Effects of ethanol on respiratory function in traumatic brain injury

Autopsy-Diagnosed Injury Deaths in Persons With Acute or Chronic Alcohol Use: A Review of 1000 Deaths With History of Alcohol Use

ABSTRACT

Acute and chronic alcohol use is associated with injury, and autopsies may be performed to ascertain injury deaths in persons with acute or chronic alcohol use. This study sought to determine how many decedents with a history of acute or chronic alcohol use had an internal physical injury diagnosed only at autopsy that caused or contributed to the death. The study reviewed medicolegal investigation and autopsy reports at the New York City Office of Chief Medical Examiner between January 1 and October 11, 2018, to identify 1000 consecutive persons with suspected acute or chronic alcohol use who were autopsied to ascertain whether internal physical injury caused or contributed to the death. Of 1000 persons with known or suspected acute or chronic alcohol use, 390 (39.0%) had an external injury. Although 115 (11.5%) had an internal injury at autopsy, only 29 (2.9%) had an injury that caused or contributed to the death. Only 1 decedent had an internal injury that caused the death with no associated external evidence of injury (0.1%). This study demonstrates the rarity of occult lethal injury diagnosed at autopsy in persons with acute or chronic alcohol use.

Ethanol Intoxication Alleviates the Inflammatory Response of Remote Organs to Experimental Traumatic Brain Injury

Traumatic brain injury (TBI) may cause damage to distant organs. Acute ethanol intoxication (EI) induces complex local and systemic anti-inflammatory effects and influences the early outcomes of traumatized patients. Here, we evaluated its effects on the BI-induced expression of local inflammatory mediators in the trauma-remote organs the lungs and liver. Male mice were exposed to ethanol as a single oral dose (5g·kg^–1, 32%) before inducing a moderate blunt TBI. Sham groups underwent the same procedures without TBI. Ether 3 or 6h after the TBI, the lung and liver were collected. The gene expression of HMGB1, IL-6, MMP9, IL-1β, and TNF as well as the homogenate protein levels of receptor for advanced glycation end products (RAGE), IL-6, IL-1β, and IL-10 were analyzed. Liver samples were immunohistologically stained for HMGB1. EI decreased the gene expressions of the proinflammatory markers HMGB1, IL-6, and MMP9 in the liver upon TBI. In line with the reduced gene expression, the TBI-induced protein expression of IL-6 in liver tissue homogenates was significantly reduced by EI at 3h after TBI. While the histological HMGB1 expression was enhanced by TBI, the RAGE protein expression in the liver tissue homogenates was diminished after TBI. EI reduced the histological HMGB1 expression and enhanced the hepatic RAGE protein expression at 6h post TBI. With regard to the lungs, EI significantly reduced the gene expressions of HMGB1, IL-6, IL-1β, and TNF upon TBI, without significantly affecting the protein expression levels of inflammatory markers (RAGE, IL-6, IL-1β, and IL-10). At the early stage of TBI-induced inflammation, the gene expression of inflammatory mediators in both the lungs and liver is susceptible to ethanol-induced remote effects. Taken together, EI may alleviate the TBI-induced pro-inflammatory response in the trauma-distant organs, the lungs and liver, via the HMGB1-RAGE axis.

Emergency department blood alcohol level associates with injury factors and six-month outcome after uncomplicated mild traumatic brain injury

The relationship between blood alcohol level (BAL) and mild traumatic brain injury (mTBI) remains in need of improved characterization. Adult patients suffering mTBI without intracranial pathology on computed tomography (CT) from the prospective Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot study with emergency department (ED) Glasgow Coma Scale (GCS) 13-15 and recorded blood alcohol level (BAL) were extracted. BAL≥80-mg/dl was set as proxy for excessive use. Multivariable regression was performed for patients with six-month Glasgow Outcome Scale-Extended (GOSE; functional recovery) and Wechsler Adult Intelligence Scale Processing Speed Index Composite Score (WAIS-PSI; nonverbal processing speed), using BAL≥80-mg/dl and <80-mg/dl cohorts, adjusting for demographic/injury factors. Overall, 107 patients were aged 42.7±16.8-years, 67.3%-male, and 80.4%-Caucasian; 65.4% had BAL=0-mg/dl, 4.6% BAL<80-mg/dl, and 30.0% BAL≥80-mg/dl (range 100-440-mg/dl). BAL differed across loss of consciousness (LOC; none: median 0-mg/dl [interquartile range (IQR) 0-0], <30-min: 0-mg/dl [0-43], ≥30-min: 224-mg/dl [50-269], unknown: 108-mg/dl [0-232]; p=0.002). GCS<15 associated with higher BAL (19-mg/dl [0-204] vs. 0-mg/dl [0-20]; p=0.013). On univariate analysis, BAL≥80-mg/dl associated with less-than-full functional recovery (GOSE≤7; 38.1% vs. 11.5%; p=0.025) and lower WAIS-PSI (92.4±12.7, 30th-percentile vs. 105.1±11.7, 63rd-percentile; p<0.001). On multivariable regression BAL≥80-mg/dl demonstrated an odds ratio of 8.05 (95% CI [1.35-47.92]; p=0.022) for GOSE≤7 and an adjusted mean decrease of 8.88-points (95% CI [0.67-17.09]; p=0.035) on WAIS-PSI. Day-of-injury BAL>80-mg/dl after uncomplicated mTBI was associated with decreased GCS score and prolongation of reported LOC. BAL may be a biomarker for impaired return to baseline function and decreased nonverbal processing speed at six-months postinjury. Future confirmatory studies are needed.

Alcohol Consumption Does not Impede Recovery from Mild to Moderate Traumatic Brain Injury

OBJECTIVES

To examine the effect of pre-injury alcohol use, acute alcohol intoxication, and post-injury alcohol use on outcome from mild to moderate traumatic brain injury (TBI).

METHODS

Prospective inception cohort of patients who presented to the Emergency Department with mild to moderate TBI and had a blood alcohol level (BAL) taken for clinical purposes. Those who completed the 1-year outcome assessment were eligible for this study (N=91). Outcomes of interest were the count of post-concussion symptoms (British Columbia Post-Concussion Symptom Inventory), low neuropsychological test scores (Neuropsychological Assessment Battery), and abnormal regions of interest on diffusion tensor imaging (low fractional anisotropy). The main predictors were pre-injury alcohol consumption (Cognitive Lifetime Drinking History interview), BAL, and post-injury alcohol use.

RESULTS

The alcohol use variables were moderately to strongly inter-correlated. None of the alcohol use variables (whether continuous or categorical) were related to 1-year TBI outcomes in generalized linear modeling. Participants in this cohort generally had a good clinical outcome, regardless of their pre-, peri-, and post-injury alcohol use.

CONCLUSIONS

Alcohol may not significantly alter long-term outcome from mild to moderate TBI. (JINS, 2016, 22, 816-827).

Alcohol and mortality after moderate to severe traumatic brain injury: a meta-analysis of observational studies

OBJECT

Experimental studies have shown numerous neuroprotective properties of alcohol (“ethanol”) after TBI, but clinical studies have provided conflicting results. The authors aimed to assess the relationship between positive blood alcohol concentration (BAC) on hospital admission and mortality after moderate to severe traumatic brain injury (TBI).

METHODS

The authors searched 8 databases for observational studies reported between January 1, 1990, and October 7, 2013, and investigated the effect of BAC on mortality after moderate to severe TBI. Reviews of each study were conducted, and data were extracted according to the MOOSE and PRISMA guidelines. Study quality was assessed using the Newcastle-Ottawa scale. The Mantel-Haenszel fixed effect methodology was used to generate pooled estimates. Heterogeneity was dealt with by multiple sensitivity analyses.

RESULTS

Eleven studies with a total of 95,941 patients (42% BAC positive and 58% BAC negative) were identified for the primary analysis (overall mortality 12%). Primary analysis showed a significantly lower risk of death for BAC-positive patients compared with BAC-negative patients (crude mortality 11.0% vs 12.3%, pooled OR 0.84 [95% CI 0.81–0.88]), although flawed by heterogeneity (I2 = 68%). Multiple sensitivity analyses, including 55,949 and 51,772 patients, yielded similar results to the primary analysis (crude mortality 12.2% vs 14.0%, pooled OR 0.87 [95% CI 0.83–0.92] and crude mortality 8.7% vs 10.7%, pooled OR 0.78 [95% CI 0.74–0.83]) but with good study homogeneity (I2 = 36% and 14%).

CONCLUSIONS

Positive BAC was significantly associated with lower mortality rates in moderate to severe TBI. Whether this observation is due to selection bias or neuroprotective effects of alcohol remains unknown. Future prospective studies adjusting for TBI heterogeneity is advocated to establish the potential favorable effects of alcohol on outcome after TBI.

Impact brain apnoea - A forgotten cause of cardiovascular collapse in trauma

OBJECTIVE

Early death following cranial trauma is often considered unsurvivable traumatic brain injury (TBI). However, Impact Brain Apnoea (IBA), the phenomenon of apnoea following TBI, may be a significant and preventable contributor to death attributed to primary injury. This paper reviews the history of IBA, cites case examples and reports a survey of emergency responder experience.

METHODS

Literature and narrative review and focused survey of pre-hospital physicians.

RESULTS

IBA was first reported in the medical literature in 1705 but has been demonstrated in multiple animal studies and is frequently anecdotally witnessed in the pre-hospital arena following human TBI. It is characterised by the cessation of spontaneous breathing following a TBI and is commonly accompanied by a catecholamine surge witnessed as hypertension followed by cardiovascular collapse. This contradicts the belief that isolated traumatic brain injury cannot be the cause of shock, raising the possibility that brain injury may be misinterpreted and therefore mismanaged in patients with isolated brain injury. Current trauma management techniques (e.g. rolling patients supine, compression only cardiopulmonary resuscitation) could theoretically compound hypoxia and worsen the effects of IBA. Anecdotal examples from clinicians attending head injured patients within a few minutes of injury are described. Proposals for the study and intervention for IBA using advances in remote technology are discussed.

CONCLUSION

IBA is a potential cause of early death in some head injured patients. The precise mechanisms in humans are poorly understood but it is likely that early, simple interventions to prevent apnoea could improve clinical outcomes.

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.

How Alcohol Kills: Alcohol-Attributable and Alcohol-Associated Deaths in a Medical Examiner Population

Forensic pathologists frequently encounter the myriad effects of acute and chronic ethanolism and the many ways that alcohol contributes to sudden natural and unnatural deaths. Alcohol may act as risk factor for sudden death or directly participate as a cause of sudden death through its acute and chronic toxic effects. This retrospective descriptive study examines the causes and manner of deaths potentially attributable to alcohol and the results of postmortem toxicology testing for ethanol in unnatural deaths and alcohol-attributable natural deaths over a five-year period in a large medical examiner's office. Ethanol was detected in all types of unnatural deaths as well as alcohol-attributable natural deaths due to the complications of chronic ethanol abuse with a wide range of overlapping concentrations. Of the unnatural deaths involving individuals with a detectable ethanol concentration, 61% were accidents, 25% suicides, and 14% were homicides; ethanol was detected in 40.2% of accidents, 42.0% of suicides, and 53.1% of homicides. Ethanol was also detected in 41% of deaths due to chronic alcoholism. For the unnatural deaths involving intoxicated individuals and deaths due to chronic alcoholism, the deaths were certified as a wide variety of causes. In general, the results are similar to those in the existing literature. Forensic pathologists need to be well-versed in interpreting postmortem ethanol concentrations and determining the role of acute and/or chronic ethanolism in sudden deaths.

Ethanol, Trauma, and the Brain

Alcohol intoxication plays a significant and causal role in various fatal injuries. In comparison to sober individuals, intoxicated people have a greater generic risk for being involved in hazardous activities that may result in fatal injuries. However, it is not clear whether the biological effects of acute alcohol intoxication result in worse injuries than those sustained by sober individuals who are injured by identical mechanisms. Alcohol intoxication has a neuroprotective effect in experimental animal models of traumatic brain injury (TBI) but the evidence for a similar effect in humans is controversial. Earlier studies found such a protective effect, but more recent large epidemiological studies have not confirmed this finding; some studies also suggest a dose-related protective or exacerbating effect of alcohol intoxication on TBI. There are two apparent alcohol-associated syndromes in which an otherwise survivable blunt force impact to the head of an intoxicated individual is fatal at the scene. The first is a fatal cardiorespiratory arrest (the so-called alcohol concussion syndrome or “commotio medullaris”); the second is “traumatic basilar subarachnoid hemorrhage” (secondary to tears in the cerebral arteries, particularly the intracranial and extracranial vertebral arteries).

Acute alcohol intoxication prolongs neuroinflammation without exacerbating neurobehavioral dysfunction following mild traumatic brain injury

Traumatic brain injury (TBI) represents a leading cause of death and disability among young persons with ∼1.7 million reported cases in the United States annually. Although acute alcohol intoxication (AAI) is frequently present at the time of TBI, conflicting animal and clinical reports have failed to establish whether AAI significantly impacts short-term outcomes after TBI. The objective of this study was to determine whether AAI at the time of TBI aggravates neurobehavioral outcomes and neuroinflammatory sequelae post-TBI. Adult male Sprague-Dawley rats were surgically instrumented with gastric and vascular catheters before a left lateral craniotomy. After recovery, rats received either a primed constant intragastric alcohol infusion (2.5 g/kg+0.3 g/kg/h for 15 h) or isocaloric/isovolumic dextrose infusion followed by a lateral fluid percussion TBI (∼1.4 J, ∼30 ms). TBI induced apnea and a delay in righting reflex. AAI at the time of injury increased the TBI induced delay in righting reflex without altering apnea duration. Neurological and behavioral dysfunction was observed at 6 h and 24 h post-TBI, and this was not exacerbated by AAI. TBI induced a transient upregulation of cortical interleukin (IL)-6 and monocyte chemotactic protein (MCP)-1 mRNA expression at 6 h, which was resolved at 24 h. AAI did not modulate the inflammatory response at 6 h but prevented resolution of inflammation (IL-1, IL-6, tumor necrosis factor-α, and MCP-1 expression) at 24 h post-TBI. AAI at the time of TBI did not delay the recovery of neurological and neurobehavioral function but prevented the resolution of neuroinflammation post-TBI.

Preinjury alcohol exposure attenuates the neuroinflammatory response to traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) initiates a neuroinflammatory response that increases the risk of TBI-related mortality. Acute alcohol intoxication at the time of TBI is associated with improved survival. Ethanol is recognized as a systemic immunomodulator that may also impart neuroprotection. The effects of alcohol on TBI-induced neuroinflammation, however, are unknown. We hypothesized that ethanol treatment prior to TBI may provide neuroprotection by diminishing the neuroinflammatory response to injury.

MATERIALS AND METHODS

Mice underwent gavage with ethanol (EtOH) or water (H2O) prior to TBI. Animals were subjected to blunt TBI or sham injury (Sham). Posttraumatic rapid righting reflex (RRR) and apnea times were assessed. Cerebral and serum samples were analyzed by ELISA for inflammatory cytokine levels. Serum neuron-specific enolase (NSE), a biomarker of injury severity, was also measured.

RESULTS

Neurologic recovery from TBI was more rapid in H2O-treated mice compared with EtOH-treated mice. However, EtOH/TBI mice had a 4-fold increase in RRR time compared with EtOH/Sham, whereas H2O/TBI mice had a 15-fold increase in RRR time compared with H2O/Sham. Ethanol intoxication at the time of TBI significantly increased posttraumatic apnea time. Preinjury EtOH treatment was associated with reduced levels of proinflammatory cytokines IL-6, KC, MCP-1, and MIP-1α post TBI. NSE was significantly increased post injury in the H2O/TBI group compared with H2O/Sham but was not significantly reduced by EtOH pretreatment.

CONCLUSIONS

Alcohol treatment prior to TBI reduces the local neuroinflammatory response to injury. The decreased neurologic and inflammatory impact of TBI in acutely intoxicated patients may be responsible for improved clinical outcomes.

Chronic alcoholism-mediated impairment in the medulla oblongata: a mechanism of alcohol-related mortality in traumatic brain injury?

Alcohol-related traumatic brain injury (TBI) is a common condition in medical and forensic practice, and results in high prehospital mortality. We investigated the mechanism of chronic alcoholism-related mortality by examining the effects of alcohol on the synapses of the medulla oblongata in a rat model of TBI. Seventy adult male Sprague-Dawley rats were randomly assigned to either ethanol (EtOH) group, EtOH-TBI group, or control groups (water group, water-TBI group). To establish chronic alcoholism model, rats in the EtOH group were given EtOH twice daily (4 g/kg for 2 weeks and 6 g/kg for another 2 weeks). The rats also received a minor strike on the occipital tuberosity with an iron pendulum. Histopathologic and ultrastructure changes and the numerical density of the synapses in the medulla oblongata were examined. Expression of postsynaptic density-95 (PSD-95) in the medulla oblongata was measured by ELISA. Compared with rats in the control group, rats in the chronic alcoholism group showed: (1) minor axonal degeneration; (2) a significant decrease in the numerical density of synapses (p < 0.01); and (3) compensatory increase in PSD-95 expression (p < 0.01). Rats in the EtOH-TBI group showed: (1) high mortality (50%, p < 0.01); (2) inhibited respiration before death; (3) severe axonal injury; and (4) decrease in PSD-95 expression (p < 0.05). Chronic alcoholism induces significant synapse loss and axonal impairment in the medulla oblongata and renders the brain more susceptible to TBI. The combined effects of chronic alcoholism and TBI induce significant synapse and axon impairment and result in high mortality.

Alcohol and psychoactive drugs increased the pre-hospital mortality in 655 fall-related fatalities in Greece: a call for management protocols

INTRODUCTION

The frequency of alcohol and psychoactive drugs in fall-related fatalities and their effect on type, severity of injury and location of death constitute the subjects of this study.

METHODS

A retrospective analysis based on autopsy and toxicology compared demographics, location of injury; intention for the injury, height of fall, Abbreviated Injury Scale--90 (AIS-90), post-mortem Injury Severity Score (ISS), and location of death.

RESULTS

Amongst 655 fall-related fatalities screened for alcohol and psychoactive drugs 123 (18.8%) were classified in the positive toxicology group (PTG) and the remaining in the negative toxicology group (NTG). The median ages were 48 (16-94) years for the PTG and 62 (12-96) years for the NTG. The screened represent 31% of the national toll. The median height of fall was 7 m and the median blood alcohol concentration was 53 (1.5-630)mg/dl. Males were more likely to be included in the PTG than females (21.6 versus 13.6%; p = 0.014) as were the aged between 11 and 60 years. The odds of severe (AIS ≥ 3) head, thoracic, abdominal, extremity, and spine injuries were not influenced by toxicology status. Fatalities of the PTG were as likely to have severe trauma (ISS ≥ 16) as were fatalities of the NTG (93.5 versus 90.8%; p = 0.34). There was no significant difference of ISS between PTG (median ISS 43, range: 6-75) and NTG (median ISS 35, range: 3-75). Nevertheless, 76.4% of the subjects of the PTG died during the pre-hospital stage of care compared to 60.5% of the subjects of the NTG, which was highly significant (or = 2.80, p = 0.001) after controlling for confounders as age, gender, intention for injury, height of fall, and ISS.

CONCLUSIONS

In fall related trauma, alcohol and psychoactive drugs increased the risk of death during the pre-hospital stage by 2.80 times. This is strong evidence that specific protocols for their early management should be instituted.

Motor vehicle collision fatalities involving alcohol and illicit drugs in Greece: the need for management protocols and a reassessment of surveillance

AIMS

The frequency and the effect of alcohol and illicit drugs on injury type, severity and location of death in motor vehicle collision (MVC) fatalities were investigated.

DESIGN

Retrospective case-control study based on autopsy and toxicology.

SETTINGS

Single faculty accepting referrals from Greater Athens and prefectures.

PARTICIPANTS

Consecutive pre-hospital and in hospital fatalities.

MEASUREMENTS

Demographics, toxicology, abbreviated injury scale (AIS), injury severity score (ISS), and location of death.

FINDINGS

Of the 1860 screened subjects, 612 (32.9%) constituted the positive toxicology group (PTG) for alcohol or illicit drugs or both and the 1248 (67.1%) the negative toxicology group (NTG). The median age was 34 (4-90) years for the PTG and 45 (3-97) years for the NTG. The PTG included significantly higher proportions of males and motorcyclists. The PTG had a 50% increased risk for a severe (AIS ≥3) cervical spine and 85% for a severe upper extremity injury, compared to the NTG. A total of 29.2% of the PTG and 22.4% of the NTG deaths were non-preventable (ISS=75). The frequency of severe trauma (ISS ≥16) was comparable between PTG and NTG (P=0.87). The PTG presented with a median ISS of 43 (6-75) versus 41 (2-75) of the NTG, hence without significant difference (P=0.11). The pre-hospital death rate was 77.8% for the PTG versus 58% of the NTG (P<0.001). The analysis confirmed that the odds of positive toxicology were considerably higher in the subjects who arrived dead at the hospital (OR 2.62, P <0.001).

CONCLUSIONS

In the greater Athens region, almost a third of motor vehicle collision-related fatalities involved alcohol, illicit drugs or both. Individuals screened positive for alcohol or drugs were 2.6 times more likely to die before hospital admission than those with a negative toxicology screen, despite comparable injury severity. Specific evidence-based management protocols and reassessment of surveillance are required.

Modification of acute cardiovascular homeostatic responses to hemorrhage following mild to moderate traumatic brain injury

OBJECTIVES

The cardiovascular homeostatic responses to hemorrhage are coordinated in the central nervous system. Coincidental brain injury, which is present in 64% of trauma patients, could impair these responses. Our objective was to test the hypothesis that mild to moderate traumatic brain injury alters cardiovascular reflex responses to acute hemorrhage.

DESIGN

Experimental prospective, randomized study in terminally anesthetized rats.

SETTING

Experimental laboratory of university.

SUBJECTS

Twenty-four male Wistar rats weighing 240-260 g.

INTERVENTIONS

Brain injury was induced using the lateral fluid percussion injury model in anesthetized rats. The fluid percussion device delivered an applied cortical pressure of 1.2 atm and 1.8 atm, producing mild and moderate injury, respectively. Control animals underwent identical surgical procedures but with no applied cortical pressure. Hemorrhage was carried out 10 mins after brain injury, at a rate of 2% of blood volume per minute until 40% blood volume was withdrawn.

MEASUREMENTS AND MAIN RESULTS

The effects of acute traumatic brain injury on the biphasic heart rate and mean arterial blood pressure response to hemorrhage were studied. Traumatic brain injury attenuated the normal bradycardic response and delayed the hypotensive response to hemorrhage. This effect was graded according to the severity of brain injury. In mild injury, the depressor phase was delayed, but the biphasic pattern of heart rate response was maintained. No mortality was observed in this group. Following moderate brain injury, marked attenuation of the biphasic heart rate and mean arterial blood pressure response (p < .001 and p = .0007) was observed. Fifty percent of this group died within 90 mins of hemorrhage completion. Significant differences in the biphasic response were observed between survivors and nonsurvivors (p = .013, p = .001, respectively). In nonsurvivors, the biphasic response was abolished.

CONCLUSIONS

Acute mild and moderate traumatic brain injury disrupts cardiovascular homeostatic responses to extracranial hemorrhage; this disruption is graded according to the severity of traumatic brain injury. Severe disruption is associated with an increase in early mortality.

Brewing controversies: Darwinian perspective on the adaptive and maladaptive effects of caffeine and ethanol as dietary autonomic modulators

Ethanol and caffeine are two of the oldest human drugs. Their pervasive integration into the modern human diet may reflect behavioral attempts to correct maladaptations induced by evolutionary displacement of the autonomic system. The dietary adoption of caffeine may parallel the emergence of cognition as an independent basis of competition. Enhancement of the cognitive ability to gather and process information likely evolved as a valuable adjunct to physical behavior in prehistoric fight-or-flight encounters. Caffeine effectively exploits this pre-existing association between adrenergic activity and cognitive readiness, leading to its use in the modern environment where success in competition increasingly depends on cognitive, rather than physical, prowess. Ethanol may have emerged as a dietary means to buffer the maladaptive chronic sympathetic activation and fear response associated with stressful lifestyles and the social phobias associated with the dissolution of kin networks. We explore the health implications of ethanol and caffeine use, with particular attention to their acute and chronic effects on the autonomic axis. The putative protective effects of ethanol in surviving major trauma or reducing inflammation and heart disease may relate to tempering the behavioral and cardiovascular consequences of catastrophic or chronic sympathetic activation. Acute or chronic abuse of ethanol manifests paradoxical pro-adrenergic effects such as tremors and insomnia that may partly represent compensatory responses. Compensatory remodeling may also explain why confirmation of detrimental effects related to caffeine-induced sympathetic activation has proven elusive; indeed, paradoxical pro-vagal benefits may eventually be recognized. Ethanol and caffeine are potential agents that may beneficially expand the dynamic range of the autonomic system. In an environment where the Darwinian value of knowledge has increasingly supplanted that of physical traits, the consumption of caffeine and alcohol may represent both a cause and an effect of modern human evolution.

Effects of ethanol on limited resuscitation in a model of traumatic brain injury and hemorrhagic shock

Object

Limited resuscitation following uncontrolled hemorrhagic shock (HS) has been associated with improved outcomes in various animal models, although it has not been previously studied in the setting of traumatic brain injury (TBI) and ethanol intoxication. The aim of the present study was to determine the effects of ethanol intoxication in a model of experimental TBI and HS treated with limited resuscitation.

Methods

After induction of anesthesia and the placement of instruments, swine were subjected to a fluid-percussion injury of 3 atm. Simultaneously, hemorrhage was induced from an arterial catheter via a computerized roller pump to a mean arterial blood pressure (MABP) of 50 mm Hg, at which time uncontrolled hemorrhage was induced by the creation of an aortic tear. When the MABP decreased to 30 mm Hg, limited resuscitation to a MABP of 60 mm Hg was begun. After 60 minutes, animals were aggressively resuscitated to baseline MABP levels. Two groups of animals were studied: those receiving tap water by gastrostomy tube and those receiving ethanol (4 g/kg) by gastrostomy tube. Animals were monitored for 180 minutes after TBI. Hemorrhage volumes were significantly greater in ethanol-infused animals (mean ± standard deviation, 41 ± 34 mm Hg) compared with tap water–infused animals (17 ± 18 mm Hg; p = 0.048). Resuscitation requirements were significantly higher and metabolic parameters significantly worse in the ethanol group. Survival time was also significantly decreased in the animals infused with ethanol (81 ± 60 minutes) compared with those infused with tap water (130 ± 51 minutes; p = 0.035).

Conclusions

Ethanol intoxication led to increased hemorrhage volume and worsened hemodynamic and metabolic profiles in this model of limited resuscitation after TBI and HS. Ethanol-exposed animals had increased resuscitation requirements and decreased survival times.

Age-Dependent Effects of Severe Traumatic Brain Injury on Cerebral Dopaminergic Activity in Newborn and Juvenile Pigs

There is evidence that the dopaminergic system is sensitive to traumatic brain injury (TBI). However, the age-dependency of this sensitivity has not been studied together with brain oxidative metabolism. We postulate that the acute effects of severe TBI on brain dopamine turnover are age-dependent. Therefore 18F-labelled 6-fluoro-L-3,4-dihydroxyphenylalanine (FDOPA) together with Positron-Emission-Tomography (PET) was used to estimate the activity of the aromatic amino acid decarboxylase (AADC) in the brain of 11 newborn piglets (7-10 days old) and nine juvenile pigs (6-7 weeks old). Six newborn and five juvenile animals were subjected to a severe fluid-percussion (FP) induced TBI. The remaining animals were used as sham operated untreated control groups. Simultaneously, the regional cerebral blood flow (CBF) was measured with colored microspheres and the cerebral metabolic rates of oxygen and glucose were determined. At 1 h after FP-TBI, [18F]FDOPA was infused and PET scanning was performed for 2 h. At 2 h after FP-TBI administration, a second series of measurements of physiological values including CBF and brain oxidative metabolism data had been obtained. Severe FP-TBI elicited a marked increase in the rate constant for fluorodopamine production (k3FDOPA) in all brain regions of newborn piglets studied by between 97% (mesencephalon) and 143% (frontal cortex) (p < 0.05). In contrast, brain hemodynamics and cerebral oxidative metabolism remained unaltered after TBI. Furthermore, the permeability-surface area product of FDOPA (PSFDOPA) was unchanged. In addition, regional blood flow differences between corresponding ipsi- and contralateral brain regions did not occur after TBI. Thus, it is suggested that severe FP-TBI induces an upregulation of AADC activity of newborn piglets that is not related to alterations in brain oxidative metabolism.

Acute ethanol intoxication in a model of traumatic brain injury: the protective role of moderate doses demonstrated by immunoreactivity of synaptophysin in hippocampal neurons

Although ethanol intoxication is reported to be a complicating factor in traumatic brain injury, some recent studies are indicating its possible protective role especially at lower doses. Ethanol inhibition of NMDA-mediated excitotoxicity which predominates at lower doses is believed to be responsible for this protection. The aim of this study was to demonstrate this neuroprotective role of alcohol using immunoreactivity for synaptophysin as an indirect marker for severity of injury. Acute ethanol intoxication at moderate doses was performed 2 h prior to trauma. Severe traumatic brain injury was administrated using an impact acceleration model in Sprague-Dawley rats. At post-traumatic 48th hour, immunorectivity for synapthophysin in the rat hippocampi was evaluated under light microscopy. According to our results there were slight increases in immunoreactivity for synaptophysin in the stratum oriens and striatum radiatum of CA1 subfield of hippocampus when ethanol was administered prior to trauma comparing to moderate increase in the trauma-only group. On the other hand vacuolar degeneration and red neuron formation was more prominent in the pyramidal cell layer of CA1 and CA3 when ethanol was not administered. Ethanol may have a neuroprotective role when administered at moderate doses prior to traumatic brain injury. This effect of ethanol may primarily be due to inhibition of NMDA receptors.

Alcohol abuse and traumatic brain injury: quantitative magnetic resonance imaging and neuropsychological outcome

Prior or concurrent alcohol use at the time of traumatic brain injury (TBI) was examined in terms of post-injury atrophic changes measured by quantitative analysis of magnetic resonance imaging (MRI) and neuropsychological outcome. Two groups of TBI subjects were examined: those with a clinically significant blood alcohol level (BAL) present at the time of injury (TBI + BAL) and those without a significant BAL (TBI-only). To explore the potential impact of both acute and chronic alcohol use, subjects in both groups were further clustered into one of four subgroups (NONE, MILD, MODERATE or HEAVY) based upon available information regarding their pre-injury alcohol use. One-way analysis of covariance (ANCOVA) and multiple analysis of covariance (MANCOVA) were used with subject grouping as the main factor. Age, injury severity as measured by Glasgow Coma Scale (GCS) score, years of education, total intracranial volume (TICV), and the number of days post-injury were included as covariates where appropriate. Increased general atrophy was observed in patients with (a) a positive BAL and/or (b) a history of moderate to heavy pre-injury alcohol use. In addition, performance on neuropsychological outcome variables (WAIS-R and WMS-R Index scores) was generally worse in the subgroups of patients with positive BAL and a history of preinjury alcohol use, as compared to the other TBI groups though not statistically significant. Implications of alcohol use, at the time of brain injury, are discussed.

Alcohol intoxication increases morbidity in drivers involved in motor vehicle accidents

We prospectively examined the correlation of alcohol intoxication with injury severity, morbidity, and mortality in drivers involved in motor vehicle accidents in a prospective cohort study. The study enrolled 923 injured patients, of whom 421 were legally intoxicated (blood alcohol concentration [BAC] > or = 50 mg/dL) and 502 were not intoxicated (BAC < 50 mg/dL). The intoxicated drivers had a significantly higher injury severity score (ISS), lower Glasgow Coma Score, lower systolic blood pressure; higher rate in old age, male sex, greater rate of habitual drinking, greater lack of use of safety gear, and greater accident-related morbidity. After logistic regression analysis, alcohol intoxication was not associated with severe injury (ISS > or = 9); however, alcohol intoxication analyzed either as a preinjury or postinjury risk factor, was one of the predictors for morbidity. Severe head injury was the only predictor of mortality. In conclusion, although alcohol intoxication is not associated with an increased incidence of severe injury or mortality in drivers involved in motor vehicle crashes, it is one of the significant predictors for morbidity after injury.

Intracranial pressure response to severe head injury induced apnea and catecholamine surge

BACKGROUND

Apnea and catecholamine surge have been known sequelae in the first few minutes of postexperimentally induced severe head injury for over a century. However, the intracranial pressure (ICP) response to these two pathophysiologic processes is poorly understood.

METHODS

We used the rat fluid percussion head injury model to study apnea and catecholamine surge separately and in combination on measured ICP response

RESULTS

The three experimental groups of apnea, hypertensive surge, and both combined revealed significantly different ICP responses with markedly elevated pressures correlating closely with mean arterial blood pressure.

CONCLUSION

ICP and mean arterial blood pressure correlate closely in the first few minutes after head injury in the absence of space-occupying hematomas, and may initiate pathophysiologic sequelae that can only be treated by earlier medical intervention at the scene.

Alcohol consumption in traumatic brain injury: attenuation of TBI-induced hyperthermia and neurocognitive deficits

Clinical and animal studies indicate that hyperthermia during or after traumatic brain injury (TBI) is associated with poor outcome. Alcohol intoxication, a complicating risk factor in many cases of head injury, has been found to both worsen or attenuate posttraumatic neural damage and outcome. The purpose of the present study was to determine whether chronic ethanol consumption would affect TBI-induced hyperthermia and deficits in spatial learning. TBI was produced by cortical contusion injury in adult male rats. We first characterized the TBI-induced febrile response using probes implanted intraperitoneally (ip) or intracerebroventricularly for continuous biotelemetric recording of core body and brain temperatures and locomotor activity. In another experiment, rats, implanted with ip probes, were fed a liquid diet containing ethanol (5% w/v, 35% ethanol-derived calories); control rats were pair-fed the isocaloric liquid diet (P-P). At 14 days after commencement of diet feeding, TBI or sham surgery was performed, and the ethanol-fed rats were divided into two groups: half were transferred to the isocaloric diet (E-P) and the other half remained on the ethanol-containing diet (E-E). TBI produced a significant febrile response in all rats, that persisted for at least 6 days in the E-P and P-P groups but lasted for only 2 days in the E-E group. When tested at 3-4 weeks after TBI, E-E rats required significantly fewer trials than E-P rats to reach criterion in the Morris water maze. In sum, continuous consumption of ethanol before and after TBI attenuated TBI-induced hyperthermia and deficits in spatial learning. Whereas the results suggest that this ethanol regimen may be neuroprotective, a causal relationship between the two outcomes remains to be determined.

Hemodynamic actions of acute ethanol after resuscitation from traumatic brain injury

BACKGROUND

The purposes of this study were to determine how clinically relevant levels of acute ethanol (EtOH) influence cerebral perfusion pressure (CPP), cerebral venous O saturation (Scvo ), and systemic hemodynamics after fluid resuscitation from traumatic brain injury (TBI); and to test the hypothesis that the actions of EtOH on these variables are mediated by adenosine.

METHODS

Anesthetized swine were ventilated (Fio = 0.4) and instrumented. In protocol 1, EtOH (3.5 g/kg, n = 11) or its vehicle (n = 17) was administered orally before TBI + 40% hemorrhage. At 90 minutes post-TBI, resuscitation consisted of shed blood + saline. In protocol 2, either saline (n = 15) or an adenosine-regulating agent (5-amino-4-imidazolecarboxamide riboside) in saline (1 mg/kg bolus + 12 mg/kg/h intravenously [i.v.]) (n = 5), was administered i.v. before TBI + 45% hemorrhage. At 90 minutes post-TBI, resuscitation consisted of saline only (three times shed blood volume). In protocol 3, EtOH was administered i.v. (1 g/kg; 20% vol/vol in saline) followed by either an adenosine receptor antagonist (theophylline, 10 mg/kg) or an adenosine uptake inhibitor (dipyridamole, 0.25 mg/kg).

RESULTS

In protocol 1, with no EtOH, 11 of 17 (65%) survived post-TBI hypotension. Mean arterial blood pressure, cardiac index, and mixed venous oxygen saturation were stable for 1 hour at 40% to 60% below their respective baselines, whereas lactate increased three- to fourfold (all p < 0.05). After fluid resuscitation, most variables rapidly corrected, but intracranial pressure was increased 10 to 15 mm Hg (p < 0.05). With EtOH, 9 of 11 (82%) survived post-TBI hypotension (p = 0.42 vs. no EtOH). After resuscitation from TBI, there were significant effects of EtOH on systemic hemodynamics (mean arterial pressure, cardiac index, mixed venous oxygen saturation), on CPP, on lactate, and on Scvo at normo- and hypercapnia (all p < 0.05). The data from protocol 2 showed that essentially none of these changes were duplicated with an adenosine-regulating agent. In protocol 3, i.v EtOH produced small but significant changes in Scvo, intracranial pressure, and lactate, at normo-, hyper-, and hypocapnia. Dipyridamole and theophylline tended to have opposite, albeit small and not statistically significant, effects on these variables relative to EtOH alone.(2) (2)

CONCLUSION

Acute EtOH (200-300 mg/dL) did not increase mortality after TBI + secondary hypotension, as long as cardiopulmonary support was provided. With EtOH, CPP was maintained and cerebral blood flow appeared to be adequate, if not excessive, with respect to cerebral metabolic demand, as judged by changes in Scvo at normo-, hyper-, and hypocapnia. These changes were probably not mediated, but might have been modulated, by increases in endogenous adenosine.

Alcohol, injury, and cellular immunity

It is widely accepted that alcohol exposure is a causative factor in the occurrence of burn or other traumatic injury. It is less well known that individuals who have consumed alcohol before sustaining an injury suffer from increased morbidity and mortality compared with the morbidity and mortality of non-alcohol-consuming subjects with similar injuries. Complications due to bacterial infection are the most common burn sequelae in injured patients and are frequently associated with depressed immunity. Independently, alcohol exposure and injury have been shown to influence cellular immunity negatively. These changes in immunity are closely linked to injury- or alcohol-induced alterations in the cytokine milieu in both clinical studies and animal models. Not surprisingly, the combination of insult of alcohol exposure and burn injury results in immune suppression that is greater in magnitude and duration compared with either insult alone. The combined effects of alcohol and injury on immunity have been examined in a limited number of studies. However, results of these studies support the suggestion that altered cytokine production is an integral part of the immune dysregulation and increased mortality that is observed. In particular, the increased presence of macrophage-derived mediators observed after burn or alcohol exposure alone seems to be synergistically increased in a combined injury model. Although more research is needed, it is likely that therapeutic modalities that include manipulation of cytokine networks to boost cellular immunity may improve outcome for patients who sustain injuries subsequent to consuming alcohol.

Impact of alcohol intoxication on hemodynamic, metabolic, and cytokine responses to hemorrhagic shock

BACKGROUND

Alcohol intoxication is associated with a high incidence of traumatic injury, particularly in the young healthy population. The impact of alcohol intoxication on the immediate pathophysiologic response to injury has not been closely examined. We hypothesized that acute alcohol intoxication would aggravate the immediate outcome from hemorrhagic shock by impairing homeostatic counterregulation to blood loss.

METHODS

Chronically catheterized male Sprague-Dawley rats were randomized to receive an intragastric infusion of ethyl alcohol (1.75 g/kg followed by 250-300 mg/kg/h) or isocaloric dextrose (3-mL bolus + 0.375 mL/h) for 15 hours. Before initiating fixed-pressure hemorrhage followed by fluid resuscitation, an additional intragastric bolus of ethyl alcohol (1.75 g/kg) was administered. Hemodynamic, metabolic, cytokine, and acid-base parameters were assessed during the hemorrhage period and at completion of resuscitation. Lungs were obtained for cytokine determinations.

RESULTS

Basal mean arterial pressure was significantly lower in alcohol-intoxicated (blood-alcohol concentration, 135 +/- 12 mg/dL) animals than in controls during baseline (20%) and after the initial fluid resuscitation period (30%). Hemorrhage decreased arterial HCO3 and Pco2, and increased Po2 without significant alteration in arterial blood pH. Alcohol intoxication blunted the decrease in Pco2 and increase in Po2 and decreased blood pH during baseline and throughout the course of the hemorrhage period. Hemorrhage produced marked and progressive elevations in plasma glucose and lactate levels in controls, and this was inhibited by alcohol intoxication. Hemorrhage elevated plasma tumor necrosis factor-alpha (TNF-alpha) (686 +/- 252 pg/mL) and interleukin (IL)-10 (178 +/- 25 pg/mL), and did not alter IL-6 and IL-1 levels. Alcohol blunted the hemorrhage-induced rise in plasma TNF-alpha (142 +/- 48 pg/mL) and enhanced the hemorrhage-induced increase in IL-10 (678 +/- 187 pg/mL). Hemorrhage produced a two- to threefold increase in lung content of TNF-alpha, IL-1alpha, and IL-6 without significantly altering lung IL-10. Alcohol exacerbated the hemorrhage-induced increase in lung TNF-alpha, and did not alter the IL-1alpha, IL-6, and IL-10 lung responses.

CONCLUSION

These results indicate marked alterations in the hemodynamic and metabolic responses to hemorrhagic shock by alcohol intoxication. Furthermore, our findings suggest that alcohol modulates the early proinflammatory responses to hemorrhagic shock. Taken together, these alterations in metabolic and inflammatory responses to hemorrhage are likely to impair immediate outcome and predispose to tissue injury.

Acute ethanol intake attenuates inflammatory cytokines after brain injury in rats: a possible role for corticosterone

It has been reported that acute ethanol intoxication exerts dose-dependent effects, both beneficial and detrimental, on the outcome of traumatic brain injury (TBI), although the mechanism(s) has not been determined. Given that pro-inflammatory cytokines are either neuroprotective or neurotoxic, depending on their tissue levels, ethanol-induced alterations in brain cytokine production may be involved in determining the recovery after TBI. The present study was undertaken to examine the effect of acute ethanol pretreatments (producing blood alcohol concentrations of 100+/-16 mg/dL, and 220+/-10 mg/dL, considered low and intoxicating doses, respectively) on interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) levels in discrete brain regions. In addition, serum corticosterone levels were also examined because the hormone is a modulator of cytokine production, its secretion is stimulated by ethanol, and it has been associated with the severity of post-injury neurologic dysfunction. The data presented in this report demonstrate that moderate cortical impact brain injury elicits a marked increase in IL-1beta and TNF-alpha in the injured cortex as well as in the hippocampus ipsilateral to the injury. Ethanol pretreatment lowered cytokine levels in the cortex, hippocampus and hypothalamus in a dose-dependent manner after TBI compared to the untreated injured rats. Serum corticosterone levels were markedly increased in the injured rats, and were further augmented in the ethanol-pretreated injured animals in a dose-dependent manner. Our findings suggest that ethanol-induced decrease in pro-inflammatory cytokine production may be linked to increased circulating corticosterone, both of which may contribute to the outcome of brain injury.

Effects of binge ethanol administration on the behavioral outcome of rats after lateral fluid percussion brain injury

This study examined the effects of 4 weeks of binge ethanol administration (BEAn) on the behavioral outcome in rats after lateral fluid percussion (FP) brain injury. Rats were intragastrically given 7.5 mL/kg of either 40% ethanol in 5% glucose solution (3 g ethanol/kg; binge ethanol group), or 5% glucose solution (vehicle group), twice on Thursday and Friday of 3 consecutive weeks. Then rats from both groups were subjected to either lateral FP brain injury of moderate severity (1.8 atm) or to sham operation. Postinjury behavioral measurements revealed that brain injury caused significant spatial learning disability in both groups. There were no significant differences in mean search latencies in the sham animals between the vehicle and binge ethanol groups. On the other hand, the mean search latency of the binge ethanol group was significantly higher than that of the vehicle group in trial blocks 2 and 4. There were no significant differences in the target visits (expressed as mean zone difference [MZD]) during the probe trial between the injured animals of binge ethanol and vehicle groups. However, there was only a minor trend towards worsened MZD score in the binge-injured animals. Histologic analysis of injured animals from both injured ethanol and vehicle groups revealed similar extents of ipsilateral cortical and observable hippocampal damage. These results suggest that 4 weeks of binge ethanol treatment followed by ethanol intoxication at the time of injury worsens some aspects of the spatial learning ability of rats. This worsening is probably caused by subtle, undetectable morphologic damage by binge ethanol administration.

Traumatic brain injury outcome: concepts for emergency care

Injury to the brain is the leading factor in mortality and morbidity from traumatic injury. The devastating personal, social, and financial consequences of traumatic brain injury (TBI) are compounded by the fact that most people with TBI are young and previously healthy. From the emergency physician's standpoint, patients with severe TBI are those with a presenting Glasgow Coma Scale score of less than 9. Over the past 30 years, mortality from severe traumatic brain injury for those patients who survive to the hospital has been reduced by half from nearly 50% to approximately 25%. Because most of the pathologic processes that determine outcome are fully active during the first hours after TBI, the decisions of emergency care providers may be crucial. This review addresses new concepts and information in the pathophysiology of TBI and secondary brain injury and demonstrates how emergency management may be linked to neurologic outcome.

Ethanol potentiates dopamine release during acute hypoxia in rat striatum

We, and others, have previously demonstrated that N-methyl-D-aspartate (NMDA) receptor is involved in hypoxia or ischemia-mediated responses. We found that the NMDA antagonist ketamine attenuates cortical nitric oxide release during cerebroischemia. It has been reported that ethanol (EtOH) antagonizes NMDA-induced responses in various systems. In the present study, the interaction of EtOH and KCl-evoked striatal dopamine release in vivo during acute hypoxia was examined. High-speed chronoamperometric recording techniques, using Nafion-coated carbon fiber electrodes, were used to evaluate extracellular dopamine (DA) concentration in the striatum of urethane-anesthetized Sprague-Dawley rats. KCl was directly applied to the striatum to evoke release of DA. These anesthetized animals were paralyzed with d-tubocurarine and connected to a respirator to allow controlled respiration. Systemic concentrations of oxygen were altered by changing the rate of the respirator. We previously reported that lowering the respiratory rates from 90 to 20 times/min for 5 min decreased arterial PO(2) and facilitated KCl-induced DA release in the striatum. In this study, we found that application of NMDA antagonist MK801 attenuates hypoxic DA release, suggesting that NMDA receptor is involved in this hypoxic reaction. In contrast, EtOH dose dependently enhanced KCl-evoked DA release during hypoxia. To further examine the interactions of excitatory amino acid and EtOH on DA release, glutamate was locally applied to the striatum. Glutamate-induced DA release was not affected by the systemic application of EtOH. Taken together, these data suggest that EtOH enhances DA release in vivo during short-term hypoxia, possibly through mechanisms other than excitatory amino acid pathways.

Three months of chronic ethanol administration and the behavioral outcome of rats after lateral fluid percussion brain injury

This study examined the effects of 3 months of chronic ethanol administration (CEAn) on the behavioral outcome in rats after lateral fluid percussion (FP) brain injury. Rats were given either an ethanol liquid diet (ethanol diet groups) or a pair-fed isocaloric sucrose control diet (control diet groups) for 3 months. Then, rats from both diet groups were subjected to either lateral FP brain injury of moderate severity (1.8 atm) or to sham operation. Postinjury behavioral measurements revealed that brain injury caused significant spatial learning disability in both diet groups. There were no significant differences in spatial learning ability in the sham or brain-injured animals between the control and ethanol diets. However, a trend towards cognitive impairment in the sham animals and a trend towards reduced deficits in the brain-injured animals were observed in the ethanol diet group. Histologic analysis of injured animals from both diet groups revealed similar extents of ipsilateral cortical and hippocampal CA3 damage. These results, in general, suggest that 3 months of CEAn does not significantly alter the behavioral and morphologic outcome of experimental brain injury.

Ethanol reduces metabolic uncoupling following experimental head injury

Previous investigations have shown that ethanol is neuroprotective following experimental traumatic brain injury (TBI). This study sought to determine if the neuroprotective effects of ethanol in a controlled cortical impact (CCI) injury model are related to its effects on cerebral glucose metabolism and blood flow. Adult rats were given ethanol (1.0 g/kg) or saline by intraperitoneal injection followed 40 min later by injury. Regional cerebral blood flow (CBF) and cerebral metabolic rates of glucose (CMRglc) were determined immediately, and at 3, 6, 12, 24, and 72 h postinjury using quantitative autoradiography. Immediately after injury, CMRglc in the contusion core and penumbra was reduced in the ethanol group compared to the saline group: (core CMRglc: 52.2 +/- 16.0 versus 94.2 +/- 14.1 micromol/100 g/min, respectively,p < 0.001; penumbral CMRglc: 58.2 +/- 12.8 versus 82.8 +/-19.7 micromol/100 g/min, respectively; p < 0.05) However, at 24 and 72 h postinjury, penumbral CMRglc in the ethanol group was increased compared to the saline group (p < 0.05 and p < 0.001, respectively). Regarding CBF, contusion core values in the ethanol group were elevated compared to the saline group immediately postinjury, (70.4 +/- 17.1 versus 31.5 +/- 27.8 mL/100 g/min, respectively (p < .05), and at 6, 12, and 24 h postinjury (p < 0.05). Penumbral CBF was also higher at 6 and 72 h in the ethanol group compared to the saline group (p < 0.05). These results indicate that low-dose ethanol is associated with a marked attenuation of immediate postinjury hyperglycolysis and with more normal glucose metabolism in the injury penumbra over the ensuing 3 days. Simultaneously, the reduction in CBF typically seen within the contusion core and penumbra after CCI is less severe when ethanol is present. The net effect of these changes is a decreased degree of uncoupling between glucose metabolism and CBF that otherwise occurs in the absence of ethanol. These changes may likely explain the neuroprotective effect of ethanol.

Effects of alcohol on the geographic variation of driver fatalities in motor vehicle crashes

OBJECTIVE

To determine whether the increased risk of dying in a rural vs nonrural motor vehicle crash (MVC) can be attributed to driver demographics, crash characteristics, or police-reported alcohol use.

METHODS

A retrospective cohort study was conducted, comparing all rural (116,242) and a 20% random sample of nonrural (104,197) Michigan drivers involved in an MVC during 1994-1996. Data consisted of all police-reported traffic crashes on public roadways. A logistic regression model was created, using survival as the dependent variable and gender, age, crash characteristics, and rural or nonrural county as independent variables. Driver alcohol use, as reported by the investigating officer, was introduced into the model, and the effect was analyzed.

RESULTS

Nonsurvivors represented 0.2% of the total; 99.8% were survivors. Police-reported alcohol use was reported for 3.9% of drivers. Drivers in rural MVCs were more likely to be male, to be more than 50 years of age, to have been drinking alcohol, and to have more severe vehicle deformation as a result of the MVC. The relative risk (RR) for MVC nonsurvivors was 1.69 [95% confidence interval (CI) = 1.3 to 2.1] times higher for drivers in rural than nonrural counties. After adjusting for demographic and crash characteristics, the RR was 1.56 (95% CI = 1.2 to 1.9). Controlling for alcohol and its interactions decreased the RR to 1.26 (95% CI = 0.6 to 2.4), a nonsignificant difference between rural and nonrural MVC mortalities.

CONCLUSIONS

Alcohol use by drivers in Michigan was a significant contributor for nonsurvivors of rural crashes. Efforts to decrease rural MVC mortality must address alcohol use.

The neglected prehospital phase of head injury: apnea and catecholamine surge

The prehospital phase of head injury, also called the critical phase, consists of trauma-induced apnea and stress catecholamine release. This immediate period after head injury remains poorly summarized in the literature and essentially ignored with respect to treatment. A MEDLINE search of the literature on apneustic response and catecholamine surge after head injury and a review of literature from my acquired references revealed 116 references (from more than 600) that were pertinent. Apnea induced by head injury produces hypoxia, hypercarbia, and subsequent cardiac failure and hypotension, which, along with substantially elevated catecholamine values, promote secondary mechanisms of organ injury. Treatment for this immediate period after head injury requires a rapid response to the scene of trauma and development of treatment options that can be instituted at the scene of injury.

The effects of acute and chronic alcohol ingestion on outcome following multiple episodes of mild traumatic brain injury in rats

OBJECTIVE

Recent studies suggest that in some circumstances, alcohol intoxication at the time of severe head injury may be neuroprotective. The objective of this study was to determine the effect of acute and chronic alcohol ingestion on outcome in rodents sustaining multiple episodes of mild traumatic brain injury while intoxicated.

METHOD

For two weeks before experimentation, adult male Sprague-Dawley rats received intoxicating levels of 95% ethanol (3 g/kg) or normal saline (NS) every other day by orogastric instillation. On the day of experimentation, the animals were randomized to receive alcohol or NS. Two hours later, the animals received either mild (1.2 +/- 0.4 ATA) fluid percussion injury (FPI) or no injury. The injured animals received a total of three episodes of FPI (once every four days). Mean reflex recovery time (RRT) was determined (seconds +/- SEM) immediately after each episode. Mean latency time (seconds +/- SEM) for Morris Water Maze (MWM) performance was assessed at post-trauma days 11-19.

RESULTS

The chronic alcohol-exposed (CA) and the non-alcohol-exposed (NA) animals intoxicated when injured had prolonged escape, righting, and corneal RRTs after each FPI compared with the nonintoxicated injured animals and the non-injured shams. However, the CA animals had significantly shorter RRTs when compared with the NA rats. All the injured animals had MWM deficits on testing days 1-6 compared with the noninjured controls. On the last two MWM testing days, the injured NA animals had significantly better MWM performance than the injured CA rats.

CONCLUSIONS

The injured intoxicated CA animals had a more rapid recovery of reflexes compared with the injured intoxicated NA animals. Despite initial MWM deficits, the injured NA rodents eventually began to learn the MWM. The injured CA rats never learned the maze. Under the conditions of this study, acute alcohol intoxication at the time of multiple episodes of minor head trauma did not provide neuroprotection for NA or CA rodents.

Effects of ethanol on brain lactate in experimental traumatic brain injury with hemorrhagic shock

OBJECTIVE

Previous studies of traumatic brain injury (TBI) and hemorrhagic shock (HS) models, have shown cardiorespiratory depression in ethanol-treated animals. This study investigated the effects of ethanol (ET) on brain lactate concentrations and acidosis in a TBI/HS model.

METHODS

Anesthetized swine were instrumented and subjected to injury (INJ) consisting of fluid percussion TBI of 3 atm with concurrent 30 ml/kg graded hemorrhage over 30 min. Three groups were studied: Sham, INJ and INJ/ET. ET was given preinjury as a 2-g/kg i.v. bolus over 30 min, and an infusion of 0.4 g kg(-1) h(-1). Cardiorespiratory and cerebral physiologic data were monitored continuously for 150 min postinjury. Cerebral and renal blood flow was measured with colored microspheres. Brains were frozen in situ with liquid nitrogen. Lactate was measured with an enzymatic method.

RESULTS

ET levels at injury were 219+/-24 mg/dl. The INJ/ET group had increased mortality, impaired ventilation, and reduced renal blood flow. Brain (cortical) lactate levels were significantly higher and cerebral venous lactate concentrations were increased in the INJ/ET group during the postinjury period. Cerebral venous glucose was significantly higher in the INJ/ET group, and cerebral venous pH was significantly lower.

CONCLUSION

In this TBI/HS model, ethanol-induced increases in lactate concentrations in brain tissue and cerebral venous blood are associated with respiratory depression and reduced organ blood flow.

Death due to concussion and alcohol

We encountered 5 deaths following blunt trauma to the face and head in which the injuries were predominantly soft tissue in nature with absence of skull fractures, intracranial bleeding, or detectable injury to the brain. All individuals were intoxicated, with blood ethanol levels ranging from 0.22 to 0.33 g/dl. We feel that in these deaths, ethanol augmentation of the effects of concussive brain injury, with resultant posttraumatic apnea, was the mechanism of death.

Acute ethanol intoxication in a model of traumatic brain injury with hemorrhagic shock: effects on early physiological response

OBJECT

Traumatic brain injury (TBI) is exacerbated by hypotension and hypoventilation. Because previous studies have shown a potentiating effect of ethanol (EtOH) on TBI and hemorrhagic shock (HS), the authors investigated the effects of EtOH on the early physiological response to TBI with and without HS.

METHODS

Anesthetized swine, weighing approximately 20 kg each, underwent fluid-percussion TBI of 3 atm with or without 30 ml/kg hemorrhage for a period of 30 minutes. The mean arterial blood pressure, intracranial pressure, cerebral perfusion pressure (CPP), cardiac output, cerebral venous oxygen saturation, and metabolic parameters were monitored for 3 hours postinjury. Ventilation and the response to hypercapnia were also measured. Regional cerebral blood flow and renal blood flow were measured using dye-labeled microspheres. Five groups were studied: control, TBI, TBI/EtOH, TBI/HS, and TBI/HS/EtOH. The EtOH (3.5 g) was given intragastrically 100 minutes preinjury. The TBI/HS/EtOH group demonstrated a 3-hour mortality rate of 56% and postinjury apnea requiring ventilation in 44% of animals compared with 0% in all other groups. Minute ventilation and the hypercapnic ventilatory response were significantly reduced in the postinjury period in the TBI/HS/EtOH group. The animals in this group had significantly lower CPP and cardiac output in the first 60 minutes postinjury, as well as lower renal and cerebral blood flow. Postinjury cerebral venous lactate levels were higher, and cerebral venous pH was lower in the TBI/HS/EtOH group.

CONCLUSIONS

In this model of TBI, acute EtOH intoxication in the presence of HS potentiates the physiological and metabolic alterations that may contribute to secondary brain injury.

The early critical phase of severe head injury: importance of apnea and dysfunctional respiration

BACKGROUND

Apnea is a known response of concussive head injury. Hypoxic or ischemic brain injury has been documented in a high percentage of severe head injury deaths. The respiratory response after head injury remains poorly defined, however, and its contribution to hypoxic or ischemic mechanisms after severe head injury is unknown.

METHODS

Eighteen anesthetized but spontaneously breathing rats were subjected to fluid percussion head injury of varying severities. Respiratory rate and volume of air were recorded before and after injury with a Hans Rudolph/Varadyne pneumotach differential pressure transducer and graphically measured. Postmortem inspection of the brains was performed.

RESULTS

Apnea and subsequent respiratory dysfunction are directly proportional to the magnitude of energy delivered to the brain. Higher energy results in a dysfunctional or absent respiratory response, probably attributable to failure or disorganized function of the medullary respiratory center.

CONCLUSION

This study for the first time graphically depicts the respiratory response after head injury. Higher energy delivered to the brain directly correlates with a markedly abnormal respiratory response that probably contributes significantly to subsequent hypoxic or ischemic brain injury. The absence of the space-occupying hematoma or gross parenchymal disruption suggests that in the clinical setting many of these patients may otherwise have survivable head injury if rescued by early ventilatory assistance.