Does endotracheal intubation increases chest compression fraction in out of hospital cardiac arrest: A substudy of the CAAM trial

Background: Optimal out of hospital cardiac arrest (OHCA) airway management strategies remain unclear. We compared chest compression fraction (CCF) between patients receiving endotracheal intubation (ETI) versus bag mask ventilation (BMV).

Methods: We studied adult OHCA enrolled from our center in the CAAM trial. Primary exposures were ETI or BMV. Primary outcome was whole intervention CCF, adjusted for Utstein confounders. Secondary outcomes were per cycle CCF, no flow time associated (NFT) with ventilation, rhythms checks and mechanical chest compression device placement.

Results: Of 2040 OHCA enrolled in the CAAM trial we analyzed 112 cases recruited by our center. Unadjusted CCF was 0.89 for ETI and 0.88 for BMV (p = 0.19). Compared with BMV, ETI achieved lower NFT associated with ventilations (32 vs 127 s; p < 0.001). ETI cases experienced higher NFT associated with rhythm checks (69.5 vs 42.5 s p = 0.02) and with mechanical chest compression placement (29 vs 20 s; p = 0.04). CCF was higher during the first cycle in BMV than in ETI patients (0.81 vs 0.74; p = 0.02). After correction for confounders we observed no difference in global intervention CCF between the ETI and BMV (ΔCCF [ETI-BMV] 0.301; [95%CI: -1.9 to 2.51]; p = 0.79).

Conclusion: In our substudy whole intervention CCF among OHCA was not modified by ETI compared to BMV. In the ETI group we observed lower NFT associated with ventilations and higher NFT associated with mechanical chest compression devices placement. CCF was lower in the ETI group during the first cycle.