Fluid & Electrolytes

1. Fluid & Electrolytes FA 08

2. Introduction • Fluid, electrolyte, and acid-base balances within the body are necessary to maintain health and function of all body systems • These balances are maintained by the intake and output of water and electrolytes and regulation by the renal and pulmonary systems. Otten, F&E

3. Water is the largest single component of the body. 60% of the average adult’s weight is fluid. 1 kg=1L • A healthy mobile and well oriented adult can usually maintain normal fluid, electrolyte and acid/base balance. Otten, F&E

4. Distribution of body fluids • Compartments • Intracellular (ICF)—all fluid within body cells. • Extracellular (ECF)—all fluid outside a cell, divided into smaller compartments • Interstitial fluid—between the cells and outside the blood vessels • Intravascular fluid—blood plasma • Transcellular—found in the spaces of the GI tract, cerebrospinal fluid and intraocular space Otten, F&E

5. Fluid Compartments in the Adult Otten, F&E

6. Body Water Otten, F&E

7. ECF check…. • When a person loses water sweating, the ECF volume is decreased • A message is sent to the hypothalamus in the brain • Thirst center stimulated Otten, F&E

8. Composition of body fluids • Water • Electrolytes—minerals or salts • Element or compound when melted or dissolved in water separates into ions and is able to carry an electrical current • Vital to body function • Value expressed as mEq/L-milli equivalents per liter, is the number of grams of the specific electrolyte dissolved in a liter of plasma

9. Charge • Negatively charged electrolytes are Anions • Chloride • Bicarbonate • Sulfate • Positively charged electrolytes are Cations • Sodium • Potassium • Calcium Otten, F&E

10. Composition of body fluids • Minerals • Act as a catalyst in nerve response, muscle contraction, and metabolism of nutrients in foods • Regulate electrolyte balance and hormone production and strengthens skeletal structures Otten, F&E

11. Movement of body fluids • Fluids and electrolytes constantly shift from compartment to compartment to facilitate body processes—tissue oxygenation, acid-base balance, urine formation Otten, F&E

12. Osmosis • Osmosis—movement of a pure solvent thru a semipermeable membrane from an area of lesser solute concentration to an area of greater solute concentration • Osmotic pressure—drawing power for water and depends on number o molecules in solution • Osmolarity—measure used to evaluate serum and urine in clinical practice Otten, F&E

13. Osmosis: Water molecules move from lower to higher concentrations H2O H2O H2O H2O H2O Solutes (Electrolytes) Water Molecules Otten, F&E

14. Classification • Isotonic—same osmolarity as blood plasma • Expands the body’s fluid volume without causing a fluid shift from one compartment to another • 0.9% Sodium Chloride = Normal Saline Otten, F&E

15. Classification • Hypertonic—a solution of higher osmotic pressure; pulls fluid from the cell (shrink) • 3% NS • 5% NS • D5NS Otten, F&E

16. Classification • Hypotonic—solution of lower osmotic pressure; moves fluid into the cells causing them to enlarge (swell) • 0.45% NaCl • 0.5% NaCl Otten, F&E

17. Diffusion • Process during which a solid in a fluid moves from an area of higher concentration to an area of lower concentration • Even distribution Otten, F&E

18. Regulation of body fluids • Regulated by fluid intake, hormonal controls, and fluid output • Homeostasis—physiological balance Otten, F&E

19. Fluid intake • Regulated primarily through the thirst mechanism • Thirst control is located in the hypothalamus • Thirst is the conscious desire for water Otten, F&E

20. Compensatory Mechanisms: Thirst Otten, F&E

21. Hormone Regulation • ADH—antidiuretic hormone • Water is saved in the kidneys thru the pituitary gland’s secretion of ADH • Aldosterone • Water reabsorption is also regulated by aldosterone produced by the adrenal cortex, which increases sodium and water reabsorption in the body and decreases sodium and water excretion in the urine Otten, F&E

22. Hormone Regulation • Renin • Secreted by the kidney • Responds to decreased renal perfusion secondary to decrease in ECF • Angiotensin Ivasoconstriction • Angiotensin IImassive selective vasoconstriction • And stimulates release of aldosterone when Na+ concentration is low Otten, F&E

23. Fluid Regulation • Kidneys 1200-1500 • Skin 500-600 • Lungs 400 • GI 100-200 Otten, F&E

24. Fluid Regulation • Kidneys • Major regulatory organ of fluid balance • Receive approximately 180L of plasma to filter each day and produce 1200-1500 ml of urine Otten, F&E

25. Fluid Regulation • Skin • Regulated by the sympathetic nervous system, which activates sweat glands • Water loss from skin can by sensible or insensible • Insensible—continuous/not perceived • Sensible—through excess perspiration Otten, F&E

26. Fluid Regulation • Lungs • Change with rate and depth of respirations • GI Tract • 3-6L of isotonic fluid is moved into GI tract and then returns again to the extracellular fluid • Average loss is 100-200 ML of the 3-6L each day thru feces • Diarrhea, GI tract may become a site of a large amount of fluid loss. Otten, F&E

27. At risk population • Infants, clients with neurological or psychological problems and some older adults who are unable to perceive or respond to the thirst mechanism are at risk for dehydration. Otten, F&E

28. Fluid & Electrolyte Homeostasis In Older Adults Older Adults • As percentage of body water decreases, less water is present in interstitial spaces thus at risk for F&E imbalances • Renal changes associated with aging include a 50% decrease in blood flow through kidneys (decreased cardiac output) thus causing decreased ability to concentrate urine and F&E imbalances • Note, too, that elderly clients are at risk for dehydration and F&E imbalances due to decreased oral intake of the same Otten, F&E

29. Fluid & Electrolyte Homeostasis In Adults Adults • Young and middle adults have very responsive regulatory mechanisms (aldosterone/ADH) • Least susceptible to F&E imbalances due to ability to evaluate own fluid needs • Pregnant women are one exception: Increased blood volume (30-50% near term) is associated with increased aldosterone section which causes Na+ to be reabsorbed and water retention, increased cardiac output is usually able to keep swelling down (30% of preg. women experience swelling) Otten, F&E

30. Hypovolemia—loss of fluid (excess vomiting, hemorrhage) • Dehydration • Skin turgor • Dryness of lips or oral cavity • Decreased daily intake of fluids • Concentrated urine (elevated specific gravity) Otten, F&E

31. Hydration Assessment Hypovolemia • Postural hypotension • Weight change 2-5% loss • Tachycardia • Dry mucous membranes • Poor skin turgor • Burns, diarrhea, diabetes, vomiting, sweating, diuretics, laxatives Otten, F&E

32. Dehydration • Water loss results in tachycardia • Lowering of BP • Decreased cardiac output • Weakness • Confusion/disorientation/personality changes • Check labs • Hemoconcentration of RBCs Otten, F&E

33. Hydration Assessment Hypervolumia • Excess water gain • Heart failure • Renal failure • High salt intake • Pancreatitis • Rapid weight gain, edema, HTN, polyuria, NVD Otten, F&E

34. Interventions for Fluid Overload • Restrict intake • Daily weight • I & O record—divide fluids • Oral care • Education what is considered intake • Ice chips, gelatin, ice-cream Otten, F&E

35. Regulation of Electrolytes • Cations + charge • Na • Most abundant cation • Maintain water balance thru efforts on serum osmolality, nerve impulse transmission, regulation of acid-base balance Otten, F&E

36. Regulation of Electrolytes • K+ Potassium • Major electrolyte and principle cation in intracellular compartment • Regulates metabolic activities • Necessary for glycogen deposits in liver and skeletal muscles, nerve impulse transmission and conduction, normal cardiac conduction and skeletal and smooth muscle contraction • Dietary intake/renal excretion • Release with injury Otten, F&E

37. Calcium • Stored in bones, plasma, and body cells (99% is located in bones) • Necessary for bone and teeth formation, blood clotting, hormone secretion, cell membrane integrity, cardiac conduction, transmission of nerve impulses and muscle contraction Otten, F&E

38. Mg2+ Magnesium • Essential for enzyme activities, neurochemical activities, and cardiac and skeletal muscle excitability • Regulated by dietary intake, renal mechanisms, and actions of parathyroid hormone • 50-60% in bone Otten, F&E

39. Anions • Chloride • Regulated by dietary intake and kidneys • Bicarbonate • Chemical buffer • Essential for acid-base balance • Regulated by kidneys Otten, F&E

40. Phosphate • Buffer in ECF • Acid-base • With Ca= develop and maintain bones/teeth • Neuromuscular action • GI tract • Diet, renal, intestinal Otten, F&E

41. Lab Values • Know the ranges and abbreviations • Sodium • Potassium • Calcium • Magnesium • Chloride • Bicarbonate • Phosphate Otten, F&E

42. Electrolyte Imbalance • Na • Hyponatremia—neuro, tachy, hypo • Hypernatremia—mucous membranes dry • Flushed skin, thirst Otten, F&E

43. K Potassium • Hypokalemia decreased muscle tone, ventricular dysarrhythmias and cardiac arrest • Hyperkalemia cardiac arrest, QRS widens, heart block, bradycardia Otten, F&E

44. Mg Magnesium • Hypomagnesemia—muscle tremors, hyperactive Deep Tendon Reflexes • Hypermagnesemia—hypoactive DTR’s, low BP, decreased RR Otten, F&E

45. Ca Calcium • Hypocalcemia—muscle cramps, numbness and tingling of fingers and tetany • Hypercalcemia—anorexia, lethargy, decreased LOC Otten, F&E

46. Chovosteks • Contraction of facial muscles with facial nerve is tapped • Tetany, muscle cramps and muscle tremors, dysrhythmias Otten, F&E

47. Trousseau • Carpopedal spasm with hypoxia • Seen with hypocalcemia or hypomagnesia Muscle tremors, dysrhythmias, etc Otten, F&E

48. Specific Gravity • Urine 1.010-1.025 • Weight of a substance compared to the weight of an equal amount of water • H2O specific gravity is 1.0 • Urine 95% water 5% solids Otten, F&E

49. Regulation of Acid-Base Balance

50. Disturbances in Electrolyte, Fluid, and Acid-Base Balances