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