DOI: 10.1097/01.sa.0000177145.17532.b0
,
Issn Print: 0039-6206
Publication Date: 2005/10/01
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Excerpt
Anders Holmström and J. Äkeson
(J Neurosurg Anesthesiol, 16:136-143, 2004)
Department of Anesthesia and Intensive Care and the Department of Experimental Research, Malmö University Hospital, Lund University, Malmö, Sweden.
Although isoflurane has long been considered the agent of choice in clinical neuroanesthesia, desflurane and sevoflurane are being evaluated for potential advantages over isoflurane. A porcine model was used to compare the effects of these 3 agents on intracranial pressure (ICP), cerebral blood flow (CBF), and cerebrovascular resistance (CVR).
The experimental model simulated the neuroanesthesiologic challenge occurring with an intracranial mass lesion, primarily an epidural hematoma. Stability of the intracranial hypertension in the model was of sufficiently long duration to allow each of the 3 study drugs to be evaluated. The agents, given in sequence to each of 6 pigs, were compared at 0.5 and 1.0 minimal alveolar concentration (MAC) and 3 mean arterial blood pressure (MAP) levels (50, 70, and 90 mm Hg) at normocapnia and 1 MAP level (70 mm Hg) at hypocapnia. Two extradurally positioned Fogarty catheters were inflated to a baseline ICP of 20 to 22 mm Hg at 0.2 MAC of each agent.
CBF, ICP, and CVR were markedly higher at MAP 90 mm Hg than at MAP 50 mm Hg for all 3 agents at both 0.5 and 1.0 MACs. The relationships for CBF and for ICP between the 3 agents at normocapnia at MAP 70 and 90 were as follows: for both 0.5 and 1.0 MACs: desflurane > isoflurane > sevoflurane; and for CVR at both 0.5 and 1.0 MACs, it was sevoflurane > isoflurane > desflurane. At MAP 50 and normocapnia, only CBF and CVR differed importantly between agents; CBF at 0.5 and 1.0 MACs was higher, and CVR was lower, with desflurane than with isoflurane or sevoflurane. For all 3 agents and at both 0.5 and 1.0 MACs, CBF and ICP were both markedly lower, and CVR was markedly higher at hypocapnia than at normocapnia.
The study agents dose-dependently affected cerebral autoregulation of CBF, and all 3 agents preserved some vasoreactivity to hypocapnia. Compared with isoflurane, desflurane increased ICP more, and sevoflurane decreased ICP less, during normoventilation. Differences among the agents disappeared during hyperventilation.
