Canadian Journal of Anesthesia, Vol 11, 123-146, Copyright © 1964 by Canadian Anesthesiologists' Society

The Control of the Acid-Base Balance during Open-Heart Surgery

¹ Department of Surgery, The University of Manitoba, Winnipeg Children's Hospital, and Winnipeg General Hospital Work supported by the Manitoba Heart Foundation

Many aspects of the acid-base balance during extracorporeal circulation and during hypothermia are still problematic. In this paper the theoretical background is reviewed which led to the adoption of the following working hypothesis.

The acid-base balance has a direct influence on two important aspects of cardiopulmonary bypass. During bypass a high carbon dioxide tension wii ensure an adequate cerebral blood flow and at the end of the bypass a low pH is said to facilitate defibrillation. Both these condition can be created by avoiding excessive hyperventilation of the patient before bypass and by increasing the _pCO₂ during bypass. The arterial _pCO₂ was controlled by varying the volume of the O₂/CO₂ gas mixture delivered to the oxygenator.

The method has been employed in 72 consecutive patients. The acid-base balance was monitored using Astrup's apparatus Large pH shifts were avoided and clinically the patients appeared to do well under this type of management.

The rationale of the concept is discussed and it is concluded that it has been of benefit for the patients upon whom it was used.

Note:

Presented, in part, at the Annual Meeting, The Royal College of Physicians and Surgeons of Canada, Edmonton, Alberta, January 17, 1963

Medical College, Winnipeg 3, Manitoba