[Peroperative pneumothorax in thoracotomy: the value of pulse oximetry].

Two cases of pneumothorax occurring during thoracotomy under one-lung ventilation are reported. One case occurred before pneumonectomy was carried out. The decrease in Spo2 shown by pulse oximetry, together with the increase in airway pressures, rapidly led to the diagnosis of pneumothorax. In the other case, the accident occurred after pneumonectomy, with a suddenly impossible ventilation, and a drastic decrease in Spo2 leading to hypoxic circulatory arrest. Hypoxaemia occurring during one-lung ventilation may be due to different causes. Shunting in the upper part of the lung is the main cause, but other diagnoses must be discussed, such as airway obstruction by blood or sputum, displacement of the selective endotracheal tube, bronchospasm, and pneumothorax. Monitoring of Spo2 by pulse oximetry would therefore seem to be mandatory during thoracic surgery, in order to allow an early diagnosis of hypoxaemia and speed up the treatment of its cause.