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October 1974

Carbon Dioxide as an Otic Vasodilator: Otic Blood Flow as Measured by the Microsphere Technique

Author Affiliations

From the Division of Otolaryngology, Emory University School of Medicine, Atlanta.

Arch Otolaryngol. 1974;100(4):309-313. doi:10.1001/archotol.1974.00780040319015

Carbon dioxide (CO2 ) is a potent dilator of cerebral blood vessels. In this experiment, the effect of CO on the blood flow of temporal bone, mastoid bone, brain, and several other tissues was measured using radioactive microsphere techniques. Mongrel dogs were tested with one of four gas mixtures for times varying from ten minutes to two hours.

Control blood gas values and cerebral blood flows corresponded quite closely to values reported by investigators using other techniques. Temporal bone blood flow prior to exposure to CO2 was approximately one tenth that of brain. Following administration of CO2, both brain and temporal bone blood flows were markedly increased. The effect of 10% CO2 on brain tissue was prolonged, but in temporal bone, the increase in blood flow progressively diminished with time. Maximum otic blood flow was obtained using 10% CO2-90% O2.

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