DOPAMINE REVERSES LUNG FUNCTION DETERIORATION AFTER CARDIOPULMONARY BYPASS WITHOUT AFFECTING GAS EXCHANGE
Abstract
Objective
To investigate the effects of dopamine on the adverse pulmonary changes following cardiopulmonary bypass
Design
Prospective, nonrandomized clinical investigation
Setting
University hospital
Participants
One hundred and fifty-seven patients who underwent elective cardiac surgery that required cardiopulmonary bypass
Interventions
Fifty-two patients were administered intravenous infusion of dopamine (3 µg/kg/min) for five minutes after weaning from cardiopulmonary bypass; no intervention was applied in the other 105 patients.
Measurements and Main Results
Measurements were performed under general anesthesia and mechanical ventilation before cardiopulmonary bypass, after cardiopulmonary bypass, and after the intervention. In each protocol stage, forced oscillatory lung impedance was measured to assess airway and tissue mechanical changes. Mainstream capnography was performed to assess ventilation/ perfusion matching by calculating the normalized phase 3 slopes of the time and volumetric capnograms and the physiologic dead space. Arterial and central venous blood samples were analyzed to characterize lung oxygenation and intrapulmonary shunt. After cardiopulmonary bypass, dopamine-induced marked improvements in airway resistance and tissue damping, with relatively small decrease in lung tissue elastance. These changes were associated with decreases in the normalized phase 3 slopes of the time and volumetric capnograms. The inotrope had no effect on physiologic dead space, intrapulmonary shunt, or lung oxygenation.
Conclusions
Dopamine reversed the complex detrimental lung mechanical changes induced by cardiopulmonary bypass and alleviated ventilation heterogeneities without affecting the physiologic dead space or intrapulmonary shunt. Therefore, dopamine has a potential benefit on the gas exchange abnormalities after weaning from cardiopulmonary bypass.