Cardio-respiratory changes during pneumoencephalography

Carbon-respiratory changes associated with changes in posture and injection of intrathecal oxygen were studied in fifeen patients undergoing pneumoencephalography in a Phillips isocentric chair, while breathing spontaneously and anaesthetised with halothane in oxygen. Haemodynamic changes associated with changes in posture were of a minor nature. A rise in PaCO2 occurred in the prone position in two obese patients. There were significant rises in blood pressure following injection of more than 5 ml of oxygen as a bolus into the subarachnoid space.