Blood Pressure Agents and Medications

Blood Pressure Agents

• Blood pressure (BP) is determined by heart rate, stroke volume, and total peripheral resistance
• Baroreceptors and the renin-angiotensin-aldosterone system (RAAS) work together to regulate BP
• Uncontrolled hypertension increases the risk for coronary artery disease, stroke, renal failure, and vision loss
• Hypertension is categorized as elevated, stage 1, stage 2, and hypertensive crisis based on BP readings
• Risk factors for hypertension include stress, chronic kidney disease, obesity, decreased physical activity, insulin resistance, diabetes, increased age, cigarette smoking, alcohol use, and genetic predisposition

Medications for Hypertension

• Antihypertensive agents are grouped into five categories: drugs affecting the RAAS, sympathetic nervous system blockers, calcium channel blockers, vasodilators, and diuretics

Drugs Affecting the RAAS

• Angiotensin-converting enzyme inhibitors (ACEIs)

  • Action: Blocks angiotensin I from converting to angiotensin II, lowering BP, increasing sodium and water excretion, and slightly increasing potassium levels
  • Indications: Hypertension, congestive heart failure, left ventricular dysfunction, and prevention of diabetic nephropathy
  • Adverse Effects: Hypotension, renal insufficiency, fatigue, dizziness, pancytopenia, GI irritation, rash, hyperkalemia, and cough
  • Nursing Considerations: Monitor for cough, check CBC labs

• Angiotensin II Receptor Blockers (ARBs)

  • Action: Blocks angiotensin II from binding to receptors, resulting in vasodilation and reduction of aldosterone release
  • Indications: Hypertension, congestive heart failure, and prevention of diabetic nephropathy
  • Adverse Effects: Headache, dizziness, syncope, weakness, hypotension, GI complaints, rash, hyperkalemia, renal damage
  • Nursing Considerations: Assess for liver impairment and monitor liver function

• Renin Inhibitors

  • Action: Inhibits renin, leading to a decrease in BP, aldosterone, and sodium reabsorption
  • Indication: Hypertension
  • Adverse Effects: Hyperkalemia and diarrhea
  • Nursing Considerations: Monitor for hyperkalemia

Calcium Channel Blockers

• Action: Inhibits calcium movement across cell membranes in cardiac and arterial muscle, leading to decreased heart rate and relaxation/dilation of arteries
• Indications: Hypertension, angina, and arrhythmias
• Adverse Effects: CNS effects, cardiovascular effects (hypotension), GI effects, skin reactions
• Nursing Considerations: Monitor blood pressure, cardiac rhythm, and cardiac output; Provide patient education about drug interactions with grapefruit juice

Vasodilators

• Action: Directly acts on vascular smooth muscle, causing relaxation and vasodilation, reducing BP
• Indications: Severe hypertension, hypertensive emergencies, and malignant hypertension
• Adverse Effects: CNS effects, cardiovascular effects, skin reactions, GI upset, potential for cyanide toxicity, headache, dizziness, dyspnea, and vomiting
• Nursing Considerations: Monitor BP closely, provide patient education about adverse effects, and maintain comfort

Diuretics

• Action: Increase sodium and water excretion from the kidneys, leading to reduced BP
• Indications: Hypertension
• Nursing Considerations: Refer to Chapter 51 for detailed information about various diuretics

Sympathetic Nervous System Blockers

• Beta-Blockers:
  • Action: Blocks beta-adrenergic receptors, decreasing heart rate and contractility
• Alpha-Adrenergic Blockers:
  • Action: Blocks alpha-adrenergic receptors, causing vasodilation and reducing peripheral resistance
• Alpha- and Beta-Blockers:
  • Action: Blocks both alpha and beta receptors, resulting in combined effects on heart rate, contractility, and vasodilation

General Nursing Considerations for Antihypertensive Agents

• Assess for allergies, pregnancy, impaired renal function, previous heart failure, and history of salt or volume depletion
• Monitor vital signs, weight, urine output, and electrolytes
• Educate patients regarding drug actions, adverse effects, and lifestyle modifications
• Encourage adherence to prescribed drug therapy, lifestyle changes, and use of appropriate contraceptive methods
• Monitor for drug interactions, particularly with NSAIDs and other RAAS drugs, grapefruit juice, cyclosporine, and other medications
• Provide comfort measures and safety precautions to minimize risk of injury
• Carefully monitor patients in situations that may lead to fluid volume depletion (e.g., dehydration, vomiting, diarrhea)
• Teach patients to report adverse effects immediately

Nonselective Adrenergic Blocking Agents

• Alpha2-Agonist: Clonidine
  • Stimulates alpha2 receptors in the CNS, inhibiting cardiovascular centers
  • Decreases sympathetic outflow from the CNS, leading to lower blood pressure
  • Used for treating hypertension
  • Available in oral and transdermal formulations
  • Absolute Contraindications: Allergy
  • Relative Contraindications: Narrow Angle Glaucoma, Severe Hypertension, Hypotension, Bradycardia
  • Cautions: Cardiovascular Disease, Diabetes, Hyperthyroidism, Renal/Hepatic Impairment
  • Adverse Effects: CNS, Cardiovascular, Genitourinary
  • Drug Interactions: Beta-blockers, Adrenergic-antagonists, CNS depressants/alcohol

Beta-Blockers

• Actions
  • Blocks beta receptors in the heart
  • Decreases heart rate and cardiac muscle contraction
  • Vasodilates, increasing blood flow to the kidneys, decreasing renin release
• Indications: Hypertension, angina, tachyarrhythmias, migraine headache, Myocardial Infarction (MI), glaucoma
• Absolute Contraindications: Allergy
• Relative Contraindications: Acute/unstable heart failure, bradycardia and heart block, bronchospasm, Chronic Obstructive Pulmonary Disease (COPD), acute asthma
• Cautions: Renal and hepatic dysfunction, diabetes
• Adverse Effects:
  • CNS: Headache, fatigue, dizziness, depression, sleep issues, disorientation, memory loss
  • Cardiovascular: Bradycardia, hypotension
  • Respiratory: Bronchospasm, dyspnea, pulmonary edema
  • Gastrointestinal: Nausea/vomiting/diarrhea, pain
  • Genitourinary: Decreased libido and impotence
  • Alterations in glucose levels
• Drug Interactions: Clonidine, NSAIDs, insulin/hypoglycemic agents
• Nursing Considerations:
  • Assessment: History of lung conditions or diabetes
  • Implementation: Take apical pulse prior to administering and hold if below 60bpm, do not abruptly stop medication, patients with diabetes should monitor blood glucose closely

Alpha-adrenergic Blocker (Non-selective)

• Actions:
  • Blocks Alpha1 receptors: vasodilation resulting in decreased blood pressure
  • Blocks Alpha2 receptors: prevents norepinephrine feedback loop, resulting in increased reflex tachycardia
• Indications: Diagnose and manage episodes of hypertension
• Administration: Intramuscular (IM) or intravenous (IV) only
• Absolute Contraindications: Allergy
• Relative Contraindications: Coronary artery disease (CAD), Myocardial Infarction (MI)
• Drug Interactions: Alcohol
• Adverse Effects:
  • Cardiovascular: Hypotension, angina, MI, arrhythmia, increased reflex tachycardia, flushing
  • Central Nervous System: Cerebral vascular accident (CVA), headache, weakness, dizziness
• Note: This is a short acting agent and should not be used for long-term therapy.

Alpha1-blockers

• Actions:
  • Blocks alpha1-receptor sites
  • Decreases vascular tone resulting in vasodilation, decreasing blood pressure
• Indications: Hypertension
• Absolute Contraindications: Allergy
• Cautions: Heart failure, renal failure or hepatic impairment
• Adverse Effects: CNS, cardiovascular, genitourinary, skin
• Drug Interactions: Drugs used for erectile dysfunction (ED)

Alpha- and Beta-blockers (Nonselective Adrenergic Blocking Agents)

• Actions:
  • Blocks norepinephrine at all alpha and beta receptors in the Sympathetic Nervous System (SNS)
  • Lower blood pressure and heart rate
  • Increased renal perfusion
  • Decreased renin
• Indications: Hypertension
• Drugs: Carvedilol, Labetalol
• Absolute Contraindications: Allergy
• Relative Contraindications: Heart block, bradycardia, liver disease
• Cautions: Lung disease/bronchospasm, diabetes
• Adverse Effects: CNS, cardiovascular, respiratory, hypoglycemia, skin rash, GI/GU issues, liver failure
• Drug Interactions: Antidiabetic agents

Hypotension

• Blood pressure becomes too low
  • When the heart muscle is damaged and unable to pump effectively
  • With severe blood or fluid loss, when volume drops dramatically
  • When there is extreme stress and the body's levels of norepinephrine are depleted, leaving the body unable to respond to stimuli to raise blood pressure

Antihypotensive Agents: Vasopressors

• Actions:
  • Stimulate all adrenergic receptors/SNS
  • Increase heart rate and myocardial contractility
  • Constricts blood vessels, increasing blood pressure
  • Dilates bronchi, increasing rate/depth of breathing
• Indications: Hypotensive states, shock, heart failure, anaphylaxis, bronchospasm/acute asthma
• Drugs: Dobutamine, Dopamine, Epinephrine, Norepinephrine
• Absolute Contraindications: Allergy, Pheochromocytoma
• Relative Contraindications: Hypovolemia
• Cautions: Tachycardia, hypertension, disease that limits blood flow
• Adverse Effects: Cardiovascular, Central Nervous System
• Drug Interactions: Any drug or substance that increases heart rate or blood pressure

Sympathetic Nervous System Blockers

• Nursing Process
  • Assessment:
    • History: Contraindications and cautions
    • Physical: CNS, cardiac/perfusion, respiratory, abdominal, urinary, vitals, ECG
    • Labs: Electrolytes, renal and hepatic function, glucose
  • Nursing Diagnoses/Conclusions:
    • Impaired comfort
    • Altered tissue perfusion
    • Altered cardiac output
    • Altered breathing pattern
    • Injury risk
    • Activity intolerance
    • Altered sensory perception
    • Knowledge deficit
  • Implementation:
    • Take apical pulse prior to administering and hold if below 60bpm
    • Prepare medication carefully
    • Monitor blood pressure
    • Do not abruptly stop medication
    • Encourage patient to make lifestyle modifications
    • Change position slowly
    • Safety and comfort measures
    • Patients with diabetes should monitor blood glucose closely
    • Do not crush extended release (ER) formulations
    • Patient teaching:
      • Consult a healthcare professional before taking any over-the-counter (OTC) medication or herbal/alternative therapies
      • Emphasize the importance of follow-up exams
  • Evaluation:
    • Evaluate response to drug
    • Evaluate effectiveness of the teaching plan
    • Evaluate effectiveness of comfort and safety measures
    • Evaluate compliance with the regimen

Antihypotensive Drugs: The Nursing Process

• Assessment:
  • History: Contraindications and cautions
  • Physical: Respiratory, cardiac/perfusion, abdominal, skin, weight, vitals
  • Labs: Kidney and liver function
• Nursing Diagnoses/Conclusions:
  • Altered tissue perfusion
  • Altered sensory perception
  • Impaired comfort
  • Knowledge deficit
• Implementation:
  • Monitor blood pressure and heart rate
  • Provide safety and comfort measures
  • Provide thorough patient teaching
• Evaluation:
  • Evaluate response to drug
  • Evaluate effectiveness of teaching plan
  • Evaluate effectiveness of comfort and safety measures
  • Evaluate compliance with regimen

Explore the key concepts of blood pressure regulation and the various antihypertensive medications. This quiz covers the mechanisms of blood pressure control, risk factors for hypertension, and the different classes of medications used to manage high blood pressure. Test your understanding of these crucial health topics.