Fluid & electrolytes
Prepared by:
Maria Carmela L. Domocmat, RN, MSN
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Did you know?
● The total amount of water in the body of an average adult is 37 litres.
● Human brains are 75% water.
● Human bones are 25% water.
● Human blood is 83% water.
Factors affecting body fluids
• Age
• Gender
• Body fat
FACTORS AFFECTING BODY FLUIDS
1. AGE - Older adults have less water content than younger adults because of muscle mass loss and decreased ratio of lean body mass to total body weight.
2. GENDER - Males have more water content than females because of increased stature and lean body mass. Females have more body fats.
3. BODY FAT - contain little water
Water, Electrolyte
• Of the 40 liters of water in the body of an average adult male, about two-thirds is intracellular, and one-third is extracellular
Fluid Compartments
Composition of Body Fluids
• Water is the universal solvent
• Solutes are broadly classified into
▫ Electrolytes
inorganic salts, all acids and bases, some proteins
▫ Nonelectrolytes
glucose, lipids, creatinine, urea
• Electrolytes have greater osmotic power than nonelectrolytes
• Water moves according to osmotic gradients
Fluid & Elec
Composition
Electrolyte Composition of Body Fluids
Continuous
Mixing of Body
Fluids
Water intake and output
Water Balance
Water Balance and ECF Osmolality
• To remain properly hydrated, water intake must equal water output
• Water intake sources
▫ Ingested fluid (60%) and solid food (30%)
▫ Metabolic water or water of oxidation (10%)
intake output
• Oral fluids
• Solid foods
• Metabolism
• Others
▫ Parenteral fluids
▫ Enemas
▫ Irrigating fluids
• Urine
• Insensible fluid loss
▫ Perspiration
▫ Feces
▫ Vaporization from lungs
• Others
▫ Emesis
▫ Drainage from fistula
Water Balance
• urine production is most important in the regulation of water balance
Water Intake and Output
• Water output
▫ Urine (60%) and feces (4%)
▫ Insensible losses (28%), sweat (8%)
• Increases in plasma osmolality trigger thirst and release of antidiuretic hormone (ADH)
Regulation of Water Output
1. KIDNEY
• kidney excrete 1-2 L/day
• Obligatory urine output/day = 400-600mL depending on fluid intake
• What if you have less than 400mL output in 24hrs?
▫ effect: retention of waste products
▫ can lead to lethal electrolyte imbalances, acidosis and toxic buildup of nitrogen.
.
2. INSENSIBLE WATER LOSS
• Water loss from skin, lungs and stool is 15-20 mL/kg/day in healthy adult.
• Excessive insensible water loss result in more hypertonic ECF with smaller volume
• If this loss is not balanced by intake, the hypertonic and dehydration can lead to hypernatremia (elevated serum level).
.
Regulation of Water Output
• Dehydration
• osmotic pressure increases in extracellular fluids
• osmoreceptors in hypothalamus stimulated
• hypothalamus signals posterior pituitary to release ADH
• urine output decreases
• Excess Water Intake
• osmotic pressure decreases in extracellular fluids
• osmoreceptors stimulated in hypothalamus
• hypothalamus signals posterior pituitary to decrease ADH output
• urine output increases
Regulation of Water Intake
• The hypothalamic thirst center is stimulated: • (increase in osmotic pressure of extracellular fluid stimulates
osmoreceptors in thirst center)
▫ 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
Regulation of Water Intake
• Thirst is quenched as soon as we begin to drink water
• water is absorbed • osmotic pressure of extracellular fluid returns to
normal • Feedback signals that stimulate nerve impulses that
inhibit thirst center include: ▫ Drinking - moistening of the mucosa of the mouth and
throat ▫ distension of the stomach by water (activation of
stomach and intestinal stretch receptors)
Regulation
of Water
Intake:
Thirst
Mechanism
REGULATORY PROCESSES OF FLUID
AND ELECTROLYTE BALANCE
1. FILTRATION( SOLVENT FLOW)
• movement of water through cells and blood vessels because of hydrostatic pressure, that is from greater amount of pressure to membrane with lesser pressure.
CLINICAL FUNCTION AND
SIGNIFICANCE Blood pressure is a hydrostatic filtering force that
moves whole blood from the heart to tissue area where exchange of water, nutrients and waste products occur when blood arrives at the tissue capillary.
CLINICAL FUNCTION AND
SIGNIFICANCE
2. DIFFUSION (SOLUTE FLOW)
Solutes move or spread from areas of high concentration to areas of low concentration until the particles are evenly distributed throughout a space.
If the membrane is impermeable to substance, it is "helped" across by carrier proteins - the process
called facilitated diffusion.
2. DIFFUSION (SOLUTE FLOW)
CLINICAL SIGNIFICANCE
• Diffusion is important in control and transport of gases and in the movement of most electrolytes, atoms, and molecules through cell membrane.
• Unlike capillaries, cell membranes are selective.
• They permit some substances while inhibit movement of other substances.
• Ex. Even though glucose is higher in ECF, it cannot pass through the cell without the help of insulin.
2. DIFFUSION (SOLUTE FLOW)
3.OSMOSIS (WATER FLOW)
The movement of water across cell membrane in the
direction where there is a high concentration of solute but lower concentration of water until both spaces contain same proportion of solutes and solvent.
A simple rule to remember is: SALT SUCKS Salt is a solute. When it is concentrated inside or outside the cell, it
will suck the water in its direction.
3.OSMOSIS (WATER FLOW)
2. Tonicity determines the direction of
water flow
CLINICAL SIGNIFICANCE AND
FUNCTION
• The thirst mechanism is how osmosis helps maintain balance.
• When a person loses body water through sweats and most solutes
remain in
• ECF volume decreases that lead to increase osmolarity(solute
concentration).
CLINICAL SIGNIFICANCE AND
FUNCTION
• The cells in the thirst center shrinks as water moves to the
hypertonic ECF(higher solute conc.) cells in the thirst center shrinks
as water moves to the hypertonic ECF(higher solute conc.).
• The shrinking of cells trigger a person to drink enough water to
restore amount of water lost thorough sweats and therefore restore
ECF normal fluid osmolarity(fluid volume.
CLINICAL SIGNIFICANCE AND
FUNCTION
Regulation
of Water
Intake:
Thirst
Mechanism
Movement of Fluids
Between Compartments • Net movements
of fluids between compartments result from differences in hydrostatic and osmotic pressures
4. ACTIVE TRANSPORT
movement of a solute across the cell
membrane with expenditure of energy
(ATP) from high to low concentration or low to high concentration
4. ACTIVE TRANSPORT
CLINICAL SIGNIFICANCE
Cells use active transport to
control cell volume.
All cells function best when their
internal environments are
maintained separately from
the changes occurring in the
ECF environment.
Hormonal regulation
FLUID AND ELECTROLYTE BALANCE
Hormones secreted by the adrenal cortex is either stimulated by decreased level of Na+ in ECF or increased Na+ level in urine.
Hormones
1. Aldosterone
2. Antidiuretic hormone (ADH) or vasopressin
3. Natriuretic peptides (NPs)
a. Aldosterone
• Protects Na+ balance by preventing Na+ loss.
• Because Na+ exerts osmotic (water pulling) pressure, water attempts to follow Na+ in proportionate amount. As a result this Na+ -water relationship and aldosterone secretion helps regulate water balance.
Aldosterone
b. Anti-diuretic hormone
• vasopressin
• In an increased blood Na+ level( increased osmolarity) result in shrinkage of cell and triggers ADH release from posterior pituitary gland. ADH acts on kidney tubules and collecting ducts making them more permeable to water. As a result more water is reabsorbed and returned to the blood making it more dilute.
Influence and Regulation of ADH
• Water reabsorption in collecting ducts is proportional to ADH release
• Low ADH levels produce dilute urine and reduced volume of body fluids
• High ADH levels produce concentrated urine
• Hypothalamic osmoreceptors trigger or inhibit ADH release
• 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
c. Lymph
• extra fluid that leaks from the capillaries.
• It is returned from the systemic circulation by lymph vessels to prevent blood volume deficits and edema in the interstitial spaces
d. Natriuretic peptides
• hormones secreted by special cells that line the heart's atria and ventricles in response to increased blood volume and pressure, which stretch the heart tissue.
• NP binds to the receptor sites in the nephrons, creating effects that oppose renin-angiotensin system.
• When either ANP or BNP is secreted, kidney reabsorption of Na+ is inhibited.
• The outcome is increased urine output with high Na+ content which result in decreased circulating volume and decreased blood osmolarity
Figure 26.10
Mechanisms
and
Consequences
of ANP Release
Pathway of RAAS
Disorders of Water Balance
Fluid Imbalances Dehydration Hypovolemia Hypervolemia Water intoxication
Disorders of Water Balance:
Dehydration • Water loss exceeds water intake and the body is
in negative fluid balance
• Causes include:
▫ hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, and diuretic abuse
Disorders of Water Balance:
Dehydration • Signs and symptoms:
▫ cottonmouth, thirst, dry flushed skin, and oliguria
• Prolonged dehydration may lead to weight loss,
fever, and mental confusion
• Other consequences include hypovolemic shock
and loss of electrolytes
Disorders of Water Balance:
Dehydration Excessive loss of H2O from
ECF
1 2 3 ECF osmotic
pressure rises Cells lose H2O
to ECF by
osmosis; cells
shrink
(a) Mechanism of dehydration
• Renal insufficiency or an extraordinary amount of water ingested quickly can lead to cellular overhydration, or water intoxication
• ECF is diluted – sodium content is normal but excess water is present
• The resulting hyponatremia promotes net osmosis into tissue cells, causing swelling
• These events must be quickly reversed to prevent severe metabolic disturbances, particularly in neurons
Disorders of Water Balance:
Hypotonic Hydration
Figure 26.7b
Disorders of Water Balance:
Hypotonic Hydration
Excessive H2O enters
the ECF
1 2 ECF osmotic
pressure falls
3 H2O moves into
cells by osmosis;
cells swell
(b) Mechanism of hypotonic hydration
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Clinical Correlates of Dehydration
Severity Fluid Deficit in mL/kg (percent body wt)*
Signs
Infants Adolescents
Mild 50 (5%) 30 (3%) Slightly dry buccal mucous membranes, increased thirst, slightly decreased urine output
Moderate 100 (10%) 50–60 (5–6%) Dry buccal mucous membranes, tachycardia, little or no urine output, lethargy, sunken eyes and fontanelles, loss of skin turgor
Severe 150 (15%) 70–90 (7–9%) Same as moderate plus a rapid, thready pulse; no tears; cyanosis; rapid breathing; delayed capillary refill; hypotension; mottled skin; coma
*Standard estimates for children between infancy and adolescence have not been established. For children between these age ranges, clinicians must estimate values between those for infants and those for adolescents based on clinical judgment.
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Dehydration • Loss of body fluids increased
concentration of solutes in the blood and a rise in serum Na+ levels
• Fluid shifts out of cells into the blood to restore balance
• Cells shrink from fluid loss and can no longer function properly
Clients at Risk •Confused
•Comatose
•Bedridden
•Infants
•Elderly
•Enterally fed
What Do You See?
• Irritability
•Confusion
•Dizziness
•Weakness
•Extreme thirst
• urine output
•Fever
•Dry skin/mucous membranes
•Sunken eyes
•Poor skin turgor
•Tachycardia
Management
• Fluid restoration
▫ Oral rehydration
▫ IV rehydration
• Correction of underlying problem
▫ Antiemetic
▫ Antidiarrheal
▫ Antibiotics
▫ Antipyretics
• Fluid Replacement - oral or IV
over 48 hrs.
• Monitor symptoms and vital
signs
• Maintain I&O
• Maintain IV access
• Daily weights
• Skin and mouth care
Composition of Appropriate Oral
Rehydration Solutions
Solution Carbo-hydrate (g/dL)
Sodium (mEq/L)
Potassium (mEq/L)
Base (mEq/L)
Osmo-lality
Pedialyte 2.5 45 20 30 250
Infalyte 3 50 25 30 200
Rehydralyte 2.5 75 20 30 310
WHO/UNICEF* 2 90 20 30 310
* World Health Organization/United Nations Children's Fund
Composition of Inappropriate Oral
Rehydration Solutions
Solution Carbohydrate (g/dL)
Sodium (mEq/L)
Potassium (mEq/L)
Base (mEq/L)
Osmolality
Apple juice 12 0.4 26 0 700
Ginger ale 9 3.5 0.1 3.6 565
Milk 4.9 22 36 30 260
Chicken broth
0 2 3 3 330
Hypovolemia • Isotonic fluid loss
from the extracellular space
• Can progress to hypovolemic shock
• Caused by:
▫ Excessive fluid loss (hemorrhage)
▫ Decreased fluid intake
▫ Third space fluid shifting
What Do You See? • Mental status
deterioration
• Thirst
• Tachycardia
• Delayed capillary refill
• Orthostatic hypotension
• Urine output < 30 ml/hr
• Cool, pale extremities
• Weight loss
What Do We Do? • Fluid replacement
• Albumin replacement
• Blood transfusions for hemorrhage
• Dopamine to maintain BP
• MAST trousers for severe shock
• Assess for fluid overload with treatment
Hypervolemia • Excess fluid in the extracellular compartment
as a result of fluid or sodium retention, excessive intake, or renal failure
• Occurs when compensatory mechanisms fail to restore fluid balance
• Leads to CHF and pulmonary edema
What Do You See?
• Tachypnea
• Dyspnea
• Crackles
• Rapid, bounding pulse
• Hypertension
• S3 gallop
• Increased CVP, pulmonary artery pressure and pulmonary artery wedge pressure (Swan-Ganz)
• JVD
• Acute weight gain
• Edema
Edema • Fluid is forced into tissues by the hydrostatic
pressure
• First seen in dependent areas
• Anasarca - severe generalized edema
• Pitting edema
• Pulmonary edema
Disorders of Water Balance: Edema
• Atypical accumulation of fluid in the interstitial space, leading to tissue swelling
• Caused by anything that increases flow of fluids out of the bloodstream or hinders their return
• 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
• 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
Edema
• 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
• Interstitial fluid accumulation results in low blood pressure and severely impaired circulation
Management
• Restriction of Sodium and fluids
• Monitor vital signs
• Hourly I&O
• Breath sounds
• Monitor ABGs and labs
• Elevate HOB and give O2 as ordered
• Maintain IV access
• Skin & mouth care
• Daily weights
• Promote urine output
▫ Diuretics
▫ ACE inhibitors, ARBs (angiotensin II receptor blockers), low-dose beta-blockers, aldactone antagonists
Water Intoxication
• Hypotonic extracellular fluid shifts into cells to attempt to restore balance
• Cells swell
Water Intoxication
• Causes:
▫ SIADH
▫ Rapid infusion of hypotonic solution
▫ Excessive tap water NG irrigation or enemas
▫ Psychogenic polydipsia
What Do You See?
• Signs and symptoms of increased intracranial
pressure
▫ Early: change in LOC, N/V, muscle weakness,
twitching, cramping
▫ Late: bradycardia, widened pulse pressure,
seizures, coma
What Do We Do? • Prevention is the best
treatment
• Assess neuro status
• Monitor I&O and vital signs
• Fluid restrictions
• IV access
• Daily weights
• Monitor serum Na+
• Seizure precautions
Volume depletion
• Postural hypotension
• Tachycardia
• Absence of JVP @ 45o
• Decreased skin turgor
• Dry mucosae
• Supine hypotension
• Ascites
• Organ failure
Volume overload
• Hypertension
• Tachycardia
• Raised JVP / gallop rhythm
• Edema
• Pleural effusions
• Pulmonary edema
• Oliguria
• Organ failure
ASSESSMENT OF FLUID AND
ELECTROLYTE BALANCE
1. History data – Gordon’s Functional Health Pattern
a. INTAKE AND OUTPUT
exact intake and output volume.
amount of fluids and foods ingested
to determine amount of osmolarity.
b. MEDICATIONS
check laxatives, diuretics with dosage and the length of time taken and adherence with drug regimen. Misuse and over use of these
drugs can lead to serious imbalance.
c. WEIGHT daily weight measurement and body weight changes,
thirst or excessive drinking, exposure to hot environments, and presence of disorders such as kidney and endocrine diseases.(DM, Addison's disease, Cushing's and diabetic insipidus).
d. Level of consciousness awareness of time, place and person. confusion
associated with electrolyte imbalance.
PHYSICAL ASSESSMENT
a. Hydration alert, moist eyes and mucous membranes. b. Urine output nearly the same with amount
ingested with urine specific gravity of 1.015.
c. Good skin turgor
Pinch a fold of skin in areas that have little fat tissue such as over the sternum, forehead or back of hand. Folded skin should return immediately to its original shape. Decreased turgor is a sign of dehydration when the fold slowly rebounds. (tenting) Older person is hard to assess because of loss of skin elasticity related to aging.
• Check for dryness of skin including nose, eyes, conjunctiva and mucous membranes. A dry, sticky, cottony mouth, the absence of tears, weight loss and decreased urine output all indicate decreased fluid volume.
d. NEUROLOGIC AND BEHAVIORAL ASSESSMENT
In hypertonic states, neuron shrinkage may induce nervous excitability, hyperactivity and convulsions, coma and death.
Muscle tone and strength, movement, coordination and tremors
e. CARDIAC SYSTEM
Heart rate, strength of contractions and presence of
dysrhythmias
f. GASTROINTESTINAL SYSTEM
Peristalsis may indicate changes of excitable membrane function. Decreased or increased motility
g. INSENSIBLE WATER LOSS
Fluid loss from wounds, gastric or intestinal drainage, hemorrhage and other body secretions.
h. Previous Findings
Mental status, physical exam, and laboratory data. Fluid and electrolyte imbalance can occur quickly, be familiar with the patient's baseline assessment data to detect changes.
3. PSYCHOSOCIAL ASSESSMENT
Depressed clients may refuse fluids.
Clients with bulimia or anorexia nervosa may abuse laxatives or may induce vomiting.
Alcohol or drug abuse