The respiratory aspect of the treatment of brain injury associated with acute alcohol intoxication--results of an animal experiment

Ethanol and isolated traumatic brain injury

The aim of this systematic review was to determine whether ethanol is neuroprotective or associated with adverse effects in the context of traumatic brain injury (TBI). Approximately 30-60% of TBI patients are intoxicated with ethanol at the time of injury. We performed a systematic review of the literature using a combination of keywords for ethanol and TBI. Manuscripts were included if the population studied was human subjects with isolated moderate to severe TBI, acute ethanol intoxication was studied as an exposure variable and mortality reported as an outcome. The included studies were assessed for heterogeneity. A meta-analysis was performed and the pooled odds ratio (OR) for the association between ethanol and in-hospital mortality reported. There were seven studies eligible for analysis. A statistically significant association favouring reduced mortality with ethanol intoxication was found (OR 0.78; 95% confidence interval 0.73-0.83). Heterogeneity among selected studies was not statistically significant (p=0.25). Following isolated moderate-severe TBI, ethanol intoxication was associated with reduced in-hospital mortality. The retrospective nature of the studies, varying definitions of brain injury, degree of intoxication and presence of potential confounders limits our confidence in this conclusion. Further research is recommended to explore the potential use of ethanol as a therapeutic strategy following TBI.

Effects of alcohol on respiratory variables in normal humans

The study is designed to clarify the effect of low doses of alcohol on respiratory variables in air breathing normal subjects. Each subject was given an initial loading dose of alcohol (0.270 g/kg) followed, half an hour later, by a second dose (0.135 g/kg). Blood alcohol increased to a mean value of 52.0 +/- 3.0 (SEM) mg/100 ml at 1 hour. Resting ventilation increased significantly from a mean value of 6.25 +/- 0.41 litres min(-1) to 7.20 +/- 0.31 litres min(-1) 1 hour after alcohol (p= 0.025). Mean inspiratory flow was also increased (p= 0.045). End-tidal PCO² (PET CO²) showed a highly significant fall (1.87 +/- 0.35 mm Hg; p < 0.001) without a significant change in CO2 production rate (p > 0.05). PET CO² variability (100 x SD/mean) was low (mean 2.4%) and unaffected by alcohol. The longest end-expiratory pauses (apnoeas) observed for each subject were shortened significantly by alcohol (1.030 +/- 0.194 s and 0.690 +/- 0.138 s; p = 0.01). Moderate doses of alcohol in normal subjects, therefore lower PET CO² and shorten end-expiratory pauses (apnoeic periods) but do not affect PET CO² variability.