Monitoring of Brain Oxygenation During and After Cardiopulmonary Resuscitation: A Prospective Porcine Study

Cerebral oximetry: a developing tool for monitoring cerebral oxygenation during cardiopulmonary resuscitation

Despite improvements in cardiopulmonary resuscitation (CPR), survival and neurologic recovery after cardiac arrest remain very poor because of the impact of severe ischemia and subsequent reperfusion injury. As the likelihood of survival and favorable neurologic outcome decreases with increasing severity of ischemia during CPR, developing methods to measure the magnitude of ischemia during resuscitation, particularly cerebral ischemia, is critical for improving overall outcomes. Cerebral oximetry, which measures regional cerebral oxygen saturation (rSO₂ ) by near-infrared spectroscopy, has emerged as a potentially beneficial marker of cerebral ischemia during CPR. In numerous preclinical and clinical studies, higher rSO₂ during CPR has been associated with improved cardiac arrest survival and neurologic outcome. In this narrative review, we summarize the scientific rationale and validation of cerebral oximetry across populations and pathophysiologic states, discuss the evidence surrounding its use to predict return of spontaneous circulation, rearrest, and neurologic outcome, and provide suggestions for incorporation of cerebral oximetry into CPR practice.

Assessment of Cerebral Blood Oxygenation by Near-Infrared Spectroscopy before and after Resuscitation in a Rat Asphyxia Cardiac Arrest Model

Clinical investigators have focused on the real-time evaluation of cerebral blood oxygenation (CBO) by near-infrared spectroscopy (NIRS) during cardiopulmonary resuscitation (CPR). A previous study showed that an abrupt increase of oxy-hemoglobin (Hb) level and tissue oxygenation index (TOI) was associated with the timing of return of spontaneous circulation (ROSC). However, it is not clear how TOI alters before and after CPR including a period of cardiac arrest (CA). Therefore, this study aimed to assess CBO with asphyxia CA and its association with CPR to ROSC in rats. Male Sprague-Dawley rats were used. We attached NIRS (NIRO-200NX, Hamamatsu Photonics, Japan) from the nasion to the upper cervical spine in rats. A ten-minute asphyxia was given to induce CA. After CA, mechanical ventilation was restarted, and manual CPR was performed. We examined the mean arterial pressure (MAP), end-tidal carbon dioxide (ETCO2), and Oxy/Deoxy-Hb and TOI. Out of 14 rats, 11 obtained sustained ROSC. After the induction of asphyxia, a rapid drop of TOI was observed, followed by a subsequent increase of Oxy-Hb, Deoxy-Hb, and TOI with CPR. Recent CPR guidelines suggest the use of ETCO2 during CPR since its abrupt increase is a reasonable indicator of ROSC. In this study, abrupt increases in MAP, ETCO2, and TOI were observed at the time of ROSC. TOI can be an alternative to ETCO2 for identifying ROSC after CA, and it also has the capability of monitoring CBO during and after CPR.

Time-Domain Near-Infrared Spectroscopy and Imaging: A Review

This article reviews the past and current statuses of time-domain near-infrared spectroscopy (TD-NIRS) and imaging. Although time-domain technology is not yet widely employed due to its drawbacks of being cumbersome, bulky, and very expensive compared to commercial continuous wave (CW) and frequency-domain (FD) fNIRS systems, TD-NIRS has great advantages over CW and FD systems because time-resolved data measured by TD systems contain the richest information about optical properties inside measured objects. This article focuses on reviewing the theoretical background, advanced theories and methods, instruments, and studies on clinical applications for TD-NIRS including some clinical studies which used TD-NIRS systems. Major events in the development of TD-NIRS and imaging are identified and summarized in chronological tables and figures. Finally, prospects for TD-NIRS in the near future are briefly described.