1. Unit 8 (Chapters 18&19) - Fluid & Electrolyte Balance and Acid-Base Balance Presented by Dawn Duran, PT, MHS, CSCS Adjunct Professor, Kaplan University

2. Welcome to Seminar!

3. Fluid & Electrolyte Balance

4. Body Fluids Water is the most abundant body compound Water is the most abundant body compound References to “average” body water volume in reference tables based on a healthy, non-obese, 70- kg male References to “average” body water volume in reference tables based on a healthy, non-obese, 70- kg male Volume averages 40 L in a 70-kg male Volume averages 40 L in a 70-kg male Plasma (3 L) Plasma (3 L) Interstitial fluid (12 L) Interstitial fluid (12 L) Intracellular fluid (25 L) Intracellular fluid (25 L) Water is 80% of body weight in newborn infant; 60% in adult non-obese males; 50% in adult females Water is 80% of body weight in newborn infant; 60% in adult non-obese males; 50% in adult females

5. Body Fluids Variation in total body water is related to: Variation in total body water is related to: Total body weight of individual Total body weight of individual Gender - female body about 5-10% less than male body Gender - female body about 5-10% less than male body Females tend to carry more body fat than males Females tend to carry more body fat than males Fat content of body Fat content of body Adipose tissue contains the least amount of water of any body tissue Adipose tissue contains the least amount of water of any body tissue The more fat in the body the less the total water content per kilogram of body weight The more fat in the body the less the total water content per kilogram of body weight Fat is nearly water-free; therefore individuals with more body fat will have lower water content per pound of body weight Fat is nearly water-free; therefore individuals with more body fat will have lower water content per pound of body weight The percent body weight of water in an obese individual compared to a non-obese individual is less in the obese individual The percent body weight of water in an obese individual compared to a non-obese individual is less in the obese individual

6. Body Fluids Age Age In a newborn infant, water may account for 80% of total body weight. In a newborn infant, water may account for 80% of total body weight. An infant’s percentage of total body weight made up of water is greater than an adult’s An infant’s percentage of total body weight made up of water is greater than an adult’s  In the elderly, water per kilogram of weight decreases (muscle tissue is high in water, and it is replaced by fat as we age, which is lower in water)

7. Body Fluid Compartments Two major fluid compartments Two major fluid compartments Extracellular fluid (ECF) Extracellular fluid (ECF) Types: Types: Plasma Plasma Interstitial fluid (IF) Interstitial fluid (IF) Miscellaneous—lymph, joint fluids, cerebrospinal fluid, eye humors Miscellaneous—lymph, joint fluids, cerebrospinal fluid, eye humors Called internal environment of body Called internal environment of body Surrounds cells and transports substances to and from them Surrounds cells and transports substances to and from them

8. Body Fluid Compartments Intracellular fluid (ICF) Intracellular fluid (ICF) Comprises the largest volume of water in the body (~33% of body weight) Comprises the largest volume of water in the body (~33% of body weight) Largest fluid compartment Largest fluid compartment Located inside cells Located inside cells Serves as solvent to facilitate intracellular chemical reactions Serves as solvent to facilitate intracellular chemical reactions

9. Body Fluid Compartments Of the main fluid compartments… Of the main fluid compartments… plasma varies the least in terms of its volume plasma varies the least in terms of its volume interstitial fluid varies the most in terms of its volume interstitial fluid varies the most in terms of its volume

10. Fluid Balance When the volume of ICF, ECF and the total volume of water in the body all remain constant it is known as fluid balance. When the volume of ICF, ECF and the total volume of water in the body all remain constant it is known as fluid balance.

11. Fluid Balance Major factors that influence ECF and ICF volumes include: Major factors that influence ECF and ICF volumes include: The concentration of electrolytes in ECF The concentration of electrolytes in ECF The capillary blood pressure The capillary blood pressure The concentration of proteins in the blood The concentration of proteins in the blood An excessive increase in interstitial fluid is EDEMA An excessive increase in interstitial fluid is EDEMA This may be in part due to an increase in plasma proteins in the blood, which help to move interstitial fluid into the plasma. This may be in part due to an increase in plasma proteins in the blood, which help to move interstitial fluid into the plasma.

12. Water Intake Water intake is achieved through Water intake is achieved through Water in foods Water in foods Catabolism Catabolism Ingested liquids Ingested liquids

13. Water Output Water loss in urine Water loss in urine The greatest amount of water output occurs via the kidneys The greatest amount of water output occurs via the kidneys Water loss in feces Water loss in feces Very little sodium is lost in the feces Very little sodium is lost in the feces Water loss through the skin Water loss through the skin Water loss through the lungs Water loss through the lungs Fluid output is MORE important in maintaining homeostasis than fluid intake is. Fluid output is MORE important in maintaining homeostasis than fluid intake is.

14. Mechanisms that Maintain Fluid Balance Fluid output, mainly urine volume, adjusts to fluid intake Fluid output, mainly urine volume, adjusts to fluid intake If fluid intake equals fluid output, then the total amount of water in the body will not change.

15. Mechanisms that Maintain Fluid Balance Regulation of urine excretion is accomplished by Regulation of urine excretion is accomplished by Aldosterone Aldosterone Secreted by the adrenal cortex Secreted by the adrenal cortex Targets the kidneys Targets the kidneys Helps to regulate sodium Helps to regulate sodium Antidiuretic hormone (ADH) Antidiuretic hormone (ADH) Secreted by the posterior pituitary gland Secreted by the posterior pituitary gland Atrial natriuretic hormone Atrial natriuretic hormone

16. Mechanisms that Maintain Fluid Balance ECF electrolyte concentration influences ECF volume ECF electrolyte concentration influences ECF volume Electrolytes are substances such as salts that break apart in water and can conduct an electrical current Electrolytes are substances such as salts that break apart in water and can conduct an electrical current An increase in Na + concentration in the blood increases blood volume An increase in Na + concentration in the blood increases blood volume Sodium (Na) is the most abundant electrolyte found in blood plasma. Sodium (Na) is the most abundant electrolyte found in blood plasma. The chief regulators of Na within the body are the kidneys The chief regulators of Na within the body are the kidneys

17. Mechanisms that Maintain Fluid Balance Capillary blood pressure pushes water out of blood, into interstitial fluid Capillary blood pressure pushes water out of blood, into interstitial fluid An increase in capillary pressure will shift fluid out of the capillaries An increase in capillary pressure will shift fluid out of the capillaries If capillary blood pressure increase then interstitial fluid volume increases If capillary blood pressure increase then interstitial fluid volume increases Blood hydrostatic pressure tends to force fluid out of capillaries and into interstitial fluid Blood hydrostatic pressure tends to force fluid out of capillaries and into interstitial fluid Blood protein concentration pulls water into blood from interstitial fluid Blood protein concentration pulls water into blood from interstitial fluid Hence these two forces regulate plasma and IF volume under usual conditions Hence these two forces regulate plasma and IF volume under usual conditions

18. Mechanisms that Maintain Fluid Balance Importance of electrolytes in body fluids Importance of electrolytes in body fluids Nonelectrolytes—organic substances that do not break up or dissociate when placed in water solution (e.g., glucose) Nonelectrolytes—organic substances that do not break up or dissociate when placed in water solution (e.g., glucose) Electrolytes—compounds that break up or dissociate in water solution into separate particles called ions (e.g., ordinary table salt or sodium chloride) Electrolytes—compounds that break up or dissociate in water solution into separate particles called ions (e.g., ordinary table salt or sodium chloride)

19. Mechanisms that Maintain Fluid Balance Ions—the dissociated particles of an electrolyte that carry an electrical charge (e.g., sodium ion [Na + ]) Ions—the dissociated particles of an electrolyte that carry an electrical charge (e.g., sodium ion [Na + ]) Positively charged ions/cations (e.g., potassium [K + ], sodium [Na + ] and calcium [Ca+]) Positively charged ions/cations (e.g., potassium [K + ], sodium [Na + ] and calcium [Ca+]) Negatively charged particles (ions) (e.g., chloride [Cl – and bicarbonate [HCO3 – ]) Negatively charged particles (ions) (e.g., chloride [Cl – and bicarbonate [HCO3 – ])

20. Mechanisms that Maintain Fluid Balance Electrolyte composition of blood plasma Electrolyte composition of blood plasma Sodium is the most abundant and important positively charged ion of plasma Sodium is the most abundant and important positively charged ion of plasma A normal saline (0.9% NaCl) solution is used to treat acute blood loss because it will help the body to retain fluid. Normal plasma level—142 mEq/L Normal plasma level—142 mEq/L Average daily intake (diet)—100 mEq Average daily intake (diet)—100 mEq Chief method of regulation—kidney Chief method of regulation—kidney Intestinal secretions are one of the highest sodium-containing internal secretions (3000mL in 24 hrs) Intestinal secretions are one of the highest sodium-containing internal secretions (3000mL in 24 hrs) Most of the sodium in our internal secretions is reabsorbed in the large intestine Most of the sodium in our internal secretions is reabsorbed in the large intestine

21. Fluid Imbalances Dehydration occurs when the total volume of body fluids is smaller than normal Dehydration occurs when the total volume of body fluids is smaller than normal Interstital fluid volume shrinks first, and then if treatment is not given, ICF volume and plasma volume decrease Interstital fluid volume shrinks first, and then if treatment is not given, ICF volume and plasma volume decrease Dehydration occurs when fluid output exceeds intake for an extended period Dehydration occurs when fluid output exceeds intake for an extended period Dehydration caused by vomiting or diarrhea is of greater concern in infants Dehydration caused by vomiting or diarrhea is of greater concern in infants

22. Fluid Imbalances Overhydration occurs when the total volume of body fluids is larger than normal Overhydration occurs when the total volume of body fluids is larger than normal Overhydration occurs when fluid intake exceeds output Overhydration occurs when fluid intake exceeds output Various factors may cause this (for example, giving excessive amounts of intravenous fluids or giving them too rapidly may increase intake above output) Various factors may cause this (for example, giving excessive amounts of intravenous fluids or giving them too rapidly may increase intake above output) Overhydration may put an excessive burden on the heart Overhydration may put an excessive burden on the heart

23. Electrolyte Imbalances Related to “intake” and “output” of electrolytes; also important is absorption, distribution of electrolytes in body fluids and availability for use by body cells Related to “intake” and “output” of electrolytes; also important is absorption, distribution of electrolytes in body fluids and availability for use by body cells

24. Electrolyte Imbalances Examples Examples Sodium imbalance Sodium imbalance Hypernatremia—blood sodium above 145 mEq/L Characterized by relative deficit of water to salt in extracellular fluid Characterized by relative deficit of water to salt in extracellular fluid Causes include overuse of salt tablets; dehydration; and prolonged diarrhea Causes include overuse of salt tablets; dehydration; and prolonged diarrhea

25. Electrolyte Imbalances Hyponatremia—blood sodium below 136 mEq/L Hyponatremia—blood sodium below 136 mEq/L Results when there is relatively too much water in the extracellular fluid for the amount of sodium present Results when there is relatively too much water in the extracellular fluid for the amount of sodium present Causes include excessive secretion of antidiuretic hormone; massive infusion of sodium free IV solution; burns; and prolonged use of certain diuretics Causes include excessive secretion of antidiuretic hormone; massive infusion of sodium free IV solution; burns; and prolonged use of certain diuretics Symptoms of both hyper- and hyponatremia are related to CNS malfunction and include headache, confusion, seizures, and coma Symptoms of both hyper- and hyponatremia are related to CNS malfunction and include headache, confusion, seizures, and coma

26. Electrolyte Imbalances Potassium imbalance Potassium imbalance Hyperkalemia—blood potassium above 5.1 mEq/L Hyperkalemia—blood potassium above 5.1 mEq/L Causes include increased intake; shift potassium from ICF to blood caused by tissue trauma and burns; renal failure Causes include increased intake; shift potassium from ICF to blood caused by tissue trauma and burns; renal failure Clinical signs of hyperkalemia are related to muscle malfunction and include skeletal muscle weakness, paralysis, and cardiac arrest Clinical signs of hyperkalemia are related to muscle malfunction and include skeletal muscle weakness, paralysis, and cardiac arrest

27. Electrolyte Imbalances Hypokalemia—blood potassium below 3.8 mEq/L Hypokalemia—blood potassium below 3.8 mEq/L Causes include fasting; diets low in potassium; abuse of laxatives and certain diuretics; diarrhea; vomiting; gastric suction Causes include fasting; diets low in potassium; abuse of laxatives and certain diuretics; diarrhea; vomiting; gastric suction Clinical signs include skeletal muscle and cardiac problems; smooth muscle weakness causing abdominal distention; and slow rate of passage of GI contents Clinical signs include skeletal muscle and cardiac problems; smooth muscle weakness causing abdominal distention; and slow rate of passage of GI contents

28. Electrolyte Imbalances Calcium imbalance Calcium imbalance Hypercalcemia—blood calcium levels above 10.5 mg/dL Hypercalcemia—blood calcium levels above 10.5 mg/dL Caused by excessive input; increased absorption; shifts of calcium from bone to ECF; Paget disease and other bone tumors; hyperparathyroidism Caused by excessive input; increased absorption; shifts of calcium from bone to ECF; Paget disease and other bone tumors; hyperparathyroidism Clinical signs related to decreased neuromuscular activity—fatigue; muscle weakness; diminished reflexes; cardiac problems Clinical signs related to decreased neuromuscular activity—fatigue; muscle weakness; diminished reflexes; cardiac problems Hypocalcemia—blood calcium levels below 8.4 mg/dL Hypocalcemia—blood calcium levels below 8.4 mg/dL

29. Acid-Base Balance

30. pH of Body Fluids pH is a number that indicates the hydrogen ion (H+) concentration of a fluid pH is a number that indicates the hydrogen ion (H+) concentration of a fluid pH 7.0 indicates neutrality pH 7.0 indicates neutrality pH higher than 7.0 indicates alkalinity pH higher than 7.0 indicates alkalinity pH less than 7.0 indicates acidity pH less than 7.0 indicates acidity The pH of blood ranges from 7.35-7.45 The pH of blood ranges from 7.35-7.45 Normal arterial blood pH—about 7.45 Normal arterial blood pH—about 7.45 Normal venous blood pH—about 7.35 Normal venous blood pH—about 7.35

31. Mechanisms That Control pH of Body Fluids Three coordinated homeostatic mechanisms act to maintain the normal pH of body fluids and prevent pH swings when excess acids or bases are present Three coordinated homeostatic mechanisms act to maintain the normal pH of body fluids and prevent pH swings when excess acids or bases are present Chemical pH control mechanism Chemical pH control mechanism Physiological pH control mechanisms Physiological pH control mechanisms Includes urinary mechanism of pH control Includes urinary mechanism of pH control Includes respiratory mechanism of pH control Includes respiratory mechanism of pH control

32. Chemical pH control mechanism Buffers in blood/RBCs/and body fluids act immediately to control pH changes Buffers in blood/RBCs/and body fluids act immediately to control pH changes Buffers Buffers Definition - chemical substances that prevent a sharp change in the pH of a fluid when an acid or base is added to it Definition - chemical substances that prevent a sharp change in the pH of a fluid when an acid or base is added to it “Fixed” acids are buffered mainly by sodium bicarbonate (NaHCO3) “Fixed” acids are buffered mainly by sodium bicarbonate (NaHCO3) Changes in blood produced by buffering of “fixed” acids in the tissue capillaries Changes in blood produced by buffering of “fixed” acids in the tissue capillaries

33. Physiological pH control mechanisms Changes in pH regulated by changes in respiratory rate which result in changes in blood CO2 Changes in pH regulated by changes in respiratory rate which result in changes in blood CO2 act within minutes act within minutes Changes in pH regulated by specialized renal activity Changes in pH regulated by specialized renal activity act within hours act within hours

34. Respiratory mechanism of pH control  Respirations remove some CO2 from blood as blood flows through lung capillaries  the amount of H2CO3 in blood is decreased and thereby its H+ concentration is decreased,  this in turn increases blood pH from its venous to its arterial level

35. Urinary mechanism of pH control  This is the body’s most effective regulator of blood pH  In other words, the body’s best defense against wide variations in blood pH are the kidneys  Kidneys usually acidify urine by the distal tubules secreting hydrogen ions and ammonia (NH3) into the urine from blood in exchange for NaHCO3 being reabsorbed into the blood

36. Regulation of pH In summary, the body regulates the pH of its fluids through In summary, the body regulates the pH of its fluids through Buffer mechanisms Buffer mechanisms Respiration Respiration Urination Urination

37. pH Imbalances Acidosis and alkalosis are the two kinds of pH or acid-base imbalances Acidosis and alkalosis are the two kinds of pH or acid-base imbalances Disturbances in acid-base balance depend on relative quantities of NaHCO3 and H2CO3 in the blood Disturbances in acid-base balance depend on relative quantities of NaHCO3 and H2CO3 in the blood Body can regulate both of the components of the NaHCO3–H2CO3 buffer system Body can regulate both of the components of the NaHCO3–H2CO3 buffer system Blood levels of NaHCO3 regulated by kidneys Blood levels of NaHCO3 regulated by kidneys H2CO3 levels regulated by lungs H2CO3 levels regulated by lungs

38. pH Imbalances Two basic types of pH disturbances, metabolic and respiratory, can alter the normal 20:1 ratio of NaHCO3 to H2CO3 in blood Two basic types of pH disturbances, metabolic and respiratory, can alter the normal 20:1 ratio of NaHCO3 to H2CO3 in blood Metabolic disturbances affect the NaHCO3 levels in blood Metabolic disturbances affect the NaHCO3 levels in blood Respiratory disturbances affect the H2CO3 levels in blood Respiratory disturbances affect the H2CO3 levels in blood

39. pH Imbalances Types of pH or acid-base imbalances Types of pH or acid-base imbalances Metabolic disturbances Metabolic disturbances Metabolic acidosis—bicarbonate (NaHCO3) deficit Metabolic acidosis—bicarbonate (NaHCO3) deficit Metabolic alkalosis—bicarbonate (NaHCO3) excess; complication of severe vomiting Metabolic alkalosis—bicarbonate (NaHCO3) excess; complication of severe vomiting

40. pH Imbalances Respiratory disturbances Respiratory disturbances Respiratory acidosis (H2CO3 excess) Respiratory acidosis (H2CO3 excess) Example: Example: Emphysema reduces the oxygenation of blood, leading to hypoxia and excessive carbon dioxide in the blood. Respiratory alkalosis (H2CO3 deficit) Respiratory alkalosis (H2CO3 deficit) Prolonged hyperventilation tends to produce alkalosis which involves an increase in blood pH. Prolonged hyperventilation tends to produce alkalosis which involves an increase in blood pH. In uncompensated metabolic acidosis, the normal ratio of NaHCO3 to H2CO3 is changed; in compensated metabolic acidosis, the ratio remains at 20:1, but the total amount of NaHCO3 and H2CO3 changes In uncompensated metabolic acidosis, the normal ratio of NaHCO3 to H2CO3 is changed; in compensated metabolic acidosis, the ratio remains at 20:1, but the total amount of NaHCO3 and H2CO3 changes

41. Important Information Severe vomiting, prolonged diarrhea and hyperventilation will alter pH balance. Severe vomiting, prolonged diarrhea and hyperventilation will alter pH balance. If a patient’s blood level ration of NaHCO3 to H2CO3 is 12:1 it is an example of uncompensated metabolic acidosis. If a patient’s blood level ration of NaHCO3 to H2CO3 is 12:1 it is an example of uncompensated metabolic acidosis. Uncontrolled diabetes mellitus may result in ketoacidosis.

42. In a nutshell… Metabolic acidosis is a bicarbonate deficit. Metabolic acidosis is a bicarbonate deficit. Metabolic alkalosis is a bicarbonate excess. Metabolic alkalosis is a bicarbonate excess. Respiratory acidosis is a carbonic acid excess. Respiratory acidosis is a carbonic acid excess. Respiratory alkalosis is a carbonic acid deficit. Respiratory alkalosis is a carbonic acid deficit. Normal saline is a chloride-containing solution that is often used for excessive vomiting. Normal saline is a chloride-containing solution that is often used for excessive vomiting.

43. Any Questions? Ask Me or your Classmates!

44. Thanks for attending! See you in Discussion!