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Introduction

  1. Pharmacology
    1. Vasopressin is a peptide hormone that is synthesized in the hypothalamus. The primary stimuli for endogenous physiologic release are hyperosmolality, hypotension, and hypovolemia. It is used in the critical care setting for severe catecholamine-resistant vasodilatory shock, in which case, it acts as a potent vasoconstrictor. Conditions in which vasopressin has been used include septic shock, postcardiotomy shock, hemorrhagic shock and toxin-induced cardiogenic shock. There are insufficient and conflicting human and animal data to recommend its use routinely to manage shock from poisoning. Further data are needed to define its risks, benefits, and optimum dose. Increases in arterial pressure should be evident within 15 minutes. Its serum half-life is 5-15 minutes.
  2. Indications
    1. Note: Vasopressin should not be used as a first-line agent to treat hypotension. It is used as add-on therapy to treat severe vasodilatory hypotension that is unresponsive or refractory to adrenergic agents (eg, norepinephrine, epinephrine, phenylephrine, high-dose dopamine). There are limited case reports in the medical literature in which vasopressin was used for drug overdose.
    2. As a means to reduce adrenergic agent requirements during the treatment of vasodilatory hypotension.
  3. Contraindications
    1. Vasopressin infusion should be discontinued if there is a decrease in the cardiac output and/or stroke volume. Note: Consider employing advanced hemodynamic monitoring of cardiac indices in order to titrate dosing to desired hemodynamic effects.
    2. Use with extreme caution if there is evidence of decreased cardiac output despite adequate intravascular volume or evidence of cardiogenic shock.
    3. Vasopressin should be used cautiously in treating a patient with an overdose of an agent that has myocardial depressant effects (eg, calcium channel blockers, beta-blockers).
  4. Adverse effects
    1. Negative inotropic effect. Vasopressin may result in a decrease in cardiac output. This may be attributed to an increase in systemic vascular resistance and afterload on a depressed myocardium or may be related in part to a compensatory decrease in the heart rate.
    2. Ischemia (especially at doses >0.05 U/min).
      1. Cardiac arrest has been reported at doses above 0.05 U/min.
      2. Ischemic skin lesions of the distal extremities and trunk and lingual regions.
      3. Mesenteric ischemia and hepatitis may occur.
    3. Hyponatremia
    4. Thrombocytopenia
    5. Use in pregnancy. FDA Category C (Introduction). There are no reports linking the use of vasopressin with congenital defects. Vasopressin and the related synthetic agents desmopressin and lypressin have been used during pregnancy to treat diabetes insipidus. Vasopressin and structurally related polypeptides may increase the frequency and amplitude of uterine contractions.
  5. Dosage and method of administration
    1. Intravenous infusion at 0.01-0.04 U/min. Vasopressin should be diluted with normal saline or 5% dextrose in water to a final concentration of 0.1-1 U/mL.
      1. Doses of up to 0.07-0.1 U/min have been used for patients in septic shock or with postcardiotomy vasodilatory shock. However, doses higher than 0.04 U/min are associated with a greater incidence of adverse effects.
      2. Administration through central venous access is recommended to minimize the risk of extravasation. Local skin necrosis has occurred when vasopressin was infused through a peripheral venous catheter.
    2. Once an adequate blood pressure is achieved and stabilized, steps should be taken to reduce the doses of adrenergic agents and vasopressin gradually.