A Randomized Trial of Drug Route in Out-of-Hospital Cardiac Arrest

Abstract

Background: In patients with out-of-hospital cardiac arrest, the effectiveness of drugs such as epinephrine is highly time-dependent. An intraosseous route of drug administration may enable more rapid drug administration than an intravenous route; however, its effect on clinical outcomes is uncertain.

Methods: We conducted a multicenter, open-label, randomized trial across 11 emergency medical systems in the United Kingdom that involved adults in cardiac arrest for whom vascular access for drug administration was needed. Patients were randomly assigned to receive treatment from paramedics by means of an intraosseous-first or intravenous-first vascular access strategy. The primary outcome was survival at 30 days. Key secondary outcomes included any return of spontaneous circulation and favorable neurologic function at hospital discharge (defined by a score of 3 or less on the modified Rankin scale, on which scores range from 0 to 6, with higher scores indicating greater disability). No adjustment for multiplicity was made.

Results: A total of 6082 patients were assigned to a trial group: 3040 to the intraosseous group and 3042 to the intravenous group. At 30 days, 137 of 3030 patients (4.5%) in the intraosseous group and 155 of 3034 (5.1%) in the intravenous group were alive (adjusted odds ratio, 0.94; 95% confidence interval [CI], 0.68 to 1.32; P = 0.74). At the time of hospital discharge, a favorable neurologic outcome was observed in 80 of 2994 patients (2.7%) in the intraosseous group and in 85 of 2986 (2.8%) in the intravenous group (adjusted odds ratio, 0.91; 95% CI, 0.57 to 1.47); a return of spontaneous circulation at any time occurred in 1092 of 3031 patients (36.0%) and in 1186 of 3035 patients (39.1%), respectively (adjusted odds ratio, 0.86; 95% CI, 0.76 to 0.97). During the trial, one adverse event, which occurred in the intraosseous group, was reported.

Conclusions: Among adults with out-of-hospital cardiac arrest requiring drug therapy, the use of an intraosseous-first vascular access strategy did not result in higher 30-day survival than an intravenous-first strategy. (Funded by the National Institute for Health and Care Research; PARAMEDIC-3 ISRCTN Registry number, ISRCTN14223494.).

Figure one. enrolment and outcomes

Note: 3914 patients were excluded due to pre-existing vascular access. This likely occurred most frequently where a paramedic not trained in the trial protocol arrived on scene and secured vascular access, before the arrival of a trial-trained paramedic. Crossover is defined as the use of the non-randomized drug route prior to two unsuccessful attempts at the randomized route.

Figure two. Summary of adjusted subgroup analyses for primary outcome

Note: EMS denotes emergency medical service; CPR denotes cardiopulmonary resuscitation. Subgroup analyses adjusted for age, sex, witnessed, bystander CPR, initial rhythm, time from emergency call to drug administration (time from EMS arrival at scene to drug administration for time from call to EMS arrival analysis), etiology of cardiac arrest where applicable. Confidence interval widths have not been adjusted for multiplicity and may not be used in place of hypothesis testing.