vi medicine informatics




Treatment for pheochromocytoma is surgical removal when possible. To protect against hypertensive crisis during surgery, patients must be treated preoperatively with phenoxybenzamine, a long-acting irreversible α-antagonist. Blockade of α-adrenergic receptors causes relaxation of the vessels and a decrease in blood pressure. Miosis, or pupillary constriction, is a possible adverse effect, and patients may find that their vision is particularly affected in the dark. A β-blocker must also be administered to address the excessive stimulation of β-adrenergic receptors and to reduce the risk of reflex tachycardia. It is essential that the β-blocker be administered after administration of the α-blocker. Reversing this order poses a danger to the patient in this situation.

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