Isoflurane cerebral blood flow

Functioning of Isoflurane cerebral blood flow is discussed here. Isoflurane reduces cerebral metabolism and so the oxygen consumption is reduced. At 1 MAC there is a 23% reduction in CMRO2.

Isoflurane cerebral blood flow is not associated with seizure activity as opposed to Enflurane. The EEG shows progressive development of slow waves after an initial increase in amplitude culminating in an isoelectric pattern at 2 MAC.

There is an increase in intracranial pressure (IC?) in spontaneous ventilation which is eliminated by controlled ventilation. A cerebro-protective action is seen in animals with cerebral ischaemia.

Miller’s Anesthesia 7th Edition says the following about Isoflurane cerebral blood flow –

By contrast, all of the volatile anesthetics can be, depending on physiologic and pharmacologic circumstances, dose-dependent cerebral vasodilators.

The order of vasodilating potency is approximately halothane ≫ enflurane > desflurane > isoflurane > sevoflurane. The CBF differences among isoflurane, desflurane, and sevoflurane are probably not significant to the clinician.

The net CBF effect of introducing a volatile anesthetic depends on the interaction of several factors, including the concentration of the anesthetic, the extent of previous CMR depression, simultaneous blood pressure changes acting in conjunction with previous or anesthetic-induced autoregulation abnormalities, and simultaneous changes in Paco2 in conjunction with any disease-related impairment in CO2 responsiveness.

 

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