CMR is decreased by which agent?

CMR is decreased by which agent?

• A. Isoflurane
• B. Seizure
• C. Hyperthermia
• D. Ketamine

Answer: (A)

The main point is that brain energy use, or cerebral metabolic rate (CMR), decreases with volatile inhaled anesthetics. Isoflurane lowers neuronal activity and thus reduces the brain’s demand for oxygen and energy, causing a drop in CMR. While these agents can cause some cerebral blood vessel dilation, which increases blood flow, the overall metabolic demand of brain tissue falls. In contrast, conditions or agents that raise metabolic activity—like seizures, hyperthermia, or ketamine—increase CMR. Therefore, isoflurane best decreases cerebral metabolic rate.

The main point is that brain energy use, or cerebral metabolic rate (CMR), decreases with volatile inhaled anesthetics. Isoflurane lowers neuronal activity and thus reduces the brain’s demand for oxygen and energy, causing a drop in CMR. While these agents can cause some cerebral blood vessel dilation, which increases blood flow, the overall metabolic demand of brain tissue falls. In contrast, conditions or agents that raise metabolic activity—like seizures, hyperthermia, or ketamine—increase CMR. Therefore, isoflurane best decreases cerebral metabolic rate.