Are electrocardiogram changes the first sign of impending peri-operative pneumothorax?

A patient in the right lateral position underwent left nephrectomy, after which he was placed supine for insertion of an arteriovenous fistula. All haemodynamic and respiratory values, including peak inspiratory pressure, were within normal limits and unchanged from baseline measurements. However, following the position change we noted that the amplitude of the electrocardiogram complexes were dramatically reduced. Our differential diagnosis included the possibility of a pneumothorax, which was subsequently confirmed by both physical examination and chest X ray. A chest drain was planned to be inserted at the end of the surgery, but 25 min after the electrocardiogram changes were noted, the patient's vital signs suddenly deteriorated. Emergency treatment for pneumothorax was instituted with good effect. The diagnostic use of the electrocardiogram and the treatment of this intra-operative pneumothorax are discussed.