Dose-dependent effects of prolonged isoflurane administration on resting cerebral blood flow and functional connectivity: a preliminary study in rhesus monkeys

Isoflurane is widely used in biomedical research with the prolonged duration of administration up to several hours. However, the manner in which neurophysiology and functional connectivity are affected by the length of anesthesia remains poorly understood. In the present study, cerebral blood flow (CBF) and default model network (DMN) were examined using arterial spin-labeling perfusion and resting state functional MRI techniques. The functional connectivity in the dominant DMN decreased substantially during 4-hour administration of isoflurane at any given dosage. CBF in most brain regions decreased at the low dose (0.89 %), but did not change markedly when higher doses of isoflurane (1.05 %, 1.19 %) were administrated. The study revealed dose-dependent effects of isoflurane on brain functionality and regional CBF during prolonged anesthesia administration of isoflurane, suggesting those effects should be considered in the experimental design or the interpretation of the outcome of related neuroimaging studies using anesthetized animals or humans.