Effects of hypervolemia and hypertension on regional cerebral blood flow, intracranial pressure, and brain tissue oxygenation after subarachnoid hemorrhage.
OBJECTIVE
Hypertensive, hypervolemic, hemodilution therapy (triple-H therapy) is a generally accepted treatment for cerebral vasospasm after subarachnoid hemorrhage. However, the particular role of the three components of triple-H therapy remains controversial. The aim of the study was to investigate the influence of the three arms of triple-H therapy on regional cerebral blood flow and brain tissue oxygenation.


METHODS
Animal research and clinical intervention study.


METHODS
Surgical intensive care unit of a university hospital.


METHODS
Experiments were carried out in five healthy pigs, followed by a clinical investigation of ten patients with subarachnoid hemorrhage.


METHODS
First, we investigated the effect of the three components of triple-H therapy under physiologic conditions in an experimental pig model. In the next step we applied the same study protocol to patients following aneurysmal subarachnoid hemorrhage. Mean arterial pressure, intracranial pressure, cerebral perfusion pressure, cardiac output, regional cerebral blood flow, and brain tissue oxygenation were continuously recorded. Intrathoracic blood volume and central venous pressure were measured intermittently. Vasopressors and/or colloids and crystalloids were administered to stepwise establish the three components of triple-H therapy.


RESULTS
In the animals, neither induced hypertension nor hypervolemia had an effect on intracranial pressure, brain tissue oxygenation, or regional cerebral blood flow. In the patient population, induction of hypertension (mean arterial pressure 143 +/- 10 mm Hg) resulted in a significant (p < .05) increase of regional cerebral blood flow and brain tissue oxygenation at all observation time points. In contrast, hypervolemia/hemodilution (intrathoracic blood volume index 1123 +/- 152 mL/m) induced only a slight increase of regional cerebral blood flow while brain tissue oxygenation did not improve. Finally, triple-H therapy failed to improve regional cerebral blood flow more than hypertension alone and was characterized by the drawback that the hypervolemia/hemodilution component reversed the effect of induced hypertension on brain tissue oxygenation.


CONCLUSIONS
Vasopressor-induced elevation of mean arterial pressure caused a significant increase of regional cerebral blood flow and brain tissue oxygenation in all patients with subarachnoid hemorrhage. Volume expansion resulted in a slight effect on regional cerebral blood flow only but reversed the effect on brain tissue oxygenation. In view of the questionable benefit of hypervolemia on regional cerebral blood flow and the negative consequences on brain tissue oxygenation together with the increased risk of complications, hypervolemic therapy as a part of triple-H therapy should be applied with utmost caution.
Muench
Elke
E
Department of Anesthesiology, University Hospital Mannheim, Mannheim, Germany. elke.muench@t-online.de
Horn
Peter
P
Bauhuf
Christian
C
Roth
Harry
H
Philipps
Mark
M
Hermann
Peter
P
Quintel
Michael
M
Schmiedek
Peter
P
Vajkoczy
Peter
P
D000328:Adult; D000368:Aged; D000818:Animals; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D000077324:Crystalloid Solutions; D005260:Female; D006438:Hemodilution; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives / Q000008:administration & dosage / Q000494:pharmacology; D007427:Intracranial Pressure / Q000187:drug effects; D007552:Isotonic Solutions / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D010952:Plasma Substitutes / Q000008:administration & dosage / Q000494:pharmacology*; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000628:therapy*; D013552:Swine; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology*; D020301:Vasospasm, Intracranial / Q000209:etiology / Q000628:therapy*
D000077324:Crystalloid Solutions; D006895:Hydroxyethyl Starch Derivatives; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D014662:Vasoconstrictor Agents; D010100:Oxygen