Haemodynamic Effects of Combined Nitroglycerin‐ and Dobutamine‐Infusions After Coronary By‐Pass Surgery With One Nitroglycerin‐Related Complication

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Abstract
The hemodynamic effects of separate and simultaneous nitroglycerin (NTG) and dobutamine (DOB) infusions were determined to evaluate the nature of the effects of combined treatment. Ten patients were studied, 6 h after coronary bypass surgery. NTG alone reduced significantly systemic and pulmonary arterial, ventricular filling pressures and brought about a concomitant 10% decrease in the cardiac index (P < 0.05). DOB (6 .mu.g/kg per min) did not affect systemic or pulmonary arterial pressures or ventricular filling pressures. Due to the 20 beats/min rise in heart rate produced by DOB, the cardiac index was increased by 24%, but the stroke volume and work indices remained unchanged during DOB-infusion. The hemodynamic changes brought about by NTG or DOB separately were unaffected by the simultaneous infusion of the other vasoactive drug. The hemodynamic effects of the combined treatment were simply the sum of their separate effects, thereby yielding reduced arterial and ventricular filling pressures, increased heart rate and slightly augmented cardiac index with significantly reduced systemic vascular resistance; myocardial O2 consumption and unaffected by the combination therapy. A patient, whose case is discussed separately, had a hypotension-bradycardia complication during NTG-infusion.