Effects of ethanol and naltrexone in a model of traumatic brain injury with hemorrhagic shock.
BACKGROUND
Ethanol predisposes to traumatic injury and causes respiratory depression and cardiovascular compromise in models of traumatic brain injury (TBI) and hemorrhagic shock (HS). Endogenous opioids may play a role in ethanol intoxication and TBI. We studied the effects of ethanol and the opiate antagonist agent naltrexone (NTX) in a TBI/HS model.


METHODS
Fifty-six pigs (20 kg) were anesthetized with isoflurane, intubated, instrumented, and subjected to fluid percussion TBI with concurrent 30 ml/kg hemorrhage over 30 min. Seven groups were studied: Control, EtOH, NTX, INJ, INJ/EtOH, INJ/NTX, and INJ/EtOH/NTX. Ethanol (2 g/kg IV) was given preinjury, followed by infusion of 0.4 g/kg/hr. NTX 0.3 mg/kg intravenous was given 5 min postinjury. Parameters monitored for 120 min postinjury included minute ventilation (VE), blood pressure (MAP), cerebral perfusion pressure (CPP), cerebral venous lactate (Lac), arterial and cerebral venous blood gases, and brain tissue PtiO2.


RESULTS
Ethanol levels at injury were 220 mg/dL. Ethanol-treated animals had depression of hypercapnic ventilatory response, which was reversed by administration of naltrexone. MAP and CPP were significantly lower in injured animals, but were not significantly improved by NTX. Cerebral venous pH was lower and lactate was higher in ethanol-treated animals.


CONCLUSIONS
In this TBI/HS model, NTX reverses ethanol-induced depression of hypercapnic ventilatory response but does not improve MAP, CPP, or metabolic acidosis. This suggests that the respiratory effects of ethanol in TBI, but not the hemodynamic effects, may be mediated by opiate receptor activation.
Zink
B J
BJ
University of Michigan Emergency Medicine Research Laboratory and Crosby Neurosurgical Laboratory Ann Arbor, Michigan 48109-0303, USA. bzink@umich.edu
Schultz
C H
CH
Stern
S A
SA
Mertz
M
M
Wang
X
X
Johnston
P
P
Keep
R F
RF
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000098:blood supply; D001930:Brain Injuries / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D002302:Cardiac Output; D000431:Ethanol / Q000097:blood / Q000633:toxicity*; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia; D007427:Intracranial Pressure; D019344:Lactic Acid / Q000097:blood; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010101:Oxygen Consumption; D012119:Respiration; D012771:Shock, Hemorrhagic / Q000150:complications / Q000503:physiopathology*; D013552:Swine; D014680:Veins
D009292:Narcotic Antagonists; D019344:Lactic Acid; D000431:Ethanol; D009271:Naltrexone