Vasopressin

Indications

  • Cardiac Arrest (see Cardiac Arrest, [[Cardiac Arrest]]): vasopressin is a component of the Advanced Cardiac Life Support (ACLS) guideline
  • Hypotension/Sepsis (see Sepsis, [[Sepsis]])
    • Vasopressin levels are decreased in septic shock
  • Esophageal Variceal Hemorrhage (see Gastrointestinal Hemorrhage, [[Gastrointestinal Hemorrhage]])

Physiology/Pharmacology

History

  • Vasopressin was First Isolated in 1951

Site of Synthesis and Release

  • Vasopressin is a 9 Amino Acid Peptide Predominantly Synthesized in the Hypothalamus and Released from Posterior Pituitary Gland Granules
    • Triggers for Vasopressin Release
      • Hypotension (see Hypotension, [[Hypotension]])
      • Hypoxia (see Hypoxemia, [[Hypoxemia]])
      • Increased Plasma Osmolality: due to water deprivation
      • Nausea (see Nausea and Vomiting, [[Nausea and Vomiting]])
      • Pain
  • Vasopressin is Synthesized to Lesser Extent in the Heart in Response to Wall Stress
  • Vasopressin is Synthesized to Lesser Extent in the Adrenal Gland in Response to Increased Catecholamine Secretion

Physiologic Actions of Vasopressin

  • Vasopressin Acts at V2 Receptors on the Renal Collecting Duct, Resulting in Increased Collecting Duct Permeability: result in water reabsorption
    • Vasopressin is the Primary Anti-Diuretic Hormone (ADH): regulates water balance
  • Vasopressin Acts at V1a Receptors on Vascular Smooth Muscle, Resulting in Potent Vasoconstriction
    • General Comments
      • However, the vasoconstrictor effect of vasopressin occurs at doses higher than the anti-diuretic activity
      • The vasoconstrictor effects of vasopressin are relatively preserved during hypoxic and acidotic conditions (both of which develop during shock)
    • Cerebral Vasoconstriction: less direct effect than the catecholamines
    • Coronary Vasoconstriction: less direct effect than the catecholamines
    • Increased Vascular Sensitivity to Norepinephrine (see Norepinephrine, [[Norepinephrine]])
    • Neutral or Inhibitory Effect on Cardiac Output: depending on its dose-dependent increase in systemic vascular Resistance (SVR) and the reflexive increase in vagal tone
  • Vasopressin Acts at V1b Receptors in the Pituitary Gland

Administration

  • Cardiac Arrest (ACLS Guidelines): 40 U IV Bolus
  • High-Dose IV Drip (for Esophageal Variceal Hemorrhage): 0.3 to 1.5 U/min
    • At this high dose, vasopressin decreases blood flow to the splanchnic and portal venous vascular beds
    • High doses can result in cardiac and gastrointestinal ischemia and/or infarction: concomitatnt use of IV nitroglycerin has been used to reduce the risk of cardiac ischemia
  • High-Dose Intra-Arterial Drip in Superior Mesenteric Artery (for Esophageal Variceal Hemorrhage): 0.2 to 0.5 U/min
  • Low-Dose IV Drip (for Sepsis): non-titrating 0.04 U/min
    • At this low dose, vasopressin causes systemic vasoconstriction, with increased BP (and decreased CO): however, splanchnic blood flow is usually increased or unchanged
    • Low doses can also increase pulmonary pressures (usually modestly)

Adverse Effects

Cardiovascular Adverse Effects

  • Arrhythmia
  • Negative Inotropy: at doses >0.4 U/min
  • Hypertension (see Hypertension, [[Hypertension]])
  • Myocardial Ischemia
  • QT Prolongation with Definite Association with Torsade (see Torsade, [[Torsade]])

Renal Adverse Effects

  • Hyponatremia (see Hyponatremia, [[Hyponatremia]]): case reports have been described of vasopressin-induced hyponatremia when administered in the setting of septic shock [MEDLINE]

Other Adverse Effects

  • Digital Ischemia: due to peripheral vasoconstriction
  • Splanchnic Vasoconstriction
  • xxx
  • xxx

References

  • Inotropes and Vasopressors: Review of Physiology and Clinical Use in Cardiovascular Disease. Circulation. 2008 Sep 2;118(10):1047-56. doi: 10.1161/CIRCULATIONAHA.107.728840 [MEDLINE]
  • Exogenous Vasopressin-Induced Hyponatremia in Patients With Vasodilatory Shock: Two Case Reports and Literature Review. J Intensive Care Med. 2015 Jul;30(5):253-8. doi: 10.1177/0885066613507410. Epub 2013 Oct 7 [MEDLINE]