Hypertensive crisis during phaeochromocytoma surgery: what to do
During adrenalectomy in a dog with phaeochromocytoma, when the tumour is handled the systolic pressure rises to 260 mmHg and ventricular tachycardia appears.
What is the most appropriate action?
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A. Esmolol bolus as the first and only measure
Blocking beta receptors before alpha receptors leaves vasoconstriction unopposed and can worsen hypertension. Esmolol is useful, but after alpha control.
B. Deepen the anaesthetic plane with more isoflurane until pressure normalises
The hypertension is due to catecholamines released by the tumour, not to a light plane. Greatly deepening anaesthesia is ineffective and leaves the dog very hypotensive once the tumour vein is ligated.
C. Ask for handling to pause, give IV phentolamine or a nitroprusside infusion and, once alpha control is achieved, esmolol or lidocaine for the arrhythmia
Correct. Phentolamine is a short-acting alpha-blocker and nitroprusside a potent, easily titrated vasodilator. Once alpha-blockade is established, tachycardia and ventricular arrhythmias are treated.
D. Dexmedetomidine bolus to reduce sympathetic tone
The catecholamines come from the tumour, not the central nervous system, and dexmedetomidine also causes initial vasoconstriction. It does not control this crisis.
lightbulb Key takeaway
When operating on a phaeochromocytoma, expect two phases: hypertensive crises while the tumour is handled and sudden hypotension when its vein is ligated. Use invasive blood pressure monitoring and have vasodilators, antiarrhythmics, fluids and vasopressors ready.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.