Introduction: The Glasgow Coma Scale (GCS) score is the most commonly used scale for assessment of patients with acute neurological injury in critical care settings. The post-resuscitation admission GCS score is also a predictor for long term outcome in patients with acute traumatic brain injury. Similarly, cerebral autoregulation (CA) monitoring at the bedside has shown to be an accurate technique for predicting clinical outcomes. This study aimed to investigate the correlation between GCS score and continuous CA measured by near-infrared spectroscopy (NIRS).
Methods: Twenty-six comatose patients with acute neurological injury admitted to a neurocritical care unit were monitored continuously with NIRS using ICM plus software from one hour up to three days after the coma onset. The cerebral oximetry index (COx) was calculated as the correlation between the slow waves from regional cerebral oxygen saturation (rSO2) and mean arterial blood pressure (MAP). COx, rSO2, MAP and GCS data were prospectively extracted each hour. Pearson correlation was used for determining the relation between the NIRS-based measurements (rSO2 and COx) and GCS every hour of monitoring.
Results: A total of 655 observations (hours) were analyzed from 26 patients (65.4% female) with a mean age of 58 years. Eleven patients had ICH, 8 had SAH, 4 had TBI, one had an ischemic stroke, one had a cardiac arrest, and one had status epilepticus. GCS was significantly correlated with COx (r = 0.21, P < 0.001) and MAP (r = 0.15, P < 0.001). Conversely, rSO2showed non-significant correlation with GCS (r = 0.06, P = 0.12).
Conclusions: This study shows that GCS correlates well with COx, but not with rSO2. Our findings support the utility of NIRS-based COx to follow fluctuations in neurological status of critically ill patients that may be particularly useful in sedated and paralyzed patients.