In this study, transcranial Doppler ultrasonography (TCD) and photoplethysmography (PPG) have been utilized, through the observation of peripheral and cerebrovascular hemodynamic changes of the disorder of consciousness (DOC) patients, measured on clinical behavior scale of Coma Recovery Score-Revised (CRS-R) to obesrve their diagnostic value in evaluation of DOC patients. TCD ultrasound was used to evaluate the flow velocity and waveform patterns of middle cerebral artery (MCA), while PPG infrared signals were utilized to assess the peripheral circulation as a mean of measuring cardiovascular activities. The research was carried out on a sample of 36 individuals, of which 16 met the DOC criteria and 20 were healthy individuals. Each person in the patients groups was assessed by the CRS-R. The velocity of middle cerebral artery in tested patients in a whole cardiac cycle, detected by TCD, decreased comparing with normal values. The values of pulsatility index (PI) of the MCA increased in patients groups comparing with normal. Through binary variables correlation analysis, we found that the PI of the left MCA of TCD of the patients significantly inversely correlated with their motor subscore, included in their CRS-R in the level of α = 0.05 (Pearson's product-moment correlation coefficient = -0.556, p = 0.025). The values of photoplethysmographic augmentation index (PAI) that were detected by PPG increased comparing with normal. Finally, using binary variables correlation analysis we found the significant inverse correlation between the PAI of PPG and the mean velocity of the left MCA of the TCD in the level of α = 0.05 (Pearson's product-moment correlation coefficient = -0.377, p = 0.022) in all the groups. The results of this study revealed a specific relationship between PI and PAI in the DOC patients. That relationship can potentially be exploited to enhance the capabilities in early assessment of the deconditioning of the DOC patients' cardiovascular system and its influence on their cerebral vascular system. Ultimately, the dependency discovered can assist in predicting the tendency of the prognosis of the DOC patients in clinic.
Keywords: Coma Recovery Score-Revised; Disorder of consciousness; Photoplethysmography; The deconditioning of the cardiovascular system; Transcranial Doppler ultrasonography.