1. FLUID, ELECTROLYTE,
AND ACID-BASE
BALANCE

3. Anatomy and Composition of
Fluid Compartments
 Total Body Water (TBW) adult
• 45-70% of body weight
• lowest in aged & obese
• highest in very lean & young
 TBW
• 60% -- male 70kg
• 50-55% female

4. Anatomy and Composition of
Fluid Compartments
 The composition of body fluid:
 Two compartments
• Intracellular Space -- 2/3 -- 40%
• Extracellular Space -- 1/3 -- 20%

5. Body fluids
 Extracellular fluids (ECF)
• Interstitial fluid - fills the spaces
between most cells of the body
• 15% of body weight
• Intravascular fluid - plasma
• (WBC, RBC and platelets
in this fluid)
5% of body weight

6. Body fluids
 Intracellular fluids (ICF)
• Liquids within cell membranes
• 40% of body weight

7. Amount and composition of
body fluids
Actual amount of body water
differs according to
Age
Sex
Body composition

8. Physiology of Body Water
Balance
 Newborn 70% 0f WT water
 1-year-old 60% of WT water
 Men: higher water content
due to greater muscle mass

9. Physiology of Body Water
Balance
 Obese: less water because fat
cells have minimal ICF
• Use ideal body weight when
estimating TBW for obese
 Elderly:
less water due to less
muscle mass

10. Fluid Shifts
“Third Spacing
 Refers to loss of ECF into a space that does
not contribute to equilibrium between ICF
and ECF
Excess fluid in interstitial spaces and connective tissues
between cells [edema] or
Excess fluid in potential spaces [effusion]
• peritoneal cavity
• pericardial sac
• synovial cavities of joints
• alveoli or intra-pleural space

11. Fluid Shifts
“Third Spacing”
 Etiology
• Caused by an increase in filtration
and/or decrease in reabsorption
due to altered capillary forces

12. Fluid Shifts
“Third Spacing”
Mechanisms causing third
spacing & edema
• massive inflammation
• venous obstruction
• increased blood volume
• low serum albumin

14. Components in body fluids
 Electrolyte
• an element that when dissolved can carry an
electrical current
• Cations - (+) ; Anions - (-)
• neuromuscular function
• acid-base balance

15. Components of body fluids
 Minerals
• ingested compounds
• serve as catalysts in nerve response, muscle
contraction, and metabolism of nutrients in
foods, regulate electrolyte balance

16. Movement of body fluids
 Diffusion
• Area of higher concentration to an area of
lower concentration till even distribution
 Osmosis
• Movement of a pure solvent, e.g. water
through a semipermeable membrane from a
solution that has a lower solute concentration
to one that has a higher solute concentration

17. Osmotic pressure
 Drawing power of water (dependent on
the number or molecules in solution)
• Isotonic
• Hypotonic
• Hypertonic

18. Movement of body fluids
 Filtration
• Water and diffusible substances move
together in response to fluid pressure
 Active transport
• Requires energy
• Able to move larger molecules and go from
less to greater concentration

19. Fluid Intake
 Hypothalamus - thirst control center
 Oral fluid intake requires an alert state
 Osmoreceptors - monitor osmolality

20. Fluid Output
 Loss through the kidneys and GI tract
 Insensible
 Sensible

21. Cations
 Sodium (Na+)
• Most abundant in the extracellular fluid
• Maintains water balance, transmits nerve
impulses, contracts muscles
• Values - 135-145 mEq/L

22. Cation
 Potassium (K+)
• Major intracellular cation
• Regulates neuromuscular excitability,
muscular contraction, and acid-base
• Value - 3.5 -5.3 mEq/L

23. Cation
 Calcium (Ca2+)
• Cardiac conduction, blood coagulation, bone
growth and formation, & muscular relaxation
• Value - 4 - 5 mEq/L

24. Cation
 Magnesium (Mg2+)
• Second most important of intracellular fluids
• Enzyme activities, muscular excitability
• Value - 1.5 - 2.5 mEq/L

25. Electrolyte Imbalances
 Hyponatremia
• GI losses, sweating, & diuretics
• S/S: N/V/D, abd cramps, personality change
 Hypernatremia
• Ingestion of large amounts
• S/S: Dry tongue and mucous membranes,
restlessness, convulsions, thirst, dry skin

26. Electrolyte imbalances
 Hypokalemia
 Causes: K+ wasting diuretics
 N/V/D
 polyuria
 S/S: weak, irregular pulse
• hypotension
• weakness

27. Electrolyte imbalances
 Hyperkalemia
• Causes: Renal failure
• S/S: irregular slow pulse, weakness, irritability

28. Electrolyte Imbalances
 Hypocalcemia
• Causes: Vitamin D deficiency
• S/S: Numb and tingling fingers and circumoral
region, muscle cramps
 Hypercalcemia
• Causes: osteoporosis, prolonged
immobilization
• S/S: decreased muscle tone, weakness,
lethargy, kidney stones

29. Electrolyte imbalances
 Hypomagnesemia
• Causes: malnutrition and alcoholism polyuria
• S/S: muscular tremors, hyperactive deep
tendon reflexes
 Hypermagnesemia
• Causes: Renal failure
• S/S: hypoactive deep tendon reflexes,
shallow and slow respirations

30. Acid - Base Balance
 Blood pH - 7.35 - 7.45
 paCO2 - 35 - 45
 Bicarbonate (HCO3) - 22-26 mEq/L

31. Respiratory Acidosis
 pH < 7.35
 paCO2 > 45 mm Hg
 Causes: Respiratory failure
 Hypoventilation
 Resp muscles paralysis
 Airway obstruction

32. Respiratory Alkalosis
 pH > 7.45
 paCO2 < 35 mm Hg
 Causes: excessive exhalation of CO2
(hyperventilation)

33. Metabolic Acidosis
 pH < 7.35
 bicarbonate - < 22 mEq/L
 Causes: Starvation, DKA, Diarrhea, drug
use

34. Metabolic Alkalosis
 pH > 7.45
 bicarbonate > 26 mEq/L
 Causes: excessive vomiting, prolonged
gastric suctioning

35. Fluid & Electrolyte Imbalances
 Burns - body fluid loss
 Renal D/O - abnormal retention of Na,
Cl, K
 GI Disturbances - Loss of fluid,
potassium, and chloride
 Exercise

36. S/S electrolyte imbalance
 Head: irritability
 Fontanels: depressed, bulging
 Eyes: sunken
periorbital edema
 Mouth: mucous membranes
 CV: neck veins, edema, blood pressure

37. Imbalances
 GI: abdomen, V/D
 Renal: Oliguria or anuria (FVD, FE)
 Diuresis (FVE)
 Increased urine spec. gravity (FVD)
 Skin (Temp)
• increased - met acidosis, hypernatremia
• decreased - FVD

38. Replacement of fluids and
electrolytes
 Types of IV fluids
 Isotonic
 Hypertonic
 Hypotonic

39. IV complications
 Infiltration
• IVF enter SQ space
 Phlebitis
• vein inflammation
• S/S: pain, redness, warmth
 Fluid overload
• Fluids given too rapidly
 Bleeding

40. Discontinuing an IV
 Stop infusion
 Remove tape
 1 - 2 minute pressure

41. Blood transfusions
 Large bore catheter (18 ga or larger)
 Give with normal saline
 Baseline vital signs
 Double check with two RNs
 Begin transfusion slowly
 Observe closely for first 15 min

42. Transfusion Reactions
 Caused by:
• blood incompatibility
• allergic sensitivity
• S/S: fever, chills, rash, hypotension, shock
 Treatment: stop transfusion, give NS,
save tubing, prepare for emergency
drugs