1. Diuretics and Antihypertensives
Chapter 18

2. Diuretics and Antihypertensives
Remove sodium and water
Remove extracellular fluid (edema)
Antihypertensives
Lower blood pressure
Both diuretics and antihypertensives
Used to treat hypertension

3. Hypertension Abnormal rise in arterial blood pressure
Diagnosed at 140/90 mmHg or higher
Caused by a variety of disorders or can have no known cause

4. 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

5. 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

6. Classifications Thiazide diuretics Loop diuretics
Potassium-sparing diuretics
Osmotic diuretics
Carbonic anhydrase inhibitors
Combination potassium-sparing and hydrochlorothiazide diuretics

7. Excess Fluid Removal of excess fluid results in: Decreased preload
Decreased cardiac output
Decreased total peripheral resistance

8. 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

9. 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

10. Potassium and Chloride Replacement
Replacement is essential to avoid electrolyte imbalances
Administered as potassium chloride
May be administered orally or IV

11. Loop Diuretics Furosemide (Lasix) Works directly on the ascending limb
of the loop of Henle
Inhibits sodium and chloride
reabsorption
More potent then thiazides

12. Loop Diuretics: Side Effects
Dry mouth
Potassium depletion (hypokalemia)
Hearing loss (ototoxic)
Fatigue
Dehydration
Hypotension

13. 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

14. Osmotic Diuretics Action Produce a profound diuretic effect
Used to treat intracranial pressure and renal failure
Mannitol

15. Carbonic Anhydrase Inhibitors
Carbonic Anhydrase (enzyme)
Promotes reabsorption of sodium
and bicarbonate from the renal nephrons proximal tubule
Maintains alkalinity of the blood
Normal blood pH
Very weak diuretic
Treats glaucoma

16. Nursing Considerations
Monitor patients with gout or diabetes
Monitor potassium levels
Encourage potassium rich foods
Monitor blood pressure and weight

17. 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

18. Antihypertensives Diuretics Central acting antiadrenergics
Peripherally acting antiadrenergics
Beta-adrenergic blocking agents

19. Antihypertensives Vasodilators
(cont’d)
Vasodilators
Angiotensin-converting enzyme inhibitors
Angiotensin II antagonists
Calcium channel blockers

20. Diuretics and Antihypertensives
Effective control of blood pressure
Diuretics frequently given in combination with another class of
antihypertensives

21. 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

22. ACE Inhibitors
Result of vasodilation: decreased blood pressure, decreased systemic vascular resistance, and decreased afterload

23. 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

24. Calcium Channel Blockers
Action:
Dilate peripheral arterioles and reduce peripheral resistance
Reduce arterial blood pressure at rest and during exercise

25. 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

26. Peripherally Acting Antiadrenergic Agents
Two main actions:
Deplete norepinephrine
Adverse effect: depression, hypotension
Block adrenergic receptors
Prevent sympathetic nervous system stimulation

27. 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

28. 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

29. 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

30. 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