Twenty-five years of treatment of circulatory failure

Over the last twenty-five years, the treatment of circulatory failure has been profoundly modified not only by the introduction of new therapeutic agents but also by considerable advances in the understanding of the circulation in the severely ill patient. The considerable hazards of increasing blood pressure by the administration of vasoconstrictive agents have been recognized and it has become obvious that the first step in the treatment of circulatory failure is to ensure adequate filling of the vascular compartment. If correction of the pre-load does not improve the circulation, positive inotropic agents may find their indication and may improve cardiac output. The increased myocardial oxygen demand, the development of tachycardia and dysrhythmias may limit their usefulness. In the presence of high filling pressures, inotropic agents may improve the circulation but often better results are obtained from the administration of vasodilators. Artificial circulatory support by aortic balloon counterpulsation may have to be used as a last resource. The difficulties encountered in the treatment of acute circulatory failure relate to the delicate balance between myocardial oxygen demand and supply. Inotropic agents enhance performance, increase heart rate, systolic pressure and oxygen demand. Conversely, vasodilators by decreasing diastolic pressure may also decrease oxygen supply. Thus, it is not surprising that the treatment of circulatory failure remains difficult.