The Effect of Intraoperative Cerebral Oxygen Desaturation on Post-Operative Delirium in Thoracic Surgical Patients: A Pilot Study

This will be a prospective, observational study on 200 patients. Consenting thoracic surgical patients presenting for open thoracotomy or VATS will be assessed pre-operatively for baseline cognitive status and clinically relevant risk factors for delirium. Intra-operatively, patients will undergo cerebral oxygenation monitoring using near infra-red spectroscopy cerebral oximetry. Postoperatively, patients will be assessed twice daily for the presence or absence of delirium using the Confusion Assessment Methodology (CAM) scoring system during their hospital stay.

A clinically relevant desaturation will be defined as a 25% decrease from the patient's baseline saturation, which will be determined while the patient is breathing room air pre-operatively. The severity and duration of any desaturation will be recorded and subsequently analyzed for correlation with post-operative delirium. Bivariate associations between the risk of delirium and predictor variables will be sought. If appropriate, logistic regression models will be constructed with the outcome of delirium.

Significance: Previous studies at our centre have resulted in over 35% of thoracic surgical patients developing significant, intra-operative cerebral desaturation. We propose to study a convenience sample of 200 consecutive patients. Depending on the relative risk of developing delirium with a significant cerebral desaturation, this study may be adequately powered to determine the associated risk of delirium. This study will provide background information in planning further interventional trials to prevent desaturation and possibly reduce the incidence of delirium, as well as aid in the planning of larger multi-center trials to more accurately assess the risk of intra-operative decreases in cerebral oxygenation and the role this event contributes to the occurrence of delirium.