Effects of vasopressin and catecholamines on the maintenance of circulatory stability in brain-dead patients.

The effectiveness and reliability of long-term control of circulatory stability in brain-dead patients by combined administration of vasopressin and catecholamine was examined in detail. Twenty-five patients were divided into three groups according to the dose of vasopressin. The first group (n = 10) received no vasopressin, the second group (n = 2) an antidiuretic dose (0.1-0.4 U/hr), and the third group (n = 13) a pressor dose (1-2 U/hr), respectively. Patients given no vasopressin or an antidiuretic dose demonstrated circulatory deterioration and cardiac arrest within a short time after brain death, despite administration of a large dose of epinephrine. All patients with a pressor dose of vasopressin, however, demonstrated stable circulation as long as vasopressin and epinephrine were administered. Five patients in whom stable circulation was maintained by this technique were randomly chosen from the third group and studied under the following four conditions: (1) neither vasopressin nor epinephrine; (2) vasopressin only; (3) epinephrine only; and (4) both vasopressin and epinephrine. Compared with the controls (neither vasopressin nor epinephrine), vasopressin only increased the total peripheral resistance index, whereas epinephrine alone increased the cardiac index. Combined administration, however, raised the mean arterial blood pressure significantly by markedly increasing the total peripheral resistance index and cardiac index. Finally, in four brain-dead patients also randomly chosen from the third group, epinephrine, norepinephrine, and dopamine were compared in their circulatory effects with a pressor dose of vasopressin. Epinephrine increased both the total peripheral resistance index and cardiac index, whereas norepinephrine increased the total peripheral resistance index, compared with the baseline (no catecholamine). The required dose of norepinephrine, however, was four times that of epinephrine. The major effect of dopamine was to increase the cardiac index. We conclude that a pressor dose of vasopressin plays a central role in circulatory stabilization of brain-dead patients, and that long-term maintenance of stable circulation for a desired length of time is possible by the combined use of vasopressin and a catecholamine. Individually, catecholamines exhibit characteristic differences. Epinephrine has significant effects on both peripheral vessels and the heart, whereas norepinephrine keeps the circulation stable by increasing the total peripheral resistance index, with a much larger dose than epinephrine. Dopamine acts primarily on the heart.

RCT Entities:   Population Interventions Outcomes