Lower Mean Arterial Pressure

(Do not reduce MAP > 20–25% over 30–60 min).

Dose: 20 mg IV bolus then 2 mg/min IV to target BP

See: Infusion Pump

Preparation of IV infusion:
Dilute 200 mg labetalol in 160 mL of a compatible IV solution for a final concentration of 1 mg/mL. Alternatively, dilute 200 mg in 250 mL of a compatible IV solution for a final concentration of approximately 2 mg/3 mL. Compatible IV solutions include 0.9% Sodium Chloride, 5% Dextrose in Water, Lactated Ringer's, or 5% Dextrose/0.9% Sodium Chloride .

Solution:(calculate cc/minute)


Sodium Nitroprusside

Dose: 0.5 mcg/kg/min to max (10 mcg/kg/min)


Antihypertensive Drug Classes
Drug Class Examples of Widely Used Agents
Thiazide-type diuretics Hydrochlorothiazide, chlorthalidone
Potassium-sparing agent–mineralocorticoid receptor blocker Spironolactone, eplerenone
Potassium-sparing agent (sodium epithelial channel blocker) Triamterene, amiloride
Loop diuretics Furosemide, bumetanide, torsemide
Angiotensin-converting enzyme inhibitors Lisinopril, enalapril, etc
Angiotensin receptor blockers Losartan, valsartan, irbesartan
Direct renin inhibitor Aliskiren
Beta-receptor blockers Metoprolol, atenolol, carvedilol, nebivolol
Combined alpha-/beta-blockers Labetalol, carvedilol
Alpha-receptor blockers Doxazosin, terazosin, prazosin
Dihydropyridine calcium channel blockers (DHP CCBs) Nifedipine, amlodipine, felodipine
Non-DHP CCB blockers Diltiazem, verapamil
Direct vasodilators Hydralazine, minoxidil
Central antiadrenergic agents Clonidine, reserpine (partial), methyldopa
Peripheral adrenergic neuron depletors Reserpine (partial), guanethidine

Evaluate for the presence of heart failure: jugular venous distention, crackles on auscultation, and peripheral edema.


Chest pain may indicate myocardial ischemia or infarction,

back pain may denote aortic dissection, and

dyspnea may suggest pulmonary edema or congestive heart failure.



Initiate parenteral therapy in emergency room

Immediate admission to intensive care unit; treat to initial goal BP; additional diagnostic studies



Baseline laboratory tests; intravenous line; monitor BP

BP should not only be measured in both the supine position and the standing position (assess volume depletion), but it should also be measured in both arms (a significant difference may suggest aortic dissection).


Autoregulation of cerebral blood flow in normotensive and hypertensive subjects.

In both groups, initial increases or decreases in mean arterial pressure are associated with maintenance of cerebral blood flow due to appropriate changes in arteriolar resistance.

More marked changes in pressure are eventually associated with loss of autoregulation, leading to a reduction (with hypotension) or an elevation (with marked hypertension) in cerebral blood flow. These changes occur at higher pressures in patients with hypertension, presumably due to arteriolar thickening. Thus, aggressive antihypertensive therapy will produce cerebral ischemia at a higher mean arterial pressure in patients with underlying hypertension.

From: Kaplan, NM. Management of hypertensive emergencies. Lancet 1994; 344:1335.


  1. There are 3 categories of patients:when the BP exceeds 180/110 mm Hg,

      1. Severe hypertension—BP >180/110 in the absence of symptoms beyond mild or moderate headache without evidence of acute target organ damage.

      1. Hypertensive urgency—BP exceeds 180/110 mm Hg with significant symptoms, such as severe headache or dyspnea, but absent or only minimal acute target organ damage.

      1. Hypertensive emergency—BP >220/140 mm Hg accompanied by evidence of life-threatening end-organ dysfunction.

Hypertensive emergencies include accelerated hypertension, defined as progressive hypertension with the funduscopic vascular changes of malignant hypertension but without papilledema, and malignant hypertension, defined as a severe hypertensive state with papilledema of the ocular fundi and vascular hemorrhagic lesions, thickening of the small arteries and arterioles, left ventricular hypertrophy, and a poor prognosis.

Target Organ Manifestations

Organ System Manifestations
Vascular Aneurysmal dilation
Accelerated atherosclerosis
Aortic dissection
Acute Pulmonary edema, myocardial infarction
Chronic Clinical or EKG evidence of coronary artery disease (CAD); left
Ventricular hypertrophy (LVH) by EKG or echocardiogram
Acute Intracerebral bleeding, coma, seizures, mental status changes, transient ischemic attack (TIA), stroke
Chronic TIA, stroke
Acute Hematuria, azotemia
Chronic Serum creatinine >1.5 mg/dL, proteinuria >1+ on dipstick
Acute Papilledema, hemorrhages
Chronic Hemorrhages, exudates, arterial nicking




Among the 65 million Americans with hypertension, hypertensive crises occur in less than 1% of individuals. Even though crises are infrequent, significantly elevated BP is a common clinical scenario.


Complications of Injecting Drug Use

  • Local problems—Abscess (Figures 240-2 
    Image not available.

    A 32-year-old woman with type 1 diabetes developed large abscesses all over her body secondary to injection of cocaine and heroin. Her back shows the large scars remaining after the healing of these abscesses. (Courtesy of ­Richard P. Usatine, MD.)

    and 240-3; Abscess), cellulitis, septic thrombophlebitis, local induration, necrotizing fasciitis, gas gangrene, pyomyositis, mycotic aneurysm, compartmental syndromes, and foreign bodies (e.g., broken needle parts) in local areas.2
    • IDUs are at higher risk of getting methicillin-resistant Staphylococcus aureus(MRSA) skin infections that the patient may think are spider bites (Figure 240-4).
    • Some IDUs give up trying to inject into their veins and put the cocaine directly into the skin. This causes local skin necrosis that produces round atrophic scars (Figure 240-5).
  • IDUs are at risk for contracting systemic infections, including HIV and hepatitis B or hepatitis C.
    • Injecting drug users are at risk of endocarditis, osteomyelitis (Figures 240-6and 240-7), and an abscess of the epidural region. These infections can lead to long hospitalizations for intravenous antibiotics. The endocarditis that occurs in IDUs involves the right-sided heart valves (see Chapter 50, Bacterial Endocarditis).2 They are also at risk of septic emboli to the lungs, group A β-hemolytic streptococcal septicemia, septic arthritis, and candidal and other fungal infections.


Content 3

Content 13

Content 11


Which of the following agents is used in a hypertensive emergency?

Answer is 1.


A 75-year-old triathlete complains of gradually worsening vision over the past year. It seems to be involving near and far vision. The patient has never required corrective lenses and has no significant medical history other than diet-controlled hypertension. He takes no regular medications. Physical examination is normal except for bilateral visual acuity of 20/100. There are no focal visual field defects and no redness of the eyes or eyelids. Which of the following is the most likely diagnosis?

Complete Quiz and View Results
You will be able to view all answers at the end of your quiz.

The correct answer is A. You answered A.

Age-related macular degeneration is a major cause of painless, gradual bilateral central visual loss. It occurs as nonexudative (dry) or exudative (wet) forms. Recent genetic data have shown an association with the alternative complement pathway gene for complement factor H. The mechanism link for that association is unknown. The nonexudative form is associated with retinal drusen that leads to retinal atrophy. Treatment with vitamin C, vitamin E, beta-carotene, and zinc may retard the visual loss. Exudative macular degeneration, which is less common, is caused by neovascular proliferation and leakage of choroidal blood vessels. Acute visual loss may occur because of bleeding. Exudative macular degeneration may be treated with intraocular injection of a vascular endothelial growth factor antagonist (bevacizumab or ranibizumab). Blepharitis is inflammation of the eyelids usually related to acne rosacea, seborrheic dermatitis, or staphylococcal infection. Diabetic retinopathy, now a leading cause of blindness in the United States, causes gradual bilateral visual loss in patients with long-standing diabetes. Retinal detachment is usually unilateral and causes visual loss and an afferent pupillary defect.


Mr. Jenson is a 40-year-old man with a congenital bicuspid aortic valve who you have been seeing for more than a decade. You obtain an echocardiogram every other year to follow the progression of his disease knowing that bicuspid valves often develop stenosis or regurgitation requiring replacement in middle age. Given his specific congenital abnormality, what other anatomic structure is important to follow on his biannual echocardiograms?

Next Question
You will be able to view all answers at the end of your quiz.

The correct answer is A. You answered A.

The answer is A. (Chap. 282) Bicuspid aortic valve is among the most common of congenital heart cardiac abnormalities. Valvular function is often normal in early life and thus may escape detection. Due to abnormal flow dynamics through the bicuspid aortic valve, the valve leaflets can become rigid and fibrosed, leading to either stenosis or regurgitation. However, pathology in patients with bicuspid aortic valve is not limited to the valve alone. The ascending aorta is often dilated, misnamed “poststenotic” dilatation; this is due to histologic abnormalities of the aortic media and may result in aortic dissection. It is important to screen specifically for aortopathy because dissection is a common cause of sudden death in these patients.



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