Evidence from a new study further questions the routine administration of sodium bicarbonate for patients with in-hospital cardiac arrest.
The BIHCA trial, conducted across 21 hospitals in Denmark, found no significant difference in sustained return of spontaneous circulation between sodium bicarbonate and placebo in adults with in-hospital cardiac arrest.
The trial, the first of its kind for patients with in-hospital cardiac arrest, included 913 patients, of which 770 were eligible for the primary analyses. Of this group, 372 were randomised to receive 50mL of 8.4% sodium bicarbonate and 407 to receive a placebo, given as soon as possible after the first dose of epinephrine.
The primary outcome was sustained return of spontaneous circulation, with key secondary outcomes of survival at 30 days and survival at 30 days with a favourable neurological outcome.
Sustained return of spontaneous circulation occurred in 146 patients (39%) in the sodium bicarbonate group and 150 (37%) of those in the placebo group (risk ratio, 1.05; P = .62).
At 30 days, 12% of patients in the sodium bicarbonate group and 9.1% in the placebo group were alive (risk ratio, 1.25). The proportion of patients with a favourable neurologic outcome was 8.1% and 5.4%, respectively (risk ratio 1.39).
“Recent European and US guidelines suggest against the routine use of sodium bicarbonate during cardiac arrest,” the investigators wrote. “These recommendations are based on lack of clinical trial data and US guidelines explicitly acknowledge clinical equipoise.”
“Many clinicians consider sodium bicarbonate beneficial in this setting. Findings from this trial do not support this practice,” they added.
Quality-of-life scores in survivors at 30 days showed no clear differences between the two groups, and there were no differences between the groups in organ dysfunction at 2, 24, 48 and 72 hours after the cardiac arrest.
In addition, of those discharged alive, 30 of 44 (68%) and 26 of 37 (70%) were discharged home in the sodium bicarbonate and placebo groups, respectively.
Those in the sodium bicarbonate group were also more likely to experience alkalosis (35% vs. 20%) and hypernatremia (42% vs 29%) after cardiac arrest.
Outcomes generally remain poor for in-hospital cardiac arrest, with 50% to 70% of patients achieving return of spontaneous circulation, but only 25% to 30% surviving to hospital discharge, the researchers found.
In addition, they said, evidence to support interventions during in-hospital cardiac arrest is in short supply and largely extrapolated from out-of-hospital cardiac arrest research.
The results of the study are published in JAMA [link here].
Heroic effort
In an accompanying editorial [link here], Professor Clifton Calloway, executive vice chair of emergency medicine at the University of Pittsburgh Medical School, noted that sodium bicarbonate is usually administered to reduce severe acidosis that develops during cardiac arrest, reverse myocardial depression and improve catecholamine action.
Current American Heart Association guidelines have recommended against routine use of sodium bicarbonate during cardiac arrest since 2010, except in special circumstances, such as metabolic acidosis, hyperkalemia, or tricyclic antidepressant overdose.
Bicarbonate use has nevertheless increased in hospital settings since 2001, he noted, adding that many clinicians still believe the drug to be useful and “will require high certainty of evidence to remove it from their practice.”
One reason for this, despite the results of the latest trial, is the fact that clinicians focus treatment on individual patients rather than populations, Prof Calloway suggested, with the former sometimes differing from the average effect.
Although the BIHCA trial looked at treatment effects among several subgroups, none of those identified had a different response to the drug, he noted.
“Even if those analyses cannot identify a subgroup of patients who do benefit from sodium bicarbonate, clinicians still may not stop using this drug as a heroic effort,” he said.