chapter 14 fluid and electrolytes: balance and...

Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins

Revised by Randa Albusoul

Chapter 14

Fluid and Electrolytes: Balance and

Disturbance


Fluid and Electrolyte Balance

• Necessary for life, homeostasis (maintenance of a constant internal equilibrium in a biologic system that involves positive and negative feedback mechanisms).

• Nursing role: prevent, identify, respond to, and treat fluid and electrolyte disturbances.


Fluid (Amount and Composition of Body Fluids)• Approximately 60% of a typical adult is fluid

– Varies with age, gender, and body fat.

1-Intracellular fluid (2/3) [skeletal muscle mass].


2-Extracellular fluid (1/3) [transports electrolytes, carries other

substances, such as enzymes and hormones].

A-Intravascular (plasma) [3L of the average 6 L of blood

volume is made up of plasma] The remaining 3L is

erythrocytes, leukocytes, and thrombocytes].

B-Interstitial

(fluid surround the cells 11-12L)

Include lymph


C-Transcellular (1L) [contained within epithelial lined spaces]

(eg. cerebrospinal, pericardial, synovial, intraocular, and

pleural fluids, digestive secretions, sweat).


Serum vs. plasma

• Plasma = blood – cells (RBCs, WBCs, platelets)

• Serum = plasma – clotting factors (eg. Fibrinogen)

• Blood serum is mostly water

that is dissolved with proteins

, hormones, minerals and

carbon dioxide


• Body fluid normally moves between the two major spaces (ICF and intravascular) in an effort to maintain an equilibrium between the spaces.

• Loss of fluids into a space that does not contribute to

equilibrium is referred to as a third-space fluid shift

• Early evidence of a third-space fluid shift is a decrease in

urine output, decrease blood pressure, increase heart

rate, edema, increase body weight, imbalance in fluid

intake and output

• Third-space shift occurs in patients with hypocalcemia,

decrease iron, severe liver disease, hypothyroidism,

immobility, burns, cancer, malabsorption


Active chemicals that carry positive (cations), negative (anions)

electrical charges (mEq/L)

Major cations: sodium, potassium, calcium, magnesium,

hydrogen ions

Major anions: chloride, bicarbonate, phosphate, sulfate, and

proteinate ions

Electrolyte concentrations differ in fluid compartments

Electrolytes

What is major electrolyte present in

ICS and ECS?


Regulation of Fluid

• Movement of fluid through capillary walls depends on

– Hydrostatic pressure: the pressure exerted by the fluids on walls of blood vessels

– Osmotic pressure: the pressure exerted by protein in plasma

Direction of fluid movement depends on differences of hydrostatic, osmotic pressure


Regulation of Fluid

• Osmosis: fluid shifts from the area of low solute concentration to area of high solute concentration

• Tonicity is the ability of all the solutes to cause an osmotic driving force that promotes water movement from one compartment to another. (cellular hydration and cell size).

• Osmotic diuresis is the increase in urine output caused by the excretion of substances such as glucose, mannitol..

• Diffusion: solutes move from area of higher concentration

to one of lower concentration

• Filtration: movement of water, solutes occurs from area of

high hydrostatic pressure to area of low hydrostatic

pressure


Active Transport• Movement against concentration gradient

• implies that energy must be expended for the movement to occur against a concentration gradient.

• Sodium-potassium pump: maintains higher concentration of extracellular sodium, intracellular potassium

• Requires adenosine (ATP) for energy


Routes of Gains and Losses

• Gain

– Dietary intake of fluid, food or enteral feeding

– Parenteral fluids


Routes of Gains and Losses (cont’d)

• Loss

– Kidney: urine output (1ml/kg/h) (1-2 L/day)

– Skin loss: sensible, insensible losses (500ml); fever increase it

– Lungs: water vapor (300ml); increase respiratory rate, dry climate

– GI tract (100-200ml); fistula increase it


Laboratory Tests for Evaluating Fluid Status

• Osmolality is the concentration of fluid that affects the movement of water between fluid compartments by osmosis.

• Serum osmolality primarily reflects the concentration of sodium, blood urea nitrogen (BUN), and glucose.

• Urine osmolality is determined by urea, creatinine, and uric acid.

• serum osmolality is 270 to 300 mOsm/kg, and normal urine osmolality is 200 to 800 mOsm/kg

• Urine specific gravity measures the kidneys’ ability to excrete or conserve water. (1.010 to 1.025).

What effects serum and urine osmolality? (see Table 13-3)


Urinary specific gravity (SG) is a measure of the

concentration of solutes in the urine. It measures the ratio

of urine density compared with distilled water density and

provides information on the kidney's ability to

concentrate urine.


• BUN is made up of urea, which is an end product of the metabolism of protein (diet, muscle) by the liver. (10 to 20 mg/dL).

• Creatinine is the end product of muscle metabolism. (0.7 to 1.4 mg/dL). Best than BUN for determining renal function because it does not change with protein intake

• Hematocrit measures the volume percentage of red blood cells (erythrocytes) in whole blood and normally ranges from 42% to 52% for males and 35% to 47% for females.

• Urine sodium (75 to 200 mEq/24)


Homeostatic Mechanisms

• Kidney Functions filter plasma

• Heart and Blood Vessel Functions circulates blood under sufficient pressure

• Lung Functions exhalation

• Pituitary Functions antidiuretic hormone (ADH) control water excretion by urine

• Adrenal Functions Aldosterone; Na retention (water retention), K loss

• Parathyroid Functions Parathyroid hormone (PTH); regulate Calcium and phosphate balance; ca reabsorption from renal tubules, absorption from intestine, and bone reabsorption

• Baroreceptors located in left atrium, carotid, aortic arch, if blood volume decrease stimulate sympathetic nervous system, increase heart rate, release aldosterone

• Renin–Angiotensin–Aldosterone System Angiotensin II, vasoconstriction, stimulate thirst, increase ADH

• Antidiuretic Hormone and Thirst if blood volume decrease or osmolality increase the thirst centers are stimulated in hypothalamus

• Osmoreceptors on hypothalamus sense Na concentration, release ADH from pituitary

• Release of Atrial Natriuretic Peptide hormones affect fluid volume and cardiovascular function through excretion of Na, vasodilation, and oppose renin-angiotensine-aldosterone system


Gerontologic Considerations

• Reduced homeostatic mechanisms: cardiac, renal, respiratory function

• Decreased body fluid percentage

• Alteration in fluid or electrolytes in older adults may produce serious symptoms, for example fluid deficit may cause delirium in older adults


Electrolyte Imbalances

• Sodium: hyponatremia, hypernatremia (135-145 mEq/L)

• Potassium: hypokalemia, hyperkalemia (3.5-5 mEq/L)

• Calcium: hypocalcemia, hypercalcemia (8.5-10.5 mEq/L)

• Magnesium: hypomagnesemia, hypermagnesemia (1.3-2.3 mg/dL)

• Phosphorus: hypophosphatemia, hyperphosphatemia (2.5-4.5 mg/dL)

• Chloride: hypochloremia, hyperchloremia (97-107 mEq/L )

The concentration of electrolyte in the blood


Hyponatremia

• Serum sodium less than 135 mEq/L

• Causes: adrenal insufficiency, water intoxication, SIADH (syndrome of inappropriate secretion of antidiuretic hormone) or losses by vomiting, diarrhea, sweating, diuretics

• Manifestations: poor skin turgor, dry mucosa, headache, decreased salivation, decreased BP, nausea, abdominal cramping, neurologic changes (altered mental status, status epilepticus, coma cellular swelling in brain (edema) from

hyponatremia )

• Medical management: water restriction, sodium replacement (no more than 12 mEq/L q 24 hours) can give Ringer’s lactate or isotonic saline example, .9% sodium chloride

• Nursing management: assessment and prevention, dietary sodium and fluid intake, identify and monitor at-risk patients, effects of medications (diuretics, lithium)


Hypernatremia• Serum sodium greater than 145mEq/L

• Causes: excess water loss, excess sodium administration, diabetes insipidus, heat stroke, hypertonic IV solutions

• Manifestations: thirst; elevated temperature; dry, swollen tongue; sticky mucosa; neurologic symptoms; restlessness; weakness

• Note: thirst may be impaired in elderly or the ill

• Medical management: hypotonic electrolyte solution or D5W

• Nursing management: assessment and prevention, assess for OTC medication with sodium, offer and encourage fluids to meet patient needs, provide sufficient water with tube feedings


Hypokalemia• Below-normal serum potassium (<3.5 mEq/L), may

occur with normal potassium levels with alkalosis due to shift of serum potassium into cells

• Causes: GI losses, medications, alterations of acid-base balance, hyperaldosterism, poor dietary intake

• Manifestations (when less than 3 mEq/L): fatigue, anorexia, nausea, vomiting, dysrhythmias, muscle weakness and cramps, paresthesia, glucose intolerance (decrease insulin

secretion), decrease Deep Tendon Reflexes

• Medical management: increased dietary potassium, potassium replacement, IV for severe deficit (2 mEq/L KCL)

• Nursing management: assessment, severe hypokalemia is life-threatening (Death by respiratory or cardiac arrest), monitor ECG and ABGs, dietary potassium, nursing care related to IV potassium administration


Hyperkalemia

• Serum potassium greater than 5.0 mEq/L

• Causes: usually treatment related, impaired renal function, hypoaldosteronism, tissue trauma, burns, acidosis

• Manifestations: cardiac changes and dysrhythmias (may lead to

arrest), muscle weakness with potential respiratory impairment, paresthesias, anxiety, GI manifestations

• Medical management: monitor ECG, limitation of dietary potassium, cation-exchange resin (Kayexalate), IV sodium bicarbonate (decrease metabolic acidosis) , IV calcium gluconate (antagonized the action of hyperkalemia on heart), regular insulin and hypertonic dextrose IV, -2 agonists (move K into cells), dialysis


Hyperkalemia (cont’d)

• Nursing management: assessment of serum potassium levels, monitor medication affects, dietary potassium restriction/dietary teaching for patients at risk

• Hemolysis of blood specimen or drawing of blood above IV site may result in false laboratory result

• Salt substitutes, medications may contain potassium

• Potassium-sparing diuretics may cause elevation of potassium

– Should not be used in patients with renal dysfunction

• Pseudohyperkalemia: causes: improper collection or transport of the blood, traumatic venipuncture, tight tourniquet


Hypocalcemia

• Serum level less than 8.5 mg/dL, must be considered in conjunction with serum albumin level

• Causes: hypoparathyroidism, malabsorption (decrease vit D), pancreatitis (break down proteins and lipid), alkalosis, massive transfusion of citrated blood (treated with a citrate especially of sodium

or potassium to prevent coagulations combine with Ca), renal failure (high

phosphate), medications

• Manifestations: tetany, circumoral numbness, paresthesias, hyperactive DTRs, Trousseau’s sign, Chvostek's sign, seizures, respiratory symptoms of dyspnea and laryngospasm, abnormal clotting, anxiety


Trousseau’s Sign

Chvostek's sign


Hypocalcemia (cont’d)

• Medical management: IV of calcium gluconate, calcium and vitamin D supplements; diet

• Nursing management: assessment, severe hypocalcemia is life-threatening, weight-bearing exercises to decrease bone calcium loss, patient teaching related to diet and medications, and nursing care related to IV calcium administration (not with normal saline .9% because it increase ca loss, not with phosphate,

bicarbonate precipitation)


Hypercalcemia

• Serum level above 10.5 mg/dL

• Causes: malignancy and hyperparathyroidism, bone loss related to immobility

• Manifestations: muscle weakness, incoordination, anorexia, constipation, nausea and vomiting, abdominal and bone pain, polyuria, thirst, ECG changes (shortening QT

interval, and ST segment), dysrhythmias

• Medical management: treat underlying cause, fluids, decrease Ca intake, furosemide, phosphates, calcitonin, biphosphonates

• Nursing management: assessment, hypercalcemic crisis has high mortality, encourage ambulation, fluids of 3 to 4 L/d, provide fluids containing sodium unless contraindicated, fiber for constipation, ensure safety


Hypomagnesemia

• Serum level less than 1.3 mg/dL, evaluate in conjunction with serum albumin (1/3 bind to albumin)

• Causes: alcoholism, GI losses, enteral or parenteral feeding deficient in magnesium, medications, rapid administration of citrated blood; contributing causes include diabetic ketoacidosis, sepsis, burns, hypothermia

• Manifestations: neuromuscular irritability, muscle weakness, tremors, athetoid movements (يتلوى), ECG changes and dysrhythmias, alterations in mood and level of consciousness

• Medical management: diet, oral magnesium, magnesium sulfate IV (give slowly and assess V/S)


Athetoid movements


Hypomagnesemia (cont’d)

• Nursing management: assessment, ensure safety, patient teaching related to diet, medications, alcohol use, and nursing care related to IV magnesium sulfate

• Hypomagnesemia often accompanied by hypocalcemia

– Need to monitor, treat potential hypocalcemia

• Dysphasia common in magnesium-depleted patients

– Assess ability to swallow with water before administering food or medications


Hypermagnesemia

• Serum level more than 2.3 mg/dL

• Causes: renal failure, diabetic ketoacidosis, excessive administration of magnesium

• Manifestations: flushing, lowered BP, nausea, vomiting, hypoactive reflexes, drowsiness, muscle weakness, depressed respirations, ECG changes, dysrhythmias

• Medical management: IV calcium gluconate (antagonizes the

effect on Mg on heart and neuromascular system), loop diuretics, IV NS or RL (help in excretion in pt with normal renal function), hemodialysis

• Nursing management: assessment, do not administer medications containing magnesium, patient teaching regarding magnesium containing OTC medications


Hypophosphatemia

• Serum level below 2.5 mg/dL

• Causes: alcoholism, refeeding of patients after starvation, heat stroke, respiratory alkalosis, hyperventilation, diabetic ketoacidosis, hepatic encephalopathy, major burns, hyperparathyroidism, low magnesium, low potassium, diarrhea, vitamin D deficiency, use of diuretic and antacids

• Manifestations: neurologic symptoms, confusion, muscle weakness deficiency in ATP, tissue hypoxia help release O2 from hemoglobin, muscle and bone pain, increased susceptibility to infection

• Medical management: oral or IV phosphorus replacement

• Nursing management: assessment, encourage foods high in phosphorus, gradually introduce calories for malnourished patients receiving parenteral nutrition, prevent infection


Hyperphosphatemia

• Serum level above 4.5 mg/dL

• Causes: renal failure, excess phosphorus, excess vitamin D, acidosis, hypoparathyroidism, chemotherapy

• Manifestations: hypocalcemia, soft-tissue calcifications there is reciprocal relationship between phosphorus and calcium

• Medical management: treat underlying disorder, phosphate-binding gels or antacids, loop diuretics, NS IV, dialysis

• Nursing management: assessment, avoid high-phosphorus foods; patient teaching related to diet, phosphate-containing substances, signs of hypocalcemia


Hypochloremia

• Serum level less than 97 mEq/L is produced in stomach

• Causes: Addison’s disease, reduced chloride intake table salt, GI loss, diabetic ketoacidosis, excessive sweating, fever, burns, medications, metabolic alkalosis, gastric suctioning, vomiting and diarrhea, low sodium intake

• Loss of chloride occurs with loss of other electrolytes, potassium, sodium

• Manifestations: agitation, irritability, weakness, hyperexcitability of muscles, dysrhythmias, seizures, coma

• Medical management: replace chloride-IV Normal saline 0.9% or 0.45%

• Nursing management: assessment electrolytes, ABGs, avoid free water, encourage high-chloride foods, patient teaching related to high-chloride foods


Hyperchloremia• Serum level more than 107 mEq/L, may come with

hypernatremia, and bicarbonate loss

• Causes: excess sodium chloride infusions with water loss, head injury, hypernatremia, loss of bicarbonate, dehydration, severe diarrhea from dehydration, respiratory alkalosis, metabolic acidosis, hyperparathyroidism, renal problem

• Manifestations: tachypnea, lethargy, weakness, rapid, deep respirations, hypertension, cognitive changes

• Normal serum anion gap = (([Na+] + [K+]) − ([Cl−] + [HCO3−]))

• Medical management: restore electrolyte, fluid and acid-base balance, hypotonic solution, sodium bicarbonate helps chloride

excretion by kidney, ringer lactate lactate converts to bicarbonate in the liver ,

diuretics to eliminate chloride, Na and Cl are restricted

• Nursing management: assessment v/s, ABGs, patient teaching related to diet and hydration

chapter 14 fluid and electrolytes: balance and...

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