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Diuretics and Antihypertensives
Diuretics and Antihypertensives Diuretics
Remove sodium and waterRemove extracellular fluid (edema)
AntihypertensivesLower blood pressure
Both diuretics and antihypertensives Used to treat hypertension
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Hypertension
Abnormal rise in arterial blood pressureDiagnosed at 140/90 mmHg or
higher Caused by a variety of disorders
or can have no known cause
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Hypertension Blood pressure dependent on two factors
cardiac output- controlled by kidney
and heart vessels peripheral resistance- mediated by the
resistance vessels Untreated hypertension can cause:
deterioration of cardiac, renal, and
ocular function stroke
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Hypertension (HTN) All forms of drug therapy focus on
one or both of these systems New guidelines for treatment Life style changes first when
appropriate Then drug therapy diuretics non-diuretic antihypertensive agents
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Classifications Thiazide diuretics Loop diuretics Potassium-sparing diuretics Osmotic diuretics Carbonic anhydrase inhibitors Combination potassium-sparing and
hydrochlorothiazide diuretics
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Excess Fluid Removal of excess fluid results in:
Decreased preload Decreased cardiac output Decreased total peripheral
resistance
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Thiazide Diuretics Developed in the 1950’s, safest in current use Inhibits sodium and chloride reabsorption in
the early portion of the distal tubule May block chloride reabsorption in the
ascending loop of Henle Greater than normal sodium/potassium
exchange rakes place Results in hypokalemia May have increased excretion of chloride
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Thiazide Diuretics Selection of drug based on action desired
and cost Some adverse effects
Elevation of blood glucose Elevation of blood uric acid Sensitivity reactions Hypokalemia Low chloride levels
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Potassium and Chloride Replacement
Replacement is essential to avoid electrolyte imbalances
Administered as potassium chloride May be administered orally or IV
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Loop Diuretics Furosemide (Lasix) Works directly on the ascending limb
of the loop of Henle Inhibits sodium and chloride
reabsorption More potent then thiazides
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Loop Diuretics: Side Effects Dry mouth Potassium depletion
(hypokalemia) Hearing loss (ototoxic) Fatigue Dehydration Hypotension
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Potassium-Sparing Diuretics Inhibit aldosterone
Example: Spironolactone Weak action: They competitively
bind to aldosterone receptors and block the reabsorption of sodium and water Conservation of water
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Osmotic Diuretics
Action Produce a profound diuretic
effect Used to treat intracranial
pressure and renal failure Mannitol
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Carbonic Anhydrase Inhibitors Carbonic Anhydrase (enzyme) Promotes reabsorption of sodium
and bicarbonate from the renal nephrons proximal tubule
Maintains alkalinity of the bloodNormal blood pH 7.35-7.45
Very weak diuretic Treats glaucoma
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Nursing Considerations Monitor patients with gout or
diabetes Monitor potassium levels Encourage potassium rich foods Monitor blood pressure and
weight
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Nursing Considerations Record intake and output on
hospitalized patients Give early in the day If you record a hypertensive B/P,
re-check it to rule out error or sympathetic nervous system stimulation
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Antihypertensives Diuretics Central acting antiadrenergics Peripherally acting antiadrenergics Beta-adrenergic blocking agents
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Antihypertensives
(cont’d)
Vasodilators Angiotensin-converting enzyme
inhibitors Angiotensin II antagonists Calcium channel blockers
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Diuretics and Antihypertensives Effective control of blood
pressure Diuretics frequently given in
combination with another class of
antihypertensives
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Angiotensin-Converting Enzyme (ACE) Inhibitors Action: Antagonists to the renin-
angiotensin-aldosterone system ACE inhibitors prevent: Angiotensin I conversion to
angiotensin II produces potent
vasoconstriction and stimulation of
aldosterone
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ACE Inhibitors
Result of vasodilation: decreased blood pressure, decreased systemic vascular resistance, and decreased afterload
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Angiotensin II Antagonist Allow angiotensin I to be concerted to
angiotensin II, but block the receptors that receive angiotensin II
Block vasoconstriction and release of
aldosterone Lower blood pressure
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Calcium Channel Blockers Action:
Dilate peripheral arterioles and reduce peripheral resistance
Reduce arterial blood pressure at rest and during exercise
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Beta-adrenergic Blocking Agents Inhibit beta1and beta 2 receptors in
the heart and both the heart and lung Reduce
Heart rate Force of contraction
Adverse Effect Bronchoconstriction
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Peripherally Acting Antiadrenergic Agents Two main actions:
Deplete norepinephrine Adverse effect: depression,
hypotension Block adrenergic receptors
Prevent sympathetic nervous system stimulation
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Central Acting Antiadrenergics
Action unclear Theory 1: replace norepinephrine in
adrenergic storage sites Theory 2: sympathetic outflow from
the central nervous system is decreased Adverse Effects:
Sedation Orthostatic hypotension
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Patient Teaching Instruct your clients to:
Do not stop taking abruptly Rebound hypertensive crisis Oral forms should be given with meals
so the absorption is more gradual and
effective IV usage should be by pump
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Nursing Considerations
Use appropriate size cuff when measuring blood pressure
If the reading is high, retake in the other arm
Take a thorough patient history Observe for signs of anxiety Ongoing assessment of blood pressure,
weight, diet, alcohol use, smoking and medications
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Nursing Considerations
Assess potassium needs Salt substitutes may contain
potassium Education on the disease process and
medication regiment Teach the patient to report concerns
and side effects Report changes in status to health
care provider
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