New concepts of atelectasis during general anaesthesia.

At the beginning of the last century, Pasteur described postoperative pulmonary atelectasis, analysed postoperative pulmonary complications (PCC; see below) and noted: `when the true history of postoperative lung complications comes to be written, active collapse of the lung, from de®ciency of inspiratory power, will be found to occupy an important position among determining causes'. Indeed, atelectasis occurs regularly during general anaesthesia induction, persists postoperatively and may contribute to signi®cant morbidity 8 and additional healthcare costs. This review article will review the mechanism of perioperative atelectasis, discuss its clinical signi®cance and describe preventive measures.