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.
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
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
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
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)
35.
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
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
49.
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.