Fluid and Electrolytes PDF

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Fluid and Electrolytes: Balance and Disturbance Fluid and Electrolyte Balance •

Necessary for life, homeostasis

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Nursing role: help prevent, treat fluid, electrolyte disturbances

Fluid •

Approximately 60% of typical adult is fluid – Varies with age, body size, gender

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Intracellular fluid

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Extracellular fluid – Intravascular: the fluid within the blood vessels e.g. plazma – Interstitial: fluid surrounds the cell (e.g. lymph – Transcellular: cerebrospinal, pericardial, synovial, intraocular, pleural, sweat and digestive secretion

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“Third spacing”: loss of ECF into space that does not contribute to equilibrium

Third spacing  Third spaces are extra-cellular body spaces where fluid can accumulate  This accumulated fluid is useless to the body  Unavailable for use as reserve fluid  Unable to transport nutrients  Common locations for third space fluid to accumulate  Tissue spaces (edema)  Abdomen (ascites)  Pleural spaces (pleural effusion)  Pericardial space (pericardial effusion)  Electrolytes •

Active chemicals that carry positive (cations), negative (anions) electrical charges – Major cations: sodium, potassium, calcium, magnesium, hydrogen ions – Major anions: chloride, bicarbonate, phosphate, sulfate, and proteinate ions

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Electrolyte concentrations differ in fluid compartments

Regulation of Fluid

Regulation of Fluid •

Osmosis: area of low solute concentration to area of high solute concentration

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Diffusion: solutes move from area of higher concentration to one of lower concentration

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Filtration: movement of water, solutes occurs from area of high hydrostatic pressure to area of low hydrostatic pressure

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Active transport: physiologic pump that moves fluid from area of lower concentration of one of higher concentration

Active Transport •

Physiologic pump that moves fluid from area of lower concentration to one of higher concentration

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Movement against concentration gradient

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

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Requires adenosine (ATP) for energy

Question •

Tell whether the following statement is true or false:

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Osmosis is the movement of a substance from an area of higher concentration to one of lower concentration.

Answer •

False.

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Rationale: Diffusion is the movement of a substance from an area of higher concentration to one of lower concentration. The concentration of dissolved substances draws fluid in that direction. Osmosis is the movement of fluid, through a semipermeable membrane, from an area of low solute concentration to an area of high solute concentration until the solutions are of equal concentration.

Routes of Gains and Losses •

Gain – Dietary intake of fluid, food or enteral feeding Ingested fluid (60%) and solid food (30%) – Metabolic water or water of oxidation (10%) – Parenteral fluids

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Loss – Kidney: urine output – Skin loss: sensible, insensible losses – Lungs – GI tract – Other – Urine (60%) and feces (4%) – Insensible losses (28%), sweat (8%)

Water Intake and Output

Question •

What is the average daily urinary output in an adult?

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0.5 L

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1.0 L

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1.5 L

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2.5 L

Answer •

C. 1.5 L

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Rationale: Vital to the regulation of fluid and electrolyte balance, the kidneys normal filter 170 L of plasma every day in the adult, while excreting only 1.5 L of urine.

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Regulation of Water Intake The hypothalamic thirst center is stimulated: – By a decline in plasma volume of 10%–15% – By increases in plasma osmolality of 1–2% – Via baroreceptor input, angiotensin II, and other stimuli

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Thirst is reduced as soon as we begin to drink water

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Feedback signals that inhibit the thirst centers include: – Moistening of the mucosa of the mouth and throat

– Activation of stomach and intestinal stretch receptors Regulation of Water Output •

Obligatory water losses include: – Insensible water losses from lungs and skin – Water that accompanies undigested food residues in feces

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Obligatory water loss reflects the fact that: – Kidneys excrete 900-1200 mOsm of solutes to maintain blood homeostasis – Urine solutes must be flushed out of the body in water

Influence and Regulation of ADH •

Water reabsorption in collecting ducts is proportional to ADH release

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Low ADH levels produce dilute urine and reduced volume of body fluids

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High ADH levels produce concentrated urine

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Hypothalamic osmoreceptors trigger or inhibit ADH release

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Factors that specifically trigger ADH release include prolonged fever; excessive sweating, vomiting, or diarrhea; severe blood loss; and traumatic burns

Mechanisms and Consequences of ADH Release

Fluid Volume Imbalances •

Fluid volume deficit (FVD): hypovolemia

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Fluid volume excess (FVE): hypervolemia

Fluid Volume Deficit •

Loss of extracellular fluid exceeds intake ratio of water – Electrolytes lost in same proportion as they exist in normal body fluids

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Dehydration: loss of water along with increased serum sodium level – May occur in combination with other imbalances

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Dehydration – Causes: fluid loss from vomiting, diarrhea, GI suctioning, sweating, decreased intake, inability to gain access to fluid – Risk factors: diabetes insipidus, adrenal insufficiency, osmotic diuresis, hemorrhage, coma,

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Manifestations: rapid weight loss, decreased skin turgor, oliguria, concentrated urine, postural hypotension, rapid weak pulse, increased temperature, cool clammy skin due to vasoconstriction, lethargy, thirst, nausea, muscle weakness, cramps

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Laboratory data: elevated BUN in relation to serum creatinine, increased hematocrit

– Serum electrolyte changes may occur •

Medical management: provide fluids to meet body needs – Oral fluids – IV solutions (isotonic electrolytes solution; e.g. ringer lactate solution or 0.9 sodium chloride)

Fluid Volume Deficit - Nursing Management •

I&O, VS

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Monitor for symptoms: skin and tongue turgor, mucosa, UO, mental status

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Measures to minimize fluid loss

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Oral care

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Administration of oral fluids

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Administration of parenteral fluids

Question •

What is a major indicator of extracellular FVD?

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Full and bounding pulse

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Drop in postural blood pressure

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Elevated temperature

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Pitting edema of lower extremities

Answer •

B. Drop in postural blood pressure

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Rationale: FVD signs and symptoms include acute weight loss; decreased skin turgor; oliguria; concentrated urine; orthostatic hypotension due to volume depletion; a weak, rapid heart rate; flattened neck veins; increased temperature; thirst; decreased or delayed capillary refill; decreased central venous pressure; cool, clammy, pale skin related to peripheral vasoconstriction; anorexia; nausea; lassitude; muscle weakness; and cramps. Clinical manifestations of FVE result from expansion of the ECF and include edema, distended neck veins, and crackles (abnormal lung sounds).

Fluid Volume Excess •

Due to fluid overload or diminished homeostatic mechanisms

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Risk factors: heart failure, renal failure, cirrhosis of liver

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Contributing factors: excessive dietary sodium or sodium-containing IV solutions

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Manifestations: edema, distended neck veins, abnormal lung sounds (crackles), tachycardia, increased BP, pulse pressure and CVP, increased weight, increased UO, shortness of breath and wheezing

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Medical management: directed at cause, restriction of fluids and sodium, administration of diuretics

Edema: is defined as a palpable swelling caused by a increase in interstitial fluid volume Edema, other than localized edema, does not become clinically apparent until the interstitial volume has increased by 2.5 to 3 liters Disorders of Water Balance: Edema •

Atypical accumulation of fluid in the interstitial space, leading to tissue swelling

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Caused by anything that increases flow of fluids out of the bloodstream or hinders their return

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Factors that accelerate fluid loss include: – Increased blood pressure, capillary permeability – Incompetent venous valves, localized blood vessel blockage – Congestive heart failure, hypertension, high blood volume

Edema •

Hindered fluid return usually reflects an imbalance in colloid osmotic pressures

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Hypoproteinemia – low levels of plasma proteins – Forces fluids out of capillary beds at the arterial ends – Fluids fail to return at the venous ends – Results from protein malnutrition, liver disease, or glomerulonephritis

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Blocked (or surgically removed) lymph vessels: – Cause leaked proteins to accumulate in interstitial fluid – Exert increasing colloid osmotic pressure, which draws fluid from the blood

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Interstitial fluid accumulation results in low blood pressure and severely impaired circulation

Fluid Volume Excess - Nursing Management •

I&O and daily weights; assess lung sounds, edema, other symptoms; monitor responses to medications- diuretics

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Promote adherence to fluid restrictions, patient teaching related to sodium and fluid restrictions

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Monitor, avoid sources of excessive sodium, including medications

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Promote rest

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Semi-Fowler’s position for orthopnea

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Skin care, positioning/turning

Electrolyte Imbalances •

Sodium (Na= 135-145) : hyponatremia, hypernatremia

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Potassium (k= 3.5-5.0) : hypokalemia, hyperkalemia

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Calcium (Ca= 9-11): hypocalcemia, hypercalcemia

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Magnesium (Mg= 1.8-3): hypomagnesemia, hypermagnesemia

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Phosphorus (P=3.0-4.5): hypophosphatemia, hyperphosphatemia

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Chloride (Cl= 96-106): hypochloremia, hyperchloremia

Hyponatremia •

Serum sodium less than 135 mEq/L

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Causes:

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 Adrenal insufficiency,  Water intoxication,  SIADH (syndrome of inappropriate adh secretion) or  Losses by vomiting, diarrhea, sweating, diuretics Manifestations:

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 Poor skin turgor,  Dry mucosa,  Headache,  Decreased salivation,  Decreased bp,  Nausea,  Abdominal cramping,  Neurologic changes Medical management:

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 Water restriction,  Sodium replacement 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

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Causes:

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 Excess water loss,  Excess sodium administration,  Diabetes insipidus,  Heat stroke,  Hypertonic IV solutions Manifestations:

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 Thirst;  Elevated temperature;  Dry, swollen tongue;  Sticky mucosa;  Neurologic symptoms; restlessness; weakness Note: thirst may be impaired in elderly or the ill

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Medical management:

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 Hypotonic electrolyte solution or D5W Nursing management:     

Assessment and prevention, Assess for OTC (Over the counter drugs) Sources of sodium, Offer and encourage fluids to meet patient needs, Provide sufficient water with tube feedings

Hypokalemia •

Below-normal serum potassium (...