fluid, electrolyte, and acid- base balance. functions of water in the body transporting nutrients to...
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Functions of Water in the Body
Transporting nutrients to cells and wastes from cells Transporting hormones, enzymes, blood platelets,
and red and white blood cells Facilitating cellular metabolism and proper cellular
chemical functioning Acting as a solvent for electrolytes and
nonelectrolytes Helping maintain normal body temperature Facilitating digestion and promoting elimination Acting as a tissue lubricant
Two Compartments of Fluid in the Body
Intracellular fluid (ICF) — fluid within cells (70%)
Extracellular fluid (ECF) — fluid outside cells (30%) Includes intravascular and interstitial
fluids
Variations in Fluid Content
Healthy person — total body water is 50% to 60% of body weight
An infant has considerably more body fluid and ECF than an adult More prone to fluid volume deficits
Sex and amount of fat cells affect body water Women and obese people have less body
water
Electrolytes
Ions Cations — positive charge Anions — negative charge
Homeostasis — total cations equal to total anions
Fluid Balance
Solvents — liquids that hold a substance in solution (water)
Solutes — substances dissolved in a solution (electrolytes and non-electrolytes)
FLUID AND ELECTROLYTE MOVEMENT
Osmosis – Fluid passes from areas of low solute concentration to areas of high solute concentration
Diffusion – tendency of solutes to move freely from areas of high concentration to low concentration (down hill)
Active Transport – requires energy to move through a cell membrane from area of lesser concentration to one of greater concentration
Filtration – passage of fluid through a permeable membrane. Movement is from high to low pressure
COMMON ELECTROLYTES
Sodium (Na++)Functions Regulates volume of body fluids Maintains water balance Regulates ECF Influences ICF Generation and transmission of nerve
impulses Sodium-Potassium pump
POTASSIUM (K+)
Major cation in ICF Reciprocal to sodium Functions
Regulates cellular enzyme activity and water content
Transmission of nerve and muscle impulses Metabolism of proteins and carbohydrates Regulation of acid-base balance by cellular
exchange with H+
CALCIUM (Ca++)
Most abundant electrolyte in body 99% found in bones and teeth Functions Nerve impulse transmission and blood
clotting Catalyst for muscle contraction Thickness and strength of of cell
membranes
MAGNESIUM (Mg++)
Second most important cation in ICF Functions
Metabolism of carbohydrates and proteins Vital enzyme actions Protein and DNA synthesis Maintaining intracellular levels of Potassium Maintain electrical activity in nervous tissue and
muscle tissue membranes
CHLORIDE (Cl-)
Chief extracellular anion Functions
Works with sodium to maintain osmotic pressure of blood
Regulates acid-base balance Buffering action during O2/CO2 exchange Production of Hydrochloric acid in
digestion
BICARBONATE (HCO3-)
Major chemical base buffer Found in ECF and ICF Function
Essential for acid base balance. Works with carbonic acid to make up the body’s acid base buffer system
PHOSPHATE (PO4-)
Major anion in body cells Buffer in ICF and ECF Functions
Maintains body’s acid-base balance Cell division and transmission of heredity Chemical reactions use of Vit B, CHO
metabolism, nerve and muscle action
OTHER ELECTROLYTES
Sulfate Anion ICF Excreted in the kidney
Lactic acid Anion Facilitates diffusion to and from
capillaries
Osmolarity of a solution
Isotonic — same concentration of particles as plasma
Hypertonic — greater concentration of particles than plasma
Hypotonic — lesser concentration of particles than plasma
Fluid Imbalances Involves either volume or distribution of water
or electrolytes Hypovolemia — deficiency in amount of water
and electrolytes in ECF with near normal water/electrolyte proportions
Dehydration — decreased volume of water and electrolyte change
Third-space fluid shift — distributional shift of body fluids into potential body spaces
Fluid Volume Excess Hypervolemia — excessive retention of
water and sodium in ECF Overhydration — above normal amounts
of water in extracellular spaces Edema — excessive ECF accumulates in
tissue spaces Interstitial-to-plasma shift — movement of
fluid from space surrounding cells to blood
Electrolyte Imbalances
Hyponatremia and hypernatremia Hypokalemia and hyperkalemia Hypocalcemia and hypercalcemia Hypomagnesemia and
hypermagnesemia Hypophosphatemia and
hyperphosphatemia
Nursing Assessments
Identify patients at risk for imbalances. Determine a specific imbalance is
present and its severity, etiology, and characteristics.
Determine effectiveness of plan of care.
Parameters of Assessment
Nursing history and physical assessment
Fluid intake and output Daily weights Laboratory studies
Lab Studies to Assess for Imbalances
Complete blood count Serum electrolytes Urine pH and specific gravity Arterial blood gases
Risk Factors for Imbalances
Pathophysiology underlying acute and chronic illnesses
Abnormal losses of body fluids Burns Trauma Therapies that disrupt fluid and
electrolyte balance
Nursing Diagnoses Related to Imbalances
Excess fluid volume Deficient fluid volume Risk for imbalanced fluid volume
Expected Outcomes
Maintain approximate fluid intake and output balance (2500mL intake and output over 3 days)
Maintain urine specific gravity within normal range (1.010 to 1.025)
Practice self-care behaviors to promote balance
Implementing
Dietary modifications Modifications of fluid intake Medication administration IV therapy Blood and blood products replacement TPN
Intravenous Therapy
Vascular access devices Peripheral venous catheters Midline peripheral catheter Central venous access devices Implanted ports
Vein Site Selection
Accessibility of a vein Condition of vein Type of fluid to be infused Anticipated duration of infusion
MECHANISMS OF HOMEOSTASIS
Kidneys Cardiovascular system Lungs Adrenal Glands Thyroid Gland Parathyroid Gland Gastrointestinal tract Nervous system
Primary Organs of Homeostasis
Kidneys normally filter 170 L plasma, excrete 1.5 L urine.
Cardiovascular system pumps and carries nutrients and water in body.
Lungs regulate oxygen and carbon dioxide levels of blood.
Primary Organs of Homeostasis, continued
Adrenal glands help body conserve sodium, save chloride and water, and excrete potassium.
Thyroid gland increases blood flow in body and increases renal circulation.
ACID – BASE BALANCE
Acid contains hydrogen atoms that can be released Acidosis too many circulating H+ ions
Base accepts hydrogen atoms Alkalosis not enough H+ ions in the ECF
pH is the unit of measure used to describe acid base balance
Buffer prevents ECF from becoming too acidic or too alkaline
BUFFER SYSTEMS
Carbonic Acid-Sodium Bicarbonate System
Phosphate Buffer System Protein Buffer System
IMBALANCE IN ACID – BASE BALANCE
Respiratory Alkalosis Deficit in carbonic acid in the ECF
Respiratory Acidosis Excess in carbonic acid in the ECF
Metabolic Alkalosis Excess of bicarbonate in the ECF
Metabolic Acidosis Deficit of bicarbonate in the ECF
EXERCISE #1 For the patient with hyperkalemia related to
decreased renal excretion secondary to potassium conserving diuretic therapy” an appropriate expected outcome would be which of the following?
a) Bowel motility will be restored within 24 hours after beginning supplemental K+
b) ECG will show no cardiac arrhythmias within 48 hours after removing salt substitutes, coffee, tea and other K+ rich foods from the diet
c) ECG will show no cardiac arrhythmias within 24 hours after beginning supplemental K+
d) Bowel motility will be restored within 24 hours after eliminating salt substitutes, coffee, tea, and other K+ rich foods from the diet
EXERCISE #2
Which of the following nursing diagnoses would you expect to find based on the effects of fluid and electrolyte imbalance on human functioning?
a) Constipation related to immobilityb) Pain related to surgical incisionc) Altered thought processes related to cerebral
edema, including mental confusion and disorientation
d) Health risk for infection related to inadequate personal hygiene
EXERCISE #3
A nurse who diagnoses a patient as having “fluid volume excess” related to compromised regulatory mechanisms (kidneys) may have been alerted by which of the following symptoms?
a) Muscular twitching
b) Distended neck veins
c) Fingerprinting over sternum
d) Nausea and vomiting