2. 
Fluid and Electrolytes
 At the end of this lecture, we will be able to:
 Discuss the importance of homeostasis.
 Enumerate and discuss the importance of
laboratory assessment of fluid and
electrolyte balance.
 Interpret laboratory results of fluids and
electrolytes.
 correlate clinically

3. 
Acid-Base Balance
 Discuss the control of pH in the blood with
emphasis on the role of lungs/kidneys
 Enumerate and discuss the four major
possible abnormalities of acid-base balance
 Metabolic vs Respiratory
 Acidosis vs Alkalosis
 Compensated vs Uncompensated
 Correlate clinically

4. 
A delicate balance of fluids, electrolytes,
acids and bases is required to maintain good
health.

This balance is called Homeostasis.

5. 
Intracellular fluid (ICF)
found within the cells of the body
 constitutes 2/3 of total body fluid in adults
 major cation is potassium


Extracellular fluid (ECF)
found outside the cells
 accounts of 1/3 of total body fluid
 major cation is sodium


6. 
Osmosis


Solutes


movement of water across cell
membranes from less concentrated to
more concentrated
substances dissolved in a liquid
Osmolality

the concentration within a fluid

7. 
Diffusion


Filtration


movement of molecules in liquids from an area
of higher concentration to lower concentration
fluid and solutes move together across a
membrane from area of higher pressure to one of
lower pressure
Active Transport

substance moves across cell membranes from
less concentrated solution to more concentrated requires a carrier and energy.

8. 


Urine
Insensible fluid loss
Feces

9. 



Sodium
Potassium
Chloride
Phosphate



Magnesium
Calcium
Bicarbonate
Electrolytes are important for:
Maintaining fluid balance
Contributing to acid-base regulation
Facilitating enzyme reactions
Transmitting neuromuscular reactions

10. 

Sodium (Na) NV 135-145 mEq/L
Potassium (K) NV 3.5 – 5.5 mEq/L
Ion-selective electrodes most common method
 Atomic absorption spectroscopy reference
method


Osmolality NV 275-300mOsm/kg H2O

Freezing point depression, most common
method (serum or urine)

11. 

Hypernatremia
Conditions causing dehydration
and absolute Na excess
Hyponatremia
Conditions causing loss of Na and
increase in body water (dilutional)

12. 

Hyperkalemia
 Conditions causing absolute
increase in body K and
extracellular shift of K
Hypokalemia
 Conditions causing loss of K,
decreased K intake, and
intracellular shift of K

13. 
Hyperosmolality (osmolal gap)
 Normal: dehydration, high Na,
azotemia, DI
 Moderately elevated: Ketoacidosis,
Renal and lactic acidosis
 Markedly elevated: alcohol ingestion
and poisoning of selected substances

14. 
Water Distribution
 60% of BW
 60% ICF and 33% ECF
 8% in plasma
 freely permeable
 Na, K, glucose, urea and protein
 balance between intake and body
loss

15. 
Sodium Distribution
major EC cation
135 to 145 mmol/L
relatively impermeable
leakage is actively pump out by
Na-K ATPase
balance intake and loss
excessive intake contributes to
hypertension
massive internal turnover

16. 
Potassium Distribution
major IC cation
constant tendency to diffuse
down its concentration gradient
opposed by Na-K ATPase
EC concentration is accessible
for measurement

17. Changes in H2O content independent of the
amount of solute will alter osmolality
 Water Loss
 movement from ICF to ECF
 stimulation of ADH secretion
 stimulates thirst center
 ECF volume is directly dependent upon the total
sodium content
 Sodium Balance: regulated by its renal excretion
(GFR, aldosterone); atrial natriuretic hormone
and natriuretic factor (cardiac glycosides) which
acts against Na-K ATPase


18. 
Abnormalities:
 Combined Water and Sodium Depletion
 Pure Water Depletion
 Pure Sodium Depletion (Hyponatremia)
 Combined Water and Sodium Excess
 Pure Water Excess
 Pure Sodium Excess (Hypernatremia)

19.  Hypotonic fluid loss
 thirst, dryness of mouth, difficulty of
swallowing, weakness, confusion
 weight loss, dry mucous membrane,
decreased saliva secretion, loss of skin
turgor, decreased urine volume
 Causes:
 Increased Loss: renal, GIT, lungs, skin
 Decreased Intake

20. Isotonic or hypotonic fluid loss
 hypertonic loss (excessive sweating)
 corresponding decrease in ECF
 response: aldosterone, inc. reabsorption, low GFR
 increased Hct and plasma protein
 reduced ECF volume
 peripheral circulatory failure
 plasma Na concentration
 isotonic loss = decreased
 hypotonic loss = increased
 Causes: Excessive Loss or Inadequate Intake


21. Failure of normal
excretion
Excessive intake
(iatrogenic)

22. Impairment of water excretion
hyponatremia
load is shared by ICF and
ECF
cerebral over-hydration
causes: increased intake and
decreased excretion

23. Peripheral edema, dyspnea,
pulmonary edema, venous
congestion, HPN, effusions,
weight gain
Causes: Increased Intake,
Decreased Excretion
mostly has paradoxical
hyponatremia due to defect in
free water excretion

24. 


Plasma Na is dependent upon relative
amounts of Na and water in the plasma
Indications for serum Na determination:
 dehydration or excessive fluid loss - as a
guide to appropriate replacement
 on parenteral fluid replacement who are
unable to indicate or respond to thirst
 with unexplained confusion, abnormal
behavior or signs of CNS irritability
Correlated with clinical observations

25. 


Balance is controlled by kidneys and GIT
related to Hydrogen Ions
Kidney: complete reabsorption and active
secretion
 amount of Na for reabsorption
 relative availability of K and H
 ability to secrete H
 aldosterone concentration
 rate of flow of tubular fluid

26. 

GIT: secreted in gastric juice,
reabsorb in the SI, secreted in LI in
exchange of Na
movement between ECF and ICF
 influence of insulin
 integrity of cell membranes
 Na-K ATPase
 H ion concentration

27. 





Output exceeds intake
inadequate intake is rarely the sole
cause
increased loss
drug therapy
redistribution in the ECF and ICF
asymptomatic, neuromuscular
disturbance, cardiac, renal (impaired
concentration), metabolic alkalosis

28. 




Excessive intake if excretion is
decreased
iatrogenic and parenteral
decreased excretion
redistribution of ECF and ICF
spurious (hemolysis, delayed
separation, contamination)

29. 

Hypokalemia
 low ST wave
 T depression/inversion
 prolonged PR interval
 prominent U wave
Hyperkalemia
 peaking of T waves
 loss of P waves
 abnormal QRS complexes
 ventricular fibrillation

30. 
Acid-Base balance is:
the regulation of
HYDROGEN ions.


31. 




The acidity or alkalinity of a solution is
measured as pH.
The more acidic a solution, the lower
the pH.
The more alkaline a solution , the
higher the pH.
Water has a pH of 7 and is neutral.
The pH of arterial blood is normally
between 7.35 and 7.45

32. 
The more Hydrogen ions, the more acidic the
solution and the LOWER the pH

The lower Hydrogen concentration, the more
alkaline the solution and the HIGHER the pH

33. 
Know what is normal.

34. 
Regulate pH by binding or releasing
Hydrogen

Most important buffer system:
 Bicarbonate-Carbonic Acid Buffer System
 (Blood Buffer systems act
instantaneously and thus constitute the
body’s first line of defense against acidbase imbalance)

36. 
Lungs
 help regulate acid-base balance by eliminating
or retaining carbon dioxide
 pH may be regulated by altering the rate and
depth of respirations
 changes in pH are rapid,
 occurring within minutes
 normal
CO2 level
 35 to 45 mm Hg

37. 
Kidneys
 the long-term regulator of acid-base balance
 slower to respond
 may take hours or days to correct pH
 kidneys maintain balance by excreting or
conserving bicarbonate and hydrogen ions
 normal
bicarbonate level
 22 to 26 mEq/L.

38. 



Age
 especially infants and the elderly
Gender and Body Size
 amount of fat
Environmental Temperature
Lifestyle
 stress

39. 



Respiratory Acidosis
Respiratory Alkalosis
Metabolic Acidosis
Metabolic Alkalosis

40. 
Mechanism
 Hypoventilation or Excess CO2 Production

Etiology
 COPD
 Neuromuscular Disease
 Respiratory Center Depression
 Late ARDS
 Inadequate mechanical ventilation
 Sepsis or Burns
 Excess carbohydrate intake

41. 

Symptoms
 Dyspnea, Disorientation or coma
 Dysrhythmias
 pH < 7.35, PaCO2 > 45mm Hg
 Hyperkalemia or Hypoxemia
Treatment
 Treat underlying cause
 Support ventilation
 Correct electrolyte imbalance
 IV Sodium Bicarb

42. 
Risk Factors and etiology
 Hyperventilation due to
 extreme anxiety, stress, or pain
 elevated body temperature
 overventilation with ventilator
 hypoxia
 salicylate overdose
 hypoxemia (emphysema or pneumonia)
 CNS trauma or tumor

43. 
Symptoms
 Tachypnea or Hyperpnea
 Complaints of SOB, chest pain
 Light-headedness, syncope, coma, seizures
 Numbness and tingling of extremities
 Difficult concentrating, tremors, blurred vision
 Weakness, paresthesias, tetany
 Lab findings
 pH above 7.45
 CO2 less than 35

44. 
Treatment
 Monitor VS and ABGs
 Treat underlying disease
 Assist client to breathe more slowly
 Help client breathe in a paper bag
 or apply rebreather mask
 Sedation

45. 
Risk Factors/Etiology
 Conditions that increase acids in the blood
 Renal Failure
 DKA
 Starvation
 Lactic acidosis
 Prolonged
 Toxins
diarrhea
(antifreeze or aspirin)
 Carbonic anhydrase inhibitors - Diamox

46. 

Symptoms
 Kussmaul’s respiration
 Lethargy, confusion, headache, weakness
 Nausea and Vomiting
 Lab:
 pH below 7.35
 Bicarb less than 22
Treatment
 treat underlying cause
 monitor ABG, I&O, VS, LOC, NaHCO3

47. 
Risk Factors/Etiology
 Acid loss due to
 vomiting
 gastric suction
 Loss of potassium due to
 steroids
 diuresis
 Antacids (overuse of)

48. 

Symptoms
 Hypoventilation (compensatory)
 Dysrhythmias, dizziness
 Paresthesia, numbness, tingling of extremities
 Hypertonic muscles, tetany
 Lab: pH above 7.45, Bicarb above 26
 CO2 normal or increased w/comp
 Hypokalmia, Hypocalcemia
Treatment
 I&O, VS, LOC
 give potassium
 treat underlying cause

50. 
1. Look at the pH
 is the primary problem acidosis (low) or alkalosis (high)

2. Check the CO2 (respiratory indicator)
 is it less than 35 (alkalosis) or more than 45 (acidosis)

3. Check the HCO3 (metabolic indicator)
 is it less than 22 (acidosis) or more than 26 (alkalosis)

4. Which is primary disorder (Respiratory
or Metabolic)?
 If the pH is low (acidosis), then look to see if CO2 or HCO3 is
acidosis (which ever is acidosis will be primary).
 If the pH is high (alkalosis), then look to see if CO2 or HCO3 is
alkalosis (which ever is alkalosis is the primary).
 The one that matches the pH (acidosis or alkalosis), is the primary
disorder.

51. 
The Respiratory system and Renal systems
compensate for each other
 attempt

ABG’s show that compensation is present when
 the


to return the pH to normal
pH returns to normal or near normal
If the nonprimary system is in the normal range
(CO2 35 to 45) (HCO3 22-26), then that system is
not compensating for the primary.
For example:
 In respiratory acidosis (pH<7.35, CO2>45), if the HCO3
is >26, then the kidneys are compensating by retaining
bicarbonate.
 If HCO3 is normal, then not compensating.

52. THE END