according to a review of three recent studies.
“Patients with septic shock require vasoactive agents to restore adequate tissue perfusion,” writes Gretchen L. Sacha, PharmD, of the Cleveland Clinic and colleagues.
Vasopressin is an attractive alternative to norepinephrine because it avoids the adverse effects associated with catecholamines, the researchers say. Although vasopressin is the recommended second-line adjunct after norepinephrine for patients with septic shock, findings to guide its use are inconsistent and data on the timing are limited, they note.
In a review published in the journal CHEST, the researchers summarize the three large, randomized trials to date examining the use of norepinephrine and vasopressin in patients with septic shock.
In the Vasopressin in Septic Shock Trial (VASST), 382 patients with septic shock were randomized to open-label norepinephrine with blinded norepinephrine, and 382 were randomized to open-label norepinephrine with blinded adjunctive vasopressin.
After initiation of the study drug, patients randomized to vasopressin had significantly lower requirements for open-label norepinephrine (P < .001). Although no differences occurred in the primary outcome of 28-day mortality, 90-day mortality was lower in the vasopressin group.
In the Vasopressin vs Norepinephrine as Initial Therapy in Septic Shock (VANISH) trial, 204 patients with septic shock were randomized to norepinephrine and 204 to vasopressin as an initial vasoactive agent. Although no differences appeared between the groups for the two primary outcomes of 28-day mortality and days free of kidney failure, the vasopressin group had a lower frequency of the use of kidney replacement therapy (absolute difference –9.9% vs. –0.6%).
The VANISH study was limited by the fact that 85% of the patients were receiving norepinephrine when they were randomized; “therefore, this study is best described as evaluating catecholamine-adjunctive vasopressin,” the researchers say.
The third clinical trial, published only as an abstract, randomized 387 patients with septic shock who were already receiving low doses of norepinephrine to either norepinephrine with adjunctive vasopressin or norepinephrine alone. Rates of 28-day mortality were significantly lower in the vasopressin group (34.0% vs. 42.3%; P = .03).
Several meta-analyses involving multiple vasopressin receptor agonists have shown an association between reduced mortality and their use. In addition, recent observational studies have shown an association between lower mortality and the initiation of vasopressors at a lower norepinephrine-equivalent dose or lower lactate concentration.
As for clinical implications, the 2021 version of the Surviving Sepsis Campaign (SSC) guidelines included a meta-analysis of 10 randomized, controlled trials that showed improved mortality associated with vasopressin use. This version of the guidelines was the first to address the timing of vasopressin initiation.
Because of insufficient evidence, the guidance was worded as “in our practice, vasopressin is usually started when the dose of norepinephrine is in the range of 0.25-0.5 mcg/kg/min,” the researchers write. “Although this is not a recommendation by the SSC for a specific threshold of catecholamine dose where vasopressin should be initiated, this statement represents clinician interest and the need for further research on the topic,” they note.
“Future studies of vasopressin should focus on the timing of its initiation at various clinical thresholds and patient selection for receipt of vasopressin,” they conclude.
The study was supported by the National Institutes of Health, National Institute of General Medical Sciences. Dr. Sacha has disclosed consulting for Wolters Kluwer.
A version of this article first appeared on Medscape.com.