Comparative effects of enoximone and theophylline on plasma catecholamines and haemodynamics in cardiosurgical patients.

The release of endogenous catecholamines in aorto-coronary bypass graft patients receiving either 0.5 mg/kg enoximone (n = 10), 4.0 mg/kg theophylline (n = 10) or saline solution (control, n = 10) has been studied, as well as certain haemodynamic parameters. Adrenaline (A) and noradrenaline (NA) concentrations were not significantly changed by the administration of enoximone. Theophylline caused a small increase in NA (+40% in the 1st min) and a marked increase in A (approximately +7000% in the 1st min), which still remained elevated at the end of the investigation period (+220% in the 30th min). The major haemodynamic effects of enoximone were a significant increase in cardiac index (CI; +35%) and a decrease in pulmonary capillary wedge pressure (PCWP; -27%), pulmonary artery pressure (PAP; -21%), RVEDV and RVESV, while the heart rate (HR) remained almost unchanged. The dominant haemodynamic effects of theophylline were an increase in HR (+26%; arrhythmia in 3 patients), PAP (+22%), and RVEDV (+19%), while RVESV (+26%), MAP (-16%), CI (-14%), and RVEF (-15%) fell significantly. It is concluded that the haemodynamic actions of enoximone are not mediated by catecholamine release, whereas the adverse cardiovascular effects of theophylline might partly be explained by the significant increase in plasma adrenaline.