INTRODUCTION: Previous studies have described interactions between the success rate of tracheal intubation (TI) and chest compression during resuscitation from cardiac arrest. However, it is not clear if chest compression increases the complexity of TI. The aim of this study was to determine the risk factors for difficulty with tracheal intubation during resuscitation of patients with out-of-hospital cardiac arrest, focusing in particular on the impact of ongoing chest compressions on the success of the first intubation attempt. METHODS: We performed a secondary analysis of data obtained during an observational, prospective multicenter study. After each TI, the operator provided information on both the operator and the patient, and the TI environment. We included only OHCA data. The primary endpoint was failure of the first intubation attempt. RESULTS: Data on a total of 848 OHCA patients were analyzed. A total of 291 first TI attempts failed (34.3%). Multivariate analysis revealed that six variables were associated with an increased risk of failure: an operator who had performed ≤ 50 prior intubations (odds ratio [OR] [95% confidence interval] = 2.0 [1.4-2.9]), male patient gender (OR = 1.5 [1.0-2.3]), a small inter-incisor space (OR = 3.4 [2.2-5.4]), ear, nose, and throat disease (OR = 2.8 [1.8-4.4]), vomiting (OR = 2.1 [1.4-3.2]), and continued chest compression during the TI attempt (OR = 1.6 [1.1-2.3]). CONCLUSION: The first intubation attempt failed in 34% of cases, and ongoing chest compressions during intubation was one of six variables associated with the risk of failure. However, this must be weighed against the need for invasive airway management and the negative effects of interrupting chest compressions.< Réduire