Hypertension Etiology and Management

 

Pre-Hypertension

  • systolic 130-139

  • diastolic readings of 85-89

 NB: normal BP = 120/80

 

Hypertension

  • systolic greater than 140 mmHg

  • diastolic 90 mm Hg

 

Etiology:

 

  • thickening of the arterial walls

  • loss of elasticity in the arterial walls

  • Increase in peripheral vascular resistance within the thick and inelastic vessels

  • Heart pumps against greater resistance

  • result: blood flow to vital organs (heart, brain and kidneys) decreases

 

Anti-Hypertension Medications

Class

Names

Mechanism of Action

Diuretics

Furosenmide (Lasix)

Spironolactone (Aldactone)

Metolazone

Plolythiazide

Benzthiazide

Lowers blood pressure by reducing reabsorption of sodium and water.by the kidneys and thereby lowering the volume of circulating blood

Beta-Adrenergic Blockers

Atenolol (Tenormin)

Nadolo (Corgard)

Timolol Maleate (Blocadren)

Propranolol (Inderal)

Combine with beta-andrenergic receptors in the heart, arteries and arterioles to block response to sympathetic nerve impulses

reduce heart rate and thereby reduce cardiac output

Vasodilators

Hydralasine hydrochloride (Apresoline)

Minoxidil (Loniten)

Act on arteriolar smooth muscle to cause relaxation and reduce peripheral vascular resistance

Calcium channel blockers

Diltiazem (Cardizem, Dilacor XR)Verpamil hydrochloride (Calan SR)

Nifeddipine (Procardia)

Nicardipine (Cardine)

Reduce peripheral vascular resistance by systemic vasodilation

Angiotensin-converting enzyme (ACE) inhibitors

Captopril (Capoten)

Enalapril (Vasotec)

Lisinopril (Prinivil, Zestril)

Benazepril (Lotensin)

Lower blood pressure by blocking the conversion of angiotensin I to angiotensin II, preventing vasoconstriction, reduce aldosterone production and fluid retension, lowering circulating fluid volume

 

Step approach to Antihypertensive therapy

 

  1. Initially begin with less than the maximum dose of a thiazide type diuretic, then gradually increase the dose as required until maximum dosage is reached

 2. If blood pressure is not controlled with diuretics alone a sympathetic inhibitor should be added. The dose is increased as required until maximum dosage is reached or side effects appear at the higher level of this medication.

 3. If a third drug is needed to manage the hypertension, hydralazine type peripheral vasodilators are used in combination with the sympathetic inhibitor and diuretic.

 4. If the first three steps are ineffective and reasons other than drug failure have been ruled out, guanethidine, minoxidil or captopril may be added in increasing doses as needed or substituted for one of the drugs.

Perry, A, G, Potter, P, A, Ross-Kerr, J, C and Wood, M, J. 2006. Canadian fundamentals of nursing. 3rded. Toronto: Elselvier

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