Introduction: There are some critical ill patients who cannot measure oxygen saturation (SpO2) by pulse oximeter at the pre-hospital settings. For example, among emergency patients who were treated by emergency medical service (EMS) personnel of Osaka Municipal Fire Department in 2016, there were 3,571 patients who had urgent conditions judged by on-scene EMS personnel but did not have cardiopulmonary arrest (CPA), but the measurement of SpO2 at the scene could not be measured for 395 patients. On the other hand, the measurement of cerebral regional oxygen saturation (rSO2) during resuscitation has been recently paid to attention.
Purpose: To evaluate whether rSO2 could be measured for these patients.
Materials and methods: We developed portable rSO2 monitors and equipped them in nine ambulances (There are 63 ambulances in Osaka City). We measured serial changes in cerebral rSO2 among emergency patients who had urgent conditions judged by on-scene EMS personnel and could not be measured SpO2 at the scene from April 1st 2017 through March 31th 2018.
Results: During the study period, there were 523 patients with incapable-measurement SpO2 who had urgent conditions judged by on-scene EMS personnel but did not have CPA. We evaluated serial changes in cerebral rSO2 among nine patients at the pre-hospital settings. The values of many cases were lower than the normal range measured from healthy adults (71.2 ± 3.9%, on room air). Of them, SpO2 among 3 cases could not be measured at once during transport to a hospital in spite of any oxygenation. Three cases had <60mmHg of systolic blood pressure or an un-palpable radial artery.
Conclusions: We could measure serial changes in cerebral rSO2 among nine patients without the measurement of SpO2 at the scene. Our data suggest that pre-hospital monitoring of cerebral rSO2 might be a new physiological monitoring for urgent patients during transport.

7 - New method to evaluate an oxygenation for emergency patients who cannot measure SpO2at the scene.