Article
Effects of hypervolemia, hemodilution and hypertension on regional cerebral blood flow and brain tissue oxygenation
Einfluss von "triple-H" Therapie auf zerebralen Blutfluss und zerebrale Oxygenierung
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Published: | May 8, 2006 |
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Objective: Hypertensive, hypervolemic, hemodilution therapy (triple-H therapy) is a generally accepted treatment for cerebral vasospasm after subarachnoid hemorrhage (SAH). 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 triple-H therapy on regional cerebral blood flow (rCBF) and brain tissue oxygenation (PtiO2).
Methods: Ten intubated and ventilated patients (8 female, 2 male; mean age 52,3±11,6 yrs) with high-grade aneurysmal subarachnoid hemorrhage (aSAH) (H&H III-V) were examined on day 1,3 and 7 after bleeding. After baseline recordings of thermal diffusion rCBF (TD-rCBF), and brain tissue oxygenation (ptiO2), vasopressors and/or colloids and cristalloids were administered for the stepwise establishment of the three components of triple-H therapy.
Results: Elevations of MAP by noradrenalin infusion resulted in an increase of TD-rCBF from 29±16 to 39±19 ml/100g/min. Hypervolemia alone did not lead to a significant increase of MAP and resulted in a slight increase of TD-rCBF only on day one and seven after bleeding. Significant improvement of TD-rCBF (48±22 ml/100g/min) was achieved after restoration of hypervolemia and hypertension (MAP>130mmHg). None of the three components of triple-H therapy affected PtiO2 measurements significantly.
Conclusions: Vasopressor-induced elevation of MAP caused a significant increase of TD-rCBF in all SAH patients. Volume expansion resulted in a slight effect on TD-rCBF only. In view of the increased risk of complications due to hypervolemic therapy, the added benefit of hypervolemia remains questionable. However, these findings suggest that the effect of triple-H therapy should be monitored by direct CBF measurements.