Association between base excess level at hospital arrival and neurological outcomes in adult out-of-hospital cardiac arrest: A multicentre cohort study

Aim

We aimed to assess the association between base excess (BE) levels and neurological outcomes in patients with out-of-hospital cardiac arrest (OHCA), accounting for the time from cardiac arrest onset to blood sampling.

Methods

This multicentre study was conducted in Osaka, Japan, and enrolled consecutive patients with OHCA who were transported to 16 medical centres between 2012 and 2021. Patients aged ≥ 18 years with witnessed OHCA and available BE measurements upon hospital arrival were examined. Patients were stratified into Q1 (BE ≤ −21.1 mmol/L), Q2 (−21.1 < BE ≤ −15.7 mmol/L), Q3 (−15.7 < BE ≤ −10.4 mmol/L) and Q4 (BE > −10.4 mmol/L) groups based on BE levels. The primary outcome was 1-month survival with a favourable neurological outcome (Cerebral Performance Category scale score: 1 or 2).

Results

Among the 23,854 patients with OHCA, only 6066 were included in the final analysis. Approximately 3.2 %, 4.7 %, 9.9 % and 23.7 % of patients in the Q1, Q2, Q3 and Q4 groups, respectively, achieved favourable neurological outcomes at 1 month. Compared with Q4, the adjusted odds ratio for a favourable neurological outcome in Q1 was 0.13. Subgroup analysis revealed a significant interaction between prehospital return of spontaneous circulation (ROSC) and neurological outcomes; neurological outcomes worsened as BE decreased in patients with ROSC but not in those without ROSC.

Conclusion

Lower BE levels upon hospital arrival are associated with poorer neurological outcomes and may serve as prognostic indicators in patients with OHCA who achieved prehospital ROSC.