Understanding Loop Diuretics for the Treatment of Heart Failure Michael Pedroso California State University San Marcos Pharmacology and Pathophysiology Nurs 312 Professor Gary Veale
What are Loop Diuretics Work in the loop of Henle of the kidneys Also known as High-ceiling diuretics Four current loop diuretics available • • • •
Ethacrynic acid (Edecrin) Bumetanide (Bumex) Furosemide (Lasix) Torsemide (Demadex)
Therapeutic Effects of Loop Diuretics
Treat patients affected with fluid volume overload leading to a variety of conditions
• • • • • • •
Heart failure (HF) Hypertension Pulmonary edema Impared gas exchange Peripheral edema Decreased mobility Increased risk of infection
Heart Failure pathophysiology Caused by structural or functional damage to the heart Heart unable to pump efficiently causes a decrease of Cardiac output (CO) A decreased CO reduces blood flow to the kidneys Activates renin-angiotensin system
Renin-Angiotensin system Renin released from kidneys triggered by a decreased blood flow Renin signals angiotensin II production Angiotensin II causes vasoconstriction and aldosterone production Aldosterone causes water retention by sodium reabsorption Excess volume is backed up from the lungs throughout the venous system The back up of blood causes the excess fluid to leak into the pulmonary system and the interstitial spaces of the peripheral vascular system
Indications for Loop Diuretics Acute Heart Failure Acute Pulmonary Edema Peripheral Edema Renal or Liver Disease
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Emergent situations for Loop diuretics Pulmonary Edema • Respiratory distress • Confusion • Rhonchi
Severe Edema
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• Commonly seen in bilateral lower extremites • Greater risk for infection Retrieved from WebMD.com
Mechanisms of Action Blocks the chloride pump in the ascending loop of Henle Decreases the amount of reabsorption of both sodium and chloride Results in copious amounts of sodium rich urine and decreased water retention
Mechanism of Action Cont. The inhibition of the chloride pump prevents the reabsorption of sodium back into circulation in the blood
Causes a more hypertonic concentration of the blood as diuresis occurs
Pulls fluid from the interstitial spaces of the lungs and rest of the body
Delivers excess fluid to the kidneys for excretion
Pharmacokinetics
Oral use Intravenous Intramuscular
• Daily use • Peak levels at 60 – 120 minutes • Acute care and emergent settings • Peak levels at 30 minutes • Furosemide only
Contraindications and Cautions Allergies Electrolyte depletion Anuria Hepatic Coma Hypotension
• To prevent a hypersensitivity reaction • Increased loss of electrolytes such as sodium and potassium • My prevent the diuretic from working and precipitate a crisis due to blood flow changes • May exacerbate the condition due to fluid shifts associated with diuretic use • May further decrease blood pressure due to fluid volume loss
Adverse Effects Electrolyte imbalance • Hypokalemia • Hypocalemia
Alkalosis • Decreased bicarbonate levels
Hypotension • Rapid fluid and volume loss
Hyperglycemia • Increased blood glucose levels
Drug to Drug Interactions and other considerations Indomethacin, Ibuprofen, Salicylates, NSAIDS • May cause a decrease in the effectiveness of loop diuretics such as decreased sodium excretion and decreased antihypertension effects
Anticoagulants • May cause an increase of the anticoagulation properties
Aminoglycosides or Cisplatin • May cause ototoxicity leading to deafness
Furosemide (Lasix) Loop diuretic used in the treatment of acute HF; acute pulmonary edema, hypertension, edema associated with HF, renal or liver disease Usual dosage • • • •
20-80mg/day PO, up to 600 mg/day may be given 40 mg PO BID for hypertension 20-40mg/day IM or IV slowly 40mg IV push given slowly over 1-2 minutes for acute pulmonary edema. May repeat and increase dose to 80 mg after one hour if response is inadaquate
Nursing considerations when using Furosemide Obtain daily weight Monitoring daily intake and output Safety measures Comfort measures Lifestyle changes
• Taken same time each day with same weighing scale • Keep diary or journal with documented information • To assess for effectiveness • Taken with food to prevent stomach discomfort • Taken in the morning to prevent diuresis at night • Provide clear path with easy access to bathroom with proper lighting
• Oral care and lozenges to prevent dry mouth • Skin care • Reduction in sodium intake and increases in potassium and calcium rich foods
Patient Education Diuretics or “water pills� are used to reduce the amount of excess fluid retain in the body It is used to reduce the effects of heart failure such as leg or ankle swelling and shortness of breath Take with food, resume normal fluid intake Avoid excessive salt intake and increase potassium rich foods Keep journal with daily weights
Patient Education regarding side effects Common effects include large and frequent urination A decreased blood pressure may occur when using diuretics • Dizziness and drowsiness • Dry mouth and/or increased thrust
If these symptoms are experienced: • • • •
Change positions slowly Do not stand up quickly Ask for help Avoid alcohol
Store medication safely. Inform healthcare provider regarding use of this medication
Research regarding Loop Diuretics Loop Diuretics should be taken with Angiotensin Converting Enzyme Inhibitors (ACE inhibitors) and Beta Blockers to reduce decompensation and maintain clinical stability if tolerated (Khatib, 2011). Patients first using loop diuretics should be started with 40-80 mg and should be adjusted accordingly to produced an optimal desired effect (Khatib, 2011).
Loop Diuretic Resistance in the ICU Loop diuretic resistance in ICU setting caused by frequent use of medication Can be explained by: • Rebound sodium retention- sodium reabsorption at the distal site of the nephron • Post diuretic effect-body increases sodium retention as sodium is lost due to the effects of loop diuretics • Diuretic breaking- loss of potency with frequent use
Can be prevented by including thiazide diuretics and continuous IV therapy
References:
Asare, K. (2009). Management of Loop Diuretic Resistance in the Intensive Care Unit. Clinical Consultation, 1635-1640. Beckerman, J. (2015, April 20 ). A Visual Guide to Heart Disease. Retrieved from Web MD: http://www.webmd.com/heart-disease/ss/slideshowvisual-guide-to-heart-disease Karch, A. M. (2013). Focus on Nursing Pharmacology 6th edition. Philadelphia: Lippincott Williams & Wilkins. Khatib, R. (2011). Prescribing Diuretics in the Managment of Heart Failure. Clinical Focus, 435-441. Porth, C. M. (2011). Essentials of Pathophysiology. Philadelphia: Lippincott Williams & Wilkins.