuvre (VCM), performed a few minutes before extubation followed by the use of 40% of O2 will prevent postoperative atelectasis formation. This is not the case if VCM is followed by application of 100% of O2. However the use of 100% of O2 before tracheal extubation is still recommended for safety reason. Application of PEEP associated with pressure controlled ventilation before intubation prevents atelectasis formation despite the use of 100% of O2. The goal of our study was to show that performing a VCM 15 minutes before arousal followed by application of PEEP and pressure support ventilation (PSV) before and after tracheal extubation will prevent the recurrence of atelectasis despite the use of 100% of O2.

Materials and Methods With the ethic committee for research on human beings approval, the investigators randomly assigned 16 non-obese patients scheduled for a gynaecological laparoscopic surgery in two groups. At the end of the surgery the investigators performed a VCM (40cmH2O applied for 12 seconds), then O2 was increased to 100% in both groups. In the patients of the study group, a PEEP of 6 cmH2O was applied associated with a PSV of 8 cmH2O. This was continued after the extubation for 3 minutes. The O2 was then decreased to 40% and, when the expired oxygen saturation was < 50%, PEEP and PSV were removed. For the patients in the control group, no positive pressure was applied during spontaneous ventilation (PEEP = 0 and no PSV). The atelectasis were then measured by computed tomographic scanning.