Cardiac function and cerebral blood flow in the beachchair surgical patient.

During shoulder surgery patients are commonly positioned into an upright sitting position for optimal access to the shoulder joint. In some patients blood pressure may decrease and a concern of the anaesthetist is whether sufficient blood reaches the brain during such surgery. Even though this can be routinely treated with cardiac drugs, the exact effect of this treatment on the brain is unknown. This study plans to investigate the changes in cardiac function and flow to the brain when patients are anaesthetised and placed upright. The surgery will be performed using the anaesthetic technique that we use for the majority of the surgeon’s cases. The patient will receive a nerve block that will anaesthetise the arm receiving surgery. This will be combined with a general anaesthetic. Special monitoring of the heart and blood flow using sound waves, and brain function using reflected light waves will be used. These techniques are both non-invasive and present no harm to the patient. The study will investigate whether the administration of medication to gently increase blood pressure has an effect on hypotension and blood flow to the brain. In addition postoperative cognitive recovery will be assessed via a questionaire. By agreeing to the study patients will give us permission to make these extra measurements during anaesthesia, in order to understand whether we are protecting the brain during surgery.