Abstract:

Background and Objectives: The use of ketamine as an induction agent in Medication Assisted Intubation (MAI) is enjoying increased interest in the prehospital setting. It is desirable for its favorable hemodynamic profile, bronchodilatory effect, and ability to provide analgesia and sedation without inducing apnea. In some prehospital protocols, it is replacing traditional agents such as etomidate, although it must be used with some caution in certain populations. The objective of this study was to compare MAI success rates by choice of induction agent in the prehospital setting.

Methods: A single-center retrospective chart review was conducted of all intubations attempted by an urban hospital-based paramedic service with MAI capabilities in 2018. Demographic data were collected as well as outcome measures including endotracheal intubation success rates for each induction agent. Chi square testing and two-tailed T tests were utilized to determine statistical significance.

Results: In total, 407 patients underwent attempted intubation; 390 were successful (mean age 58, 71% male). Patient characteristics between the ketamine, and etomidate cohort were not significantly different with regards to age (p = 0.440), gender (p= 0.228), weight (p=0.624) or the presence of cardiac arrest (p=0.916). For all MAI attempts, Succinylcholine was utilized as a paralytic. There were 38 attempts made using etomidate with 95% success and 132 attempts made using ketamine with 98% success. There was no significant difference in success rates between these two cohorts (P= 0.320). Additionally, there was no difference between overall success rates for intubation attempts without medication or either induction agent (p= 0.193 for ketamine and 0.958 for etomidate).

Conclusion: In an urban prehospital paramedic service, the use of etomidate and ketamine as induction agents for MAI were associated with equal success rates. Additional study is required to determine if hospital outcomes are different for patient who received each induction agent. Both agents have desirable qualities and adverse effect profiles that render them appropriate for certain patient populations. It may be prudent to maintain the availability of both given their comparable performance in the prehospital setting and to continue to educate paramedics on the optimal choice for each patient encounter that necessitates MAI.