1. Intravenous Therapy Module
Fluid and Electrolyte Balance

2. Body Fluids Comprise 45-77% of the body’s weight Vary depending on Age
Lean body mass
sex

3. Body Fluids Contain these dissolved substances Electrolytes Gases
Nonelectrolytes

4. Body Fluids Divided into two main compartments Intracellular (ICF)
Extracellular (ECF)

5. Body Fluids ICF – fluid within the cells (64-70%)
ECF – all fluid outside the cells (30-36%)
Intravascular fluid (plasma)
Interstitial fluids (fluid surrounding tissue cells and includes lymph)

6. Water as a Percentage of Body Weight
Compartment
Infant %
Adult
Man %
Woman %
Elderly
Person %
Extracellular
Intravascular 4 5
Interstitial 25 11 10 15
Intracellular 48 45 35
Total-body water 77 60 50
Source: Taylor, Lillis & LeMone, page 1273.

7. Electrolytes
Electrically charged ions which are dissolved in a solution
positive charged ions – cations
negative charged ions – anions
Homeostasis requires an equal number of total cations and anions
When not in balance, the person is at risk for alterations in health

8. Cations
Anions

9. Electrolytes Major intracellular electrolytes
Potassium – major cation of ICF; has a reciprocal relationship with sodium
Magnesium – 2nd. Most important cation in ICF; mostly found in cells of heart, bone, nerve and muscle tissues
Phosphate – Major anion in body cells; acts as a buffer anion in both ICF and ECF
Sulfate – anion found primarily within cells and is associated with cellular protein

10. Electrolytes Major extracellular electrolytes
Sodium – Chief electrolyte of ECF; moves across cell membranes by active transport
Chloride – Chief extracellular anion; found in blood, interstitial fluid, and lymph
Bicarbonate – the major chemical base buffer within the body; found in both ECF and ICF

11. Fluid and Electrolyte Movement
Transportation of materials between the fluid compartments is accomplished through
Osmosis
Diffusion
Active transport
Filtration

12. Osmosis Major method of transporting water
Water shifts and thus balance depends on osmosis
Water passes from an area of lesser concentration to one of greater concentration

13. Osmolarity Concentration of particles in a solution
Osmolarity of plasma ( mOsm/L)
3 types of solutions
Isotonic – same osmolarity as plasma
Hypotonic – less osmolarity than plasma
Hypertonic – greater osmolarity than plasma25 30 35

14. Diffusion Tendency of solutes and gases to move throughout a solvent
Solute and gases move from an area of greater concentration to an area of lower concentration
O2 and CO2 exchange in the lung’s alveoli and capillaries by diffusion

15. Active Transport
Requires energy for the movement of substances through a cell membrane
Moves from an area of lesser concentration to an area of higher concentration
Amino acids, glucose, Na+, K+, Ca2+, H, Cl-, PO4- and Mg2+ are believed to use
active transport

16. Filtration
Moves from an area of high pressure to one of lower pressure
Controls the movement of body fluid between the intravascular and interstitial space through two opposing forces
Colloid osmotic pressure (oncotic pressure)
Hydrostatic pressure

17. Filtration Pressure Difference between
Colloid osmotic pressure (certain substances which have a high molecular weight hold fluid in the vessels)
example: plasma proteins
AND
Hydrostatic pressure (force exerted by a fluid against the container wall)
example: pressure of plasma and blood cells in the capillaries

18. Filtration
Facilitates fluid exit from the arterioles (+ pressure) into the interstitial compartment and eventually into the venules (- pressure)
Also involved in the proper functioning of the glomeruli of the kidneys

19. Body Water Balance Result of physiologic homeostatic responses to
Fluid gains (oral intake & cellular catabolism)
Fluid losses (urine, evaporation from the skin, vapor loss through the lungs, and feces)

20. Thirst Major regulator of intake Stimulated by receptors in the CNS
Individuals ingest fluids when these receptors are activated
Illness, an altered LOC, or a depressed thirst response (as in the aged) may result
in hypovolemia – Fluid Volume Deficit

21. Kidneys Primary organ of fluid balance
Excrete end products of cellular metabolism
Eliminate excess fluids
Normally filter 170L of plasma daily in the adult

22. Kidneys
Must produce a minimum of mL of urine to clear the blood of wastes
Usual daily amount of urine production varies from 1-2 liters

23. Urine Production Influenced by two hormonal regulatory systems
Antidiuretic hormone (ADH) – stored and released by the pituitary gland
Aldosterone – mineral corticoid secreted by the adrenal cortex

24. Antidiuretic Hormone
Maintains osmotic pressure of the cells by controlling renal water retention or excretion
When osmotic pressure of the ECF is > cells – ADH secretion is increased,
causing renal retention of water
When osmotic pressure of the ECF is < cells – ADH secretion is decreased, causing renal excretion of water

25. Antidiuretic Hormone Other conditions that can stimulate the
secretion of ADH (retention of water)
Hemorrhage
Decreased cardiac output
Trauma
Pain
Fear
Surgery
dehydration

26. Drugs that increase the secretion of ADH
Antidiuretic Hormone
Drugs that increase the secretion of ADH
Morphine
Barbiturates
Nicotine
Some anesthetics
Some tranquilizers

27. Antidiuretic Hormone Can be inhibited by Alcohol
Decreased concentration of ECF
Hypervolemic states

28. Aldosterone Regulated by renin-angiotension system
When blood flow to the kidney is decreased, the glomerulus of the nephron releases the enzyme renin
Circulating renin converts a plasma protein in the liver into the vasoconstrictor angiotensin I
When angiotensin I enters the lungs, it is converted into antiotensin II
Angiotensin II stimulates the adrenal cortex to increase aldosterone secretion
Leads to ECF volume expansion

29. Aldosterone
Regulates fluid volume by stimulating the kidneys to reabsorb Na+ and water
Na+ is exchanged for K+ or H+
K+ and H+ are thus affected by aldosterone

30. Aldosterone Secretion is increased in response to Decreased Na+
Increased extracellular K+
Hypovolemia
Stress states

31. Assessment of Fluid and Electrolyte Status
Comparison of total I & O
Urine volume and concentration
Skin and tongue turgor
Degree of moisture in oral cavity
Body weight
Thirst
Neuromuscular irritability
Tearing and salivation
Appearance and temperature of skin
Facial appearance
Edema
Vital signs
Neck and hand vein filling
Results of hemodynamic monitoring
Source: Metheny, N. (2000). Fluid and Electrolyte Balance.

32. Quick Assessment Guide for Fluid Imbalance
Body System Assessed
Fluid Volume
Excess
Deficit
Neurologic
Changes in orientation; Confusion
Cardiovascular
Bounding pulse;
Increased pulse rate;
Jugular vein distention;
Overdistended hand veins that are slow to empty (>3s)
Decreased pulse rate;
Decreased BP;
Narrow pulse pressure;
Slow hand filling (>3s)
Respiratory
Moist crackles;
Respiratory rate > 20 bpm;
Dyspnea
Pulmonary edema
Lungs clear
Source: Phillips, L. (2001). Manual of I.V. Therapeutics (3rd. Edition), Philadelphia: F. A. Davis

33. Quick Assessment Guide for Fluid Imbalance
Body System Assessed
Fluid Volume
Excess
Deficit
Integument
Warm, moist skin;
Fingerprinting over sternum
Decreased turgor over sternum and forehead;
Decreased skin temperature
Eyes
Periorbital edema (suggests significant fluid retention)
Dry conjunctive;
Sunken eyes;
Decreasing tearing
Mouth
Sticky, dry mucous membranes
Source: Phillips, L. (2001). Manual of I.V. Therapeutics (3rd. Edition), Philadelphia: F. A. Davis

34. Quick Assessment Guide for Fluid Imbalance
Body System Assessed
Fluid Volume
Excess
Deficit
Lips
Dry, cracked
Tongue
Extralongitudinal furrows
Body Weight
Mild: <5% over normal;
Moderate: 5% to 10% over normal;
Severe: >15% over normal
Mild: <5% less than normal;
Moderate: 5% to 10% less than normal;
Severe: >15% less than normal
Source: Phillips, L. (2001). Manual of I.V. Therapeutics (3rd. Edition), Philadelphia: F. A. Davis

35. References
Phillips, L. Manual of I.V. Therapeutics, 3rd edition. Philadelphia, F. A. Davis Co., 2001.
Smith, S., Duell, D., and Martin, B. Clinical Nursing Skills, 5th edition. Upper Saddle River, Prentice-Hall, Inc., 2000.
Taylor, C., Lillis, C., and LeMone, P., Fundamental of Nursing, 4th
edition. Philadelphia, Lippincott Co., 2001.