Clinical paperTemporal changes in peripheral regional oxygen saturation associated with return of spontaneous circulation after out-of-hospital cardiac arrest: A prospective observational cohort study in Japan
Introduction
The prognosis for out-of-hospital cardiac arrest (OHCA) patients is extremely poor, with 6–10% surviving and only 3% returning to society without complications.1 There are 120,000 cases of OHCA in Japan every year, and the number is increasing annually as the population ages.2., 3. In other countries, paramedics can make the decision to stop resuscitation at the scene; however, in Japan, paramedics cannot make this decision, and efforts must be continued to resuscitate the patient.4., 5. In principle, resuscitation efforts and subsequent transport to an emergency hospital are made for almost all OHCA patients in Japan. The Japanese population is the oldest in the world; therefore, it is necessary to consider the appropriate allocation of medical resources to treat OHCA patients with poor prognoses.6.
To address this situation, an objective index of return of spontaneous circulation (ROSC) is necessary. Guidelines suggest that the evaluation of mean arterial pressure (MAP),7 coronary perfusion pressure (CCP),nd end-tidal CO2 (EtCO2)9 during cardiopulmonary resuscitation (CPR) 8 a can relate to ROSC; however, assessing these parameters is invasive and inconvenient for application in emergency care settings. Cerebral regional oxygen saturation (crSO2), which evaluates cerebral circulation, has been suggested to be a useful index for ROSC in OHCA patients.10., 11., 12., 13. Moreover, temporal changes in crSO2 are a more useful index for ROSC in patients with OHCA.14 Regional oxygen saturation (rSO2) is a non-invasive and convenient way to evaluate tissue blood flow, and it has been reported that Peripheral rSO2 (prSO2) can be used to evaluate tissue blood flow in paediatric and neonatal patients rather than crSO2.15., 16. crSO2 is affected by autoregulation and remains constant even in shock, while prSO2 reflects tissue blood flow without modification and can be a more sensitive indicator of circulation failure.16 However, little is known regarding the association of prSO2 with outcomes in OHCA patients.
Therefore, the purpose of this study was to evaluate the association between temporal changes in prSO2 and ROSC in OHCA patients. We hypothesised that the association of temporal changes in prSO2 with ROSC in patients with OHCA could be more sensitive than those in crSO2. This finding would contribute to more effective monitoring of patients with OHCA.
Section snippets
Patients and study protocol
This was a prospective, two-centre cohort study conducted at the Yokosuka Kyousai Hospital and Yokohama Minami Kyousai Hospital. Both hospitals are emergency and critical care centres in southern Tokyo. The inclusion criteria were as follows: (1) patients aged over 18 years and (2) those who were admitted to these hospitals between September 2017 and March 2019. The exclusion criteria were as follows: (1) ROSC before arrival, (2) traumatic cardiopulmonary arrest (CPA), (3) hypothermia, (4)
Results
The study included 342 patients with OHCA during the study period; of these, 197 were excluded. The reason for exclusion was as follows: 115 patients with no rSO2 data owing to prioritising the treatment procedure, 18 without continuous rSO2 measurements, 40 with ROSC before arrival, 12 with traumatic CPA, 5 with an indication of extracorporeal membrane oxygenation, 3 with the previous completion of the DNAR, 3 with hypothermia, and 1 under 18 years of age.
Therefore, 145 patients were enrolled
Discussion
In this study, we demonstrated for the first time that prSO2 was associated with ROSC in patients with OHCA. In addition, the temporal changes in prSO2 were different from those in crSO2 during CPR but not different following ROSC in the ROSC group. However, no temporal changes were observed in both prSO2 and crSO2 in the non-ROSC patient group. Considering the pattern of changes over time, the temporal changes in prSO2 could occur earlier than those in crSO2 during CPR.
An animal study
Conclusions
In this study, we demonstrated for the first time that prSO2 was associated with ROSC in OHCA patients. In addition, we showed that temporal changes in prSO2 could predict ROSC earlier than those in crSO2. However, both prSO2 and crSO2 did not change temporally in the non-ROSC patient group. Our findings could provide time to prepare early interventions after ROSC and assist in determining the TOR for OHCA patients in emergency care settings in Japan. Further studies are needed to validate
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We thank our colleagues in the Department of Emergency Medicine, Yokosuka Kyousai Hospital, and Yokohama Minami Kyousai Hospital.
Funding
This work was supported by Grants-in-Federation of National Public Service Personnel Mutual Aid Association in Japan (No. 17-30).
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