Changes in tissue pH after circulatory arrest

¹ Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi

The circulation of dogs was stopped by fibrillation of the heart, and needle pH electrodes were placed in various tissues of dogs. The pH electrodes were connected to a continuous recording pH meter and the pH of the tissues was measured for a period of 1 hour following circulatory arrest. A few incidental studies on metabolic inhibitors, hypothermia and alkalinizing agents were made in addition to studies on the normal animals. It was found that the initial pH in the normal animals was 7.2–7.3, but within a short period of time decreased to values lethal to an animal with a normal circulation. The cerebral cortex showed the most rapid decrease in pH following circulatory arrest. The injection of sodium bicarbonate before circulatory arrest was of little value in preventing the development of acidity. Oxythiamine was effective in preventing the development of severe acidity but appears of little practical use. Hypothermia to 25°C proved effective in retarding the development of severe acidity in the two animals studied.