Effects of nitroglycerin on central haemodynamics and VA/Q distribution during ventilation with FIO2 = 1.0 in patients after coronary bypass surgery.
The effects of nitroglycerin (TNG) infusion during ventilation with FIO2 = 1.0 on central haemodynamics and the distribution of ventilation-perfusion (VA/Q) were studied with the multiple inert gas elimination technique in eight patients after coronary bypass surgery. Administration of TNG resulted in a significant decrease in mean arterial pressure, and an increase in heart rate while cardiac output remained unchanged. Mean right atrial, pulmonary arterial and pulmonary wedge pressures all decreased. There was a significant reduction in PaO2 from 50.5 to 32.7 kPa, while Pao2 remained unchanged in a control group of eight patients. This was mainly due to an increase in shunt from 9.3 to 16.5% of cardiac output during TNG-infusion. In the control group there was also an increase in shunt from 9.7 to 12.1% of cardiac output with a simultaneous decrease of the same magnitude in perfusion of regions with low VA/Q (0.005-0.1). This was not evident in the group receiving TNG. Twenty min after termination of TNG-infusion the effects on central haemodynamics and gas exchange were not fully reversed. The mechanism behind the increase in inert gas shunt observed with infusion of TNG during oxygen breathing is probably a selective effect on vessels with remaining high vasomotor tone despite high alveolar oxygen tension.
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D001026:Coronary Artery Bypass; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin / Q000494:pharmacology*; D011184:Postoperative Period; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D012121:Respiration, Artificial; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects
D005996:Nitroglycerin