British Journal of Anaesthesia, Vol 79, Issue 1 97-102, Copyright © 1997 by The Board of Management and Trustees of the British Journal of Anaesthesia
M. J. Souter, PJD. Andrews, I. R. Piper and J. D. Miller
Alfentanil is reported to increase intracranial pressure (ICP) after
neurotrauma. A direct cerebral vasodilator effect has been postulated. We
studied 17 Sprague-Dawley rats allocated to one of three groups. Animals
were anaesthetized and their lungs ventilated, and arterial pressure, ICP
and/or regional cerebral blood flow (CBF) measurements were undertaken.
Group 1 (n = 6) received a severe closed head injury while group 2 (n = 5)
received no injury. ICP and mean arterial pressure (MAP) were measured
before, during and after rapid infusion of alfentanil 250, 500 and 750
micrograms kg-1. CBF was measured by hydrogen clearance before rapid
infusions and at 30-min intervals after starting a subsequent slow infusion
of alfentanil 500 micrograms kg-1 h- 1. Group 3 (n = 6) underwent CBF
measurement only, for comparison with those of groups 1 and 2. They
received an injury but no alfentanil. ICP or MAP values did not differ
significantly between groups 1 and 2. Rapid i.v. doses of alfentanil
produced increases in ICP and reductions in MAP. ICP changes were
consistent with a drug effect (P < 0.001) but were small. Reductions in
MAP were significant (P < 0.05) and preceded changes in ICP. CBF values
were similar and unaffected by slow alfentanil infusion in groups 1 and 2,
and did not differ significantly between groups 1 and 3. We conclude that
alfentanil did not appear to exert a direct effect on the cerebral
circulation. Changes in ICP after rapid infusion were secondary to
reductions in SAP. Slow infusion did not cause such changes.
LABORATORY INVESTIGATIONS
Effects of alfentanil on cerebral haemodynamics in an experimental model of traumatic brain injury
University Department of Clinical Neurosciences, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU
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