Introduction: Recently, the development of physiological monitoring to guide cardiopulmonary resuscitation (CPR) or predict survival with good neurologic outcome after out-of-hospital cardiac arrest (OHCA) is important, and the measurement of regional cerebral oxygen saturation (rSO2) during CPR might be useful in pre-hospital settings. This simplified monitoring system of rSO2 is a non-invasive technology for cerebral perfusion, but continuous changes of cerebral rSO2 values among OHCA patients in pre-hospital settings have been insufficiently investigated.
Methods: We recently developed a portable rSO2 monitoring system that is very small (170х100х50mm in size and 600g in weight) and can use in pre-hospital settings. The sensor pad is attached to the patient’s forehead by the emergency-medical-service (EMS) personnel, and it can monitor cerebral rSO2 immediately and continuously during CPR. From June 2013 through June 2017 in Osaka City, Japan, we assessed continuous changes in cerebral rSO2 values for 51 OHCA patients during CPR by EMS personnel.
Results: According to the analyses of continuous changes in rSO2values, four patterns of changes in cerebral rSO2 values were found as follows; Type 1: No change rSO2 type (n=27) Measured rSO2 did not change during CPR. Type 2: Increasing rSO2 type (n=18). Measured rSO2 increased gradually during CPR or after ROSC. Type 3: Gradually decreasing rSO2 type (n=3). Measured rSO2 decreased gradually despite performing CPR by EMS personnel. Type 4: Dropping rSO2 type (n=3). Measured rSO2 dropped after confirmation of ROSC, which suggests that the re-arrest occurred during monitoring.
Conclusion: We measured continuous changes in cerebral rSO2 values among 51 patients with OHCA pre-hospital settings and found the 4-specific patterns regarding continuous changes in rSO2 values. Furthermore, it is needed to collect many cases to establish resuscitation strategies for OHCA by using cerebral rSO2 monitoring.