Category: Critical Care
Keywords: vasopressors, vasopressin, septic shock (PubMed Search)
Posted: 8/18/2025 by Jessica Downing, MD
(Updated: 8/19/2025)
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Norepinephrine (NE) is widely accepted as the first-line vasopressor for the management of septic shock, supported by the Surviving Sepsis Guidelines (1). The use of vasopressin as a second-line agent is also supported by the Surviving Sepsis Campaign, although the appropriate “triggers” for its addition remain vague. The SSG recommend adding vasopressin when NE infusion rates reach 0.25-0.6 mcg/kg/min, citing a catecholamine-sparing effect and potentially improved mortality (1, 2, 3).
What’s New?
The OVISS study (“Optimal vasopressin initiation in septic shock. The OVISS reinforcement learning study”) used machine learning to derive and internally validate a set of rules guiding the addition of vasopressin to NE for patients with septic shock using multiple databases of patient encounters across multiple institutions (4).
The machine learning model suggested initiation of vasopressin in more patients (87% vs 31%), earlier, and in less sick patients than was seen to be common practice:
Practice consistent with the above triggers was associated with decreased odds of in-hospital mortality (AOR 0.81, 95% CI 0.73-0.91).
Limitations
This was not a prospective study or RCT and was only internally validated. Using databases may limit the number of clinical variables available for analysis, and clinical judgment (how the patient looks) is not reflected.
Bottom Line
Consider adding vasopressin for patients with vasodilatory shock with low MAP despite NE >0.2mcg/kg/min and adequate fluid resuscitation, though more evidence is needed for a strong recommendation. As dual-pressor therapy may be riskier via peripheral IV and vasopressin does not have a direct antidote for extravasation, consider central line placement when adding vasopressin (5,6)
