Waiting for the Patient to “Sober Up”: Effect of Alcohol Intoxication on Glasgow Coma Scale Score of Brain Injured Patients Jason L. Sperry, MD, Larry M. Gentilello, MD, Joseph P. Minei, MD, Ramon R. Diaz-Arrastia, MD, PhD, Randall S. Friese, MD, and Shahid Shafi, MD, MPH J Trauma. 2006;61:1305–1311.
Background • The Glasgow Coma Scale (GCS) is a physiologic measure of level of consciousness. It is commonly used to assess severity of traumatic brain injury (TBI). • 13~15 (mild), 9~12 (moderate), ≤8 (severe) • widely used for clinical decision making • ATLS guideline: GCS ≤8 :endotracheal intubation • Brain Trauma Foundation’s (BTF) management guidelines: GCS ≤8 and abnormal head CT scan: intracranial pressure monitoring
TBI is the most important determinant of GCS score, but factors other than TBI may alter level of consciousness and GCS score. • Alcohol (CNS depressant) intoxication is reported to be present in 35% to 50% of TBI patients • ≥80 mg/dL: minor motor impairments • ≥150 mg/dL: gross motor impairment (balance and coordination) • ≥200 mg/dL: amnesia or coma
The implications of whether alcohol confounds the GCS score of patients with brain injury are important. • If alcohol intoxication decreases the GCS score of TBI patients, • the effect of alcohol needs to be accounted for, so that unnecessary interventions are not performed. • if alcohol intoxication does not significantly decrease the GCS score of TBI patients, • a low GCS score should not be attributed to alcohol intoxication, and other causes should be aggressively sought so that a delay in needed interventions does not occur.
Published data on the effects of alcohol on GCS scores of TBI patients are conflicting. • The purpose of the current study was to determine whether alcohol intoxication alters GCS scores of patients with and without TBI. • Our specific hypothesis was that patients intoxicated with alcohol had a reduced GCS score compared with nonintoxicated patients with similar severity of brain injury.
Methods • A 10-year retrospective analysis of a large, urban Level I trauma center registry (1995–2004) was undertaken. • The study population consisted of blunt head-injured patients who were tested for BAC in the emergency department. • Patients with incomplete information on initial GCS score or final Abbreviated Injury Score (AIS) for head injuries, and those with fatal head injuries (AIS 6), were excluded.
Nonintoxicated (BAC=0 mg/dL) n=571 Intoxicated (≥legal limit for driving, 80mg/dL) n=504 n=1075
Nonintoxicated patients were more often injured because of MVC whereas intoxicated patients were more likely injured by assault. nonintoxicated patients sustaining more severe head injuries
Correlation between BAC level and GCS score • stratified by severity of head injury • The effects of systemic hypotension, airway control, and severity of injury on measurement of GCS score • Severely intoxicated patients (BAC >250 mg/dL) • Specific GCS components (eye, verbal, and motor scores). • Patients without documented TBI (n= 4,988) • Multivariate linear regression techniques were used to determine whether BAC was an independent predictors of GCS score.
For all statistical tests, a p value <0.05 was considered significant. • Because a small change in mean GCS score may be statistically significant with this larger sample size, we defined a difference of at least one point in total GCS score as clinically significant.
Results • There was no linear relationship between blood alcohol concentration and GCS score. (Spearman correlation coefficient =0.033, p= 0.275) • There was no difference in mean GCS score between the two groups. (nonintoxicated 10.1± 4.8, intoxicated 10.3± 4.7, p =0.500)
When stratified by severity of head injury, difference in mean GCS score between the two groups was less than a single point in all grades of TBI, except in those with head AIS 5, where the difference was 1.4 GCS points.
Endotracheal intubation Hypotension (SBP<90 mmHg) Severe injury (ISS>18) Normotensive differencein mean GCS score was 1.5 Severely injured differencein mean GCS score was 1.4
Similarly, mean GCS score did not differ by more than 1 point in each TBI category in the severely intoxicated patients (BAC >250 mg/dL).
We compared mean eye, verbal, and motor scores in nonintoxicated versus intoxicated patients for each TBI category and did not find any difference greater than 1 point.
Mean GCS score for patients without documented TBI (n=4,988) also showed no difference greater than a single GCS point. (nontoxicated 12.8 ±0.08 versus intoxicated 13.2 ±0.06, p >0.001)
Blood alcohol concentration was not an independent determinant of GCS score in a multivariate model.
Discussion • The primary finding of this study is that alcohol intoxication does not significantly alter the GCS score of trauma patients with TBI, except for patients with the most severe Injuries. • These results reject the study hypothesis (and conventional wisdom), and validate the value of the GCS as a measure of level of consciousness determined by severity of TBI, unaffected by alcohol intoxication.
Possible explanation of our findings • The effect of alcohol on an individual patient’s level of consciousness is highly variable, depending upon the frequency and rate of alcohol consumption, as well as the rate of its metabolism. • Hence, although an individual patient’s GCS score may be lowered by alcohol intoxication, it may not be true for the group as a whole.
Possible explanation of our findings • level of intoxication used in this study (mean and median BAC around 200 mg/dL) was not high enough to impair patients’ mental status. • Galbraith reported that a BAC>200 mg/dL was required to depress the level of consciousness. • Jagger found that alcohol significantly lowered GCS scores of TBI patients and the effect was most pronounced in those with a BAC>200. But, interestingly, even in this group, there was no effect of alcohol on GCS score of 70% of the patients. • In another study, Minion reported that 88% of patients with BAC in excess of 400 mg/dL were alert and oriented to time, place, and person. • It is also entirely possible that BAC has little meaning because of the individual’s tolerance of alcohol.
Possible explanation of our findings • Finally, it is possible that the GCS score is not a sensitive measure of mental status in intoxicated patients with TBI. • Of course, the most logical explanation of our findings is that any decrease in the level of consciousness in trauma patients is a result of factors other than alcohol intoxication, most important of which is the severity of brain injury.
Other factors that may affect the level of consciousness include severity of other non-neurologic injuries, presence of shock or hypothermia, concomitant use of other CNS depressants, and hypoxia or hypercarbia. • Our findings underscore the fact that in patients with depressed GCS score, these factors should be aggressively sought and treated, without waiting for alcohol to wear off.
Limitations of this study • It is a single institution experience, and may only reflect local patient characteristics. • Retrospective reviews: unmeasured or unknown confounding variables • Throughout the study period, BAC levels were drawn selectively, likely resulting in selection bias.
Conclusion • Alcohol intoxication does not reduce the GCS score more than one point for patients with TBI, except for patients with the most severe injuries. • Hence,diagnostic and therapeutic interventions indicated by patients’ GCS scores should be undertaken promptly, and not delayed waiting for patients to “sober up”.