FLUIDS AND ELECTROLYTES
60% of the weight of a typical adult consists of fluid
Factors that influence the amount of body fluid are age, gender, and body fat
Body fluids is located in two fluid compartments: intracellular space and the extracellular space
The ECF compartment is further divided into the intravascular, interstitial, and transcellular spaces
Loss of ECF into a space that does not contribute to equilibrium between the ICF and ECF is referred to as a third-space fluid shift or third spacing
Early evidence of a third-space fluid shift is a decrease in urine output despite adequate fluid intake
Other signs and symptoms of third spacing that indicate an IVF volume deficit include increased heart rate, decreased BP, edema, increased body weight, decreased CVP, and imbalances in fluid intake and output
Electrolytes in body fluids are active chemicals
Major cations are: sodium, potassium, calcium, magnesium, and hydrogen ions
The major anions are: chloride, bicarbonate, phosphate, sulfate, and proteinate ions
Regulation of Body Fluid Compartments
Osmosis and Osmolality
Osmosis occurs when fluid shifts through the membrane from the region of low solute concentration to the region of high solute concentration until the solutions are of equal concentration
Diffusion Is the natural tendency of a
substance to move from an area of higher concentration to one of lower concentration
FiltrationMovement of water and solutes
occur from an area of high hydrostatic pressure to an area of low hydrostatic pressure
Sodium – Potassium PumpLocated in the cell membrane
and actively moves sodium from the cell into the ECF
Maintaining Fluid and Electrolyte Balance
Homeostasis is a term that indicates the relative stability of the internal environment
Concentration and composition of body fluid must be nearly constant
If a substance must be deficient it must be replaced normally
The kidneys play a major role in controlling all types of balance in fluid and electrolytes
The adrenal glands, through the secretion of aldosterone, also aids in controlling extracellular fluid volume by regulating the amount of sodium reabsorbed by the kidneys
Antidiuretic hormone from the pituitary gland regulates the osmotic pressure of extracellular fluid by regulating the amount of water reabsorbed by the kidney
FLUID VOLUME DEFICITDehydration occurs when the
fluid intake of the body is not sufficient to meet the fluid needs of the body
The goal of treatment is to restore fluid volume, replace electrolytes as needed, and eliminate the cause of the fluid volume deficit
Types of Fluid Volume Deficits1. Isotonic Dehydration – water
and dissolved electrolytes are lost in equal proportion
2. Hypertonic Dehydration – water loss exceeds electrolyte loss, shrinks cells
3. Hypotonic Dehydration – electrolyte loss exceeds water loss, cells swell
Causes of FVDIsotonic dehydration
Inadequate intake of fluids and solutesFluid shifts between compartment
Hypertonic dehydrationExcessive perspirationHyperventilation DiarrheaESRDDiabetes insipidus
Hypotonic dehydrationExcessive fluid replacementRenal failureChronic malnutritionChronic illness
Assessment findingsIncreased pulse rateDecreased BP and orthostatic
(postural) hypotensionDiminished peripheral pulsesFeverDecreased urinary outputDry skinPoor skin turgorDry mouth
ConstipationIncreased rate and depth of
respirationsThirstDecreased body weightIncreased hematocrit
InterventionsMonitor cardiovascular,
respiratory, neuromuscular, renal, integumentary, and gastrointestinal status
Prevent further fluid losses and increase fluid compartment volumes to normal ranges
Monitor intake and output
Provide oral rehydration therapy and IV fluid replacement
Administer medications as prescribed such as antidiarrheal, antimicrobial, antiemetic, and antipyretic medications
Administer oxygen as prescribed
Monitor electrolyte values
FLUID VOLUME EXCESSFluid intake or fluid retention exceeds
the fluid needs of the body
Also called overhydration or fluid overload
The goal of treatment is to restore fluid balance, correct electrolyte imbalances if present, and eliminate or control the underlying cause of the overload
Types of Fluid Volume Excess1. Isotonic Overhydration – known as
hypervolemia, results from excessive fluid in the extracellular fluid compartment, causes circulatory overload and interstitial edema
2. Hypertonic Overhydration – caused by excessive sodium intake
3. Hypotonic Overhydration – water intoxication; electrolyte imbalance due to dilution
CausesIsotonic overhydration
Inadequately controlled IV therapyRenal failureLong term corticosteroid therapy
Hypertonic overhydrationExcessive sodium ingestionRapid infusion of hypertonic saline
Hypotonic overhydration Congestive heart failureSIADHInadequately controlled IV therapy
Assessment findingsBounding, increased pulse rateElevated BPDistended neck and hand veinsElevated CVPDyspneaMoist crackles on auscultationPitting edema in dependent areasSkin pale and cool to touch
Increased motility of the GI tractPolyuriaProjectile vomitingDecreased hematocrit
InterventionsMonitor cardiovascular,
respiratory, neuromuscular, renal, integumentary, and gastrointestinal status
Prevent further fluid overload, and restore normal fluid balance
Administer diuretics as prescribed
Control fluid and sodium intake
Monitor intake, output, and weight
Monitor electrolyte values
DIURETIC
D – diet; increase sodium for all except aldactone
I – intake and output, daily weight
U – undesirable effects: F&E imbalance
R – review HR, BP, and electrolytes
E – elderly careful, evening dose not recommended
T – take with or after meals and in AM
I – increase risk of orthostatic hypotension’ move slowly
C – cancel alcohol, cigarettes
Loop DiureticsInhibits sodium, chloride, and
water reabsorption in the proximal portion of the ascending loop of Henle
Edema associated with CHF, ascites, hypertension (furosemide)
Bumetanide (Bumex, Furosemide (Lasix), Torsemide (Demadex)
ThiazidesIncreases urine output by inhibiting
reabsorption of sodium, chloride, and water in the distal portion of the ascending loop of Henle
Edema associated with CHF, ascites, hypertension
Chlorothiazide (Diuril), Hydrochlorothiazide (Hydrodiuril)
Potassium Sparing DiureticsPromotes excretion of sodium
and water, but retains potassium in the distal renal tubule
Used with loop or thiazide diuretics in treating CHF and hypertension, edema
Spironolactone (Aldactone)
Osmotic DiureticsIncreases osmotic pressure of
glomerular filtrate, thus preventing reabsorption of water
Oliguria, edema, increased ICP, increased IOP
Mannitol (Osmitrol)
AssignmentForm 4 groups, do a drug study
of the chosen class of diuretic, and make your own mnemonic for that chosen class
Be creative in presenting your work, use of powerpoint is not allowed
Presentation will be next week, indicate your reference
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