Fine-tuning a treatment for hearts

Sudden cardiac arrest is unfortunately common and often deadly — bringing many people to hospital emergency rooms. Among the challenges of treating them is the fact that the malfunctioning heart can’t properly send enough blood to the brain and other organs and tissues throughout the body, causing further damage.

Doctors have long used epinephrine, which causes blood vessels to constrict and squeeze more blood through the circulatory system to where it’s needed. One problem is that many cardiac arrest patients suffer a build-up of acid in their bodies when their hearts aren’t functioning properly over time — a condition called acidosis, which can blunt the effects of epinephrine.

Vasopressin works similarly to epinephrine and isn’t affected by acidosis. However, studies have failed to show improved survival or faster improvement in normal blood flow — known as return of spontaneous circulation — when using either of these agents alone or in combination. And research on the effect of acidosis on return to spontaneous circulation has only been explored in animals, not humans.

Given the limited options for improving blood flow in these patients, pharmacists at University Health System decided to dig into the question a little deeper. And what they found after reviewing the records of 101 patients treated at University Hospital’s Emergency Department over a two-year period was that substituting the first or second dose of epinephrine with vasopressin did  in fact speed up the return of spontaneous circulation — but only in patients with acidosis.

“When we looked at that subset of patients that had acidosis — a pH of less than 7.2 — there was a significant difference,” said DeAnna Turner, a second-year pharmacy resident at University Health System, who led the study. “In patients who got vasopressin, there was an increase in return of spontaneous circulation, versus those who just got epinephrine alone.”

That group of acidotic patients makes up a majority of cardiac arrest victims, so the findings are of broad interest.  “And although the group that got vasopressin and epinephrine didn’t have improved survival over those who got epinephrine alone, the increased rate of return of spontaneous circulation could potentially mean less organ damage and long-term disability in the patients that do survive — something that further research would have to determine,” Turner said.

The study appeared online ahead of print last week in the journal, Annals of Pharmacotherapy.