How Does Hypertension Affect Anaesthesia?

October 11, 2025 •

3 min read

Chronic hypertension is the most frequent medical comorbidity encountered in adult patients undergoing surgery, impacting as many as 46% of the U.S. population. As a result, understanding how does hypertension affect anaesthesia is crucial for mitigating risks and ensuring a safe surgical outcome. The condition significantly increases the likelihood of hemodynamic instability—wide swings in blood pressure—throughout the perioperative period.

Quick Summary

Hypertension poses multiple challenges during anaesthesia, primarily by causing significant hemodynamic instability and increasing the risk of adverse cardiovascular events. Special attention is required during preoperative assessment, intraoperative monitoring, and postoperative management, including careful handling of antihypertensive medications to prevent complications like myocardial injury, stroke, and kidney issues.

Key Points

Hemodynamic Instability: Hypertensive patients are prone to dramatic and rapid blood pressure fluctuations during anaesthesia, increasing cardiac and cerebrovascular risks.
Preoperative Control: Uncontrolled severe hypertension (≥180/110 mmHg) may necessitate postponing elective surgery until blood pressure is better managed.
Medication Adjustments: Some antihypertensive medications, such as ACE inhibitors and ARBs, may be withheld before surgery to prevent severe hypotension, while others like beta-blockers are typically continued.
Hypotension Intolerance: Due to altered autoregulation, hypertensive patients can suffer from organ damage from drops in blood pressure that a healthy person would tolerate.
Postoperative Hypertension: Pain, fluid shifts, and hypothermia can cause blood pressure to spike in the recovery period, requiring careful management.
Risk Management: A thorough evaluation and individualized anaesthetic plan are crucial for minimizing complications such as heart attack, stroke, and kidney injury.

The Pathophysiology of Hypertension and Anesthetic Impact

Chronic hypertension causes the body's blood pressure autoregulatory systems to reset to a higher baseline. This means that the organs of a hypertensive patient are accustomed to higher pressure and are more susceptible to insufficient blood flow (hypoperfusion) if blood pressure drops, even to a level considered normal for a non-hypertensive person. This altered physiology makes anesthetic management more complex.

Perioperative Stages and Challenges for Hypertensive Patients

Effective anaesthetic management for hypertensive patients involves three key stages.

Preoperative Considerations

Risk Stratification: Assessment of blood pressure control and any existing organ damage helps determine cardiovascular risk.
Surgical Postponement: Elective surgery might be deferred if blood pressure is severely elevated (e.g., systolic ≥180 mmHg or diastolic ≥110 mmHg) to achieve better control.
Medication Management: Deciding whether to continue or stop antihypertensive medications pre-surgery depends on the drug class. Stopping beta-blockers or alpha-2 agonists abruptly can cause dangerous rebound hypertension.
Addressing Anxiety: Pre-surgical anxiety can temporarily raise blood pressure, so anxiolytic medication may be used to obtain a more accurate baseline.

Intraoperative Challenges

During surgery, hypertensive patients are prone to significant blood pressure fluctuations.

Hypertension Spikes: Surgical stress, like during intubation, can cause temporary increases in blood pressure due to the release of stress hormones.
Hypotension Risk: Anaesthetic agents can cause blood pressure to drop significantly. Hypertensive patients tolerate these drops poorly due to their altered autoregulation, increasing the risk of organ hypoperfusion.
Medication Interactions: Certain blood pressure medications, particularly ACE inhibitors and ARBs, can increase the likelihood of severe hypotension during anaesthesia that is difficult to treat. Anesthesiologists must be prepared to manage these changes with specific intravenous drugs.

Postoperative Recovery

The period after surgery also presents challenges.

Hypertension Predominance: Pain, shivering, and fluid shifts can lead to acute hypertension post-surgery, especially in the recovery room.
Rebound Effect: Missing doses of certain medications like beta-blockers increases the risk of rebound hypertension and rapid heart rate.
Resuming Medications: Restarting oral antihypertensive medications promptly is important for maintaining blood pressure control and reducing cardiovascular risks.

Potential Complications of Uncontrolled Perioperative Hypertension

Poorly managed blood pressure in hypertensive patients during surgery can lead to serious issues.

Cardiac Events: Unstable blood pressure can strain the heart, potentially leading to heart attack.
Strokes: High blood pressure spikes increase the risk of bleeding in the brain (hemorrhagic stroke), while low blood pressure can reduce blood flow to the brain, causing ischemic stroke.
Acute Kidney Injury (AKI): Low blood pressure episodes can reduce blood flow to the kidneys, potentially causing AKI.
Increased Bleeding: High blood pressure can lead to more bleeding during and after surgery.

Perioperative Antihypertensive Medication Management

Managing chronic antihypertensive medications during surgery requires specific decisions.


Medicine Class	Perioperative Management	Rationale	Potential Risk
Beta-blockers	Continue usual dose, including morning of surgery.	Prevents rebound effects. Stopping them is harmful.	Potential for slow heart rate or low blood pressure.
ACE Inhibitors / ARBs	Withhold 24 hours before surgery.	Reduces the risk of severe low blood pressure during anaesthesia.	Low blood pressure and kidney problems.
Calcium Channel Blockers	Continue usual dose, including morning of surgery.	Generally safe and helps control blood pressure.	Possible increased bleeding risk.
Diuretics	Withhold morning of surgery.	Helps prevent dehydration and electrolyte imbalances.	Dehydration and electrolyte issues.

Conclusion

Hypertension significantly affects anaesthesia by making patients vulnerable to large swings in blood pressure. A thorough preoperative evaluation and individualized plan are essential for managing risks. Close monitoring and readiness to treat both high and low blood pressure during surgery are critical for safety. By understanding the relationship between hypertension and anaesthesia, healthcare providers can minimize the chances of serious complications like heart attack and stroke, allowing patients with high blood pressure to undergo surgery safely.

Frequently Asked Questions

Yes, it is safe to have anaesthesia if your high blood pressure is well-controlled. Your anaesthesiologist will perform a careful evaluation to manage any risks and create a plan tailored to your condition.

For elective surgery, a systolic pressure over 180 mmHg or a diastolic pressure over 110 mmHg may be considered too high, and the procedure might be postponed until blood pressure is better managed.

It depends on the medication. ACE inhibitors and ARBs are often stopped 24 hours before surgery, while other medications like beta-blockers and calcium channel blockers are usually continued. Your anaesthesiologist will provide specific instructions.

Hypertensive patients are more prone to swings in blood pressure due to anaesthetic agents affecting your body's regulatory systems. Your anaesthesiologist will use medications to manage these fluctuations.

The risks include serious complications such as myocardial infarction (heart attack), stroke, and acute kidney injury. Proper management is vital to prevent these outcomes.

Yes, some anaesthetic agents can cause a drop in blood pressure (hypotension). This is particularly dangerous for hypertensive patients, who are more sensitive to such drops due to their altered physiology.

Postoperative hypertension is common and can be caused by pain, fluid shifts, or stress. Anesthesiologists will monitor your blood pressure and administer appropriate medications to bring it down if necessary.