Association Between Tracheal Intubation During In-Hospital Cardiac Arrest and Survival

Anderson LW, Granfeldt A, Callaway CW et al.

JAMA. 2017;317(5):494-506. DOI:10.1001/jama.2016.20165

AIM OF STUDY

Is tracheal intubation during in-hospital cardiac arrest associated with survival to hospital discharge?

DESIGN

Retrospective, observational cohort-study

METHODOLOGY

Data collected from January 2000 to December 2014 from a US-based multi-centre prospective registry of in-hospital cardiac arrest

Patients populated in to two groups, those undergoing endotracheal intubation within fifteen minutes and those not.

Patients were then 1:1 matched with patients at risk of being intubated within the same minute 1:1 using a propensity score with nearest neighbour-matching algorithm

Propensity score based on Cox Proportional Hazard Score which calculated risk of needing intubation at any given minute according to multiple covariates.

PRIMARY OUTCOME

Survival to discharge

SECONDARY OUTCOMES

ROSC, meaningful neurological recovery (1 or 2 on Utstein scale)

STATISTICS

Independent categorical variables were compared with the χ2 test, and the Cochran-Armitage test was used to test for trends in tracheal intubation over time.

Time-Dependent Propensity Score–Matched Analysis

Sensitivity analysis to evaluate effect of missing data

Risk ratios with 95%confidence intervals for predefined subgroup analyses

RESULTS

Survival to hospital discharge significantly lower in intubation group (p<0.001)

33.2% NO TUBE vs. 17% TUBE, risk ratio (RR) 0.58 (95% C.I. 0.57-0.59)

Propensity Score-Matched Analysis (p<0.001) 19.4% vs. 16.3%, RR 0.84 (95% C.I. 0.81-0.87)

Return of spontaneous circulation significantly lower in intubation group (p<0.001)

69% vs. 59.2%, RR 0.75 (95% C.I. 0.73-0.76)

Propensity Score-Matched Analysis (p<0.001) 59.3% vs. 57.8%, RR 0.97 (95% C.I. 0.96-0.99)

Favourable functional outcome at discharge significantly lower in intubation group (p<0.001) 25.7% vs. 11.2%, RR 0.55 (95% C.I. 0.54-0.56)

Propensity Score-Matched Analysis (p<0.001) 13.6% vs. 10.6%, RR 0.78 (95% C.I. 0.75-0.81)

CONCLUSIONS/DISCUSSION

Among adult patients with in-hospital cardiac arrest, initiation of tracheal intubation within any given minute during the first 15 minutes of resuscitation, compared with no intubation during that minute, was associated with decreased survival to hospital discharge. Although the study design does not eliminate the potential for confounding by indication, these findings do not support early tracheal intubation for adult in- hospital cardiac arrest.

STATED LIMITATIONS FROM STUDY

Unsuccessful intubations not recorded

Time taken to intubate, which is likely to be a large confounding factor in outcome.

Patients who are intubated might be more sick, despite efforts, residual bias may exist

Intubation may result in hyperoxia which can be associated with harm.

Practices in resuscitation have changed over the 15 years of data collection

Control patients are individuals who were not intubated during the same minute Vs intubated. However, these controls may be intubated in subsequent minutes. In the propensity matched groups, a number of patients that were intubated within 15 minutes were included in the no intubation group. These patients could have also been included in the intubation group.

Baseline difference – significantly more patients with VF/VT and witnessed arrest in no intubation group; and significantly lower use of adrenaline

Due to the difficulty of collecting accurate data during a cardiac arrest there is the possibility of timings being misclassified

DISCUSSION FROM JOURNAL CLUB MEETING

Raised questions and discussion surrounding current practice

Emphasis on time taken for intubation

Importance of minimizing delays to other interventions, such as cardioversion, adrenaline and CPR

Summary by Dr W Turner. Journal Club 28 September 2017.