Constitutional factors promoting development of atelectasis during anaesthesia.

The extent of atelectasis was correlated to constitutional factors in 38 patients who underwent computed tomography prior to and during general anaesthesia with halothane. All patients but two developed atelectasis in dependent regions of both lungs immediately after induction of anaesthesia prior to surgery. The transverse area of the densities ranged from 0 to 27 cm2, and there were no significant differences between patients of different age or sex, or with different smoking habits. A significant linear regression was found between Broca's index weight (kg)/height (cm)-100 and the area of the densities, and also between an index describing the shape of the thorax and the density area. Thus, patients who were overweight and/or had a low and wide thorax tended to develop more extensive atelectasis during anaesthesia. This finding might partly explain why overweight patients develop postoperative pulmonary complications more often than non-obese patients.