Which of the following is LEAST likely to impair cerebral blood flow autoregulation?

Which of the following is LEAST likely to impair cerebral blood flow autoregulation?

• A. Halothane 1 MAC
• B. Intracranial tumors
• C. Nitrous oxide 50%
• D. Cerebral ischemia

Answer: (C)

Cerebral blood flow autoregulation keeps the brain’s blood flow constant across a range of mean arterial pressures by adjusting the diameter of cerebral vessels. When this ability is blunted, CBF becomes more pressure-passive, which is dangerous in brain-injury or mass lesions. Halothane at 1 MAC relaxes cerebral vessels and blunts the vessels’ normal constrictive response, so the autoregulatory adjustment is reduced. Intracranial tumors raise ICP and disrupt normal vascular control, often leading to impaired autoregulation. Cerebral ischemia damages the vessels and the mechanisms that respond to pressure changes, causing loss of autoregulation. Nitrous oxide, although it increases CBF and ICP, does not impair the autoregulatory mechanism to the same extent as the volatile anesthetic or structural brain pathology, making it the least likely to impair autoregulation among the options.

Cerebral blood flow autoregulation keeps the brain’s blood flow constant across a range of mean arterial pressures by adjusting the diameter of cerebral vessels. When this ability is blunted, CBF becomes more pressure-passive, which is dangerous in brain-injury or mass lesions.

Halothane at 1 MAC relaxes cerebral vessels and blunts the vessels’ normal constrictive response, so the autoregulatory adjustment is reduced. Intracranial tumors raise ICP and disrupt normal vascular control, often leading to impaired autoregulation. Cerebral ischemia damages the vessels and the mechanisms that respond to pressure changes, causing loss of autoregulation. Nitrous oxide, although it increases CBF and ICP, does not impair the autoregulatory mechanism to the same extent as the volatile anesthetic or structural brain pathology, making it the least likely to impair autoregulation among the options.