Regional cerebral oxygen saturation in cardiac arrest survivors undergoing targeted temperature management 36 °C versus 33 °C: A randomized clinical trial.

AIM OF STUDY: To investigate whether regional cerebral oxygen saturation (rSO2) differs in out-of-hospital cardiac arrest (OHCA) survivors undergoing targeted temperature management (TTM) 36 °C versus 33 °C.

METHODS

A randomized clinical trial was conducted at intensive care units in two referral hospitals. Fifty-seven comatose OHCA survivors were randomized into either a 36 °C or 33 °C group. Patients were cooled and maintained at an oesophageal temperature of either 36 °C or 33 °C for 24 hours, rewarmed at a rate of 0.25 °C/hour, and maintained at <37.5 °C until 72 hours. During 72 hours of TTM, rSO2 was continuously monitored on the left forehead using near-infrared spectroscopy (INVOSTM 5100C). The rSO2 level at 72 hours was compared between the two groups. Next, serial rSO2 levels for 72 hours were compared using mixed effects regression. The association between rSO2 levels and 6-month neurological outcomes was also evaluated.

RESULTS

There were no significant differences in the rSO2 level at 72 hours between the 36 °C and 33 °C groups (p = 0.372). Furthermore, serial rSO2 levels for 72 hours of TTM were not different between the two groups (p = 0.733). However, low rSO2 levels, particularly at 24 hours of TTM, were significantly associated with poor 6-month neurological outcomes (odds ratio = 0.899, 95% confidence interval: 0.831-0.974). The area under the receiver operating characteristic curve of the rSO2 level at 24 hours for poor neurological outcomes was 0.800.

CONCLUSIONS

Regardless of target temperatures, low rSO2 levels during TTM were significantly associated with poor 6-month neurological outcomes in OHCA survivors.