Chapter 10 : Notes-Altered Fluid, Electrolyte & Acid-Base Balance

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Medical Surgical Nursing-Lemone

Acidosis

The condition in which the hydrogen ion concentration increases above normal (reflected in a pH below 7.35).

Active Transport

Movement of molecules across cell membranes and epithelial membranes against a concentration gradient; requires energy.

Alkalis

Alkalis are bases that accept hydrogen ions in solution.

Alkalosis

The condition where the hydrogen ion concentration decreases below normal (reflected in a pH above 7.45).

Anasarca

Severe, generalized edema.

Anion gap

The difference between the sum of two measured anions, chloride and bicarbonate, and the principal measured cation, sodium.

Arterial blood gas (ABG)

A laboratory test used to evaluate acid-base balance and gas exchange.

Atrial natriuretic peptide (ANP)

A hormone released by atrial muscle cells in response to distention from fluid overload.

Base excess (BE)

A calculated value also known as buffer base capacity. Base excess reflects the degree of acid-base imbalance by indicating the status of the body's total buffering capacity.

Bradycardia

A heart rate of less than 60 beats per minute.

Compartment

A space enclosed by a fibrous membrane or fascia.

Dehydration

Loss of water.

Depolarization

The rapid inflow of sodium ions, causing an electrical change in which the inside of a cell becomes positive in relation to the outside.

Diffusion

The process by which solute molecules move from an area of high solute concentration to an area of low solute concentration to become evenly distributed.

Filtration

The process by which water and dissolved substances (solutes) move from an area of higher hydrostatic pressure to an area of lower hydrostatic pressure.

Fistula

Abnormal opening or passage between two organs or spaces that are normally separated or an abnormal passage to the outside of the body.

Fluid volume deficit (FVD)

A decrease in intravascular, interstitial, and/or intracellular fluid in the body.

Fluid volume excess (FVE)

Excess extracellular fluid resulting from retention of both water and sodium in the body.

Gland

Tissue that produces secretions or synthesizes hormones.

Glucocorticoid

A group of hormones secreted by the adrenal cortex; they regulate carbohydrate levels in the body.

Hemolysis

The process of RBC destruction.

Homeostasis

The body's tendency to maintain a state of physiologic balance in the presence of constantly changing conditions.

Hypovolemia

Decreased circulating blood volume.

Ketoacidosis

A condition of very high blood glucose and insufficient insulin that results in accumulation of ketones and fatty acids in the blood; a form of metabolic acidosis.

Kussmaul's respirations

Deep, rapid respirations associated with compensatory mechanisms.

Orthopnea

Difficulty breathing when supine

Osmosis

The process by which water moves across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
Will continue until concentration = on both sides.

PaCO2

Partial pressure of carbon dioxide in arterial blood.

PaO2

Partial pressuer of oxygen in arterial blood.

Serum bicarbonate

The serum bicarbonate (HCO3-) reflects the renal regulation of acid-base balance. It is often called the metabolic component of arterial blood gases. The normal HCO3- value is 22 to 26 mEq/L.

Stridor

High-pitched, harsh inspiratory sound indicative of upper airway obstruction.

Tetany

Tonic muscular spasms.

Third spacing

The accumulation and sequestration of trapped extra-cellular fluid in an actual or potential body space as a result of disease or injury.

Traction

The application of a straightening or pulling force to return or maintain the fractured bones in normal anatomic position.

Volatile acids

Acids eliminated from th body as gas.

Body Fluid Composition: Water

60% of total body wt (varies with age gender and body fat) so women have more fat so less water.
Intake and output should be about equal.
average is 2500ml over 24-hr
-urine output about 1500ml+urine used to excrete feces, inesensible water losses, perspiration

Body Fluid Composition: Electrolytes

chemical compounds-can be intact or dissociate into particles.
Electrolytes are substances that dissociate in solution to form charged particles called ions.
Functios: assist with regulation of water blance, regulate and maintain acid-base blance, contribute to enzyme reactions, essential for neuromuscular activity.

Cations

positively charged electrolytes (Na, K, Ca, Mg)

Anions

Negatively charged electrolytes (HCO3, HPO4, Cl, SO4)

Body Fluid Distribution

classefied by in or outside of cells ICF and ECF

Intracellular fluid (ICF)

found within cells, essention for normal cell fx, provides medium for metabolic processes.

Extracellular fluid (ECF)

located outside of cells and classified further into locations, Interstitial, intravascular, transcellular.

Interstitial fluid

located in spaces between most of the cells of the body

Intravascular fluid (plamsa)

within arteries, veins and capillaries

Transcellular fluid

urine, digestive secretions; perspiration, cerebrospinal, pleural, synovial, intraocular, gonadal and peridcardial fluids.

Solutes

Overall ICF and ECF identical except some specific electrolytes differ a great deal (see previous pic)
ICF 40% of tbw
total body fluid is 60% of TBW
plasma 5% of TBW-interstitial and transcellular fluid is 15% of TBW, Extracellular fluid is 20% of TBW.

ICF concentrations

High potassium (K+), magnesium (Mg 2+) and phosphate (PO4 2-) as well as other solutes such as glucose and oxygen.

Extracellular electrolytes

Sodium (Na+), chloride (Cl-) and bicarbonate (HC)3-) principalones. High sodium concentration in ECF is essential to regulating body fluid volume. Potassium in ECF is low.

Difference between plasma and interstitial fluid

Minimal

Sodium (Na+)

135-145 mEq/L

Choride (Cl-)

98-106 mEq/L

Bicarbonate (HCO3-)

22-26 mEq/L

Calcium (Ca2+) total

8.5-10.0 mg/dL

Potassium (K+)

3.5-5.0 mEq/L

Phosphate/inorganic phosphorus (PO4 -2)

1.7.2.6 mEq/L (2.5-4.5 mg/dL)

Magnesium (Mg 2+)

1.6-2.6 mg/dL (1.3-2.1 mEq/L

Serum osmolality

275-295 mOsm/kg

Selective permeability

passage of water, oxygen, carbon dioxide and small water soluble molecules but not proteins and other intracellular colloids.

Capillary membranes

separate plasma from interstitail fluid (squamous epithelial cells). Allow solute molecules (glucose, sodium), dissolved gases, water to cross.

Epithelial membranes

separate transcellular fluid from interstitial fluid and plasma (include mucosa of stomach, intestines, gallbladder; pleural, peritoneal, synovial membranes and tubules of kidney

Osmolality

concentration of a solution= #solutes/kg ofwater (by weight). reported in milliosmoles per kilogram (MOsm/kg).
Osmality of ECF depends mainly on sodium consentration. Serum osmolity can be estimated by doubling the serum sodium concentration (about 142 mEq/L) glucose and urea contribute to osmolality of ECF but not as much as sodium.

Osmotic Pressure

Power of solution to draw water across a membrane. Interstitial fluid and intravascular plasm composition about same except higher concentration of proteins in plamsa (esp albumin) exert colloid osmotic pressure (called oncotic pressure) pulling fluid from the interstitial space into the intravascular compartment. OSMOTIC ACTIVITY OF PLASMA PRTOEINS IMPORT TO MAINTAIN BALANCE AND HELP HOLD WATER IN VASCULAR SYSTEM.

Tonicity

Effect a solution's osmotic pressure has on water movement across the cell membrane of cells within that solution.

Isotonic solution

same concentration of solutes as plasma. (cells placed in isotonci solution will either shrink nor swell. Normal saline (o.9%) NaCl solution is isotonic

Hypertonic solutions

Greater concentration of solutes than plasma. if present water is drawn out o the cell causing it to shrink. 3% NaCl is hypertonic

Hypotonic solutions

lower solute concentration than plasma so they will swell. 0.45% NaCl is hypotonic.

Hemolysis

rupture-may occur if cells in extremely hypotonic solution.

Diffusion

2 types: simple and facilitated. Both are trying to establish equal concentrations of the molecules on both sides of a membrane.

Simple

Simple: random movement of particles through solution, ex water, carbon dioxide, oxygen and solutes move between plasma and interstitial space through capillary membrane. water and solutes move into the cell by protein channels or dissolving in the lipid cell membrane.

Facilitated

Facilitatied diffusion(carrier-mediated diffusion)-allows large water-soluble molecules (glucose and amino acids) to diffuse across cell membranes.

Diffusion Rate

influenced by # of factors: concentration of solute, availability of carrier proteins.

FIltration

The process by which water and dissolved substances (solutes) move from an area of higher hydrostatic pressure to an area of lower hydrostatic pressure.
Usually across capillary membranes.
Occurs in the glomerulus of the kidneys and arterial end of capillaries.

Hydrostatic pressure

Created by pumping action of the heart and gravity against the capillary wall. Hydrostatic pressure within the arterial end of the capillary pushes water into the interstitial space. At the venous end of the capillary, the osmotic force of plasma proteins draws fluid back into the capillary.

Active Transport

Allows molecules to move across cell membranes and epithelial membranes against a concentration gradient. ATP and carrier mechanisms is needed. Sodium potassium pump is important example. High concentrations of potassium in intracellular fluids and sodium in extracellular fluids are maintained because cells actively transport potassium from interstital fluid into intracellular fluid.

Body Fluid Regulation

several regulatory mechanisms to balnce fluid intake and excretion: thirst, kidneys, renin-angiotensin-aldosterone mechanism, antidiuretic hormone, and atrial natriuretic peptide.

Thirst

Primary regulator of water intake.
Thirst center-hypothalamus, stimulated when blood volume drops. Very effective regulating extracellular sodium levels.
Incrased Na in ECF increases serum osmolality which stimulates thirst center.
Fluid intake reduces the Na concentration of ECF and lowers serum osmolality. If serum sodium drups then thirst center inhibited.

Practice Alert

Thirst mechanism declines with aging so older adults more vulnerable to dehydration and hyperosmolality. Pts with altered LOC or unable to respond to thrist (intubated, artificially fed) also at risk.

Kidneys

Primary responsible for regulating fluid volume and electrolyte balance by controlling excretion of water and electrolytes.
Adults: 170 L of plasma filtered throug glomeruli daily. About 99% glomerular filtrate reabsorbed only about 1500mL of urine is produced over 24-hr period.

Renin-Angiotensin-Aldosterone System

Helps maintain intravascular fluid balance and blood pressure.
↓ blood flow or bp to kidneys stimulates juxtaglomerular cells of nephrons to produce renin (enzyme). Renin converts angiotensionogen (plasma protein) to angiotensin I. Angiotensin I goes to lungs converted to angiotenesin II by ACE. Angiotensin II raises blood pressure. Angiotensin II also stimulates thirst mechanism to promote fluid intake, it acts on kidneys causing them to retain sodium and water. Angiotensin II stimulates the adrenal cortex to release aldosterone. Aldosterone promotes sodium and water retention in the distal nephron of the kidney restoring blood volume.

Angiotensin

"Angie tenses the angios"
Vasoconstrictor

Aldosterone

"Al Do Save Sodium"

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Renin-angiotensin-aldosterone system

Antidiuretic hormone (ADH)

ADH released by posterior pituitary gland
ADH regulates water excretion from kidneys
Osmoreceptors (hypothalamus) respond to increase in serum osmolality and decreases in blood volume stimulating ADH production and release.
ADH makes distal tubules of kidneys more permeable to water thus increasing water reabsorption.
SO urine output falls, blood volume is restored and serum osmolaility drops as water dilutes body fluids.
ADH also increases to stress situations like nausea, pain, surgery, anesthesia, narcotic, nicotine.
ADH is inhibited by alcohol, certain medications (phenytoin) and increased blood volume and decreased serum osmolality.

ADH release and effect.

ADH release and effect.

ADH release and effect.

ADH release and effect.

Atrial natriuretic peptide (ANP)

Hormone released by atrial muscle cells in response to distension from fluid overload.
Affects several body systems: cardio, renal, neural, GI + endocrine.
Primary Fx: oppose renin-angiotensin-aldosterone system by inhibiting renin secretion and bloocking the secretion and sodium-retaining effects of aldosterone.
ANP-promotes sodium wasting and increased urine output.

Fluid Volume Deficit-older adult

Older adults total body water 10% less.
Lean muscle mass lower (body fat % higher)
Sodium and water regulation less efficient
Renal blood flow and glomerular filtration decline.
Kidneys less able to concentrate urine and conserve sodium+water.
Thirst perception decreases.
VERY EASY TO DEHYDRATE
Risk factors: Undetected fevers, self-dcare deficits, confused, depressed, tube fed, bed rest, certain medications (sedative, tranquilizers, diuretics laxatives), no air conditioning, fear of incontinence, physical disabilities (arthritis or stroke), cognitive impairments.
Recognition: may be m ore difficult look for change in mental status, memory or attention, skin turgor not as reliable but do assess over sternum or inner aspect of thigh. Dry oral mucous membraines, increased tongue furrows, subnormal temp, tachycardia and pinched facial expression.

Fluid Volume Deficit

Decrease in intravascular, interstitial and/or intracellular fluid in body.
Can develop slowly or rapidly. Severe fluid loss, hemorrhage, can lead to shock and cardiovascular collapse.

Fluid Volume Deficit-causes

Excessive loss of GI fluids from vomiting, diarrhea, GI suctioning, intestinal fistualas and intestinal drainage. Other causes: diuretics, renal disorders, endocrine disorders, excessive exercise, hot environment, hemorrhage, chronic abuse of laxaties and/or enemas, inability to access fluids, request or swallow fluids, oral trauma, altered thirst mechanisms.

Hypovolemia

Loss of extracellular fluid volume. Electrolytes often lost with fluid resulting in isotonic fluid volume deficit.
Both water and electrolytes lost the serum sodium levels remain normal but other electrolytes such as potassium may fall. Fluid is drawn into the vascular compartment from the interstiial spaces as body attempts to maintain tissue perfusion.
-regulatory mechanisms are stiumlated to maintain circulation: SNS, thirst mechanism, ADH and aldosterone released.

Third Spacing

shift of fluid from vascular space into area not usefuls for normal physiologic processes like abdomen, bowel, pleural or peritoneal space. Fuid may be trapped within soft tissues following trauma or burns. May be in interstitial tissues and unable to support cardio function.

Difficult to assess as may not be reflected in weight or I&O's. Can lead to irreversible shock and multiorgan failure.

Hypovolemia manifestations

Rapid weight loss: 2% of body weight=mild FVD; 5%=moderate FVD; 8% or > = severe FVD.
Sking turgor diminishes skin will remain elevated when pinched.
Postural or orthostatic hypotension. (drop >15 mmHg in systolic BP when changing from lying to standing)
Venous pressure falls=flat neck veins even when pt recumbent.
Tachycardia; pale cool skin (due to vasoconstriction); decreased urine output. Specific gravity of urine increases as water reabsorbed in tubules.

Diagnostic Tests: Serum Electrolytes

Isotonic fluid deficit: Na normal
Water loss only: Na high
Potassium decrease common.
Picture 194

Hemoglobin and hematocirt

Hematocrit often elevated

Urine specific gravity and osmolality

Both increase due to kidneys conserving water.

FVD signs: Mucous Membranes

• Dry; may be sticky
• ↓tongue size, longitudinal furrows ↑

Central venous pressure (CVP)

CVP is mean pressuer in the superior vena cava or right atrium. It is an accurate assesment of fluid volume status.

Neurologic

• Altered mental status
• Anxiety, restlessness
• Diminished alertness/cognition
• Possible coma (severe FVD)

Integumentary

• Diminished skin turgor
• Dry skin
• Pale, cool extremities

Urinary

• ↓urine output
• Oliguria (severe FVD)
• ↑urine specific gravity

Cardiovascular

• Tachycardia
• Orthostatic hypotension (moderate FVD)
• Falling systolic/diastolic pressure (severe FVD)
• Flat neck veins
• ↓venous filling
• ↓pulse volume
• ↓capillary refill
• ↑hematocrit

Musculoskeletal

• Fatigue

Metabolic Processes

• ↓body temperature (isotonic FVD)
• ↑body temperature (dehydration)
• Thirst
• Weight loss
• 2-5% mild FVD
• 6-9% moderate FVD
• > 10% severe FVD

Fluid Management

Mild: Oral rehydration safest. Adults=1500mL/day or 20mL/kg of IBW. replace gradually.
More severe with electrolyte loss: carb/electrolyte solution (sports drink, ginger aile, pedialyte or rehydralyte.
Severe or unable to ingest fluids: IV Therapy with isotonic solutions, hypotonic solutions, hypertonic solutions.

Isotonic electrolyte solutions

0.9% NaCl or Lactated Ringer's solution. Used to expand plasma volume in hypotensive pts or replace abnormal losses. Lactated Ringer preferred to hep prevent acid-base imbalances.

Hypotonic

5% dextros in 0.45% saline (D5, 1/2; NS) or 0.45% NaCl (o1/2 normal saline or 1/2NS) provide water for total body water deficits. D5W (isotonic in bag) but becomes hypotonic.

Maintenance solutions

0.45% NaCl with or without added electrolytes. 5% dextrose in 0.45% sodium chloride (D5 1/2NS).

Hypertonic Solutions

Assess/Diagnoses and Interventions

Assess: I&O; fluid balance. Acute: hourly I&O.
Urine output of < 30mL/hour REPORT. IS inadequate renal perfusion and increased risk for acute renal failure and inadequate tissue perfusion.
Vital signs, CVP, peripheral pulse volume=q4hrs. Hypotension, tachycardia, low CVP and weak easily obliterated peripheral pulses indicate hypovolemia.
Weigh daily (standard conditions).

Assess/Diagnoses and Interventions

Interventions:
-Administer and monitor intake fluids, id beverage preferences. Oral replacement preferred.
-Administer IV as prescribed with infusion pump. Monitor for indicators of fluid overload if rapid fluid replacemtn is ordered: dyspnea, tachypnea, tachycardia, increased CVP, jugular vein distention, edema. Rapid may lead to hypervolemia yielding pulmonary edema and cardiac failure.
-Monitor lab valuers: electrolytes, serum osmolality, BUN, hematocrit.

Assess/Diagnoses and Interventions: Inneffective Tissue Perfusion

-LOC changes: restless, anxious, confused, agitated may indicate inadequate cerebral blood flow and cirulatory collapes
-Monitor serum creatinine, BUN, cardiac enzymes-report elevated to physician. Elevate levles may be impaired renal function or cardiac perfusion related to cirulatory failure.
-Tun Q 2 hrs. good skin care, monitor skin, keep clen, dry, moisturized.

Risk for Injury-dizzy, loss of balance

-safety precautions
-teach pt and family how to reduce orthostatic hypotension: moving in stages, avoid prolonged standing, rest in recliner rather than bed, use assistive devices.

FVD community-based care

Teach:
=imp 1500mL/day +extra to replace perspiration, fever or diarrhea
-manifestations of imbalance
-prevention: dont exercise during heat, more water during heat, sm volume intake if vomiting, reduce caffience, fruit juices or bouillon rather than large amts of tap water, alternate sources of fluid (geletain, frozen juices, ice cream.

Fluid Volume excess

Results when both water and sodium are retained in body.

Causes

Heart failure, cirrhosis of liver, renal failure, adrenal gland disorders, corticosteroid administration, ,stress conditions causing release of ADH and aldosterone. Excessive intake of sodium, drugs that cause Na retention, administering excess IV sodium-contianing IV fluids.

iatrogenic

Induced by effects of treatment. p. 198

Manifestations

Peripheral edema, or if severe, anascara (severe generalized edema)

Manifestations

Full bounding pulse
distended neck and peripheral veins
incrased central venous pressure (>11-12cm of water)
cough
dyspnea (labored or difficult breathing)
orthopnea (difficult breathing when supine)

Manifestations

Dyspnea at rest
Tachycardia and hypertension
Reduced oxygen saturation
Moist crackles on auscultation of the lungs, pulmonary edema
INcreased urine output (polyuria)
Ascites (excess fluid in the peritoneal cavity)
Decreased hematocrit and BUN
Altered mental status and anxiety
Pulmonary edema.

Complications

CHF potential cause and compication
Pulmonary edema

Management

limit sodium and water intake
administer diuretics

Diagnostics

Serum electrolytes+ osmolality measured but usually normal
Serum hematocrit and hemoglobin-decreased
serum creatinine, BUN and liver enzymes may be ordered to help determine cause of excess

Medications

Loop diuretics (promote excretion of Na, Cl, K, H2O-loop of henle): Furosemide (lasix), Ethacrynic Acid (edecrin), Bumetanide (Bumex), Torsemide (Demadex).

Thiazide-type diuretics (promote excretion of Na, Cl, K, H2O-distal tubule): Indapamide (Lozol), Bendroflumethiazide (Naturetin), Chlorothiazide(Diuril), Hydrochlorothiazide (HydroDiuril, Oretic), several others p. 199

Potassium sparing diuretics (excretion Na and water by inhibiting sodium potassium exchange in distal tubule): Spironolactone (Aldactone), Amiloride HCL (Midamor, Triamterene (Dyrenium)

Diuretics used to enhance renal function and tx vascular fluid overload and edema.
Common Side effects: orthostatic hypotension, dehydration, electrolyte imbalnce, hyperglycemia.

Patient teaching about diuretics

Drug increase amt an frequency of urination
take even if feel well
take in am
change position slowly
report dizziness; trouble breathing; swelling face, hands or feet
weigh daily report sudden gains and losses
avoid salt
if drug increases potassium loss eat high in potassium foods: OJ and banans,
no salt substitute if you take potassium sparing.

Treatment

Fluid Management-may be restricted
Dietary Management-sodium restrictions. (high Na foods: lunch meat, bacon, cheese, dry cereal, canned soup, popcorn, ketchup, pickles, seafood.
Oral care may help with fluid restriction. (brush 2x/day; oral moisturizing q 2-4 hrs)

Note

Report to PCP gain of more than 5lb in a week or less

Health History

risk factors: meds, heart failure, acute or chronic renal or endocrine disease; recent illness, changes in diet or meds, recent wt gain, persistent cough, SOB, swelling of feet, ankles, difficulty sleeping when lying down.

Physical Assessment

Wt; vitals, peripheral pulses, capillary refill; jugular vein distention; edema; lung sounds (crackles or wheezes), dyspnea, coug, sputum; urine output; mental status

Nursing Diagnosis/Interventions: Fluid Volume Excess

Fluid Volume Excess
-diuretics
-fluid restrictions
-assess vitals, heart sounds, volume of peripheral arteries.
Hypervolemia can cause hypertension, bounding peripheral pulses and third heart sound (s3)
-Assess edema-usually dependent portions of body, perioribital edema indicates more generalized edema
-daily wts. wt gain 2.2 lbs=1L of fluid gain
-administer oral fluids-record liquids used
-oral hygiene q 2 hours
-teach pt Na restrictions
-administer diuretics and monitor response. loop or high-ceiling diuretics like furosemide can lead to manifestations of hypovolemia +electrolyte imbalance
-report significant changes in serum electrolytes or osmolality.

Practice alert

Assess urine output hourly. Note output less than 30mL/hour or positive fluid balance on 24-hour total intake and output sheet. CHF and inadequate renal perfusion may result in decreased urine output and fluid retention.

Nursing Diagnosis/Interventions: Risk for Impaired Skin Integrity

-frequen skin assessment, esp pressure areas and bony prominences
-reposition q 2 hours
-egg-crate mattress or alternating pressure mattress, foot cradle, heel protectors, other

Nursing Diagnosis/Interventions: Impaired Gas Exchange

-ausculate lungs-crackles, wheezes (indicate pulmonary congestion and edema; ausculate heart for extra heart sounds. (gallop rhythm (s3) may indicate diastolic overloading of the ventricles secondary to fluid volume excess). http://www.youtube.com/watch?v=D6DSKN3jsKE
-Fowler's position for dypnea or orthopnea. (fowlers increases lung expansion)
http://www.medtrng.com/posturesdirection.htm
-monitor O2 sats (<92%-95%); ABG's for impaired gas exchange (PaO2 < 80mmgHg). administer O2 if indicated-it promotes gas exchange improving tissue oxygenation.

Community-based care

-teach manifestations of exccess fluid, when to contact pcp about meds (when to take, adverse effects); diet restrictions; water restrictions, monitoring wt, ways to decrease dependent edema: position changes, no restrictive clothing, no crossing legs, support hose/stockings, elevation of feet and leggs; protecting edematous skin )no barefoot, good fitting shoes; pillows or recliner to sleep to relieve orthopnea.

Low-Sodium Diet

-low Na helps body excrette excess Na and water
-body needs less than 1/10 tsp salt /day
-1/3 salt from added; 1/4 from processed food/ rest in water and foods high in Na
-Na used in preservatives, leavegning agents, flavor enhances
-Na in nonprescription drugs (analgesics cough meds, laxatives, antacids) toothpastes, mouthwashes
-low na not sodium free
-desire for salt will decrease
-salt, monosodium glutamate, baking soda and baking powder have Na
-read labels
-herbs, spices, lemon juice, vinegar and wine instead

Sodium

-most plentiful electrolyte in ECF
-normal 135-145 mEq/L
-500mg/day sufficient to mt needs; CDC 1500mg most americans have 3500mg/day

Hyponatremia

-Serum sodium < 135 mEq/L (may not see manifestations until 125 mEq/L
-Causes: diuretics, kidney disorders, adrenal insufficiency, vomiting, diarrhea, gastrointestinal suction, GI tube irrigation with water instead saline, repeated water enemas, excessive sweating, loss of skin surface (burns) and 3rd spacing.
--decrease in serum osmolality, ceslls swell
-Manifestations: early( muscle cramps, weakness, fatigue),
below 120 mEq/L: headache, depression, dulled sensorium, personality changes, irritability, lethargy, hyperreflexia, muscle twitching and tremos.
If very low coma likley
- decreased sodium osmolality, decreased hematocrit and BUN, weight loss, lethargy, stupor, coma, anorexia, nausea, vomiting, diarrhea, hypotension, shock

Diagnostics

Serum sodium and osmolality decreased
24-hr urine: evaluate sodium excretion
Differential: Increased: SIADH; Decreased: loss of isotonic fluids-sweating, diarrhea, vomiting, 3rd space fluid accumulation)

Medications

-Sodium-containing fluids
-Isotonic Ringer's solution or isotonic saline (0.9% NaCl); cautious Iv 3% or 5 % NaCl in pts with low plasma sodium levels (110-115 mEq/L)
-Loop diuretics with normal or excess ECF volume
-drugs to tx cause of hyponatremia

Fluid and Dietary Management

Mild: increase foods high in Na; fluid restriction

Health History

Current manifestations (nausea, vomiting, abdominal discomfort, muscle weakness, headache), duration, precipitating factors (heavy perspiration, vomiting, diarrhea); chronic diseases -heart or renal failure, cirrhosis of liver, endocrine disorders, meds.

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