[Clonidine in the management of hypertensive crisis (author's transl)]

Haemodynamic data were obtained by means of Swan-Ganz balloon catheters in eight patients during hypertensive crisis. After obtaining control values, 150 microgram clonidine in 10 ml isotonic sodium chloride was administered intravenously over ten minutes. During the hypertensive crisis there was a moderate rise in pulmonary artery and right ventricular pressures, in addition to a rise in systemic arterial pressure. In addition there was a lower than normal cardiac index, averaging 2.2 l/min.m2, a reduced stroke volume of 49.3 ml, a markedly elevated peripheral vascular resistance of 3584 dyn.s.cm-5, and an elevated cardiac work index of 5.08 kg.m/min.m2. After clonidine administration there was a significant fall in systolic, diastolic and mean femoral artery pressures (P less than 0.005), without any significant fall in pulmonary artery and right ventricular pressures. At the same time there was a further fall in cardiac index to an average of 1.85 l/min.m3, largely due to a reduced heart rate. Stroke volume fell slightly in only two patients. Peripheral vascular resistance did not fall significantly, while cardiac work index was significantly below the control value as late as four hours after clonidine administration.