Synopsis Provided By
Guillaume L. Hoareau, DVM, PhD, FCCM, DACVECC, DECVECC
https://www.sciencedirect.com/science/article/pii/S030095722400159X
Rationale for IM Epinephrine
Prompt epinephrine administration is critical in cardiac arrest, particularly for patients with non-shockable rhythms. Intramuscular (IM) epinephrine offers a viable alternative when intravenous (IV) or intraosseous (IO) access is delayed. It ensures rapid delivery without interrupting critical chest compressions or defibrillation efforts. Evidence highlights that IM epinephrine can be administered significantly faster than IV/IO routes, potentially improving outcomes.
Current Evidence
In a pivotal Salt Lake City Emergency Medical Services study, including 1405 people with out-of-hospital cardiac arrest, IM epinephrine reduced the median time to first administration by 3.5 minutes compared to IV/IO routes (4.3 vs. 7.8 minutes). Faster administration correlated with better outcomes:
Improved survival to hospital admission (37.1% IM vs. 31.6% IV/IO; OR 1.27, 95%CI 1.06-1.77).
Increased survival to discharge (11.0% IM vs. 7.0% IV/IO; OR 1.73, 95%CI 1.10-2.71).
Better neurologic outcomes at discharge (9.8% IM vs. 6.2% IV/IO; OR 1.72, 95%CI 1.07-2.76).
Preliminary preclinical studies further support these findings. In porcine CPR models, early IM epinephrine produced sustained plasma levels with improved safety profiles compared to delayed IV epinephrine. While IM epinephrine achieved a lower peak plasma concentration, it enhanced the area under the concentration curve, suggesting stable systemic effects.
Future Research
Although initial findings are promising, randomized controlled trials are necessary to validate these results in people. Since there is no clinical veterinary data, it is too early to make clinical recommendations for our patients. Key questions include optimal dosing strategies for IM administration, safety in various clinical contexts, and the impact on long-term neurologic outcomes. Further investigation into veterinary-specific dosing and protocols will bridge the gap in translational application.
In conclusion, IM epinephrine could emerge as a practical alternative to intravascular and intraosseous drug administration routes. It enhances the timeliness of drug delivery when vascular access is not yet established, and potentially improves survival and neurologic outcomes in people and animals with cardiopulmonary arrest.
Reference
Palatinus HN, Johnson MA, Wang HE, Hoareau GL, Youngquist ST. Early intramuscular adrenaline administration is associated with improved survival from out-of-hospital cardiac arrest. Resuscitation. 2024 Aug;201:110266. doi:10.1016/j.resuscitation.2024.110266. Epub 2024 Jun 9. PMID: 38857847.
Additional References
Pugh AE, Stoecklein HH, Tonna JE, Hoareau GL, Johnson MA, Youngquist ST. Intramuscular adrenaline for out-of-hospital cardiac arrest is associated with faster drug delivery: A feasibility study. Resusc Plus. 2021 May 31;7:100142.
Fan CY, Huang CH, Chen CH, Sung CW, Pei-Chuan Huang E. Future thoughts of intramuscular adrenaline in out-of-hospital cardiac arrest resuscitation. Resuscitation. 2024 Aug;201:110305. doi: 10.1016/j.resuscitation.2024.110305. Epub 2024 Jul 9. PMID: 38992563.
Palatinus HN, Johnson MA, Youngquist ST. Reply to letter: Future thoughts of intramuscular adrenaline in out-of-hospital cardiac arrest resuscitation. Resuscitation. 2024 Aug;201:110316. doi: 10.1016/j.resuscitation.2024.110316. Epub 2024 Jul 10. PMID: 38996905.
