Efficacy and safety of cerebral oximeter as an auxiliary diagnostic tool in the diagnosis of cerebral death

Objective: To evaluate the efficacy and safety of the cerebral oximeter as an auxiliary diagnostic tool in the diagnosis of cerebral death and to provide a basis for future studies. Material and Method: All patients above the age of 18 years with suspected cerebral death who were assessed by the Organ Transplantation-Cerebral Death Board were enrolled in the observational intervention study in order to constitute the study group, regardless of the presence of cerebral death. Cerebral oximetry monitoring was performed for all of the patients using NIRS 5100c for at least 6 hours, and the oxygen saturation (SbO2) of the cerebral tissue was recorded. Baseline SbO2 values, SbO2 value at 6 hours, mean SbO2 values obtained during 6-hour follow-up, and the lowest and highest SbO2 values detected during the 6-hour recording were calculated and recorded for each patient. Afterwards, the parameters of the cerebral death group were compared with those of the control group. Findings: Ninety-three patients were evaluated for eligibility for the study. In the final analysis, 53 patients were selected for the study. There were 32 patients in the cerebral death group, and 21 patients in the control group. The average ± SD age of the patients in the cerebral death group was 54.4±20.6 compared to 67.6±14.2 in the control group. Although the baseline SbO2 levels were found to be relatively higher in the patients without cerebral death compared to those with cerebral death, the difference was not significant between the baseline SbO2measurements of both the right and left lobes (p=0.064; p=0.17). The same was applicable for the final SbO2 values at 6 hours. There was no intergroup difference in terms of the amount of the SbO2 decrease, which was obtained by calculating the difference between the baseline and final SbO2 values. The maximum values obtained in the groups were remarkable. The maximum SbO2 values of the right and left lobes were significantly lower in the cerebral death group than in the control group (p=0.015 for the right lobe; p=0.005 for the left lobe). The area under the ROC curve determined for the right maximum SbO2 was 0.69±0.07 (95% CI: 0.55-0.81) (p=0.01). The area under the ROC curve determined for the left maximum SbO2 was 0.72±0.07 (95% CI: 0.58-0.84) (p=0.002). Based on the results of the ROC analysis, patients with a maximum SbO2 level of <50% obtained during the 6-hour follow-up were likely to have cerebral death (+PV=%100).On the contrary, a maximum SbO2 level of >90% obtained during the 6-hour follow-up was determined to be reliable evidence of the absence of cerebral death in the patient (-PV=100%). Result:The cerebral oximeter is not adequate alone to identify patients with cerebral death. However, maximum SbO2 values determined during cerebral oximetry monitoring have the potential to be used in the diagnosis of cerebral death. A maximum SbO2 value of >90% obtained during the cerebral oximetry follow-up of 6 hours may exclude the diagnosis of cerebral death, whereas the maximum SbO2 measurements of <50% strongly support the diagnosis of cerebral death. Key Words: Cerebral death, emergency department, cerebral oximetry, NIRS (Near-infrared Spectroscopy), SbO2 (cerebral oxygen saturation)