Hypertension

Question 1

What is the definition of perioperative hypertension?

Answer 1

Hypertension is defined as a rise in blood pressure greater than 20% of the preoperative value.

Question 2

What are the clinical features of hypertension?

Answer 2

1. Elevated systolic, diastolic, or mean pressures
2. Headache
3. Chest pain
4. Dyspnea
5. Anxiety

Question 3

What is the differential diagnosis for perioperative hypertension?

Answer 3

1. CNS: anxiety, pain, light anesthesia, autonomic hyperreflexia, increased ICP
2. CV: essential hypertension, ischemia, acute increase in afterload, pre-eclampsia
3. Pulm: hypoxia, hypercarbia
4. Renal: full bladder, renal failure, volume overload
5. Endocrine: Cushing syndrome, pheochromocytoma, thyrotoxicosis, hypoglycemia
6. Drugs: catecholamines, anticholinergics, withdrawal of antihypertensives, withdrawal of alcohol/opioids, naloxone

Question 4

What is the management of hypertension perioperatively?

Answer 4

1. Verify that hypertension is real.
2. Assess depth of anesthesia, deepen with propofol or more volatile agent
3. Ensure adequate oxygenation and ventilation
4. Check for inadvertent vasopressor use
5. Review chart for trend of preop blood pressures
6. R/O other causes in the hx (e.g., hypoglycemia, increased ICP)
7. Assess likelihood of distended bladder, insert foley
8. if no correctable cause, consider administering antihypertensive preferably from the same class as what the patient takes chronically

Question 5

When treating intraoperative hypertension in an adult, what is the standard initial dosing of labetalol?

Answer 5

Labetalol: 5 to 10 mg at a time

Question 6

When treating intraoperative hypertension in an adult, what is the standard initial dosing of enalaprilat?

Answer 6

Enalaprilat: 1.25 to 2.5mg at a time

Question 7

When treating intraoperative hypertension in an adult, what is the standard initial dosing of verapamil?

Answer 7

Verapamil: 2.5mg IV at a time

Question 8

When treating intraoperative hypertension in an adult, what is the standard initial dosing of hydralazine?

Answer 8

Hydralazine: 10 to 20mg IV at a time

Question 9

When treating intraoperative hypertension in an adult, what is the standard initial dosing of nifedipine?

Answer 9

Nifedipine: 10 mg SL

Question 10

When treating intraoperative hypertension in an adult, what is the standard initial dosing of nicardipine as an infusion?

Answer 10

Nicardipine infusion: 2 to 5mcg/kg/min

Question 11

When treating intraoperative hypertension in an adult, what is the standard initial dosing of phentolamine?

Answer 11

Phentolamine 0.5 to 1mg IV at a time

Question 12

What are the perioperative risks of poorly controlled HTN?

Answer 12

1. Intraop BP instability more likely possibly related to IV volume depletion and vasopressor sensitivity
2. Dysrhythmias, myocardial ischemia
3. Stroke, CHF, organ hypoperfusion with hypotension

Question 13

What specifically are you looking for in the history, physical and labs in a patient with a history of HTN?

Answer 13

History - degree of control, multisystem effects
Physical - signs of CHF
Labs - BUN/Cr for renal involvement, Na/K for diuretic effects, ECG for LVH, dysrhythmias, ischemia, possible CXR for cardiomegaly, pulmonary edema.

Question 14

How does chronic HTN affect cerebral autoregulation?

Answer 14

A rightward shift of the cerebral autoregulation curve which may prevent overperfusion at high pressures but may also predispose to hypoperfusion at lower pressures.

Question 15

What are the multisystem effects of chronic HTN of anesthetic significance?

Answer 15

1. CV - LVH, diastolic dysfunction, vasopressor sensitivity, intravascular volume depletion, increased risk for MI, CHF, aortic dissection, peripheral vascular disease, and death.
2. Renal - overactivity of the renin-angiotensin-aldosterone system in some patients; hypertensive nephropathy
3. Neurologic - potentially increased risk of stroke and rightward shift of the cerebral autoregulation curve.

Question 16

What is the hemodynamic profile of the typical hypertensive patient?

Answer 16

Varies but in some patients there is an initial elevation in CO with a normal SVR. Perhaps later in the disease there in an elevation in SVR with a low CO.

Question 17

What are the typical causes of HTN?

Answer 17

80 - 95% of cases are essential. Of the remainder, renal disease is the most common. Others include endocrine (hyperaldosteronism, Cushing’s syndrome, acromegaly, pheochromocytoma), coarctation, and drug side effects (e.g., estrogen)

Question 18

At what preop BP would you cancel the case?

Answer 18

There is not absolute cutoff. In elective cases DBP of 110 is often cited as a cutoff but is not absolute. My decision would depend on the cause of the HTN, chronicity, symptoms, difficulty to control, presence of co-existing disease, type of surgery to be performed. Having said that there is little data to suggest that BPs < 180 systolic or < 110 diastolic are associated with adverse cardiac outcomes.

Question 19

If a patient has hypertension and your goal is to achieve hemodynamic stability on induction, shouldn’t you use etomidate?

Answer 19

Not necessarily. Given as a bolus, etomidate does not cause as much hypotension on induction as thiopental or propofol (accounting for its reputation for “stability”) but it is not effective in blunting the pressor response. In the normal, euvolemic or hypertensive patient, it is not as reliable in preventing hypertension with laryngoscopy and intubation.

Question 20

How would you approach postoperative HTN?

Answer 20

Not knowing anything more, I would first make sure the HTN is real and above the patient’s usual value as determined by chart review.

2. Next I check the ABCs because hypoxia and hypercarbia cause sympathetic stimulation that could cause HTN.
3. Then obvious causes such as pain, anxiety, hypervolemia, vasopressor administration, discontinuation of a vasodilator.
4. Subtle or obscure causes for new onset postop HTN include bladder distention, drug withdrawal, pheochromocytoma, thyroid storm, and MH.