1. Fluids and Electrolytes, Acids and Bases
Chapter 4

2. Distribution of Body Fluids
Total body water – all fluids – 60% weight (kg)
Intracellular fluid (ICF) 40% TBW
Extracellular fluid (ECF) 20% TBW
Interstitial fluid – between cells
Intravascular fluid – blood plasma
Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal, pericardial and intraocular fluid

3. “cells live in a fluid environment with electrolytes and acid base concentrations maintained within a narrow range” changes or shifts → radically alter metabolism → life threatening

4. Pediatrics Aging Distribution of Body Fluids 75% to 80% body weight
Susceptible to significant changes in body fluids - dehydration
Aging
↓ % of total body water
adipose and muscle mass
↓ renal function
↓ thirst perception

5. Water Movement Between ICF and ECF
“water, nutrients and waste products”
capillary interstitial space
1.Capillary hydrostatic pressure – blood pressure “fluid out”
2.Capillary oncotic pressure – water attraction “fluid in”(Plasma Proteins)
Interstitial hydrostatic pressure – fluid towards capillary
Interstitial oncotic pressure – water attraction “fluid in”

6. water movement

10. Edema: 4 Major Causes
“excessive accumulation of fluids within the interstitial space”
1.↑ hydrostatic pressure
Venous obstruction – DVT, hepatic obstruction
Salt and water retention – heart, renal failure
2.↓ plasma oncotic pressure
↓ albumin – liver disease, malnutrition, kidney disease, burns, hemorrhage

11. Edema
↑ capillary permeability – trauma, burns, neoplastic and allergic reactions
Lymph obstruction – removal nodes (surgery) inflammation or tumors

13. Water : ADH – hypothalamus – posterior pituitary Na+ and Cl-
Sodium, Chloride & Water Balance
“kidneys and hormones” – central role
Water : ADH – hypothalamus – posterior pituitary
Na+ and Cl-
aldosterone – adrenal gland
Natriuretic hormones– atrial muscle

17. Sodium, Chloride Balance
Sodium (Na+)
Primary ECF cation
Regulates osmotic forces
Role
Neuromuscular irritability, acid-base balance, cellular reactions, and membrane transport
Chloride (Cl-)
Primary ECF anion
Provides electroneutrality

18. Sodium and Water Balance
Balance between Na+ and H2O -
↑ or ↓ of salt
↑ or ↓ water
Tonicity – change in concentration of solutes (salt) with relation to solvent (water)

19. Tonicity (280 – 294m Osm)
Isotonic – 0.9% NaCl – iso osmolar imbalance no cells
Hypertonic – ECF > 0.9% NaCl – (↓ H2O or ↑ salt) cells shrink
Hypotonic – ECF < 0.9% NaCl (↑ H2O or ↓ salt) cells swell
“Extracellular Fluid”- interstitial space

21. Sodium (Na+) 90% ECF cations 135 – 145 mEq/L
Hypernatremia - > 145 mEq/L
Hyponatremia - < 135 mEq/L

22. Hypernatremia-causes
↑ Na or ↓ H2O
IV therapy – acidosis (NaHCO3)
Cushing's Syndrome - ↑ ACTH → aldosterone
fever, respiratory infection - ↓ H2O
diabetes, diarrhea - ↓ H2O
↓ H2O intake - coma
H2O movement ICF → ECF(interstitial)
Manifestations
Intracellular dehydration: convulsions, thirst, fever, muscle twitching, hyperreflexia

23. Hyponatremia ↓ Na or ↑ H2O
Vomiting, diarrhea, GI suction, burns, diuretics, D5W replacement (isotonic sol’n)
Manifestations
Lethargy, confusion, depressed reflexes, seizures, coma, hypotension, tachycardia, ↓ urine output

24. Hypochloremia Result of hyponatremia or ↑ HCO3 Vomiting – loss HCl
Cystic fibrosis

25. Potassium (resting potential)
Major intracellular electrolyte
98% intracellular – Na – K – ATP Pump
3.5 – 5.0 mEq/L
Transmission and conduction of nerve impulses, normal cardiac rhythm, skeletal and smooth muscle contractions: “action potentials”
“BAD BOY of ELECTROLYTES”

26. Potassium Levels Change in pH affects K+ balance – acidosis –
↑ ICF H+ → K+ moves out to ECF maintains
+ ion balance
Aldosterone; insulin, epinephrine, alkolosis,
K+ → into cell
Glucagon # entry into cell
Glucocorticoids → K+ excretion

27. Hypokalemia
K+ < 3.5 mEq/L
↓ intake, ↑ loss, ↑ entry into cells
Manifestations: membrane hyperpolorizations ↓ excitability – weakness, smooth muscle, atrophy, cardiac dysrhythmias (bradycardia…asystole)

28. Hyperkalemia
K+ > 5.0 mEq/L – rare
↑ shift from ICF (acidosis), ↓ renal excretion, insulin deficiency or cell trauma

29. Hyperkalemia Mild attacks Severe attacks
↑ neuromuscular irritability – tingling of lips & fingers, restlessness, intestinal cramps – diarrhea
Severe attacks
No repolarization → muscle weakness, ↓ tone, flaccid paralysis
Cardiac dysrhythmias:”funky chicken”
SeeTable 4-6 Clinical Manifestations

30. Calcium (threshold potential)
99% located in bone – hydroxyapatite
Bone, teeth, blood clotting, hormone secretion, cell receptor function
Hypo - ↓ block of Na into cell ↑ neuromuscular excitability (muscle cramps)
Hyper - ↑ block Na - ↓ neuromuscular excitability (muscle weakness, cardiac arrest, kidney stones, constipation)

31. Big Picture… Low SERUM K...decreased excitability
Nerves & muscles…bradycardia---asystole
High SERUM K …increased excitability
Cardiac dysrhythmias
Low SERUM Ca… increased excitability
“Chvostek & Trousseau’s Signs”
High SERUM Ca… decreased excitability
Big Picture…

32. Acid-Base Balance
Hydrogen ion and pH

33. pH (0 to 14)
Inverse logarithm of the H+ concentration mg/L – 1x10 -7
so pH = 7
pH = power of hydrogen
pH changes by one unit (7 → 6)
[H+] fold
Biological fluids
pH < 7.4 = acidic
> 7.4 = basic
( )

34. pH
Acids are formed as end products of protein, carbohydrate and fat metabolism
Narrow “life range” – 7.35 – 7.45
Bone – lung – kidneys – major regulatory
organs
“Absolute Range of Life: ”
see Table 4-8 pH of body fluids

35. Volatile H2CO3 (maybe eliminated as CO2) pH
Body acids exist in two forms
Volatile H2CO3 (maybe eliminated as CO2)
Nonvolatile – eliminated by kidneys
sulfuric, phosphoric

36. Consists of a PAIR of a weak acid and its conjugate base
Buffering Systems
Buffer is a chemical that binds XS H+ or OH- without a significant change in pH
Consists of a PAIR of a weak acid and its conjugate base
Most important plasma buffering system
Carbonic acid – bicarbonate system
Hemoglobin (intracellular)

37. Correction – buffer pairs →
Buffering Systems
H2O + CO H2CO H+ + HCO3-
Lung Kidney
Phosphate- HPO4
Ammonia – NH3
Compensation
Respiratory - ↑ or ↓ CO2
Renal - ↑ or ↓ acid/alkaline urine
Correction – buffer pairs →

38. Other Buffering Systems
Proteins: - charge, mostly intracellular
Hemoglobin –
H + Hb → HHb + CO2 → HHbCO2 (weak acid)

39. Buffer Systems Rate of Reaction
Bicarbonate system: instantaneously
Lungs: minutes to hours
Kidneys: hours to days
Buffer Systems Rate of Reaction

41. Respiratory acidosis - ↑ PaCO2 Respiratory alkalosis - ↓ PaCO2
Acidosis and Alkalosis
Four categories
Respiratory acidosis - ↑ PaCO2
Respiratory alkalosis - ↓ PaCO2
Metabolic acidosis - ↓ HCO3- or↑ other acids
Metabolic alkalosis - ↑ HCO3- (XS loss acids)

51. Normal Values pO2 = 80 to 100 mmHg pCO2 = 35 – 45 mmHg
pH = 7.35 – 7.45
pO2 = 80 to 100 mmHg
pCO2 = 35 – 45 mmHg
HCO3 = mEq/L
SaO2 = > 92% - here

52. Patient ABG: pH = 7. 3 pCO2 = 40 mmHg pO2 = 70 mmHg HCO3 = 20 mEq/L 1
Patient ABG: pH = 7.3 pCO2 = 40 mmHg pO2 = 70 mmHg HCO3 = 20 mEq/L 1. pH = ? → acidosis 2. pCO2 = ? → normal 3. HCO3 = ? → low 4. pO2 = ? → low

53. Must know this… PaCO2: basic <(35-45mmHg) >acidotic
HCO3: acidotic < (22-26mEq/L) >basic
Must know this…

54. ABG’s - Compensation Patient pH = 7.30 1. pH = acidotic
PCO2 = 30mm Hg 2. PCO2 = alkalotic
PO2 = 68mm Hg 3. PO2 = hypoxic
HCO3 = 14mEq/L 4. HCO3 = acidotic
O2 sat. = 92% 5. O2 sat = low
“same directions = compensation”
Metabolic acidosis with partial respiratory compensation
ABG’s - Compensation

56. Big Picture ACIDOSIS: CNS depression ALKYLOSIS: CNS irritability
Stupor to confusion to coma
ALKYLOSIS: CNS irritability
Restlessness to seizures
Big Picture

57. Brittany Murphy Died : Community acquired pneumonia, Anemia,
Drug Intoxication
Brittany Murphy