Intubation during in-hospital cardiac arrest: an instrumental variable analysis.

Introduction: Tracheal intubation is commonly performed during in-hospital cardiac arrest, but the evidence for a survival benefit remains uncertain. Methods: This was an observational study using data from the Get With The Guidelines registry. Adult patients with an in-hospital cardiac arrest between January 2013 and December 2021 were included. Instrumental variable analyses were conducted using two-stage least squares regression in an attempt to account for unmeasured confounding. Two instrumental variables were predefined as (1) tracheal intubation during the previous cardiac arrest and (2) the proportion of intubated cardiac arrest patients within the past year at a given hospital. The primary outcome was survival to hospital discharge. Secondary outcomes included return of spontaneous circulation and favorable neurological status. Results: A total of 210,115 cardiac arrests were included. The median age was 67 years, 59 % of patients were male, and 85 % of patients had an initial non-shockable rhythm. Intubation was performed in 85 % of patients. For the first and second instrumental variables, tracheal intubation was associated with absolute risk differences in survival of -11 % (95 % CI, -16 % to -5.6 %) and -12 % (95 % CI, -16 % to -8.2 %), respectively. Similar results were observed for the secondary outcomes. Conclusions: Tracheal intubation during in-hospital cardiac arrest was associated with reduced survival, although point estimates were implausibly large, and the results should be interpreted cautiously. Preference-based instrumental variables may not adequately address confounding in this setting. Randomized clinical trials are needed to inform advanced airway management during in-hospital cardiac arrest.