Introduction: Epinephrine and vasopressin are the only vasopressors associated with return of spontaneous circulation (ROSC). While current guidelines recommend rapid and frequent vasopressor administration during cardiac arrest, delays in their administration in the out-of- hospital setting remain a concern.
Objective: This study evaluated delays in vasopressor administration and their effect on field ROSC.
Methods: This retrospective review included all adult patients who experienced cardiac arrest of medical origin and received field resuscitative efforts among 10 emergency medical services (EMS) systems. Data were abstracted from the EMS medical record and included response time intervals, calculated first-dose and interdosing intervals of vasopressors, and ROSC. Data were analyzed using Mann-Whitney tests, chi-square tests, and t-tests, survival analysis, and logistic regression, with p ≤ 0.05 indicating significance.
Results: A total of 660 cardiac arrest patients were enrolled in the study. The mean EMS response time was 8.8 minutes; 52.7% of patients had witnessed cardiac arrests, 46.2% received bystander cardiopulmonary resuscitation (CPR), 23.0% had shockable initial rhythms, and 19.5% experienced field ROSC. In total, 1,913 doses of epinephrine and 111 doses of vasopressin were administered, with mean and 90th-percentile scene arrival-to-first drug intervals of 9.5 and 17 minutes, respectively. The mean and 90th-percentile interdosing intervals were 6.1 and 10 minutes, respectively. Patients experiencing ROSC had shorter scene arrival-to-first drug intervals than those without ROSC (8.1 vs. 9.8 min, p < 0.01), but there was no difference in the mean interdosing interval (6.8 vs. 6.0 min, p = 0.57). In the logistic regression analysis of ROSC, the adjusted odds ratio for call receipt-to-first drug interval ≤10 minutes was 1.91 (p = 0.04). Patients receiving advanced airway control prior to vasopressor administration were less likely to have a call receipt-to-first drug interval within 10 minutes (4.0% vs. 17.3%, p < 0.01) and were less likely to attain ROSC (15.7% vs. 25.4%, p < 0.01).
Conclusion: The interval between scene arrival and first administration of vasopressors is significantly shorter among patients who experience ROSC compared with those who do not. Airway control procedures delay vasopressor administration and reduce the likelihood of ROSC. Although the interdosing intervals of most patients were not consistent with current recommendations, there was no difference in the mean interdosing times between those who achieved ROSC and those who did not.