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Effects of normovolaemic haemodilution on middle cerebral artery blood flow velocity and oxygen delivery

Published online by Cambridge University Press:  16 August 2006

K. Karadibak
Affiliation:
Dokuz Eylül University School of Medicine, Department of Anesthesiology, İzmir, Turkey
N. Gökmen
Affiliation:
Dokuz Eylül University School of Medicine, Department of Anesthesiology, İzmir, Turkey
S. Erbayraktar
Affiliation:
Dokuz Eylül University School of Medicine, Department of Neurosurgery, İzmir, Turkey
Y. Göktay
Affiliation:
Dokuz Eylül University School of Medicine, Department of Radiology, İzmir, Turkey
A. Taplu
Affiliation:
Dokuz Eylül University School of Medicine, Department of Anesthesiology, İzmir, Turkey
A. Arkan
Affiliation:
Dokuz Eylül University School of Medicine, Department of Anesthesiology, İzmir, Turkey
N. Erkan
Affiliation:
Dokuz Eylül University School of Medicine, Department of General Surgery, İzmir, Turkey
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Abstract

Background and objective: Assessment of the effects of normovolaemic haemodilution on middle cerebral artery blood flow velocity with transcranial Doppler ultrasonography, intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery.

Methods: Normovolaemic haemodilution was induced in rabbits under general anaesthesia, and the haematocrit was allowed to decrease to 30% in Group 1 (n = 6) and to 20% in Group 2 (n = 6). Peak systolic and diastolic velocities, mean blood flow velocity, and pulsatility and resistance indices of the middle cerebral artery were measured by transcranial Doppler ultrasonography. Changes in intracranial pressure, cerebral perfusion pressure, arterial oxygen content and cerebral oxygen delivery were also assessed.

Results: In Group 2, middle cerebral artery blood flow velocity increased from 0.4 ± 0.01 to 0.51 ± 0.02 m s−1 after the induction of normovolaemic haemodilution (P = 0.04), while arterial oxygen content decreased from 16.2 ± 0.1 to 8.5 ± 0.1 mL dL−1 (P = 0.002). The decrease in cerebral oxygen delivery from 6.5 ± 0.2 to 4.3 ± 0.2 was also significant (P = 0.02). However, no associated changes in intracranial pressure and cerebral perfusion pressure could be demonstrated.

Conclusions: Normovolaemic haemodilution resulted in an increase in the mean blood flow velocity of the middle cerebral artery. However, this increase did not compensate for the consequences of the altered oxygen delivery to the brain when the haematocrit was reduced to 20%

Type
Original Article
Copyright
2002 European Society of Anaesthesiology

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