Barbiturates and hyperventilation during intracranial hypertension.
OBJECTIVE
The purpose of this study was to determine the effect of hyperventilation alone and hyperventilation plus barbiturate therapy on intracranial pressure, global and regional cerebral blood flow rates, cerebrovascular resistance, and cerebral perfusion pressure in adult dogs with and without intracranial hypertension induced by epidural balloon.


METHODS
Prospective, randomized, controlled study.


METHODS
An animal laboratory of a university hospital. Four sequential global and regional cerebral blood flow determinations were made in each animal during monitoring of heart rate and systemic arterial pressure, during respiratory control and arterial blood gas monitoring, intracranial pressure monitoring, and with or without inflation of an epidural balloon catheter.


METHODS
Acute mongrel dogs obtained from the Baylor Center for Comparative Medicine. Five groups of animals were studied. In group 1, the response to hyperventilation was assessed in dogs without increased intracranial pressure. In group 2, the response to hyperventilation was assessed in animals with acute intracranial hypertension. In group 3, the response to hyperventilation plus barbiturate therapy was assessed in dogs without increased intracranial pressure. In group 4, the response to hyperventilation plus barbiturate therapy was assessed in dogs with acute increased intracranial pressure. In group 5, a group of dogs with increased intracranial pressure was treated with neither hyperventilation nor barbiturates.


METHODS
Hyperventilation, hyperventilation plus barbiturate therapy, or no interventions were studied in these experimental paradigms.


RESULTS
The main outcome measures were changes in intracranial pressure and/or changes in regional or total cerebral blood flow. A significant decrease in intracranial pressure and cerebral blood flow rate was produced by hyperventilation alone in groups with intracranial hypertension. Combined hyperventilation and barbiturate therapy resulted in a significant further decrease in cerebral blood flow rate in animals with normal and increased intracranial pressure, but no greater decrease in intracranial pressure was seen compared with treatment with hyperventilation alone. Cerebral perfusion pressures remained normal despite significant decreases in cerebral blood flow rates.


CONCLUSIONS
These studies suggest that barbiturate administration in this model of intracranial hypertension was no more effective in reducing increased intracranial pressure than hyperventilation alone.
Louis
P T
PT
Department of Pediatrics, Baylor College of Medicine, Houston, TX.
Goddard-Finegold
J
J
Fishman
M A
MA
Griggs
J R
JR
Stein
F
F
Laurent
J P
JP
D000208:Acute Disease; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D001784:Blood Gas Analysis; D002560:Cerebrovascular Circulation / Q000187:drug effects; D003131:Combined Modality Therapy; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D005069:Evaluation Studies as Topic; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D007427:Intracranial Pressure; D008297:Male; D010424:Pentobarbital / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011559:Pseudotumor Cerebri / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D011897:Random Allocation; D012121:Respiration, Artificial / Q000379:methods*; D014655:Vascular Resistance / Q000187:drug effects
D010424:Pentobarbital