Vasopressin and vasopressin plus nitroglycerin for portal hypertension. Effects on systemic and splanchnic hemodynamics and coronary blood flow

Vasopressin: new uses in critical care

The science of medicine has evolved dramatically over recent years, with better understanding of the mechanisms of disease leading to innovative new treatments. However, the critical care patient still suffers from a high mortality rate with few advances from the traditional modalities of therapy. Arginine vasopressin has been explored as a vasoconstrictor in the treatment of the hypotension associated with septic shock. This drug has also recently been added to the advanced cardiac life support protocol for the resuscitation of pulseless ventricular tachycardia and ventricular fibrillation. Studies of arginine vasopressin in these situations have been promising but still have yet to prove a survival benefit over traditional therapies. Newer and larger trials are necessary to determine whether any mortality benefit can be sustained from the use of arginine vasopressin in critical care patients with septic shock and cardiac arrest secondary to pulseless ventricular tachycardia and ventricular fibrillation.

The role of vasopressin in the treatment of vasodilation in shock states

OBJECTIVE

To review the role of vasopressin in the treatment of vasodilatory shock.

DATA SOURCES

A MEDLINE search on published reports (1966-April 1999) was conducted.

STUDY SELECTION

English-language studies and case reports were selected and evaluated based on quality of review of vasopressin in the treatment of vasodilatory shock.

DATA SYNTHESIS

In patients with end-stage vasodilatory shock, baroreceptor reflex is impaired and vasopressin stores are depleted. Persistent elevation of catecholamines may lead to down-regulation of beta-adrenergic receptors and reduces smooth-muscle response to catecholamines, leading to inability of maintaining organ perfusion. Small-scale studies and case reports have demonstrated vasopressin's efficacy in maintaining blood pressure in patients with septic shock, cardiac arrest, and end-stage heart failure, refractory to other vasopressor therapies.

CONCLUSIONS

Vasopressin may be a reasonable alternative for patients in vasodilatory shock. However, larger-scale controlled dinical trials are warranted before its routine use can be recommended.

Acute effects of sublingual nitroglycerin on hepatic blood flow in healthy volunteers

Duplex sonography was used to assess the effects on hepatic blood flow after administering 0.6 mg nitroglycerin (NTG) sublingually to ten healthy volunteers. The study was a randomized, placebo-controlled, cross-over study in which subjects were studied on three separate occasions. Each visit involved administering either placebo or NTG followed by estimation of blood flow through a particular branch of the hepatic artery, portal vein, and hepatic vein every minute for 15 minutes after NTG and placebo administration. Two hours later, subjects were crossed over to the other treatment and the same vessel branch was again examined for 15 minutes. Total blood flow increased 7% in the portal vein and 27% in the hepatic vein during NTG treatment, but did not change significantly in the hepatic artery. Vascular resistance was increased in the hepatic artery and decreased in the portal and hepatic veins after NTG. Qualitatively, flow changed dramatically in the hepatic vein after NTG with the disappearance of normal retrograde flow. The results indicate that nitroglycerin effects hepatic blood flow through the portal and hepatic veins with a decrease in vascular resistance in the portal and hepatic veins and an increase in resistance in the hepatic artery.