What is the optimal blood pressure (BP) control strategy for a patient with hypertension (high blood pressure) scheduled to undergo surgery?

Preoperative Blood Pressure Management

Elective surgery should proceed if blood pressure is <180/110 mmHg, and only be postponed if BP is ≥180 mmHg systolic OR ≥110 mmHg diastolic, with referral back to primary care for optimization. 1, 2

Blood Pressure Thresholds for Surgical Decision-Making

The evidence provides clear cutoffs that should guide your preoperative assessment:

• BP <140/90 mmHg: Patient is normotensive; proceed with surgery without delay 1

• BP 140-179/90-109 mmHg: Surgery can proceed, but inform the primary care physician for long-term optimization of the antihypertensive regimen 1, 2. Consider ambulatory or home blood pressure monitoring to establish true baseline 1

• BP ≥180/110 mmHg: This is the only threshold that justifies postponing elective surgery 1, 2, 3. Refer back to primary care for blood pressure optimization before proceeding with non-urgent surgery 1, 2

The rationale behind the 180/110 mmHg threshold is critical: there is no evidence that acutely lowering blood pressure immediately before surgery reduces perioperative cardiovascular events beyond what would be achieved over months in primary care 2. Canceling surgery for BP between 160-179/100-109 mmHg represents unnecessary delays that harm patients psychosocially and economically 2.

Proper Blood Pressure Measurement Technique

To avoid the common pitfall of relying on falsely elevated readings due to "white coat hypertension," follow this standardized protocol:

• Measure BP in a relaxed, temperate environment using calibrated equipment 1, 4
• Patient should be seated with supported arm outstretched for at least one minute before initial reading 1, 4
• Record pulse rate and rhythm before BP measurement 1, 4
• If first measurement is ≥140/90 mmHg, take two additional readings at least one minute apart and record the lower of the last two readings 1, 4
• For vascular or renal surgery, measure BP in both arms; if systolic difference exceeds 20 mmHg, repeat and use the arm with higher readings 1, 4
• Use auscultation over the brachial artery if pulse is irregular, as automated devices are inaccurate in this setting 1, 4

Perioperative Antihypertensive Medication Management

Continue all regular antihypertensive medications preoperatively, as sudden withdrawal causes adverse events including silent myocardial ischemia that is easily missed without continuous ECG monitoring 1, 2, 5. However, specific drug classes require nuanced management:

Beta-Blockers

• Must be continued in all patients already taking them 2, 5
• Abrupt discontinuation causes rebound hypertension and silent myocardial ischemia 2, 5
• Never initiate new beta-blocker therapy perioperatively, as this increases postoperative mortality from hypotension and stroke 2

ACE Inhibitors and ARBs

• Consider withholding on the morning of surgery due to increased risk of intraoperative hypotension and hemodynamic instability 2
• Restart as soon as clinically feasible postoperatively 2, 5

Calcium Channel Blockers and Diuretics

• Continue without interruption through the perioperative period 2, 5
• Maintain to prevent rebound hypertension 5

Documentation Requirements

Obtain the following before proceeding with surgery:

• Blood pressure measurements from the past 12 months from primary care 1, 2
• Current antihypertensive medications and timing of last dose 2
• Both systolic and diastolic readings documented verbally and in writing 4
• Assessment for target organ damage (left ventricular hypertrophy, chronic kidney disease, retinopathy, previous cardiovascular events) 2

Common Pitfalls to Avoid

• Do not cancel surgery for BP 160-179/100-109 mmHg 2. This represents stage 1-2 hypertension that does not increase operative risk sufficiently to justify delay 3

• Do not attempt acute BP reduction immediately before surgery 2. There is no evidence this improves outcomes, and it unnecessarily delays necessary procedures 2

• Do not rely on a single elevated BP reading 1, 4. Blood pressure measurements in surgical settings are often elevated due to anxiety and stress, making them less accurate than primary care readings 2

• Do not abruptly discontinue beta-blockers 1, 2. Withdrawal may cause silent myocardial ischemia that requires continuous ECG monitoring and serial troponin measurements to detect 1

Intraoperative Blood Pressure Targets

Maintain mean arterial pressure (MAP) ≥60-65 mmHg or systolic blood pressure (SBP) ≥90 mmHg intraoperatively to reduce risk of myocardial injury, acute kidney injury, and mortality 5. Use intravenous agents (clevidipine, esmolol, nicardipine, or nitroglycerin) to manage perioperative hypertension until oral medications can be resumed 2.

Postoperative Management

Resume antihypertensive medications as soon as the patient can tolerate oral intake 2, 5. Delaying resumption is associated with increased 30-day mortality risk 5. Abrupt discontinuation leads to rebound hypertension, which increases risk for myocardial ischemia, acute heart failure, cerebral ischemia, and dysrhythmias 5.