Perfusion and Renal Elimination
6.9 Diuretics
Diuretics
Diuretics are used to decrease blood pressure and to decrease symptoms of fluid overload, such as edema. There are many classifications of diuretics. We will discuss loop, thiazide, and potassium-sparing diuretics. Other diuretics, such as osmotic diuretics, are used to decrease fluid from cerebrospinal fluid and the brain.
Diuretics cause diuresis (increased urine flow) by inhibiting sodium and water reabsorption from the kidney tubules. By eliminating excess water, blood volume and blood pressure, as well as preload, are decreased.
Diuretics are often used in combination with other antihypertensive agents to reduce a client’s blood pressure.
Furosemide
Mechanism of Action
Loop diuretics inhibit absorption of sodium and chloride in the Loop of Henle and proximal and distal tubules, thus causing fluid loss, along with sodium, potassium, calcium, and magnesium losses. Loop diuretics are very potent diuretics and are used when a client has an exacerbation of fluid overload.
Indications for Use
Furosemide is used to treat clients with edema, and clients with hypertension. IV furosemide is used to urgently treat pulmonary edema.
Nursing Considerations Across the Lifespan
The onset of diuresis following oral administration is within 1 hour. The peak effect occurs within the first or second hour. The duration of diuretic effect is 6 to 8 hours. When possible, loop diuretics should be administered in the morning, and evening doses should be avoided (unless urgent) so that sleep is not disturbed.
Nurses should continually monitor for dehydration and electrolyte imbalances that can occur with excessive diuresis, such as dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, arrhythmia, or gastrointestinal disturbances such as nausea and vomiting.
Use cautiously in the geriatric population who have decreased renal function. Kidney function should be monitored closely for all clients because this is a potent medication that works within the kidney tubules.
Monitor the client closely for hypokalemia if furosemide is used concomitantly with digoxin. Hypokalemia may increase the risk of digoxin toxicity.
Adverse/Side Effects
Adverse effects include dehydration, hypotension, and electrolyte imbalances such as hypokalemia. Health care providers may add potassium to a client’s scheduled medication list to decrease risk of hypokalemia. If using IV route, the administration must be given slowly to reduce the risk of the client developing ototoxicity.[1]
Client Teaching & Education
Advise clients to change position slowly, as they may experience orthostatic changes. Clients should also report weight gain of more than three pounds in a day to their healthcare provider. Clients should also be encouraged to enjoy potassium-rich foods during loop diuretic drug therapy.[2]
Furosemide Medication Card
Now let’s take a closer look at the medication card for furosemide.[3] Because information about medication is constantly changing, nurses should always consult evidence-based resources to review current recommendations before administering specific medication.
Medication Card 6.9.1: Furosemide
Class: Loop Diuretics
Prototypes: Furosemide (Lasix)
Mechanism: Loop diuretics inhibit absorption of sodium and chloride in the loop of henle and proximal and distal tubules, thus causing fluid loss, along with sodium, potassium, calcium, and magnesium losses. Loop diuretics are very potent diuretics and are used when a patient has an exacerbation of fluid overload.
Therapeutic Effects
- Decrease fluid load
- Decrease Blood Pressure (hypertension)
- Increase urine output to remove fluid
- Improve lung edema improve oxygenation-gas exchange capacity and ventilation
Administration
- PO/IV
- Ototoxicity can occur if administered too fast IV. Make sure to follow specifically hospital protocols
- Check BP before administering risk of orthostatic BP so do it standing and sitting
- Weight gain of more than 3 pounds in one day needs to be reported. Track weight daily
- Avoid taking medication 4 hrs before bedtime to prevent having to get up to urinate
- Dosage is dependent on condition and for children it is weight based.
- Usually starting dose is low and increased as wneeded
- Take regularly if ordered
Indications
- Pulmonary Edema
- Hypertension
- Peripheral edema
- Heart failure
- Kidney, heart or liver caused edema
Contraindications
- Scralfate, cholestyramine, and colestipol decrease absorption of Lasix
- If condition does not improve-report to prescribing MD
Side Effects
- Dehydration
- Low Blood pressure
- Electrolyte depletion especially potassium
- Ototoxicity
- Renal impairment
- Dizzyness
- Light headedness
- Blurred vision
- Muscle cramps
- Fainting
- Dry mouth or thirst
- Unusual tiredness
- Fast or irregular heart beat
- Sensitive to sun avoid sun lamps or tanning
- SAFETY:
- if diabetic-blood sugars could be impacted make sure to check these levels
- If diarrhea or vomiting-increase risk in dehydration follow MD instructions on fluid during this time
Nursing Considerations
- Potassium serum levels
- Renal function serum blood levels
- Assess blood pressure on administering medication
- Weigh patient to track hydration and volume status
- Strict Intake and output charts of volume status
- Promote potassium rich food like bananas
- Daily weights
Mrs. Smith is a 79-year-old widow who has lived alone for the past 5 years. Three years ago she was hospitalized for an MI, which resulted in heart failure. She is compliant with her medications, which include digoxin (Lanoxin) 0.125 mg daily, furosemide (Lasix) 40 mg daily, and potassium (K-Dur) 20 mEq daily.
Recently Mrs. Smith ran out of her potassium and thought that because it was “just a supplement,” it would be OK to go without it until the next time she went to town to fill the prescription. She has not taken her potassium for a week.
Today she is at the clinic with generalized weakness, fatigue, nausea, and diarrhea. Her BP is 104/62, pulse 98 bpm and slightly irregular, RR 20, and temp 97.2 F. Blood is drawn and shows serum sodium level of 150 mEq/L, digoxin level of 2.6ng/ml and potassium level of 3.2 mEq/L.
1. What assessments should a nurse do before and after administering a diuretic?
2. What are the signs and symptoms of digoxin toxicity? What can happen to a client who has toxic levels of digoxin?
3. What is the normal range for serum potassium level?
4. What classification of medication is furosemide (Lasix)?
5. Is dehydration a risk for clients on furosemide (Lasix)? Why or why not?
6. How would you assess for dehydration?
7. What electrolyte imbalance(s) can occur in clients taking furosemide (Lasix)?
8. What relationship exists between this client’s furosemide, digoxin, and potassium levels?
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.
Hydrochlorothiazide
Mechanism of Action
Thiazide diuretics work near the distal tubule to promote the excretion of sodium and water, thus causing diuresis. They are not effective for immediate diuresis.
Indications for Use
Hydrochlorothiazide diuretics are used to manage hypertension and edema.
Nursing Considerations Across the Lifespan
Thiazide diuretics are contraindicated for clients who have anuria or hypersensitivity.
After oral use, diuresis begins within 2 hours, peaks in about 4 hours, and lasts about 6 to 12 hours.
Use with caution in clients with severe renal disease.
Adverse/Side Effects
Clients who are taking thiazide diuretics should be monitored for electrolyte depletion, dehydration, weakness, hypotension, renal impairment, and hypersensitivities.[4]
Client Teaching & Education
Clients should be instructed to take these medications at the same time each day and notify their healthcare provider if they experience significant changes in weight. Thiazide diuretics may cause orthostatic changes so individuals should change positions slowly. Additionally, some clients may note increased photosensitivity, so protective measures should be taken. Clients should monitor their blood pressure and comply with interventions to reduce hypertension.[5]
Spironolactone
Spironolactone is a potassium-sparing diuretic that is used as a mild diuretic or in combination with another diuretic.
Mechanism of Action
Spironolactone acts primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium is retained.
Indications for Use
Spironolactone is used to treat hypertension and to control edema for clients with heart failure or liver dysfunction.
Nursing Considerations Across the Lifespan
This medication may cause hyperkalemia. Monitor urine output and report if less than 30 ml/hour. Use cautiously with clients who have renal impairment due to increased risk for hyperkalemia. Use cautiously in clients with liver impairment. Administer in the morning to avoid nocturia.
Adverse/Side Effects
Hyperkalemia, hyperglycemia, hyperuricemia, dehydration, hypotension, renal impairment, hypersensitivity, and gynecomastia. This medication may increase the risk for lithium toxicity.[6]
Client Teaching & Education
Clients should be instructed to take these medications at the same time each day and notify their healthcare provider if they experience significant changes in weight. Diuretics may cause orthostatic changes, so individuals should change positions slowly. Clients should be advised to avoid salt substitutes and foods that contain high levels of potassium.[7]
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵
- This work is a derivative of Daily Med by U.S. National Library of Medicine in the public domain. ↵
- uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral ↵