[Intrapulmonary short-circuit during coronary or aortic valve heart surgery]. / Cortocircuito intrapulmonar en cirugía cardíaca coronaria o de válvula aórtica.

ABSTRACT

BACKGROUND: The alterations in gas exchange during cardiac surgery was studied by the measurement of the perioperative intrapulmonary shunt. PATIENTS AND METHODS: Forty patients divided into two groups were studied. Group 1 consisted of 20 patients undergoing myocardial vascularization and group 2 consisted of 20 patients undergoing aortic valve replacement. The anesthetic technique was similar in both groups but the patients in group 1 received a continuous perfusion of nitroglycerin from the beginning of surgery plus a bolus of intranasal nifedipine 30 minutes prior to the exit of extracorporeal circulation. The measurement of the shunt was performed 5 times following the induction of anesthesia, prior to and after extracorporeal circulation, upon termination of surgery and one hour following admission to the ICU. RESULTS: In both groups an increase of the shunt was produced at the end of extracorporeal circulation which later returned to basal levels. The increase was greater in patients of group 1 during the different phases of surgery although significant differences only existed at the beginning and end of extracorporeal circulation. The variations of the shunt were not related with the state of preoperative pulmonary function or with the duration of extracorporeal circulation. CONCLUSIONS: Although intrapulmonary shunt increases during cardiac surgery, especially coronary, its clinical transcendence is nul and no special measures are required.