Canadian Journal of Anesthesia, Vol 3, 258-264, Copyright © 1956 by Canadian Anesthesiologists' Society

The Cardiovascular Reflexes

¹ Department of Anaesthesia, McGill University, Montreal

The carotid sinus and aortic arch pressure reflexes are of supreme importance in the regulation of the circulation. They are tonically activated by normal physiological stimuli.

The physiological rôle of the carotid and aortic body chemoreflexes in hemorrhagic shock has been described.

Certain recently discovered reflexes, which may be important in normal physiology, have been briefly mentioned.

The physiological purpose of the venous pressure receptors is not yet established.

Deeper planes of anaesthesia depress the sino-aortic pressure reflex mechanism, and on this account fall of blood pressure due to surgical trauma is liable to occur. Light planes of anaesthesia do not depress this protective compensatory mechanism. However, during light planes of anaesthesia certain detrimental reflexes may be evoked by non-physiological stimuli associated with surgical procedure. The nature of a number of these untoward reflexes–carotid sinus, intrathoracic, and cehac plexus–has been reviewed Reflex disturbances occurring during neurosurgery and in individuals with spinal cord injuries have also been mentioned.