Excessive diuresis may cause dehydration and blood volume reduction with circulatory collapse and possibly vascular thrombosis and embolism, particularly in elderly patients. As with any effective diuretic, electrolyte depletion may occur during LASIX therapy, especially in patients receiving higher doses and a restricted salt intake. Hypokalemia may develop with LASIX, especially with brisk diuresis, inadequate oral electrolyte intake, when cirrhosis is present, or during concomitant use of corticosteroids, ACTH, licorice in large amounts, or prolonged use of laxatives. Digitalis therapy may exaggerate metabolic effects of hypokalemia, especially myocardial effects.
All patients receiving LASIX therapy should be observed for these signs or symptoms of fluid or electrolyte imbalance (hyponatremia, hypochloremic alkalosis, hypokalemia, hypomagnesemia or hypocalcemia): 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. Increases in blood glucose and alterations in glucose tolerance tests (with abnormalities of the fasting and 2-hour postprandial sugar) have been observed, and rarely, precipitation of diabetes mellitus has been reported.
In patients with severe symptoms of urinary retention (because of bladder emptying disorders, prostatic hyperplasia, urethral narrowing), the administration of furosemide can cause acute urinary retention related to increased production and retention of urine. Thus, these patients require careful monitoring, especially during the initial stages of treatment.
In patients at high risk for radiocontrast nephropathy LASIX can lead to a higher incidence of deterioration in renal function after receiving radiocontrast compared to high-risk patients who received only intravenous hydration prior to receiving radiocontrast.
In patients with hypoproteinemia (e.g., associated with nephrotic syndrome) the effect of LASIX may be weakened and its ototoxicity potentiated.
Asymptomatic hyperuricemia can occur and gout may rarely be precipitated.
Patients allergic to sulfonamides may also be allergic to LASIX. The possibility exists of exacerbation or activation of systemic lupus erythematosus.
As with many other drugs, patients should be observed regularly for the possible occurrence of blood dyscrasias, liver or kidney damage, or other idiosyncratic reactions.
Laboratory Tests
Serum electrolytes (particularly potassium), CO2, creatinine and BUN should be determined frequently during the first few months of LASIX therapy and periodically thereafter. Serum and urine electrolyte determinations are particularly important when the patient is vomiting profusely or receiving parenteral fluids. Abnormalities should be corrected or the drug temporarily withdrawn. Other medications may also influence serum electrolytes.
Reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency.
Urine and blood glucose should be checked periodically in diabetics receiving LASIX, even in those suspected of latent diabetes.
LASIX may lower serum levels of calcium (rarely cases of tetany have been reported) and magnesium. Accordingly, serum levels of these electrolytes should be determined periodically.
In premature infants LASIX may precipitate nephrocalcinosis/nephrolithiasis, therefore renal function must be monitored and renal ultrasonography performed. (See PRECAUTIONS: Pediatric Use)
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Furosemide was tested for carcinogenicity by oral administration in one strain of mice and one strain of rats. A small but significantly increased incidence of mammary gland carcinomas occurred in female mice at a dose 17.5 times the maximum human dose of 600 mg. There were marginal increases in uncommon tumors in male rats at a dose of 15 mg/kg (slightly greater than the maximum human dose) but not at 30 mg/kg.
Furosemide was devoid of mutagenic activity in various strains of Salmonella typhimurium when tested in the presence or absence of an in vitro metabolic activation system, and questionably positive for gene mutation in mouse lymphoma cells in the presence of rat liver S9 at the highest dose tested. Furosemide did not induce sister chromatid exchange in human cells in vitro, but other studies on chromosomal aberrations in human cells in vitro gave conflicting results. In Chinese hamster cells it induced chromosomal damage but was questionably positive for sister chromatid exchange. Studies on the induction by furosemide of chromosomal aberrations in mice were inconclusive. The urine of rats treated with this drug did not induce gene conversion in Saccharomyces cerevisiae.
LASIX (furosemide) produced no impairment of fertility in male or female rats, at 100 mg/kg/day (the maximum effective diuretic dose in the rat and 8 times the maximal human dose of 600 mg/day).
Pregnancy
Pregnancy Category C -Furosemide has been shown to cause unexplained maternal deaths and abortions in rabbits at 2, 4 and 8 times the maximal recommended human dose. There are no adequate and well-controlled studies in pregnant women. LASIX should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Treatment during pregnancy requires monitoring of fetal growth because of the potential for higher birth weights.
The effects of furosemide on embryonic and fetal development and on pregnant dams were studied in mice, rats and rabbits.
Furosemide caused unexplained maternal deaths and abortions in the rabbit at the lowest dose of 25 mg/kg (2 times the maximal recommended human dose of 600 mg/day). In another study, a dose of 50 mg/kg (4 times the maximal recommended human dose of 600 mg/day) also caused maternal deaths and abortions when administered to rabbits between Days 12 and 17 of gestation. In a third study, none of the pregnant rabbits survived a dose of 100 mg/kg. Data from the above studies indicate fetal lethality that can precede maternal deaths.
The results of the mouse study and one of the three rabbit studies also showed an increased incidence and severity of hydronephrosis (distention of the renal pelvis and, in some cases, of the ureters) in fetuses derived from the treated dams as compared with the incidence in fetuses from the control group.
Nursing Mothers
Because it appears in breast milk, caution should be exercised when LASIX is administered to a nursing mother.
LASIX may inhibit lactation.
Pediatric Use
In premature infants LASIX may precipitate nephrocalcinosis/nephrolithiasis. Nephrocalcinosis/nephrolithiasis has also been observed in children under 4 years of age with no history of prematurity who have been treated chronically with LASIX. Monitor renal function, and renal ultrasonography should be considered, in pediatric patients receiving LASIX.
If LASIX is administered to premature infants during the first weeks of life, it may increase the risk of persistence of patent ductus arteriosus
Geriatric Use
Controlled clinical studies of LASIX did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for the elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.
This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function. (See PRECAUTIONS: General and DOSAGE AND ADMINISTRATION.)
Open Resources for Nursing (Open RN)
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 patient’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 patient has an exacerbation of fluid overload.
Indications for Use
Furosemide is used to treat patients with edema and is also used to treat 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 patients because this is a potent medication that works within the kidney tubules.
Monitor the patient 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 patient’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 patient developing ototoxicity.
Patient Teaching & Education
Advise patients to change position slowly as they may experience orthostatic changes. Patients should also report weight gain of more than three pounds in a day to their healthcare provider. Patients should also be encouraged to enjoy potassium-rich foods during loop diuretic drug therapy.
Now let’s take a closer look at the medication grid for furosemide in Table 6.9a.
Table 6.9a Furosemide Medication Grid
| furosemide | Assess blood pressure
Monitor electrolytes (potassium) Promote potassium-rich diet Assess renal function Assess for dehydration, intake and output Monitor weight |
Based on indication; decreased blood pressure or edema | Dehydration
Electrolyte depletion (especially potassium) Ototoxicity with rapid IV infusion Renal impairment |
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 comes into 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 patient 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 patients on furosemide (Lasix)? Why or why not?
6. How would you assess for dehydration?
7. What electrolyte imbalance(s) can occur in patients taking furosemide (Lasix)?
8. What relationship exists between this patient’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 patients 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 severe renal disease.
Adverse/Side Effects
Patients who are taking thiazide diuretics should be monitored for electrolyte depletion, dehydration, weakness, hypotension, renal impairment, and hypersensitivities.
Patient Teaching & Education
Patients 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 patients may note increased photosensitivity so protective measures should be taken. Patients should monitor their blood pressure and comply with interventions to reduce hypertension.
Now let’s take a closer look at the medication grid for hydrochlorothiazide in Table 6.9b.
Table 6.9b Hydrochlorothiazide Medication Grid
| hydrochlorothiazide | Assess blood pressure
Monitor electrolytes (potassium) Promote potassium-rich diet Assess renal function Assess for dehydration, intake and output Monitor weight |
Decrease blood pressure
Decrease edema |
Electrolyte depletion
Dehydration and weakness Hypotension Renal impairment Hypersensitivity (vasculitis, respiratory distress, photosensitivity, rash) |
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 patients 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 patients who have renal impairment due to increased risk for hyperkalemia. Use cautiously in patients 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 risk for lithium toxicity.
Patient Teaching & Education
Patients 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. Patients should be advised to avoid salt substitutes and foods that contain high levels of potassium.
Now let’s take a closer look at the medication grid for spironolactone in Table 6.9c
Table 6.9c Spironolactone Medication Grid
| spironolactone | Assess blood pressure
Monitor electrolytes (potassium) Assess renal function Assess for dehydration, intake and output Monitor weight |
Decrease blood pressure
Decrease edema |
Hyperkalemia, hyperglycemia,hyperuricemia
Dehydration Hypotension Renal impairment Hypersensitivity (vasculitis, fever, anaphylactic reactions, rash) Gynecomastia |
|