Fluid and Electrolytes: Drug Therapy

• Drug Therapy: Fluid and Electrolytes is the topic

Agenda

• Topics covered here include: IV fluid therapy, diuretic agents, vitamins and minerals, and electrolyte replacement

Reading Goals

• Learn differences between hypotonic, hypertonic, and isotonic IV solutions and why to use each
• Learn about indications for IV therapy
• Learn about the different types of diuretics and their uses
• Learn about fat versus water soluble vitamins
• Learn about the uses of vitamins and minerals
• Learn general information about herbal and dietary supplements

Diuretics

• These increase sodium excretion and the amount of urine produced by the kidneys
• Most prevent reabsorption of an excessive proportion of sodium ions in the glomerular filtrate
• When these components are not reabsorbed, sodium, other ions, and the water in which they are dissolved are lost in the urine
• If these components are returned to the blood, it would cause increased intravascular volume and hydrostatic pressure
• That would cause leaking of fluids at the capillary level (edema)
• Diuretics treat HF, acute pulmonary edema, liver disease, renal disease, HTN, increased intraocular pressure (IOP), and hyperkalemia
• There are five classes of diuretics – each works at a slightly different site in nephron
• Overall nursing care for diuretics is similar, but there are differences among classes
• Adverse effects are also class specific, including loss of water and chloride

Osmotic Diuretics

• Mannitol (Osmitrol) fits into this class
• This drug exerts its therapeutic effect by pulling water into the renal tubule without loss of sodium

Loop Diuretics

• bumetanide (Bumex) and Furosemide fit into this class
• Furosemide exerts its main effect on the loop of Henle
• Loop Diuretics are referred to as high-ceiling diuretics because they can cause a greater degree of diuresis compared to other types
• These are used when there is pulmonary involved

Thiazides

• Hydrochlorthiazide fits into this class
• These belong to a chemical class of drugs called sulfonamides
• Thiazide-like diuretics have different chemical structure but work in the same mechanism as that of thiazide diuretics
• This diuretics is among the most commonly used class of diuretics
• First line drugs for management of essential hypertension

Potassium-Sparing Diuretics

• Spironolactone fits into this class
• These cause a loss of sodium while promoting the retention of potassium
• Often used as adjuncts with thiazide or loop diuretics or in patients who are especially at risk if hypokalemia develops
• Spironolactone is the only diuretic recommended for children, but may cause hyperkalemia

Thiazide and Thiazide-Like Diuretics

• Prototype: hydrochlorothiazide or HCTZ
• Well absorbed from the GI tract, the onset is 1-3 hours
• Metabolized in liver, excreted in urine
• Crosses the placenta and enter human milk
• HCTZ can be used in small doses because it is potent
• Adverse effects include: GI effects, fluid and electrolyte imbalances, hypotension, hypokalemia, decreased uric acid excretion, and increased blood glucose levels with prolonged use
• Alkalinized urine can cause susceptibility to bladder infections
• Contraindications include known allergy to thiazides or sulfonamides, and severe renal disease
• Used with caution with SLE, diabetes or glucose tolerance abnormalities, gout, liver disease, hyperparathyroidism, bipolar disorder, and should not be used in pregnancy routinely
• Drug-drug interactions may result in increased digoxin toxicity due to changes in potassium levels
• Quinidine toxicity increases with alkaline urine
• There is decreased effectiveness of antidiabetic agents and risk of lithium toxicity increases

Loop Diuretics

• Prototype is Lasix (furosemide)
• These block the chloride pump in the ascending loop of Henle, decrease reabsorption of sodium and chloride, and produce copious amounts of sodium rich urine
• Commonly indicated for the treatment of acute HF, acute pulmonary edema, edema associated with HF or with renal or liver disease, and hypertension
• Oral or IV use, Lasix also available IM
• Peak levels in 1-2 hours PO or 30 minutes IV
• Contraindications include allergy, electrolyte depletion, anuria, and hepatic encephalopathy
• These should not be used in pregnancy routinely
• Caution with SLE, glucose tolerance abnormalities, DM, and gout
• Adverse effects: Electrolyte and fluid imbalance, hypokalemia, alkalosis, hypocalcemia and tetany, hypotension, dizziness, hyperglycemia with long-term use, ototoxicity & deafness if pushed too rapidly IV (usually reversible), hyperuricemia, hypomagnesemia
• Drug-drug interactions: Risk of ototoxicity increases if combined with aminoglycosides or cisplatin, anticoagulation effects may increase, decreased loss of sodium and decreased antihypertensive effects if combined with NSAIDs
• There is an increased risk of digoxin toxicity with hypokalemia, and hyponatremia can cause increased lithium levels

Carbonic Anhydrase Inhibitors

• Prototype: acetazolamide
• Carbonic anhydrase is an enzyme for sodium bicarbonate formation and hydrogen excretion, yielding slightly acidic urine
• Movement of hydrogen ions decreased, resulting in more sodium and bicarbonate lost in the urine
• Used as adjuncts to other diuretics when more intense diuresis is needed
• Often used to treat glaucoma because it results in decreased secretion of aqueous humor of the eye
• Rapidly absorbed and widely distributed
• Some are associated with fetal abnormalities in animals
• During lactation, an alternate feeding method should be used
• Contraindications include allergy to sulfonamides or thiazides, and chronic noncongestive angle-closure glaucoma
• Use caution in fluid/electrolyte imbalances, renal or hepatic disease, adrenocortical insufficiency, respiratory acidosis, COPD - all can be exacerbated by fluid/electrolyte changes
• Adverse side effects: Metabolic acidosis and hypokalemia are common, paresthesia of extremities, confusion, and drowsiness
• Drug-drug interactions: Higher risk of salicylate toxicity from metabolic acidosis potential, so high dose ASA is contraindicated
• There is an additive effect to other medications that can cause metabolic acidosis
• Excretion of medications can be increased or decreased

Potassium-Sparing Diuretics

• Prototype: Aldactone (spironolactone)
• These are not as powerful as loop diuretics, but retain potassium instead of wasting it
• Causes a loss of sodium while promoting the retention of potassium
• Spironolactone blocks action of aldosterone in the distal tubule
• Often used as adjuncts with thiazide or loop diuretics at risk of hypokalemia
• Well absorbed after PO administration, protein-bound, widely distributed
• Metabolized in liver and primarily excreted in the urine
• Contraindications include allergy, hyperkalemia, severe renal disease, and anuria
• Routine use in pregnancy not appropriate
• Diuretic effect decreases with salicylates
• There is an increased risk of hypotension with other antihypertensives
• There is an increased risk of hyperkalemia with medications that block the RAAS pathway
• Most common adverse effect = hyperkalemia
• Use caution when eating potassium rich foods and watch for hormone changes

Osmotic Diuretics

• Only one osmotic diuretic exists: Osmitrol (mannitol)
• Pull water into the renal tubule without sodium loss
• Mannitol is a sugar not well reabsorbed by the tubules, acts to pull large amounts of fluid into the urine due to osmotic pull exerted by the large sugar molecule
• Large amounts of fluid are lost to urine
• Not limited to kidney, it pulls fluid into vascular fluid from extravascular spaces
• Often used in acute situations for IOP, increase cranial pressure, acute renal failure, drug OD, and trauma cases
• Contraindications: Renal disease, anuria, pulmonary congestion, intracranial bleeding, dehydration, or HF
• Only used intravenously
• Poorly reabsorbed by the renal tubule, not secreted by the tubule, resistant to metabolism
• Action depends on concentration
• Adverse effects: Fluid shifts, which can cause HF, pulmonary edema, hypotension, or dehydration
• Monitor for new or worsening renal function
• N/V, lightheadedness, electrolyte imbalances, infusion site reactions, headache

Side Effects of Diuretics:

• Frequent urination
• Hypotension
• Hyponatremia
• Hypokalemia
• Hypochloremia, with an independent association between hypochloremia and an increased risk of mortality in both acute and chronic heart failure
• Dizziness
• Headache
• Dehydration
• Muscle cramps
• Gout
• Erectile dysfunction or impotence

Nursing Implications

• Monitor patient response to therapy to watch changes in weight, urinary output, edema, and blood pressure
• Monitor for adverse effects like: electrolyte imbalance, hyperglycemia, hyperuricemia, and acid-base disturbances
• Evaluate patient understanding of drug therapy by asking the patient to name the drug, its indication, and adverse effects to watch for
• Monitor patient compliance to drug therapy

Vitamins

• These are organic substances that the body requires to carry out essential metabolic reactions
• The body cannot synthesize enough vitamins to meet all its needs, so people must obtain vitamins through their diet
• Vitamins function as co-enzymes that activate proteins and catalyze biochemical activity
• Used to build bones, make hormones, regulate fluid volume, generate nerve action potentials, and produce red blood cells
• Nutrient dense foods contain vitamins, minerals, and other health promoting compounds
• These are either water soluble and excreted in urine, or fat soluble and are capable of being stored in adipose tissue
• Prenatal vitamins are encouraged before, during, and after pregnancy
• Most vitamins are needed in small amounts

Important vitamins

• Ascorbic Acid (vitamin C) is water soluble and used to treat scurvy and enhance wound/burn healing
• Studied for treatment of the common cold, asthma, CAD, cancer, and schizophrenia
• Found in broccoli, green peppers, spinach, Brussels sprouts, citrus, fruits, tomatoes, potatoes, strawberries, cabbage, and liver
• Vitamin D3 is fat soluble and used to treat hypocalcemia (enhances absorption of Ca+), hypoparathyroidism, and metabolic bone disease
• Found in dairy, fortified cereals, orange juice, liver, fish liver, oils, saltwater fish, butter, eggs
• Cyanocobalamin (Vitamin B12) is water soluble and used to treat folic acid deficiency and anemia
• Found in liver, kidney, shellfish, poultry, fish, eggs, milk, blue cheese, and fortified cereals
• Folate/Folic Acid (Vitamin B9) is water soluble and used to treat red blood cell formation and cell growth
• Deficiency during pregnancy can result in neural tube defects
• Found in liver, kidney beans, fresh green vegetable, and fortified grains
• Phytonadione (Vitamin K) is fat soluble and used to treat bleeding disorders
• Found in cheese, spinach, broccoli, Brussels sprouts, kale, cabbage, turnip greens, and soybean oil

Minerals

• These are naturally occurring inorganic substances and many are important for normal functioning
• These are taken in by via diet
• Some are also electrolytes
• Vitamin and mineral deficiencies can increase the risk of health problems, including anemias, osteoporosis, and heart arrhythmias
• High levels can also be harmful

Iron

• Ferrous sulfate is the preparation of choice
• 10-15% of dietary intake is absorbed and stored in the small intestine and liver, but is not metabolized
• Iron from RBC is reused
• Used to treat iron deficiency
• Take with or after meals with fluid to prevent stomach upset
• OJ will help absorption

Treating Mineral Excess:

• Penicillimine is a chelating agent that binds to copper, lead, mercury and zinc to form soluble complex excreted in urine
• Main use is removal of copper in Wilson's disease
• Succimer is a chelates lead to water soluble complex excreted in urine
• Used to treat lead poisoning in children
• Deferoxamine and Deferasirox are used to treat iron overdose
• Deferasirox is an iron-chelating agent used to treat chronic iron overload in those who require frequent blood transfusions
• Agents to treat hyperkalemia:
• Sodium bicarbonate controls acidosis
• Calcium gluconate decreases cardio toxic effects of K
• Glucose and insulin cause K to move into cells
• Cation exchange: sodium polystyrene sulfonate (kayexalate)- removes K from the body through the stool
• FDA no longer recommends that it be administered in sorbitol as it has been associated with intestinal necrosis

Herbal and dietary supplements

• These may be useful in patient care, but can potentiate or negate prescribed medications
• Clinicians need to be aware of what the patient is taking and effect it has on medication
• Major concerns surrounding these supplements:
• May not be safe because active ingredients and effect on humans is unknown
• Use of supplements might prevent patient from seeking proper care
• May interact with prescribed medications, such as how St. John's Wart affects blood clotting
• Most products have not been studied to evaluate safety and efficacy
• Many patients do not tell their providers, omission can lead to dangerous interactions

IV Therapy

• Fluids, electrolytes, and nutritional substances are often administered IV if there is an inability to have adequate oral intake
• IV access can be peripheral or central
• Parenteral agents can provide replacement fluids, sugars, electrolytes, medications, and nutrients
• Parenteral sites provide ready access for administration of medication in an emergency situation, to provide rehydration, and to restore electrolyte balance
• Fluid composition varies depending on patient's needs, and their fluid and electrolyte status
• Fluids can be simple or contain complex mixtures of salts, electrolytes, sugars, and other nutrients
• Parenteral administration is more rapid than other routes and larger volumes of fluid can be administered
• Fluids can be hypertonic, hypotonic, or isotonic

Common IV Fluids

• Hypertonic fluids include 3% Saline (3% NaCl), 5% Saline (5% NaCl), D10W, D20W, D25W, D30W, D40W, D50W, D60W, D70W
• Hypotonic fluids include 0.45% Saline (0.45% NaCl, Half NS) and 5% Dextrose (D5W)
• Isotonic fluids include Normal Saline (0.9% NaCl, NS) and Ringers Lactate or Lactated Ringers (RL or LR)

IV Fluids - Cautions and Contraindications

• Some IV drugs can only be diluted with particular solutions as precipitation or drug inactivation can occur
• IV medications SHOULD NOT be administered through the same tubing as blood, blood products, or parenteral nutrition products
• Blood can only be run with normal saline (0.9% NaCl)
• A drug guide should be checked before diluting any IV drug in solution, as well as the compatibility of different IV solutions should ALWAYS be checked
• Potassium containing solutions MUST be run via IV pump and can NEVER be pushed

Electrolyte Supplements

• Calcium: Can be administered orally or IV to facilitate MSK, nerve, CV function
• It is required to treat Ca+ and PTH deficiency and reduce risk of osteoporosis
• Use in conjunction with Vitamin D to increase Ca+ absorption
• Sources of calcium: Dairy, fortified cereals and orange juice, sardines, salmon
• Magnesium: Can be administered orally or IV to assist in Activation of many intracellular enzymes.
• Helps regulate skeletal and cardiac MSK contractility
• Used as antacid and laxative, decrease uterine contractions, and prevention of seizures in preeclampsia
• Sources of magnesium: Meat, seafood, dairy, green leafy vegetables, bran cereal, and nuts
• Phosphorus: This is administered orally to Regulate acid-base balance, bone formation, energy production and storage, and hormone activation
• May prevent kidney stone formation
• Sources of phosphorus: Milk, yogurt, cheese, peas, meat, and fish
• Potassium: Can be administered orally or IV and is necessary for regulating acid-base balance, nerve action potentials, and electrical excitability of muscles
• Prolonged QT interval and peaked T waves on EKG can indicate hyperkalemia
• Sources of potassium: Beans, dairy, fruits, clams, salmon, tomato, sweet potatoes, potatoes, beet greens, and spinach

Alternative and Complementary Therapies

• Some patients may use complementary therapies in addition to or in place of Western therapies
• Patients may use food supplements, herbs and botanicals, and Probiotic supplements
• Alternative and complementary therapies are practices outside of standard or traditional medical practices that are used for enhancing health
• Complementary therapies can be classified as nutritional, psychological, physical, and combinations of the psychological and physical
• Uses of these therapies include treatment of pain, neuropathy, depression, anxiety, insomnia, heart disease, and prostrate hyperplasia

Nonpharmacological therapies effective in treating conditions include:

• Ginger to treat nausea and vomiting
• Probiotic supplements, which are preparations of live bacteria and yeast that are part of the normal environment of the gastrointestinal tract
• Alfalfa to treat arthritis, hot flashes, increase strength, reduce cholesterol level.
• Allspice as an anesthetic for teeth and gums, soothes sore joints and muscles

Herbal therapies to treat health problem issues:

• Dose is not precise
• Ingredients are not precise
• May interact with prescribed medications
• Not strictly regulated by the Food and Drug Administration