Hypertension - NYSORA

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Learning objectives 

  • Define the stages of hypertension
  • Discuss the perioperative management of patients with hypertension
  • Describe the acute and long-term treatment of hypertension

Definition and mechanisms

  • Hypertension is defined as a systolic BP > 160 mmHg 
  • Episodes of hypertension are relatively common during anesthesia and are reported by nearly one-third of adult patients
  • Whether it is ultimately harmful to the patient depends on its degree, cause, and duration, and on the patient’s condition

Signs and symptoms

Hypertension rarely has noticeable symptoms, however, the following signs and symptoms can be associated with hypertension:

  • Headaches
  • Shortness of breath
  • Nosebleeds
  • Blurred vision
  • Chest pain
  • Dizziness


StageSystolic blood pressure (mmHg)Diastolic blood pressure (mmHg)
Prehypertension120 - 12960 - 79
Stage 1 hypertension130 - 13980 - 89
Stage 2 hypertension> 140> 90
Hypertensive crisis≥ 180≥ 120


Pre-existing hypertensionControl blood pressure prior to surgery < 160 mmHg systolic and <100 mmHg diastolic
Side effects of agentsKetamine, ergometrine, desflurane anesthesia (> 1.0 MAC)
Inadequate anesthesia/analgesiaAdjust administration
Inadequate ventilation
CO2 retention causes catecholamine release
Interaction of agents
For example monoamine oxygenase inhibitors + vasopressors or opioids
Tourniquet pain
Treat with magnesium sulfate and hypotensive agents
PheochromocytomaIf suspected, a small bolus dose of phentolamine (1–5 mg) usually gives a
significant fall in BP
If systolic BP falls more than 35 mmHg, a Pheochromocytoma is likely
Administer alpha-blockers in addition to beta-blockade
Rare causesFluid overload
Aortic cross-clamping
Hyperthyroidism/thyroid storm
Malignant hyperthermia
Increased intracranial pressure
Interference with the carotid body, brainstem, or spinal cord
Bladder distension
Alcohol withdrawal syndrome or addictive drug withdrawal
Autonomic hyperreflexia

Complications of intraoperative hypertension


  • Inform the surgeon and consider halting the surgical procedure if possible
  • Cycle BP, scan monitors for HR, ECG rhythm, EtCO2, and temperature
  • Check if the patient is adequately oxygenated and ventilated
  • Deepen the anesthetic
  • Examine the patient:
  • If severe and life-threatening, (e.g. MAP >150 mmHg with signs of myocardial ischemia), immediate therapy is warranted
  • Otherwise, seek the cause and treat this cause
  • If there is no likely cause, nonspecific therapy may need to be instituted

Acute treatment

AgentExampleAction and dose
VasodilatorsAnaesthetic agents
Easy to titrate
HydralazineArteriolar dilator
Peak action after 20 min following 5-10 slow IV (maximal dose of 30 mg)
Slow IV push every 20 minutes
NitroglycerineArterial and venous dilator
Dose: 10-200 mcg/min IV
Start infusion at 10 mcg/min
LabetalolCombined alpha and beta blockade
Dose: 10-50 mg slow IV, repeated after 5 min if necessary
Maximal dose of 200 mg
Sodium nitroprussideArterial dilator with a very rapid response
Dose: continuous IV: 0.5-1.5 mcg/kg/min starting dose
Increase every 5 min in 500 ng/kg/min graduations according to response
Large doses may cause cyanide poisoning
Beta blockersAtenololReduces vascular tone
Dose: 2.5 mg slow IV, repeated after 5 min if necessary
EsmololReduces vascular tone
Rapid onset with a short half-life of about 9 min
Dose: 50-200 mcg/kg/min infusion
Start infusion at 50 mcg/kg/min
Nicardipine (rydene)Arterial dilator
Dose: 0.1 mg/mL
Alpha blockersPhentolamineVasodilator
Relaxes vascular tone
Dose: 1-5 mg IV

Long term management

AgentExampleAction and effect
Thiazide diureticsBendrofluazide
Blocks Na+ channels
Complications: electrolyte disturbances
Loop diureticsFurosemideInhibit Na+, K+ and CL- uptake
Aldosterone antagonistsSpironolactoneInhibit Na+ reabsorption and K+ secretion
Osmotic diureticsMannitolIncrease osmotic pressure and inhibit water and solute reabsorption
Carbonic anhydrase inhibitorsAcetazolamideInhibits carbonic anhydrase thereby inhibiting HCO3- and reduces Na+ reabsorption
Sodium channel blockersTriamtereneDirectly inhibit Na+ reabsorption and K+ secretion
Beta blockers
Slow heart rate
Improved ventricular filling
Complications: lethargy, nausea, and general malaise
ACE inhibitorsPeridopril
Block angiotensin-converting enzyme
Complications: cough and deterioration of renal function
A2 inhibitorsCandesartan
Block angiotensin 2
Calcium channel blockersNipedipineVasodilation

Postoperative care

  • Continue to monitor the patient
  • Provide adequate analgesia
  • Administer oxygen titrated to SpO2 of 94%–98% (reduce myocardial ischemia)
  • Patient may need investigations to exclude complications (e.g. myocardial infarction) or to identify the cause

Keep in mind

Suggested reading

  • Tait A, Howell SJ. Preoperative hypertension: perioperative implications and management. BJA Educ. 2021;21(11):426-432.
  • Yancey R. Anesthetic Management of the Hypertensive Patient: Part I. Anesth Prog. 2018;65(2):131-138.
  • Yancey R. Anesthetic Management of the Hypertensive Patient: Part II. Anesth Prog. 2018;65(3):206-213.
  • Pollard BJ, Kitchen, G. Handbook of Clinical Anaesthesia. Fourth Edition. CRC Press. 2018. 978-1-4987-6289-2.

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