What is the proper target temperature for out-of-hospital cardiac arrest?

Prolonged targeted temperature management reduces memory retrieval deficits six months post-cardiac arrest: A randomised controlled trial

BACKGROUND

Cognitive sequelae, most frequently memory, attention, and executive dysfunctions, occur commonly in out-of-hospital cardiac arrest (OHCA) survivors. Targeted temperature management (TTM) following OHCA is associated with improved cognitive function. However, the relationship between the duration of TTM and cognitive outcome remains unclear. We hypothesised that OHCA survivors that were subjected to prolonged TTM of 48 h (TTM48) would exhibit better cognitive functions compared to those subjected to standard TTM of 24 h (TTM24) six months post-OHCA.

METHODS

A predefined, cognitive post-hoc sub-study was conducted on the multicentre clinical trial: "Target Temperature Management for 48 vs. 24 h and Neurologic Outcome after out-of-hospital cardiac arrest: A Randomised Clinical Trial" (the TTH48 trial). OHCA survivors with perceived good cognitive outcome (CPC score ≤ 2) were invited to a neuropsychological assessment of memory, attention, and executive functions six months post-OHCA.

RESULTS

In total, 79 patients were included in the study. Multivariate regression analysis revealed that TTM48 was associated with a significant better performance on three of 13 cognitive tests specific to memory retrieval after adjusting for age at follow-up and time to return of spontaneous circulation. Overall, patients in the TTM24 group were almost three times more likely (RR = 2.9 (95% CI 1.1-7.4)), p = 0.02) to be cognitively impaired.

CONCLUSIONS

This study reports an association between the duration of TTM and cognitive outcome. In OHCA survivors with perceived good cognitive outcome (CPC ≤ 2), TTM48 was associated with reduced memory retrieval deficits and lower relative risk of cognitive impairment six months after OHCA compared to standard TTM24. ClinicalTrials.gov (identifier: NCT01689077).

The effect of different target temperatures in targeted temperature management on neurologically favorable outcome after out-of-hospital cardiac arrest: A nationwide multicenter observational study in Japan (the JAAM-OHCA registry)

BACKGROUND

It has been insufficiently investigated whether neurological function after out-of-hospital cardiac arrest (OHCA) would differ by 1 °C change in ordered target temperature of 33-36 °C among patients undergoing targeted temperature management (TTM) in the real-world setting.

METHODS

This nationwide hospital-based observational study (The Japanese Association for Acute Medicine-OHCA Registry) conducted between June 2014 and December 2015 in Japan included OHCA patients aged ≥18 years who were treated with TTM. The primary outcome was one-month survival with neurologically favorable outcomes defined by cerebral performance category 1 or 2. To investigate the effect of TTM by 1 °C change in ordered target temperature of 33-36 °C on each outcome, random effects logistic regression analyses were performed.

RESULTS

The final analysis included 738 patients. The proportion of patients with neurologically favorable outcome was 30.4% (7/23), 31.7% (175/552), 28.9% (11/38), and 30.4% (38/125) in the 33 °C, 34 °C, 35 °C, and 36 °C groups, respectively. In the multivariable logistic regression analysis, no group had a higher proportion of neurologically favorable outcome compared with the 34 °C group (vs. 33 °C group, adjusted odds ratio [AOR] 0.90; 95% confidence interval [CI] 0.25-3.12, vs. 35 °C group, AOR 1.17; 95% CI 0.44-3.13, vs. 36 °C group, AOR 1.26; 95% CI 0.78-2.02).

CONCLUSIONS

In this population, we evaluated the difference in outcomes after adult OHCA patients received TTM by 1 °C change in ordered target temperature of 33-36 °C and demonstrated that there was no statistically significant difference in neurologically favorable outcomes after OHCA irrespective of target temperature.