Management of Hypertension in Patients Undergoing Anesthesia
Hypertension is not an absolute contraindication for anesthesia, but blood pressures exceeding 180 mmHg systolic or 110 mmHg diastolic warrant careful consideration before proceeding with elective surgery due to increased risk of hemodynamic instability. 1
Classification of Hypertension and Risk Assessment
Hypertension is categorized into stages based on blood pressure readings:
- Stage 1: 140-159 mmHg systolic or 90-99 mmHg diastolic 1
- Stage 2: 160-179 mmHg systolic or 100-109 mmHg diastolic 1
- Stage 3: 180-209 mmHg systolic or 110-119 mmHg diastolic 1
- Stage 4: ≥210 mmHg systolic or ≥120 mmHg diastolic 1
Perioperative Risk Considerations
Hemodynamic Instability
- Hypertensive patients (both controlled and uncontrolled) demonstrate more labile hemodynamic profiles during anesthesia compared to normotensive patients 1
- Induction of anesthesia and airway instrumentation can trigger pronounced sympathetic activation, leading to significant increases in blood pressure and heart rate 1
- Reduction in systemic vascular resistance after induction commonly leads to varying degrees of hypotension 1
Cardiovascular Risk
- Patients with Stage 1 or 2 hypertension without target organ damage do not have clearly established increased perioperative cardiovascular risk 1
- Hypertension with target organ damage is associated with a small increased incidence of perioperative major adverse cardiovascular events 1
- There is limited evidence that postponing surgery to reduce blood pressure decreases perioperative complications 1
Recommendations for Elective Surgery
Preoperative Assessment
- Blood pressure should be measured in primary care before non-urgent surgical referral 1
- Blood pressures less than 180 mmHg systolic and 110 mmHg diastolic should not preclude elective surgery 1
- For patients with blood pressure readings above these thresholds, consider the following factors:
- Age
- Comorbidities
- Functional capacity
- Urgency and indication for surgery 1
Management Strategies
For patients with well-controlled hypertension on medication:
- Continue most antihypertensive medications perioperatively 1
- Consider omitting angiotensin-converting enzyme inhibitors and receptor blockers on the day of surgery to reduce significant hemodynamic fluctuations 1
- Never abruptly withdraw clonidine, alpha-methyldopa, or beta-blockers as this can cause adverse events including rebound hypertension and myocardial ischemia 1
For patients with poorly controlled hypertension:
Anesthetic Considerations
Intraoperative Management
- Implement techniques to achieve hemodynamic stability:
- Co-induction
- Invasive arterial monitoring with titrated vasopressor therapy
- Depth-of-anesthesia monitoring
- Stroke volume optimization with appropriate fluid therapy 1
- Avoid severe hypotension and tachycardia to reduce ischemic complications 4
- There is no evidence to favor any specific type of anesthesia (regional vs. general) 4
Monitoring
- Consider more intensive monitoring for patients with significant hypertension 5
- Monitor for signs of end-organ damage, particularly myocardial ischemia 4
Special Considerations
Emergency Surgery
- Emergency or urgent surgery must almost always proceed regardless of blood pressure control 1
- All involved parties, including the patient, should be made aware of any associated increased risk 1
Common Pitfalls to Avoid
- Abrupt withdrawal of antihypertensive medications, particularly beta-blockers, which may precipitate rebound hypertension and myocardial ischemia 1
- Excessive fluid administration, which may worsen hypertension in the 24-48 hours postoperatively as fluid mobilizes from the extravascular space 1
- Failure to recognize perioperative myocardial ischemia, which can be silent and easily missed without appropriate monitoring 1