Intraoperative Hypertension: Differential and Treatment

CA-1 · draft

CA-1 Bootcamp day 12. Authored from cited abstracts; every claim carries a PMID.

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Before induction

Start with the patient rather than the pressure, because a noxious stimulus alone will do this: in unpremedicated control patients, laryngoscopy and intubation raised mean arterial pressure by an average of 39 mmHg and heart rate by about 20 beats per minute.
Look at the capnograph and the saturation before you look at the drug drawer, because both derangements raise blood pressure through the sympathetic nervous system - allowing arterial carbon dioxide to reach 56 to 65 mmHg under anaesthesia raised systolic pressure, heart rate and cardiac output with a two- to threefold rise in plasma catecholamines, and hypoxia is a recognised driver of sympathoexcitation in its own right.
A full bladder deserves a place on the list rather than a joke, because in a patient with a high spinal cord injury bladder distension is the classic trigger for autonomic dysreflexia and suprapubic pressure alone has been documented driving systolic pressure to 230 mmHg in a woman whose resting pressure was 100/64.
Phaeochromocytoma is the rare cause worth naming out loud, because in an unprepared patient the catecholamine surge provoked by induction or by the surgeon's hand on the tumour produces cardiovascular complications that are life-threatening rather than merely inconvenient.
Labetalol given as 5 mg intravenous increments lowered systolic and diastolic pressure within ten minutes and held the effect for at least two hours with only a moderate fall in heart rate, whereas esmolol in the same elderly patients produced bradycardia severe enough that the infusion had to be stopped in two of them - so labetalol is the easier choice when the pressure is high and the heart rate is not.
Hydralazine 10 mg intravenously matched incremental labetalol for lowering mean arterial pressure in a randomised trial of severe hypertension in pregnancy, but hypertensive-crisis reviews still place nicardipine, labetalol and esmolol ahead of both hydralazine and nitroglycerine, because the agents you want in an operating room are the short-acting titratable ones you can stop when the stimulus stops.

Questions in the room

Before you give anything: what are the three things on this monitor that could be causing this number?
How would you tell light anaesthesia from inadequate analgesia here, and would your treatment differ?
Why might I be reluctant to give hydralazine to this patient in the middle of a case?
The pressure comes down and then, ten minutes later, it is 200 systolic again with a temperature of 38.4 - what has changed in your differential?

Oral boards stem

A 62-year-old man with treated hypertension is having an open hemicolectomy. Forty minutes in, as the surgeon retracts hard on the mesentery, the arterial line reads 195/104 and the heart rate climbs from 62 to 94. The end-tidal sevoflurane is 0.6 MAC, the last opioid was 100 micrograms of fentanyl at induction, and the end-tidal carbon dioxide has crept from 34 to 47 mmHg over the last ten minutes. Your attending asks what you are going to do. Tell me your differential in the order you would work through it, and then tell me what you would give and why.

Sources

Stoelting, Anesthesia and Analgesia 1977 PMID 562086
Rasmussen et al., Archives of Surgery 1978 PMID 708241
Simpson et al., The Journal of Physiology 2024 PMID 38533641
Lee et al., Spinal Cord Series and Cases 2017 PMID 29423304
Naranjo et al., Journal of Cardiothoracic and Vascular Anesthesia 2017 PMID 28392094
Singh et al., Canadian Journal of Anaesthesia 1992 PMID 1353708
Muhammad et al., Pregnancy Hypertension 2022 PMID 35605426
Varon and Marik, Drugs 2008 PMID 18257607
Rodriguez et al., Cardiology in Review 2010 PMID 20160537
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