Aortic Cross-Clamp Hypertension — FRCA Final MCQ

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ModerateGeneral AnaesthesiaAortic Cross-Clamp HypertensionFRCA Final

A 68-year-old man is undergoing elective open abdominal aortic aneurysm repair. Immediately after infrarenal aortic cross-clamping, despite adequate anaesthesia, analgesia and oxygenation, his arterial pressure rises to 210/110 mmHg. His heart rate is 68 beats min−1 and new horizontal ST-segment depression appears in lead V5. Which intravenous drug is most appropriate to start?

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Correct answer: B — Glyceryl trinitrate infusion

Glyceryl trinitrate is the best choice because hypertension is accompanied by new myocardial ischaemia. Venodilatation reduces ventricular preload and wall tension, while at higher doses arterial dilatation lowers afterload; both effects reduce myocardial oxygen demand. GTN also dilates epicardial coronary arteries and is specifically indicated for perioperative hypertension and myocardial ischaemia. Sodium nitroprusside is an effective rapidly titratable treatment for cross-clamp hypertension, but it lowers coronary perfusion pressure more and is less attractive when active ischaemia is present. Esmolol or labetalol may be useful when tachycardia is driving oxygen demand, but the heart rate here is 68 beats min−1. Phenylephrine would increase vascular resistance and worsen the hypertension and myocardial workload.

Reference: Hospira UK Ltd. Glyceryl Trinitrate 5 mg/ml Sterile Concentrate, Summary of Product Characteristics, sections 4.1–4.2, revised May 2024. https://www.medicines.org.uk/emc/product/3792/smpc