Postoperative delirium: treatment with supplementary oxygen.

We have assessed postoperative delirium in 24 patients undergoing thoracotomy for pulmonary malignancy throughout their stay in hospital. Arterial oxygen saturation was measured with a pulse oximeter on the night before operation and on the second night after operation. Five patients (21%) developed clinically significant postoperative delirium, and delirium occurred in all patients who had inadequate oxygenation. All cases of delirium occurred on day 3 after surgery. Factors which were not associated with delirium were age, intake of alcohol or consumption of drugs before operation, fever, type of operation, duration of surgery, anxiety and psychosocial stress before operation, postoperative metabolic derangement or hypotension during operation. Mean arterial oxygen saturation on the second night after operation (the night preceding delirium) was smaller in patients with delirium than in other patients (median 88% vs 95%, P < 0.05). When patients were delirious, the first treatment of choice was supplementary oxygen and all patients were treated successfully by this simple regimen. In two patients, supplementary treatment with zuclopenthixol 6 mg daily was necessary. We conclude that hypoxaemia may be a contributing factor in postoperative brain dysfunction, as postoperative delirium was associated with hypoxaemia and was treated successfully with supplementary oxygen.