NCM 103 LEC 1BFluid and Electrolytes Edited

Fluid and Electrolytes

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Fluids•Body weight of adult male 55-60%, female 50-55%, newborn 75-80%•Very little in adipose tissues•Loss of 20% - fatal•Elderly - decreases to 45-50% of body weight•R/T decreased muscle mass, smaller fat stores, and decrease in body fluids

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Fluid Shifts in Infants•predisposed to serious, rapid fluid volume deficit

• limited ability to concentrate urine•proportionately greater ratio of surface area to volume

•higher metabolic rate

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Compartments• Intracellular (ICF)

• Fluid within the cells themselves • 2/3 of body fluid• Located primarily in skeletal muscle mass• Provide nutrients for metabolism:

• High in K, Po4, protein• Moderate levels of Mg, So4

• Assists in cellular metabolism

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Compartments• Extracellular (ECF)

• 1/3 of body fluid• Comprised of 3 major components

• Intravascular•Plasma

• Interstitial•Fluid in and around tissues

• Transcellular•Over or across the cells

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Compartments• Extracellular

• Nutrients for cell functioning• Na• Ca• Cl• Glucose• Fatty acids• Amino Acids

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Compartments• Intravascular Component

•Plasma• fluid portion of blood

•Made of:•water•plasma proteins•small amount of other substances

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Compartments• Interstitial component

•Made up of fluid between cells•Surrounds cells •Transport medium for nutrients, gases, waste products and other substances between blood and body cells

•Back-up fluid reservoir

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Compartments•Transcellular component

•1% of ECF•Located in joints, connective tissue, bones, body cavities, CSF, and other tissues

•Potential to increase significantly in abnormal conditions

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Regulation of Fluids in Compartments

•Osmosis•Movement of water through a selectively permeable membrane from an area of low solute concentration to a higher concentration until equilibrium occurs

•Movement occurs until near equal concentration found

•Passive process

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Regulation of Fluids• Diffusion

• Movement of solutes from an area of higher concentration to an area of lower concentration in a solution and/or across a permeable membrane (permeable for that solute)

• Movement occurs until near equal state• Passive process

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Osmosis versus Diffusion•Osmosis

•Low to high•Water potential

•Diffusion•High to low•Movement of particles

•Both can occur at the same time

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Regulation of Fluids•Active Transport

•Allows molecules to move against concentration and osmotic pressure to areas of higher concentration

•Active process – energy is expended

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Active Transport•Na / K pump

•Exchange of Na ions for K ions •More Na ions move out of cell•More water pulled into cell•ECF / ICF balance is maintained

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Active Transport• Insulin and glucose regulation

•CHO consumed•Blood glucose peaks•Pancreas secretes insulin•Blood glucose returns to normal

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Osmolality•Concentration of body fluids – affects movement of fluid by osmosis

•Reflects hydration status•Measured by serum and urine •Solutes measured - mainly urea, glucose, and sodium

•Measured as solute concentration/Kg

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Osmolality•Serum Osm/L = (serum Na x 2) + BUN/3 + Glucose/18

•Normal serum value - 280-300 mOsm/Kg

•Serum <240 or >320 is critically abnormal

•Normal urine Osm – 250 – 900 mOsm / kg

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Factors that affect Osmolality• Serum

• Increasing Osm• Free water loss• Diabetes Insipidus• Na overload• Hyperglycemia• Uremia

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Factors that affect Osmolality•Serum

•Decreasing Osm•SIADH•Renal failure•Diuretic use•Adrenal insufficiency

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Factors that affect Osmolality•Urine

• Increasing Osm•Fluid volume deficit•SIADH•Heart Failure•Acidosis

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Factors that affect Osmolality• Urine

• Decreasing Osm• Diabetes Insipidus• Fluid volume excess

• Urine specific gravity• Factors affecting urine Osm affect urine specific gravity identically

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Fluid Volume Shifts•Fluid normally shifts between intracellular and extracellular compartments to maintain equilibrium between spaces

•Fluid not lost from body but not available for use in either compartment – considered third-space fluid shift (“third-spacing”)

•Enters serous cavities (transcellular)

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Causes of Third-Spacing•Burns•Peritonitis•Bowel obstruction•Massive bleeding into joint or cavity•Liver or renal failure•Lowered plasma proteins• Increased capillary permeability•Lymphatic blockage

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Assessment of Third-Spacing• More difficult – fluid sequestered in deeper structures

• Signs/Symptoms • Decreased urine output with adequate intake

• Increased HR• Decreased BP, CVP• Increased weight• Pitting edema, ascites

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Phases of Third-Spacing• Loss phase

• Lasts 48-72 hours• Symptoms of FVD

• Reabsorption phase• Fluid gradually reabsorbed after problem subsides

• FVO possible• Monitor VS, I&O, Wt, and breath sounds

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Treatment •Treat underlying cause if possible•Close observation of VS•Monitor I & O more frequently•Daily weights•Measure abdominal girth in ascites•Measure extremities if necessary •Monitor lab values

•albumin level important

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Evaluation•Stabilized I & O•Stabilized weight•VS within normal range •Resolution of third-spacing

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Fluid volume deficit• Hypovolemia• Abnormally low volume of body fluid in intravascular and/or interstitial compartments

• Causes• Vomiting• Diarrhea• Fever• Excess sweating• Burns• Diabetes insipidus• Uncontrolled diabetes mellitus

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Fluid volume deficit• What happens

• Output > Intake -> Water extracted from ECF• ECF hypertonic (water moves out of cell -> cell dehydration) + osmotic pressure increased (stimulates thirst preceptor in hypothalamus)

• ICF hypotonic with decreased osmotic pressure -> posterior pituitary secretes more ADH

• Decreased ECF volume -> adrenal glands secrete Aldosterone

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Signs and Symptoms• Acute weight loss• Decreased skin turgor• Oliguria• Concentrated urine• Weak, rapid pulse• Capillary filling time elongated• Decreased BP• Increased pulse• Sensations of thirst, weakness, dizziness, muscle cramps

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Significant Points

•Dehydration – one of most common disturbances in infants and children

•Additional S/S•Sunken eyeballs•Depressed fontanels •Significant wt loss

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Significant Points•Older Adult

•Vein filling better indicator than skin turgor

•Have additional health problems•Take various medications •May ↓ intake to prevent incontinence

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Labs• Increased HCT• Increased BUN out of proportion to Cr• High serum osmolality• Increased urine osmolality• Increased specific gravity• Decreased urine volume, dark color

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Interventions• Major goal prevent or correct abnormal fluid volume status before ARF occurs

• Encourage fluids• IV fluids

• Isotonic solutions (0.9% NS or LR) until BP back to normal, then hypotonic (0.45% NS)

• Monitor I & O, urine specific gravity, daily weights

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Interventions•Monitor skin turgor•Monitor VS and mental status•Evaluation

•Normal skin turgor, increased UO with normal specific gravity, normal VS, clear sensorium, good oral intake of fluids, labs WNL

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Fluid Volume Excess (FVE)•Hypervolemia•Isotonic expansion of ECF caused by abnormal retention of water and sodium

•Fluid moves out of ECF into cells and cells swell

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Causes•Cardiovascular – Heart failure•Urinary – Renal failure•Hepatic – Liver failure, cirrhosis•Other – Cancer, thrombus, PVD, drug therapy (i.e., corticosteriods), high sodium intake, protein malnutrition

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Signs/Symptoms• Physical assessment

• Weight gain• Distended neck veins• Periorbital edema, pitting edema• Adventitious lung sounds (mainly crackles)• Dyspnea• Mental status changes• Generalized or dependent edema

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Signs / Symptoms•VS

•High CVP/PAWP•↑ cardiac output

•Lab data•↓ Hct (dilutional)•Low serum osmolality•Low specific gravity•↓ BUN (dilutional)

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Signs / Sympotms•Radiography

•Pulmonary vascular congestion•Pleural effusion•Pericardial effusion•Ascites

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Interventions• Sodium restriction (foods/water high in sodium)

• Fluid restriction, if necessary• Closely monitor IVF• If dyspnea or orthopnea > Semi-Fowler’s• Strict I & O, lung sounds, daily weight, degree of edema, reposition q 2 hr

• Promote rest and diuresis

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Sources of Water•Oral liquids- ~1300ml/day•Water in foods – ~1000ml/day

•Meats and vegetables ~ 60-90% water•Water from oxidation - ~300ml/day

•10ml/cal of food metabolized •Parenteral fluids•Enteral feedings

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“Normal” Water Loss• Skin

• Perspiration – 0-1000 ml/day• Lungs - ~300-400 ml/day

• Increases with increased respiratory rate or depth or dry climate

• GI Tract - ~ 100-200 ml/day• Kidneys - ~ 1-2 L/day • Insensible loss ~ 600 ml/day (evaporation)• 1ml/kg of body wt/hr in all ages

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Other Causes of Water Loss •Fever•Burns •Diarrhea•Vomiting•N-G Suction•Fistulas •Wound drainage

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Other causes of water loss•Mechanical ventilation•Increased metabolism•Diabetes Insipidus•Uncontrolled DM•ATN

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IV Fluid Replacement• IV Fluid to manage fluid volume imbalances

• Isotonic fluids (approximate normal serum plasma)•Rapid ECF expansion needed •D5W, NS, LR

•Hypotonic fluids•Treatment of cellular dehydration• .45% NS, .2% NS, 2.5% dextrose

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IV Fluid Replacement• Hypertonic

• Treatment of water intoxication• D5 ½ NS, D10W, 3% NS• Shifts fluids from ICF & ECF to intravascular component – expands blood volume

• Now can be removed by kidneys

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Sodium•Normal 135-145 mEq/L•Major cation in ECF•Regulates voltage of action potential; transmission of impulses in nerve and muscle fibers, one of main factors in determining ECF volume

•Elderly at risk•Helps maintain acid-base balance

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Hyponatremia• Results from excess Na loss or water gain

• GI losses, diuretic therapy, severe renal dysfunction, severe diaphoresis, DKA, unregulated production of ADH associated with cerebral trauma, narcotic use, lung cancer, some drugs

• Clinical manifestations• ↓ BP, confusion, headache, lethargy, seizures, decreased muscle tone, muscle twitching and tremors, vomiting, diarrhea, and cramps

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Assessment

•Labs• Increased HCT, K•Decreased Na, Cl, Bicarbonate, UOP with low Na and Cl concentration

•Urine specific gravity ↓ 1.010

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Treatment• Interventions

•Mild•Water restriction if water retention problem• Increase Na in foods if loss of Na

•Moderate• IV 0.9% NS, 0.45% NS, LR

•Severe•3% NS – short-term therapy in ICU setting

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Hypernatremia•Gain of Na in excess of water or loss of water in excess of Na

•Causes•Deprivation of water; hypertonic tube feedings without water supplements, watery diarrhea, greatly increased insensible water loss, renal failure, inadequate blood circulation to kidneys, use of large doses of adrenal corticoids, excess sodium intake

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Signs/Symptoms •Early: Generalized muscle weakness, faintness, muscle fatigue, HA

•Moderate: Confusion, thirst•Late: Edema, restlessness, thirst, hyperreflexia, muscle twitching, irritability, seizures, possible coma

•Severe: Permanent brain damage, hypertension, tachycardia, N & V

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Labs

•Increased serum Na• Increased serum osmolality• Increased urine specific gravity

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Treatment•Free water to replace ECF volume•Gradual lowering with hypotonic saline

•Decrease by no more than 2 mEq/L/hr•Offer fluids at regular intervals•Supplement tube feedings with free water•Teach about foods, medications high in Na•Treat underlying problem

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Evaluation

•Normal serum NA levels•Resolution of symptoms

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Potassium•Normal 3.5-5.5 mEq/L•Major ICF cation•Vital in maintaining normal cardiac and neuromuscular function, influences nerve impulse conduction, important in CHO metabolism, helps maintain acid-base balance, control fluid movement in and out of cells by osmosis

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Hypokalemia•Serum potassium level below 3.5 mEq/L•Causes

•Loss of GI secretions•Excessive renal excretion of K•Movement of K into the cells (DKA)•Prolonged fluid administration without K supplementation

•Diuretics (some)

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Signs/Symptoms

•Skeletal muscle weakness, ↓ smooth muscle function, ↓ DTR’s

•↓ BP, EKG changes, possible cardiac arrest

•N/V, paralytic ileus, diarrhea•Metabolic alkalosis•Mental depression and confusion

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Treatment•Hydrate if low UOP•Oral replacement through high K diet• IV supplementation

•No more than 10 mEq/hr; for child 2-4 mEq/kg/24 h

•No more than 40 mEq/L

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Treatment

•Hypertonic glucose solution•Monitor

• I & O•Bowel sounds•VS, cardiac rhythm•Muscle strength•Digoxin level if necessary

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Hyperkalemia •Serum potassium level above 5.3 mEq/L

•Causes•Excessive K intake (IV or PO) especially in renal failure

•Tissue trauma•Acidosis•Catabolic state

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Signs/Symptoms

•ECG changes – tachycardia to bradycardia to possible cardiac arrest•Tall, tented T waves

•Cardiac arrhythmias•Muscle weakness, paralysis, paresthesia of tongue, face, hands, and feet, N/V, cramping, diarrhea, metabolic acidosis

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Treatment

•10% Calcium gluconate•Sodium bicarbonate•50% glucose solution•Kayexalate PO or PR•Stop K supplements and avoid K in foods, fluids, salt substitutes

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Evaluation

•Normal serum K values•Resolution of symptoms •Treat underlying cause if possible

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Calcium •Normal 4.5-5.5 mEq/L•99% of Ca in bones, other 1% in ECF and soft tissues

•Total Calcium – bound to protein – levels influenced by nutritional state

• Ionized Calcium – used in physiologic activities – crucial for neuromuscular activity

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Calcium•Required for blood coagulation, neuromuscular contraction, enzymatic activity, and strength and durability of bones and teeth

•Nerve cell membranes less excitable with enough calcium

•Ca absorption and concentration influenced by Vit D, calcitriol (active form of Vitamin D), PTH, calcitonin, serum concentration of Ca and Phos

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Causes of Hypocalcemia •Most common – depressed function or surgical removal of the parathyroid gland

•Hypomagnesemia•Hyperphosphatemia•Administration of large quantities of stored blood (preserved with citrate)

•Renal insufficiency•↓ absorption of Vitamin D from intestines

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Signs/Symptoms•Abdominal and/or extremity cramping•Tingling and numbness•Positive Chvostek or Trousseau signs•Tetany; hyperactive reflexes• Irritability, reduced cognitive ability, seizures•Prolonged QT on ECG, hypotension, decreased myocardial contractility

•Abnormal clotting

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Treatment•High calcium diet or oral calcium salts (mild) - √ formulas for calcium content

• IV calcium as 10% calcium chloride or 10% calcium gluconate – give with caution

•Close monitoring of serum Ca and digitalis levels

•↓ Phosphorus levels ↑ Magnesium levels •Vitamin D therapy

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Hypercalcemia•Causes

•Mobilization of Ca from bone•Malignancy•Hyperparathyroidism• Immobilization – causes bone loss•Thiazide diuretics•Thyrotoxicosis•Excessive ingestion of Ca or Vit D

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Signs/Symptoms•Anorexia, constipation•Generalized muscle weakness, lethargy, loss of muscle tone, ataxia

•Depression, fatigue, confusion, coma•Dysrhythmias and heart block•Deep bone pain and demineralization•Polyuria & predisposes to renal calculi•Pathologic bone fractures

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Hypercalcemic Crisis•Emergency – level of 8-9 mEq/L• Intractable nausea, dehydration, stupor, coma, azotemia, hypokalemia, hypomagnesemia, hypernatremia

•High mortality rate from cardiac arrest

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Treatment •NS IV – match infusion rate to amount of UOP

• I&O hourly•Loop diuretics•Corticosteroids and Mithramycin in cancer clients

•Phosphorus and/or calcitonin•Encourage fluids•Keep urine acid

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Evaluation

•Normal serum calcium levels• Improvement of signs and symptoms

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Magnesium•Normal 1.5 to 2.5 mEq/L•Ensures K and Na transport across cell membrane

• Important in CHO and protein metabolism•Plays significant role in nerve cell conduction

• Important in transmitting CNS messages and maintaining neuromuscular activity

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Magnesium•Causes vasodilatation •Decreases peripheral vascular resistance

•Balance - closely related to K and Ca balance

• Intracellular compartment electrolyte•Hypomagnesemia - < 1.5 mEq/L•Hypermagnesemia - > 2.5 mEq/L

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Hypomagnesemia•Causes

•Decreased intake or decreased absorption or excessive loss through urinary or bowel elimination

•Acute pancreatitis, starvation, malabsorption syndrome, chronic alcoholism, burns, prolonged hyperalimentation without adequate Mg

•Hypoparathyroidism with hypocalcemia•Diuretic therapy

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Signs/Symptoms

•Tremors, tetany, ↑ reflexes, paresthesias of feet and legs, convulsions

•Positive Babinski, Chvostek and Trousseau signs

•Personality changes with agitation, depression or confusion, hallucinations

•ECG changes (PVC’S, V-tach and V-fib)

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Treatment•Mild

•Diet – Best sources are unprocessed cereal grains, nuts, legumes, green leafy vegetables, dairy products, dried fruits, meat, fish

•Magnesium salts•More severe

•MgSO4 IM •MgSO4 IV slowly

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Treatment

•Monitor Mg q 12 hr•Monitor VS, knee reflexes•Precautions for seizures/confusion•Check swallow reflex

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Hypermagnesemia•Most common cause is renal failure, especially if taking large amounts of Mg-containing antacids or cathartics; DKA with severe water loss

•Signs and symptoms•Hypotension, drowsiness, absent DTRs, respiratory depression, coma, cardiac arrest

•ECG – Bradycardia, CHB, cardiac arrest, tall T waves

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Treatment

•Withhold Mg-containing products•Calcium chloride or gluconate IV for acute symptoms

• IV hydration and diuretics•Monitor VS, LOC•Check patellar reflexes

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Evaluation

•Serum magnesium levels WNL• Improvement of symptoms

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Phosphorous•Normal 2.5-4.5 mg/dL • Intracellular mineral•Essential to tissue oxygenation, normal CNS function and movement of glucose into cells, assists in regulation of Ca and maintenance of acid-base balance

• Influenced by parathyroid hormone and has inverse relationship to Calcium

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Hypophosphotemia

•Causes•Malnutrition•Hyperparathyroidism•Certain renal tubular defects•Metabolic acidosis (esp. DKA)•Disorders causing hypercalcemia

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Signs/Symptoms

• Impaired cardiac function•Poor tissue oxygenation•Muscle fatigue and weakness•N/V, anorexia•Disorientation, seizures, coma

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Treatment • Closely monitor and correct imbalances

• Adequate amounts of Phos • Recommended dietary allowance for formula-fed infants 300 mg Phos/day for 1st 6 mos. and 500 mg per day for latter ½ of first year

• 1:1 ratio Phos and Ca recommended dietary allowance. Exception is infants, whose Ca requirements is 400 mg/day for 1st 6 mos and 500 mg/day for next 6 months

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Treatment•Treatment of moderate to severe deficiency •Oral or IV phosphate (do not exceed rate of 10 mEq/h)

• Identify clients at risk for disorder and monitor

•Prevent infections•Monitor levels during treatment

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Hyperphosphatemia

•Causes•Chronic renal failure (most common)•Hyperthyroidism, hypoparathyroidism•Severe catabolic states•Conditions causing hypocalcemia

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Signs/Symptoms

•Muscle cramping and weakness•↑ HR•Diarrhea, abdominal cramping, and nausea

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Treatment

•Prevention is the goal •Restrict phosphate-containing foods•Administer phosphate-binding agents •Diuretics•Treat cause•Treatment may need to focus on correcting calcium levels

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Evaluation

•Lab values within normal limits•Improvement of symptoms

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Questions / Comments

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