Pre-hospital portable monitoring of cerebral regional oxygen saturation (rSO(2)) by ambulance personnel during cardiopulmonary resuscitation: A prospective observational analysis of 87 cases in Osaka city, Japan

BACKGROUND: Regional cerebral oxygen saturation (rSO(2)) is a non-invasive method of measuring cerebral perfusion; However, serial changes in cerebral rSO(2) 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 rSO(2) pattern and patient outcome. METHODS: We evaluated rSO(2) 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 rSO(2) 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′. RESULTS: 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 < 0.045 and 17/40 [42.5%] vs. 6/41 [12.8%], AOR 3.56, 95% CI 1.11–11.43, p < 0.033). There was no significant difference in ‘1-month survival’ and ‘CPC 1 or 2′ between patterns. CONCLUSION: Type 1 (increasing pattern) was associated with ‘Prehospital ROSC’ and ‘Alive at admission’. Pre-hospital monitoring of cerebral rSO(2) might lead to a new resuscitation strategy.