title: Pre-hospital portable monitoring of cerebral regional oxygen saturation (rSO2) in seven patients with out-of-hospital cardiac arrest.
abstract: BACKGROUND
  In recent years, measurement of cerebral regional oxygen saturation (rSO2) has attracted attention during resuscitation. However, serial changes of cerebral rSO2 in pre-hospital settings are unclear. The objective of this study was to clarify serial changes in cerebral rSO2 of patients with out-of-hospital cardiac arrest (OHCA) in the pre-hospital setting.
  
  
  METHODS
  We recently developed a portable rSO2 monitor that is small (170 × 100 × 50 mm in size and 600 g in weight) enough to carry in pre-hospital settings. The sensor is attached to the patient's forehead by the ELT (Emergency Life-saving Technician), and it monitors rSO2 continuously.
  
  
  RESULTS
  From June 2013 through August 2014, serial changes in cerebral rSO2 in seven patients were evaluated. According to the results of the serial changes in rSO2, four patterns of rSO2 change were found, as follows. Type 1: High rSO2 (around about 60 %) type (n = 1). Initial electrocardiogram was ventricular fibrillation and ROSC (return of spontaneous circulation) could be diagnosed in pre-hospital setting. Her outcome at discharge was Good Recovery (GR). Type 2: Low rSO2 (around about 45-50 %) type (n = 3). They did not get ROSC even once. Type 3: Gradually decreasing rSO2 type (n = 2): ROSC could be diagnosed in hospital, but not in pre-hospital setting. Their outcomes at discharge were not GR. Type 4: other type (n = 1). In this patient with ROSC when ELT started cerebral rSO2 measurement, cerebral rSO2 was 67.3 % at measurement start, it dropped gradually to 54.5 %, and then rose to 74.3 %. The cerebral oxygenation was impaired due to possible cardiac arrest again, and after that, ROSC led to the recovery of cerebral blood flow.
  
  
  CONCLUSIONS
  We could measure serial changes in cerebral rSO2 in seven patients with OHCA in the pre-hospital setting. Our data suggest that pre-hospital monitoring of cerebral rSO2 might lead to a new resuscitation strategy.
authors: Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan. htomoya1979@hp-emerg.med.osaka-u.ac.jp.
authors: Tomoya
authors: T
authors: Hirose
authors: Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors: Tadahiko
authors: T
authors: Shiozaki
authors: Chuo Fire Station, Osaka Municipal Fire Department, 2-1-6 Uchihonmachi, Chuo-Ku Osaka-City, Osaka, 540-0026, Japan.
authors: Junji
authors: J
authors: Nomura
authors: Chuo Fire Station, Osaka Municipal Fire Department, 2-1-6 Uchihonmachi, Chuo-Ku Osaka-City, Osaka, 540-0026, Japan.
authors: Yasuto
authors: Y
authors: Hamada
authors: Chuo Fire Station, Osaka Municipal Fire Department, 2-1-6 Uchihonmachi, Chuo-Ku Osaka-City, Osaka, 540-0026, Japan.
authors: Keiichi
authors: K
authors: Sato
authors: Chuo Fire Station, Osaka Municipal Fire Department, 2-1-6 Uchihonmachi, Chuo-Ku Osaka-City, Osaka, 540-0026, Japan.
authors: Kazuya
authors: K
authors: Katsura
authors: Traumatology and Critical Care Medical Center, National Hospital Organization Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-Ku Osaka-City, Osaka, 540-0006, Japan.
authors: Naoki
authors: N
authors: Ehara
authors: Traumatology and Critical Care Medical Center, National Hospital Organization Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-Ku Osaka-City, Osaka, 540-0006, Japan.
authors: Akinori
authors: A
authors: Wakai
authors: Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors: Kentaro
authors: K
authors: Shimizu
authors: Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors: Mitsuo
authors: M
authors: Ohnishi
authors: Osaka Municipal Fire Department, 1-12-54 Kujo-Minami, Nishi-Ku, Osaka-City, Osaka, 550-8566, Japan.
authors: Sumito
authors: S
authors: Hayashida
authors: Traumatology and Critical Care Medical Center, National Hospital Organization Osaka National Hospital, 2-1-14 Hoenzaka, Chuo-Ku Osaka-City, Osaka, 540-0006, Japan.
authors: Daikai
authors: D
authors: Sadamitsu
authors: Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors: Takeshi
authors: T
authors: Shimazu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000378:metabolism*; D004634:Emergency Medical Technicians; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D058687:Out-of-Hospital Cardiac Arrest / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D016896:Treatment Outcome
chemical_list: D010100:Oxygen
keywords: Emergency life-saving technician; Out-of-hospital cardiac arrest; Portable rSO2 monitor; Pre-hospital; Regional oxygen saturation