Pre-hospital portable monitoring of cerebral regional oxygen saturation (rSO2) by ambulance personnel during cardiopulmonary resuscitation: A prospective observational analysis of 87 cases in Osaka city, Japan

Regional cerebral oxygen saturation (rSO2) is a non-invasive method of measuring cerebral perfusion; However, serial changes in cerebral rSO2 values among out-of-hospital cardiac arrest (OHCA) patients in pre-hospital settings have not been sufficiently investigated. We aimed to investigate the association between the serial change in rSO2 pattern and patient outcome. We evaluated rSO2 in OHCA patients using portable monitoring by emergency life-saving technicians (ELTs) from June 2013 to December 2019 in Osaka City, Japan. We divided the patterns of serial of rSO2 change into type 1 (increasing pattern) and type 2 (non-increasing pattern). Patients in whom measurement started after return of spontaneous circulation (ROSC) were excluded. The outcome measures were ‘Prehospital ROSC’, ‘Alive at admission’, ‘1-month survival’ and ‘Cerebral Performance Category (CPC) 1 or 2′. Eighty-seven patients were eligible for this analysis (type 1: n=40, median age: 80.5 [IQR: 72–85.5] years, male: n=20 [50.0%]; type 2: n=47, 81 [72–85.5] years, male: n=28 [59.6%]). In a multivariable logistic regression adjusted for confounding factors, outcomes of ‘Prehospital ROSC’ and ‘Alive at admission’ were significantly higher in type 1 than type 2 pattern (11/40 [27.5%] vs. 2/47 [4.26%], AOR 5.67, 95% CI 1.04–30.96, p