Real-time cerebral oximetry and outcomes during out-of-hospital resuscitation

Abstract

Background: Anoxic brain injury is a common mode of death following out-of-hospital cardiac arrest (OHCA). We assessed the course of regional cerebral oxygen saturation (rSO₂) during resuscitation to understand its association with return of spontaneous circulation (ROSC) and functional survival.

Methods: We conducted a prospective observational investigation of OHCA patients treated by Emergency Medical Services (EMS) in a suburban community. Real-time rSO₂ was characterized overall and according to ROSC and favorable survival defined by Cerebral Performance Category (CPC) 1-2. We also calculated ΔrSO₂, defined as the change in rSO₂ from pre- to post-ROSC among those who achieved ROSC, and compared to a time-matched rSO₂ difference among those receiving CPR who did not achieve ROSC.

Results: Of 140 eligible cases, 93 were enrolled. Of these, 55 % (n = 51) achieved ROSC and 10 % (n = 9) survived with CPC 1-2. Upon cerebral oximeter application, the median rSO₂ was 33 % (interquartile range = 22.45 %). Initial rSO₂ did not predict subsequent ROSC (38 % ROSC vs 27 % no ROSC, AUC = 0.61, p = 0.13) or subsequent favorable survival (45 % CPC 1-2 vs 32 % no survival with CPC 1-2, AUC = 0.77, p = 0.17). However, real-time rSO₂ and ΔrSO₂ were greater upon ROSC versus time-matched ongoing pulselessness (rSO₂ = 60 % vs. 33 %, AUC = 0.84, p < 0.001; ΔrSO₂ = 11 % vs. 1 %, AUC = 0.85, p < 0.001). Among those who achieved ROSC, rSO₂ and ΔrSO₂ during the peri-ROSC period was greater among those with subsequent favorable survival (rSO₂ = 63 % vs. 46 %, AUC = 0.74, p = 0.06; ΔrSO₂ = 29 % vs. 10 %, AUC = 0.77, p = 0.04) CONCLUSION: Greater values of rSO₂ and ΔrSO₂ identified instantaneous ROSC and predicted favorable neurological survival among those who achieved ROSC.

Keywords: Cerebral oximetry; Emergency medical services; Out-of-hospital cardiac arrest.