A new method for clinical assessment of the negative inotropic action of anaesthetics--with special reference to isoflurane and its effect on myocardial oxygenation.
A new method for maintaining the peripheral determinants of myocardial oxygen demand constant is described. Intravenously administered phenylephrine and nitroglycerin were used to control afterload and preload. Heart rate was kept constant with atrial pacing. The method was used to establish the in vivo negative inotropic effect of 1% end-tidal isoflurane in eight patients with ischaemic heart disease during positive pressure ventilation (IPPV). Stroke volume measured during steady-state isoflurane anaesthesia and IPPV with preload, afterload, and heart rate kept constant was 23% below awake control. The decrease in myocardial oxygen consumption was 22% and correlated well (r = 0.891) with the fall in left ventricular performance (stroke volume).
D000777:Anesthetics / Q000009:adverse effects*; D002302:Cardiac Output / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007385:Intermittent Positive-Pressure Ventilation; D007530:Isoflurane / Q000009:adverse effects*; D008738:Methyl Ethers / Q000009:adverse effects*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology
D000777:Anesthetics; D008738:Methyl Ethers; D010656:Phenylephrine; D007530:Isoflurane; D005996:Nitroglycerin