Abstract Body: Background: The patients most likely to benefit from targeted temperature management (TTM) after out-of-hospital cardiac arrest (OHCA) are unknown. We investigated whether a lower serum lactate/albumin ratio (SLAR) at hospital arrival was associated with favorable neurological outcomes in patients receiving TTM after OHCA.

Methods: Using the nationwide registry led by the Japanese Association for Acute Medicine, we reviewed the records of adults aged ≥18 years with OHCA who received TTM after the return of spontaneous circulation between June 1, 2014, and December 31, 2022. SLAR was recorded at hospital arrival. Patients with OHCA caused by trauma such as falls, hanging, drowning, poisoning, burns, or asphyxia were excluded, as were patients with missing data, those who received extracorporeal membrane oxygenation, and those for whom the time the emergency call to the measurement of laboratory data exceeded 120 min. The primary outcome was 30-day survival with favorable neurological outcome, defined as cerebral performance category scale 1 or 2. The enrolled patients were categorized according to the quartiles of SLAR for targeted temperatures of ≤34°C (n = 833; first quartile: SLAR ≤ 1.73, n = 209; second quartile: 1.73 < SLAR ≤ 2.54, n = 208; third quartile: 2.54 < SLAR ≤ 3.53, n = 209; fourth quartile: SLAR > 3.53, n = 207) and ≥35°C (n = 437; first quartile: SLAR ≤ 1.85, n = 111; second quartile: 1.85< SLAR ≤ 2.68, n = 108; third quartile: 2.68< SLAR ≤ 3.75, n = 109; fourth quartile: SLAR > 3.75, n = 109). Multivariable logistic regression analysis was performed to adjust for critical factors.

Results: In patients with targeted temperature ≤ 34°C, the likelihood of favorable neurological outcomes was lower in the second (adjusted odds ratio [AOR] = 0.59, 95% confidence interval [CI] = 0.35–0.98), third (AOR = 0.25, 95% CI = 0.15–0.42), and fourth quartiles (AOR = 0.10, 95% CI = 0.05–0.18) than in the first quartile. In the group with target temperature ≥ 35°C, the likelihood of favorable neurological outcomes was similarly lower in the second (AOR = 0.38, 95% CI = 0.19–0.74), third (AOR = 0.19, 95% CI = 0.09–0.40), and fourth quartiles (AOR = 0.07, 95% CI = 0.03–0.17) than in the first quartile.

Conclusions: A lower SLAR at hospital arrival was significantly associated with better neurological outcomes in patients receiving TTM after OHCA regardless of the targeted temperature.