Hypertension, also known as high blood pressure, is a condition in which the force of blood against artery walls is higher than expected.1 If it remains untreated, chronic hypertension can cause damage to the blood vessels and heart, ultimately leading to health problems such as heart attack and stroke.1 Like many other disorders, hypertension can affect the decisions associated with major surgeries, including choices made by anesthesiology practitioners. In fact, blood pressure has been a focus of anesthesia researchers since the 1920s,2 and hypertension specifically for more than 40 years.3-5 Anesthesia providers must account for hypertension throughout a procedure, as well as with patients with other special health conditions.
Risk factors associated with hypertension in anesthesiology include the harmful effects of hypertension on the heart, brain and kidneys;6 the association between hypertension, coronary artery disease, peripheral vascular diseases and diabetes; antihypertensive drugs and their interactions with anesthetic drugs; undiagnosed diseases that cause hypertension; and the need for emergency surgery in patients with uncontrolled hypertension or hypertensive crises.5 Given these risks, many scientific studies focus on controlling perioperative factors (i.e., before, during and after surgery) for patients with hypertension. A 1989 article by Estafanous emphasized the importance of selecting the proper anesthetic agents for patients with hypertension.5 More recent research has shown the effectiveness of using beta blockers or α-2 agonists to maintain hemodynamic (blood flow) stability before and after surgery, thus preventing cardiac complications.7 Some physicians suggest postponing surgery to prevent risk of a cardiac event, though recent studies show that postponement may not be necessary if appropriate antihypertensive medications are administered before surgery.6,7 One study found that premedication with clonidine, a common antihypertensive drug, effectively controlled blood pressure before surgery and reduced the increase in heart rate normally associated with laryngoscopy and endotracheal intubation.8 Another article states that if hypertension (i.e., >140/90 mmHg) is detected a few days before surgery, it may be advisable to begin a short-term treatment with an antihypertensive medication such as an angiotensin-converting enzyme (ACE) inhibitor, angiotensin receptor blocker (ARB), calcium channel blocker (CCB), diuretic or beta blocker.6 Depending on the patient’s age, different types of antihypertensive medications may be more appropriate than others.6 Thus, careful consideration of anesthetic and antihypertensive medication before a procedure is key to lowering risk of complications.
During surgery, the use of medications and potential for organ damage require an anesthesia provider to closely monitor a hypertensive patient. Despite their beneficial effects as antihypertensive medications, ACE inhibitors, ARBs and CCBs can affect a patient’s stability during anesthesia, causing issues such as increase in potassium levels, dehydration, nonfatal stroke, renal complications and—ironically—hypotension.9 Anesthesia providers must monitor patients’ vital signs throughout procedures,10 and are thus responsible for checking and preventing blood flow changes that are more common in patients with chronic hypertension.6 Acute hypertension may appear for chronically hypertensive patients in cardiac surgery, major vascular surgery, neurosurgery, head and neck surgery, renal transplantation and major trauma.11 These hypertensive emergencies may cause organ damage or failure if blood pressure is not immediately reduced.11 Therefore, in addition to taking pre-surgery precautions, anesthesiology practitioners must be vigilant throughout procedures to observe interactions between antihypertensive and anesthetic drugs and prevent hypertensive crises.12
After a procedure on a hypertensive patient is finished, the anesthesiologist is still responsible for preventing postoperative hypertensive issues. For one, many patients develop postoperative hypertension because they must withdraw from their long-term antihypertensive medication.11 This can be prevented by substituting the patient’s antihypertensive medication with longer-acting versions.11 Also, patients’ recovery from anesthesia can be affected by hypertension. For example, one study showed that patients with hypertension had prolonged recovery from anesthesia after laparoscopic bariatric surgery.13 Thus, when administering anesthesia and monitoring the patient postoperatively, anesthesia providers should be aware of potential recovery issues in hypertensive patients.
Furthermore, an anesthesiology practitioner must follow special procedures for patients with hypertension-related health conditions, such as preeclampsia (high blood pressure during pregnancy) or eclampsia (seizures due to high blood pressure in pregnancy). For patients with preeclampsia, one study recommends using neuraxial anesthesia (i.e., epidural) over traditional intubation, given its advantages in stabilizing blood flow.14 Another article suggests that spinal anesthesia has advantages over both epidural and general anesthesia.15 In eclampsia, the anesthesiologist must help the obstetrician control and prevent convulsions, control blood pressure, clear the patient’s airway, prevent major complications and provide anesthesia for labor or caesarian section.16
Anesthesia providers must account for hypertension before, during and after a procedure. Proper anesthetic and antihypertensive medications, adequate monitoring of vital signs and prevention of postoperative hypertension are only some of the duties of an anesthesiology practitioner dealing with a hypertensive patient. Future studies should investigate the best antihypertensive medications for patients undergoing surgery, as well as ways to avoid postoperative hypertension. Also, researchers should focus specifically on anesthesia for prevention of organ damage in preeclampsia and eclampsia.