Critically evaluate the role of vasopressin in septic shock.
Vasopressors have a role in septic shock to offset hypotension caused by vasoplegia. Vasopressin is an endogenous neuroendocrine peptide that acts on multiple receptors with multiple effects including potent vasoconstriction
Rationale for use of vasopressin in septic shock:
Low levels of vasopressin have been demonstrated in patients with septic shock (compared to cardiogenic shock).
Infusion of vasopressin reduces the need for other vasoactive medication and increases both urine output and creatinine clearance.
In septic shock, exogenous vasopressin appears to act preferentially on V1 receptors on the smooth muscle of the vasculature rather than the renal V2 receptors.
Patients with septic shock may be relatively catecholamine resistant and not respond well to nor-adrenaline and potentially respond better to vasoactive agents acting at different receptors.
The largest study to date is an International RCT (VASST) Patients: Septic shock on low dose nor-adrenaline infusion
Intervention: Vasopressin vs. Comparator: Noradrenaline (Other doses of open-label vasopressors given according to clinical indication)
Outcome: No effect on the primary outcome of 28-day mortality. Subgroup of those with less severe shock appeared to benefit.
Potential adverse effects:
An extensive elaboration of vasopressin and its properties can be found elsewhere.
Landry, Donald W., et al. "Vasopressin deficiency contributes to the vasodilation of septic shock." Circulation 95.5 (1997): 1122-1125.
Sharshar, Tarek, et al. "Depletion of neurohypophyseal content of vasopressin in septic shock*." Critical care medicine 30.3 (2002): 497-500.
Dünser, Martin W., et al. "Arginine Vasopressin in Advanced Vasodilatory Shock A Prospective, Randomized, Controlled Study." Circulation 107.18 (2003): 2313-2319.