Canadian Journal of Anesthesia, Vol 10, 72-82, Copyright © 1963 by Canadian Anesthesiologists' Society

Diffusion in Anaesthesia

¹ Department of Anaesthesia, The Vancouver General Hospital, Vancouver, British Columbia
² Clinical Assistant Professor, Surgery, Division of Anaesthesia, University of British Columbia, and Medical Faculty, The Vancouver General Hospital
³ Director of Anaesthesiology, The Vancouver General Hospital, and Clinical Associate Professor of Surgery, Medical Faculty, University of British Columbia

1. Diffusion of gases may be described by the equation

V=[Sd(P_a-P_c)t]/x.

2. Gas travels from the environment to the blood through the following: (a) mass flow down the trachea, (b) diffusion across the alveoli, (c) diffusion through the lung membrane, (d) diffusion through the plasma and into the red cell.

3. Diffusion of oxygen, which is relatively insoluble depends on a gradient for oxygen between the alveolus and the capillary and on the time of contact of blood and alveolar air.

4. Nitrogen and inert gases equilibrate rapidly and are not affected by diseases affecting the pulmonary membrane.

5. Carbon dioxide diffuses readily because of its high solubility.

6. Alveolar capillary block and diffusion respirations are described and some anaesthetic considerations given.