Respiratory effects of the Jarvik-7 artificial heart

In five anesthetized patients with a Jarvik-7 artificial heart, pulmonary volume displacements generated by cardiogenic oscillations were measured using an indirect spirometric method. Consequences on gas exchange were also evaluated during a 15-min period of apnea by use of a tracheal insufflation of pure O2 at a constant flow rate of 20 l/min. The Jarvik-7 artificial heart generated a mean pulmonary volume displacement of 105 +/- 29 (SD) ml/heart beat. After 15 min of apnea, arterial PCO2 (PaCO2) significantly increased from 29 +/- 5 to 47 +/- 6 (SD) Torr. PaCO2 increased by 0.8 Torr/min from the 5th to the 15th min of apnea. Mean arterial PO2, mean pulmonary shunt, mean O2 consumption, and mean metabolic production of CO2 did not change significantly during the apnea period. Because cardiac output was kept constant during the study, O2 transport was adequately maintained throughout the apnea period. In patient 1, where the period of apnea was continued for 60 min, PaCO2 progressively increased until the 45th min and then remained stable at 61 Torr during the last 15 min of apnea. This "plateau" corresponded to an alveolar ventilation of 3,907 ml/min, representing 69% of the alveolar ventilation calculated during conventional mechanical ventilation. In conclusion, the Jarvik-7 artificial heart provides a potent respiratory support through the cardiogenic oscillations it generates.