Variation in cardiac output with acid-base changes in the anesthetized dog

Studies were performed in dogs anesthetized with pentobarbital, 30 mg/kg, and ventilated mechanically during succinylcholine apnea in order to ascertain the variation in cardiac output under various acid-base conditions. The findings were: 1) metabolic acidosis decreases cardiac output; 2) increasing respiratory acidosis in the absence of severe metabolic acidosis causes increase in cardiac output; 3) increasing respiratory acidosis in the presence of severe metabolic acidosis causes depression of cardiac output. The effect on cardiac output of changing arterial pH at steady PaCOCO2 is shown quantitatively. The relationship of PaCOCO2 to “pH adjusted” cardiac output is determined. From these data a nomogram is presented from which the combined effects of arterial pH and PaCOCO2 on cardiac output can be estimated. cardiac output and anesthesia; acid-base status and cardiac output; pH and cardiac output; PaCOCO2 and cardiac output Submitted on June 29, 1964