From the Guidelines
Postoperative hypertension is most commonly contributed to by pain, anxiety, hypoxia, hypercarbia, hypothermia, urinary retention, volume overload, and withdrawal from antihypertensive medications, with pain and anxiety being particularly significant due to their activation of the sympathetic nervous system. According to the most recent and highest quality study 1, these factors can lead to increased sympathetic tone and vascular resistance, resulting in elevated blood pressure. The study highlights the importance of individualized treatment, focusing on the underlying cause of hypertension and using non-pharmacological interventions when possible, such as supplemental oxygen for hypoxemia, forced air warmer for hypothermia, and verbal reassurance for anxiety.
Some key contributors to postoperative hypertension include:
- Pain, which activates the sympathetic nervous system, causing vasoconstriction and increased heart rate
- Anxiety, which triggers catecholamine release, elevating blood pressure
- Respiratory issues like hypoxia and hypercarbia, which stimulate sympathetic activity
- Hypothermia, which induces vasoconstriction to preserve core temperature
- Urinary retention, which stimulates sympathetic response through bladder distension
- Volume overload from excessive IV fluids or blood products, which increases cardiac output and blood pressure
- Abrupt discontinuation of antihypertensive medications, particularly beta-blockers and clonidine, which can cause rebound hypertension
Management of postoperative hypertension should address the underlying cause, and treatment goals should be based on preoperative blood pressure with a target of ~10% above the baseline 1. Appropriate antihypertensive medications, such as IV labetalol, hydralazine, or nicardipine, may be necessary for acute management. It is also important to consider the side-effects of drugs used in the treatment of hypertension, as noted in the study 1.
From the Research
Postoperative Hypertension Contributors
The most common contributors to postoperative hypertension (HTN) can be identified through various studies. Some of the key factors include:
- Pain, anxiety, hypothermia, and hypoxemia, which are reversible or treatable causes of hypertension 2, 3
- Sympathetic activation, which appears to be the predominant underlying mechanism of acute postoperative hypertension (APH) 2
- Pre-existing primary hypertension, as over half of the patients who exhibit APH have this condition 3
- Increased sympathetic stimulation caused by a high level of circulating catecholamines, which can lead to APH 3
- Direct perioperative stimulants, such as:
- Volume overload
- Bladder distension
- Shivering
- Hypercapnia [+3]
Specific Etiologies
A study analyzing medical records of patients undergoing noncardiac surgeries found the following common etiologies of perioperative hypertension:
- Poorly controlled hypertension (21.8%)
- Excessive fluid therapy (19.5%)
- Excessive vasopressor (18.4%)
- Medication withdrawal (13.7%) 4 For the postoperative period specifically, the most common reason was fluid overload (20.1%) 4
Management and Treatment
The management and treatment of postoperative hypertension involve identifying and relieving the cause of APH, as well as the use of antihypertensive drug therapy with vasodilators or adrenergic inhibitors if initial interventions are not effective 2, 3