Transcript HTN: Chapter 83 Marx: Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th ed.

HTN: Chapter 83
Marx: Rosen's Emergency Medicine:
Concepts and Clinical Practice, 6th
ed.
Perspective
 Perspective
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Medical management of hypertension has reduced stroke mortality by 50% on an ageadjusted basis
Probably partially responsible for the decline in mortality from coronary artery
disease.
Although approximately 75% of patients with chronically elevated BP are aware of
their disease

as few as one half to one quarter of these patients are adequately treated.

Anxiety and pain often cause transient hypertension, but evaluation of the patient for
evidence of acute end-organ ischemia is important.
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Even if the patient's BP does remain elevated without end-organ damage, urgent treatment
is rarely beneficial, and an appropriate referral for long-term management should be made.
Principles of Disease
 Definition
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In adults, a systolic pressure less than 140 mm Hg and a diastolic pressure
less than 90 mm Hg are considered normal.
Prehypertension
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If the systolic pressure is between 140 and 159 mm Hg or if the diastolic pressure
is between 90 and 95 mm Hg, the term prehypertension is now applied.
 reflecting that the lifetime incidence of hypertension in these individuals is
twice that of individuals in the “normal” range.[2]
Hypertension

The patient with a systolic pressure of 160 mm Hg or greater or a diastolic
pressure over 95 mm Hg is considered to be hypertensive.
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Even isolated systolic hypertension in elderly patients is a significant risk factor for
cardiovascular disease, especially when combined with other risk factors.
In older patients, an elevated pulse pressure (determined by subtracting diastolic from
systolic pressure) is an equally significant risk factor for stroke and MI.
A single elevated BP does not necessarily mean that the patient has hypertension. This
is especially true in children.[9] BP measurement should be repeated after the patient
is in a reclining position for at least 10 minutes and should be checked in both arms.
 If the second reading is also elevated or close to the hypertensive range, the
patient should be advised of the potential for hypertension and referred for
follow-up.
Pathophysiology
 Essential hypertension.

No specific cause of essential hypertension has been identified, although many
factors, including heredity, age, race, obesity, and the amount of dietary sodium, may
contribute to the elevated BP
 Two major theories exist:
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(1) hypertension results from alterations in the contractile properties of
smooth muscle in arterial walls
(2) alterations of arterial smooth muscle are a response to chronically
elevated BP resulting from a primary failure of normal autoregulatory
mechanisms.
Renin, Angiotensin, and
Aldosterone
 Renin
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An enzyme produced by the kidney that splits off angiotensin I from a plasma
globulin precursor.[11] Angiotensin I is converted by an enzyme in the lung to produce
angiotensin II. Angiotensin II is a potent vasoconstrictor and also stimulates
aldosterone production in the adrenal gland.
 ACE inhibitors or angiotensin blockers are clearly the drugs of choice in
hypertensive patients with diabetes or decreased left ventricular function, or
both.
Renal Disease
 All types of renal disease have been associated with hypertension
 Renovascular hypertension results from the overproduction of renin secondary
to reduced blood flow through the stenotic renal artery. The increased levels of
renin lead to activation of the angiotensin pathway and resultant hypertension.
 Another vascular lesion associated with arterial stenosis and hypertension is
fibromuscular dysplasia of the renal arteries. This disease is predominant in
young white women, and flank bruits are often present.
 Up to 70% of patients with chronic pyelonephritis have elevated BP.
Arterial Disease
 Coarctation of the aorta
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An important cause of secondary hypertension, and early surgical
intervention can greatly improve the patient's prognosis.
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triad of upper extremity hypertension, a systolic murmur best heard over the
back, and delayed femoral pulses should alert the examiner to the diagnosis of
coarctation.
 Loss of elasticity in the larger arteries associated with the aging process
produces systolic hypertension as well as elevations in pulse pressure.
 The current literature strongly suggests that isolated systolic
hypertension is associated with an increased risk of stroke, heart disease,
and renal failure and should be treated.
Thyroid and Parathyroid
Disease
 In thyroid storm, patients are usually
hypertensive and tachycardic and β-blockade
is a mainstay of the acute management.
Pheochromocytoma
 Pheochromocytomas are responsible for less than 1% of cases of hypertension.
 The characteristic feature of pheochromocytoma is paroxysms of hypertension
associated with palpitations, tachycardia, malaise, apprehension, and sweating.
 These episodes may be related to physical and emotional stress, eating, position,
or even micturition.
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Because of the episodic nature of this syndrome, the patient is often dismissed, and a
diagnosis of hyperventilation syndrome or anxiety attack is made.
 The diagnosis is confirmed with elevated urinary levels of catecholamines,
metanephrines, and vanillylmandelic acid.
 Treatment consists of α-blockade to control hypertension and subsequent βblockade for the control of cardiac dysrhythmias.
Emergency Department
Presentation
 Hypertension is seen in the emergency department in the following four
general ways:
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1. “Hypertensive emergency” or “hypertensive crisis” with acute endorgan ischemia
2. “Hypertensive urgency,” a historical term related to arbitrarily elevated
BP with nonspecific symptoms
3. Mild hypertension without end-organ ischemia
4. Transient hypertension related to anxiety or the primary complaint
CLINICAL PRESENTATION OF
HYPERTENSIVE EMERGENCIES
 BP is usually markedly elevated and there is
evidence of acute dysfunction in the
cardiovascular, neurologic, or renal organ
system. These conditions are true medical
emergencies and mandate reduction of BP
within 1 hour.
Hypertensive Encephalopathy
 Throughout the normal range of BP, cerebral blood flow is maintained by
fluctuations in the vascular tone of the cerebral resistance vessels known as
autoregulation.
 Hypertensive encephalopathy is an uncommon syndrome resulting from an
abrupt, sustained rise of BP that exceeds the limits of cerebral autoregulation of
the small resistance arteries in the brain.
 Hypertensive encephalopathy
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(1) acute in onset
(2) reversible.
Patients present with severe headaches, vomiting, drowsiness, and confusion.
 Hypertensive encephalopathy is a true medical emergency; untreated patients
develop increasing coma, and death may ensue within a few hours. The rapid
measured reduction of BP is mandatory. The standard treatment regimen is
intravenous (IV) nitroprusside with a careful reduction of the MAP by 25% or to
a minimum diastolic pressure of 110 mm Hg over an hour.
Malignant Hypertension
 Malignant (accelerated) hypertension is severe hypertension associated
with evidence of acute and progressive damage to end organs.
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The diastolic BP is usually greater than 130 mm Hg.
 Patients with malignant hypertension appear ill and often present with
complaints of severe headache, blurred vision, dyspnea, and chest pain
or with symptoms of uremia.
 In addition to elevated BP, these patients must demonstrate evidence of
acute end-organ damage as a result of the hypertension.
 Malignant hypertension is treated by the judicious lowering of MAP by
25% of pretreatment levels over the initial minutes to hours, then toward
a target of 160/100 over 2 to 6 hours
Stroke Syndromes
 In most of these patients, elevated BP is the physiologic
response to the stroke itself and is not the immediate cause
 Some have recommended careful antihypertensive treatment
for patients with persistent, extreme elevations of BP after a
stroke (e.g., diastolic pressure >140 or MAP >130 mm Hg),
but data are lacking.
 If BP reduction is pursued in these patients, labetalol is the
agent of choice.
Pulmonary Edema
 Most patients with congestive heart failure have
some degree of increased peripheral vascular
resistance (PVR) and resultant hypertension; this is
a normal response.
 With standard treatment of pulmonary edema,
including morphine, nitrates, oxygen, ACE
inhibitors, and furosemide, catecholamine levels
fall and BP returns rapidly toward normal.
Pregnancy
 Any acute elevation of the diastolic BP above
100 mm Hg in the pregnant patient
represents a true hypertensive emergency.
 Although it may cause tachycardia and
hypotension, the antihypertensive agent of
choice in preeclampsia has classically been
IV hydralazine.
Aortic Dissection
 The goals of medical therapy are to lower the
BP to a systolic level of 100 to 120 mm Hg
and to reduce the ejection force of the heart.
 The combined α/β-blocker labetalol has been
used successfully
MANAGEMENT OF HYPERTENSIVE
EMERGENCIES
 Vasodilators
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Sodium Nitroprusside
Nitroprusside (Nipride, Nitropress) is a powerful
vasodilator, with a direct effect on the smooth muscle
of both resistance and capacitance vessels.
 Cyanide is an intermediate metabolite, but cyanide
toxicity is extremely rare
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Vasodilators
 Nitroglycerin
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Nitroglycerin is a vasodilating agent that acts
predominantly on the venous system, decreasing left
ventricular end-diastolic pressure.
 Hydralazine
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Hydralazine (Apresoline) is a direct arteriolar vasodilator that was widely
used in the past for the treatment of hypertensive emergencies of pregnancy.
The usual starting dose of hydralazine is 5 mg IV, with repeated doses of 5
to 10 mg every 20 minutes as needed to keep the diastolic pressure below
110 mm Hg
β-Blockers
 Labetalol
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Labetalol (Trandate, Normodyne) is a selective
α1-blocker and nonselective β-blocker with a
ratio of α/β-blockade between 1:3 and 1:7.
Labetalol lowers BP by blockade of the α1receptors in vascular smooth muscle and the
cardiac β-receptors.
α-Blockers
 Phentolamine (Regitine) is an α-blocking
agent used for the management of
catecholamine-induced hypertensive crises
(e.g., pheochromocytoma, MAOI crisis,
cocaine overdose).
 Nicardipine
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Nicardipine (Cardene) is a parenteral dihydropyridine
calcium channel blocker that has become very popular in
the treatment of postoperative hypertension.
Nicardipine is administered as an infusion beginning at 5
mg/hr, increasing the infusion rate every 15 minutes until
the desired reduction of BP has been achieved, to a
maximum dose of 15 mg/hr.
Enalaprilat and Enalapril
 Enalaprilat (Vasotec) is a parenteral active
metabolite of the ACE inhibitor enalapril.
 The acute dose is 0.625 to 5 mg administered
as a single bolus.
Osteopathic Considerations
 Sub-occipital release
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Normalizes the parasympathetics
 Rib raising
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Normalizes the sympathetics