Saturday July 26, 2008
Regarding Vasopressin !

Q: How vasopressin acts differently in normal healthy people versus in septic patients?

A; A low-dose infusion of exogenous vasopressin induces a brisk pressor response in sepsis patients but shows little effect in normal subjects. In septic patients endogenous levels of the vasopressin are low and the pressor response to exogenous infusion would be noted.

Lin and coll. 1 drew plasma vasopressin level at baseline early in course of sepsis in emergency department and found that the plasma vasopressin level was significantly lower for those who finally developed septic shock (3.6 +/- 2.5 pg/mL) than severe sepsis (21.8 +/- 4.1 pg/mL).

Vasopressin antagonizes the vasodilatory mechanisms that are activated during sepsis. Although the hormone is an antidiuretic, it has been shown to increase urine output and improve creatinine clearance in shock patients. Vasopressin at low dose does not alter cerebral constriction or coronary flow, nor does it influence pulmonary arterial pressure.

As a rule of thumb, vasopressin is a good choice when sepsis is complicated by renal insufficiency and should be avioded in patients with limb, cardiac or bowel ischemia.

Related previous pearl: vasopressin/norepinephrine ratio


Reference: (click to get abstract)

1. Low plasma vasopressin/norepinephrine ratio predicts septic shock. Am J Emerg Med. 2005 Oct;23(6):718-24.