Effect of Blood pH and CO 2 Tension on Performance of the Heart-Lung Preparation

Summary

When the performance of heart-lung preparations was evaluated by the relationship between stroke work and left atrial pressure, a change of the CO₂ content of the inspired air from zero to 10% caused a progressive decrease in performance. The use of HCl or NaHCO₃ allowed for changing the pH and pCO₂ of the arterial blood separately. Arterial blood pH rather than blood pCO₂ appeared to be the decisive factor in mediating this change. Whenever a change of inspired air composition was made in either direction, the new performance level was preceded by a marked overshoot. A fall in arterial pH was accompanied by a slowing of the heart rate.