The benefit of hypothermic targeted temperature management decreases when post-arrest care improves

BackgroundSeveral clinical trials and cohort studies in the past two decades have demonstrated inconsistent results regarding survival and neurologic recovery benefits for patients undergoing targeted temperature management (TTM) at 33 as compared to those undergoing TTM at 36 or normothermia. Whether the improved quality of post-arrest care over time contributes to diminishing benefit of TTM at 33 remains un-investigated. MethodsThere were 1,809 adult non-traumatic cardiac arrest survivors during 2011-2020. After excluding patients with pre-arrest poor conscious level defined as Glasgow-Pittsburgh Cerebral Performance Category (CPC) >2 (n=258), patients who regained clear consciousness after return of spontaneous circulation (ROSC) (n=300), patients with active bleeding or intracranial hemorrhage (n=48) and patients who underwent TTM of 36 due to unstable hemodynamic (n=11), a total of 1,192 eligible candidates for TTM of 33 were finally enrolled and classified into Period 1 (during 2011-2015, n = 449) and Period 2 (during 2016-2020, n = 693). ResultsPatients in Period 2 received more diagnostics procedures and specific therapies than those in Period 1. The proportion of patients with good neurological recovery at hospital discharge in Period 2 is significantly higher than that in Period 1 (21.4% vs.14.0%, adjusted odds ratio [aOR] 1.60, 95% confidence interval [CI] 1.14-2.26). TTM was beneficial for the outcomes in both Period 1 and 2, with patients in Period 1 having higher chances of survival and good neurological outcome than those in Period 2 (survival: aOR 5.66, 95% CI 3.49-9.18 vs. aOR 2.91, 95% CI 1.98-4.28; good neurological recovery: aOR 3.92, 95% CI 2.12-7.25 vs. aOR 2.19, 95% CI 1.43-3.34). Among patients with low-risk and medium-risk severity of illness, TTM benefited survival and neurological outcomes, regardless of time period. But the chance of beneficial outcomes decreased consistently from Period 1 to Period 2. ConclusionAmong cardiac arrest survivors, improvement in the quality of post-cardiac arrest care over time is associated with better neurological recovery. TTM remains beneficial for survival and neurological outcomes following cardiac arrest, regardless of the time period. However, the benefit of TTM may diminish when post-cardiac arrest care improves.