Version May 2024
INTRODUCTION — Preexisting hypertension is the most common medical reason for postponing surgery [1]. Hypertension is well known to be a risk factor for cardiovascular catastrophe, a risk that logically extends into the perioperative period [2,3]. In a case-control study of 76 patients who died of a cardiovascular cause within 30 days of elective surgery, a preoperative history of hypertension was four times more likely than among 76 matched controls [4].
The issues regarding the perioperative management of the patient with hypertension are reviewed here. Additional discussion of the intra- and immediate postoperative management of patients with hypertension are presented elsewhere:
●(See "Anesthesia for patients with hypertension".)
BLOOD PRESSURE RESPONSE DURING ANESTHESIA — Sympathetic activation during the induction of anesthesia can cause the blood pressure to rise by 20 to 30 mmHg and the heart rate to increase by 15 to 20 beats per minute in normotensive individuals [5]. These responses may be more pronounced in patients with untreated or poorly controlled hypertension in whom the systolic blood pressure can increase by 90 mmHg and the heart rate by 40 beats per minute.
The mean arterial pressure tends to fall as the period of anesthesia progresses due to a variety of factors, including direct effects of the anesthetic, inhibition of the sympathetic nervous system, and loss of the baroreceptor reflex control of arterial pressure. These changes can result in episodes of intraoperative hypotension. Patients with preexisting hypertension are more likely to experience intraoperative blood pressure lability (either hypotension or hypertension) [6], which may lead to myocardial ischemia [7]. (See "Anesthesia for patients with hypertension", section on 'Prevention and treatment of intraoperative hypertension'.)
Blood pressure and heart rate slowly increase as patients recover from the effects of anesthesia during the immediate postoperative period. Parameters generally return to preoperative levels, although hypertensive individuals, in particular, may experience significant increases in blood pressure and heart rate [8]. This is reviewed elsewhere. (See "Anesthesia for patients with hypertension", section on 'Acute postoperative hypertension'.)
PERIOPERATIVE RISKS ASSOCIATED WITH HYPERTENSION — Preexisting hypertension can induce a variety of cardiovascular responses that potentially increase the risk of surgery, including diastolic dysfunction from left ventricular hypertrophy, systolic dysfunction leading to congestive heart failure, renal impairment, and cerebrovascular and coronary occlusive disease. The level of risk is dependent upon the severity of hypertension.
However, much of the evidence for the impact of preoperative hypertension comes from uncontrolled studies performed before contemporary (more effective) hypertension management was available. Furthermore, it is unclear whether postponing surgery to achieve blood pressure control will lead to reduced cardiac risk [9]. The American College of Cardiology/American Heart Association (ACC/AHA) guidelines list uncontrolled hypertension as a "minor" risk factor for perioperative cardiovascular events [10].
Severe hypertension — An early study found that patients with untreated, severe hypertension (mean systolic and diastolic pressures of 211 and 105 mmHg, respectively) had exaggerated hypotensive responses to the induction of anesthesia and marked hypertensive responses to noxious stimuli [11]. Conversely, patients with well-controlled hypertension responded similarly to normotensive individuals. Other studies have found that a diastolic pressure over 110 mmHg immediately (within the several days) before surgery is associated with a number of complications including dysrhythmias, myocardial ischemia and infarction, neurologic complications, and kidney failure [5]. (See "Possible prevention and therapy of ischemic acute tubular necrosis".)
Stage 1 to 2 hypertension — Patients with less marked hypertension (eg, systolic pressure less than 180 and diastolic pressure less than 100 mmHg) do not appear to be at increased operative risk. This was illustrated in a study of 676 operations involving a general anesthetic in patients over the age of 40 years [6]. Subjects were divided into five groups:
●Normotensive patients (group I, no medications; group II, on diuretics for nonhypertensive reasons) were significantly less likely to experience perioperative hypertension than patients who were normotensive on medication (group III), who were hypertensive despite treatment (group IV), and who had untreated hypertension (group V) (8 and 6 versus 27, 25, and 20 percent, respectively).
●Patients with inadequately treated or untreated hypertension (groups IV and V) were no more likely to experience cardiac complications than normotensive patients not taking diuretics (group I).
●Among patients with a history of hypertension (groups III, IV, and V), multivariate analysis identified only two independent risk factors for cardiac complications: the preoperative cardiac risk index score (which does not include hypertension (table 1)); and marked reductions in intraoperative blood pressure (a decrease to less than 50 percent of preoperative levels or a decrease of 33 percent or more for more than 10 minutes).
These results suggest that elective surgery in patients with non-severe hypertension does not need to be delayed, although intra- and postoperative blood pressures should be carefully monitored to prevent hyper- or hypotensive episodes. On the other hand, when hypertension has caused end-organ disease such as heart failure and kidney function impairment, the probability of adverse cardiac outcome in the perioperative period increases significantly [12]. (See "Evaluation of cardiac risk prior to noncardiac surgery".)
The association of systolic hypertension with operative risk is less clear than the association of diastolic hypertension with risk [13]. One study of patients undergoing carotid endarterectomy found that a systolic pressure greater than 200 mmHg was associated with an increased risk of postoperative hypertension and neurologic deficits [14]. Patients with isolated systolic hypertension are at increased risk for cardiovascular morbidity after coronary artery bypass surgery [2].
Secondary hypertension — Patients with suspected secondary hypertension should ideally undergo a diagnostic evaluation prior to elective surgery (see "Evaluation of secondary hypertension"). However, most patients are not at increased perioperative risk as long as the hypertension is not severe, serum electrolytes, and kidney function are normal. An important exception is the patient with pheochromocytoma, in whom operative mortality may be as high as 80 percent in unsuspected cases [15]. (See "Clinical presentation and diagnosis of pheochromocytoma".)
MANAGEMENT OF PATIENTS ON CHRONIC ANTIHYPERTENSIVE THERAPY
Preoperative antihypertensive medication management — For the majority of patients, oral antihypertensive medications should be continued up to the time of surgery. This recommendation is based upon the following observations:
●With a few exceptions, continuing antihypertensive medications without interruption is safe.
●Abruptly discontinuing some medications (eg, beta blockers, clonidine) may be associated with significant rebound hypertension.
●There are risks associated with severe, uncontrolled hypertension. (See 'Severe hypertension' above.)
Most antihypertensive agents can be taken with small sips of water on the morning of surgery. However, the decision to temporarily discontinue the medication preoperatively is dependent upon several factors, including the specific antihypertensive agent, the indications for the drug, the patient's blood pressure, and the type of surgery and anesthesia planned (table 2).
In particular, the management of patients taking angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) preoperatively is controversial. ACE inhibitors and ARBs can theoretically blunt the compensatory activation of the renin-angiotensin system during surgery and result in prolonged hypotension. The decision to continue or discontinue these agents is based on the indications for the drug, the patient's blood pressure, and the type of surgery and anesthesia planned. For most patients, the drug can be held on the morning of surgery. However, when the indication is for heart failure or poorly controlled hypertension, the agent is continued without interruption to avoid further exacerbation of these conditions. (See "Perioperative medication management", section on 'ACE inhibitors and angiotensin II receptor blockers'.)
For diuretics, the major physiologic effects of concern in the perioperative setting are hypokalemia and hypovolemia. There is no consensus on whether diuretics should be discontinued in all patients prior to elective surgery, and our approach is individualized, depending upon the reason for diuretic use and the patient's history. (See "Perioperative medication management", section on 'Diuretics'.)
Withdrawal syndromes — The centrally acting sympatholytic drugs (eg, clonidine, methyldopa, and guanfacine) and the beta blockers are associated with acute withdrawal syndromes that can lead to adverse perioperative events. These drugs should not be abruptly stopped perioperatively.
●Centrally acting sympatholytic drugs - The primary clinical manifestation following abrupt cessation of clonidine therapy is acute, rebound hypertension above the pretreatment level. Rebound hypertension usually occurs after abrupt cessation of fairly large oral doses (eg, greater than 0.8 mg/day) but has also been noted with transdermal clonidine [16]. Withdrawal symptoms have also been reported with methyldopa and guanfacine withdrawal but are less likely because of their slower onset of action [17]. (See "Perioperative medication management", section on 'Alpha 2 agonists'.)
●Beta blockers - Beta blockers reduce intraoperative myocardial ischemia [18]. Thus, in addition to a rise in blood pressure, beta blocker withdrawal in patients with underlying coronary disease can lead to accelerated angina, myocardial infarction, or sudden death [19]. (See "Perioperative medication management", section on 'Beta blockers'.)
Furthermore, atenolol or bisoprolol given before surgery to patients with, or at high risk for, coronary heart disease decreases mortality [20,21]. Guidance on the use of perioperative beta blockers for noncardiac surgery is presented elsewhere. (See "Management of cardiac risk for noncardiac surgery", section on 'Beta blockers'.)
A detailed discussion of the perioperative management of different classes of antihypertensive agents can be found elsewhere. (See "Perioperative medication management", section on 'Cardiovascular medications'.)
MANAGEMENT OF POSTOPERATIVE HYPERTENSION — A history of preexisting hypertension is the most important risk factor for postoperative hypertension [22]. Other factors contributing to the development of hypertension are pain, excitement on emergence from anesthesia, and hypercarbia. The type of surgery may influence the likelihood of developing postoperative hypertension [6]. (See "Cardiovascular problems in the post-anesthesia care unit (PACU)", section on 'Treatment of underlying causes of hypertension'.)
As illustrated in a study of 1844 patients, hypertension usually begins within 30 minutes of the completion of surgery and lasts approximately two hours [22]. On the other hand, some patients with preexisting hypertension may experience normalization of blood pressure as a nonspecific response to surgery [23]. This response can persist for months, usually followed by a gradual return to preoperative levels.
Indications for and approach to therapy — Any patient who experiences a marked rise in blood pressure following surgery (ie, a sustained increase in systolic pressure greater than 180 mmHg not due to severe pain) should be treated immediately with quickly-titratable intravenous antihypertensive therapy. (See "Evaluation and treatment of hypertensive emergencies in adults" and "Anesthesia for patients with hypertension", section on 'Acute postoperative hypertension'.)
The following approach can be used in other cases:
●Remedial causes of hypertension such as pain, agitation, hypercarbia, hypoxia, hypervolemia, and bladder distention should be excluded or treated.
●Patients on chronic antihypertensive therapy should resume their usual medications postoperatively as needed. Those who cannot take oral medications should be given a comparable alternative. (See 'Choice of drugs' below.)
●Additional therapy should be considered for patients with a sustained systolic blood pressure above 180 mmHg or diastolic blood pressure greater than 110 mmHg, once remedial causes have been excluded or treated and the patient’s previous chronic antihypertensive medications have been resumed.
Choice of drugs — A number of parenteral antihypertensive medications are available for patients who are unable to take oral medications postoperatively. These are the same drugs used to treat patients with hypertensive emergencies (table 3) [24]. Without any data from controlled trials to indicate which is best, the experience of the surgeons, anesthesiologists, and internists/cardiologists who are caring for the patients should guide the choice. For short-term control of severe postoperative hypertension (eg, systolic pressure of >180 mmHg), we prefer intravenous labetalol or nicardipine.
In patients with chronic hypertension who were treated with antihypertensive therapy prior to surgery, we typically resume their usual medications. However, with the exception of beta blockers and clonidine, it is not necessary for patients who are unable to resume oral medications to continue the same class of drugs postoperatively. Nevertheless, in many cases, a comparable parenteral alternative is available:
●Patients taking diuretics may be given parenteral furosemide or bumetanide
●Patients taking beta blockers may be given parenteral propranolol, labetalol, or esmolol
●Patients taking an angiotensin-converting enzyme (ACE) inhibitor may be given parenteral enalaprilat
●Patients taking centrally acting agents can be given a clonidine patch
●Patients taking calcium channel blockers can be given intravenous nicardipine
Goals of therapy — Goal blood pressure in patients treated for postoperative hypertension is similar to the general population.
In patients treated for postoperative hypertension who did not have preexisting hypertension, we discontinue antihypertensive therapy once the patient is surgically stable and the blood pressure is at goal for at least 24 hours; we then observe them over a period of 48 to 72 hours. Patients who have been discharged should monitor their blood pressures at home twice daily for at least five days and report those readings to their clinician if they consistently exceed 140/80. Antihypertensive therapy should be resumed if the blood pressure remains consistently elevated.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Hypertension in adults".)
SUMMARY AND RECOMMENDATIONS
●Preexisting hypertension is the most common medical reason for postponing surgery. Hypertension is well known to be a risk factor for cardiovascular catastrophe, a risk that logically extends into the perioperative period. (See 'Introduction' above.)
●Sympathetic activation during the induction of anesthesia can cause the blood pressure to rise by 20 to 30 mmHg and the heart rate to increase by 15 to 20 beats per minute in normotensive individuals. These responses may be more pronounced in patients with untreated hypertension in whom the systolic blood pressure can increase by as much as 90 mmHg and the heart rate by as much as 40 beats per minute. The mean arterial pressure tends to fall as the period of anesthesia progresses. Blood pressure and heart rate then slowly increase as patients recover from the effects of anesthesia during the immediate postoperative period. Hypertensive individuals, in particular, may experience significant increases in these parameters. (See 'Blood pressure response during anesthesia' above.)
●Preexisting hypertension can induce a variety of cardiovascular responses that potentially increase the risk of surgery, including diastolic dysfunction from left ventricular hypertrophy, systolic dysfunction leading to congestive heart failure, renal impairment, and cerebrovascular and coronary occlusive disease. The level of risk is dependent upon the severity of hypertension. (See 'Perioperative risks associated with hypertension' above.)
●In patients treated for chronic hypertension, oral antihypertensive medications can usually be continued. In most cases, continuing antihypertensive medications is relatively safe, and discontinuing some medications (eg, beta blockers, clonidine) may be associated with significant rebound hypertension. Thus, we typically continue most antihypertensive agents until the time of surgery, taken with small sips of water on the morning of surgery. However, the decision to continue or hold angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and diuretics prior to surgery is individualized and depends upon the indications for the drug, the patient's blood pressure, and the type of surgery and anesthesia planned. (See 'Preoperative antihypertensive medication management' above and "Perioperative medication management", section on 'Cardiovascular medications'.)
Conversely, centrally acting sympatholytic drugs (eg, clonidine, methyldopa, and guanfacine) and beta blockers are associated with acute withdrawal syndromes that can lead to adverse perioperative events; these drugs should not be abruptly stopped perioperatively. (See 'Withdrawal syndromes' above.)
●Any patient who experiences a marked rise in blood pressure following surgery (ie, a sustained increase in systolic pressure to 180 mmHg or greater not due to severe pain) should be treated immediately with intravenous antihypertensive medication. In these cases, remedial causes of hypertension such as pain, agitation, hypercarbia, hypoxia, hypervolemia, and bladder distention should be excluded or treated, and patients on chronic antihypertensive therapy should resume their usual medications postoperatively. (See 'Management of postoperative hypertension' above and 'Indications for and approach to therapy' above.)
●In patients treated with parenteral antihypertensive therapy for severe postoperative hypertension, or if oral medications cannot be resumed, the experience of the surgeons, anesthesiologists, and internists who are caring for the patients should guide the choice of therapy (see 'Choice of drugs' above):
•For short-term control of severe postoperative hypertension (eg, systolic pressure of >180 mmHg), we prefer intravenous labetalol or nicardipine.
•In patients with chronic hypertension who were treated with antihypertensive drugs prior to surgery and who do not require immediate parenteral therapy for severe hypertension, we typically resume their usual oral medications. However, with the exception of beta blockers and clonidine, it is not necessary for patients who are unable to resume oral medications to necessarily continue the same class of drugs postoperatively.
●Goal blood pressure in patients treated for postoperative hypertension is similar to the general population. In patients treated for postoperative hypertension who did not have preexisting hypertension, we discontinue antihypertensive therapy once the patient is surgically stable and the blood pressure is at goal for at least 24 hours. (See 'Goals of therapy' above.)
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