Canadian Journal of Anesthesia, Vol 26, 322-327, Copyright © 1979 by Canadian Anesthesiologists' Society

Anaesthetic Considerations in Idiopathic Orthostatic Hypotension and the Shy-Drager Syndrome

¹ Department of Anaesthesia, University of Toronto, Toronto Western Hospital, Toronto, Ontario

Address reprint requests to: R.R. Crago, Toronto, Western Hospital, 399 Bathurst Street, Toronto, Ontario, Canada, M5T 2S8.

Orthostatic hypotension due to autonomic failure may occur secondary to systemic disease states (notably diabetes) or as a disease entity in its own right with a variable degree of neurological involvement that has resulted in a confused classification. The diagnosis, classification and treatment of these latter forms of orthostatic hypotension is reviewed. The pathology is in the central and efferent autonomic pathway, resulting in a disordered baro-receptor reflex, postural hypotension, abnormal responses to tilting and the Valsalva manuvre, an inappropriately fixed heart rate and other autonomic features. Anaesthesia may be associated with profound hypotension and some of the signs of anaesthesia may be absent. The response to cardiac depressant drugs and reduction of circulating blood volume may be exaggerated due to absence of compensatory mechanisms. The response to vasoactive agents is unpredictable. The importance of preoperative evaluation, monitoring during operation and the careful selection of anaesthetic agents and techniques is discussed.