Megan McClintock
Winter 2012
FLUID & ELECTROLYTES
ACID BASE IMBALANCES
CHAPTER 17
HOMEOSTASIS

Maintained by the intake and output of water and
electrolytes and regulation by the renal and
pulmonary systems

Acid-base balance is necessary for many
physiologic processes (respiration, metabolism,
function of the CNS)

Many disease and treatments
affect this balance
WATER
More important to life than any other nutrient
 60% of an adult’s body weight, more in a child,
less in the elderly
 Found in foods (but not in alcohol)
 Daily need is about 2000 mL
 1 liter of water weighs 1 kg

URINE SPECIFIC GRAVITY
Measures the kidney’s ability to concentrate or
dilute urine
 1.002 – 1.028

 High
is dehydrated
 Low is overhydrated (or unable to concentrate)
 Kidney failure often causes a fixed specific gravity
ELECTROLYTES

Cations (positively charged)
 K+,
Na+, Ca+, Mg+
 Transmit nerve impulses to muscles and contract
skeletal and smooth muscles

Anions (negatively charged)
 Attached
to cations
 Cl-, HCO3-, PO4-, SO4
Are always kept in
balance
DISTRIBUTION OF BODY FLUIDS &
ELECTROLYTES
Intracellular (2/3) – K+, PO4 Extracellular (1/3) – Na+, Cl
 Interstitial
(lymph)
 Intravascular (blood plasma)
 Transcellular (cerebrospinal, pleural, peritoneal,
synovial fluids)
REGULATION OF FLUID & ELECTROLYTE
MOVEMENT
OSMOLALITY
Indicates the water balance of the body
 Serum osmolality (275 - 295)

 High
is water deficit
 Low is water excess

Urine osmolality (100-1300)
 High
is concentrated
 Low is dilute
FLUID SPACING

First spacing
 Normal

Second spacing
 Edema

Third spacing
 Ascites
 Burn
edema
REGULATION OF WATER BALANCE

Hypothalmic Regulation
Thirst is stimulated
 ADH (vasopressin) release is stimulated


Pituitary Regulation


Adrenal Cortical Regulation


ADH (vasopressin) is released
Glucocorticoids & mineralocorticoids are released
Renal Regulation
Adjust urine volume and electrolyte excretion
 Normal is 1.5 Liters of urine/day

REGULATION OF WATER BALANCE (CONT.)

Cardiac Regulation
 ANP
& BNP will stop the action of the adrenal
cortex and the kidney

GI Regulation
 Intake
and output are reabsorbed here
 Diarrhea and vomiting can lead to significant losses

Insensible Water Loss
 600-900
mL/day from the lungs and skin
 Increases with fever, exercise
GERONTOLOGIC CONSIDERATIONS

Structural changes in the kidney and decreased renal
blood flow










Decreased GFR
Decreased creatinine clearance
Loss of ability to concentrate urine and thus conserve water
Decrease in renin and aldosterone
Increase in ADH and ANP
Loss of subcutaneous tissue
Decrease in thirst mechanism
Musculoskeletal changes
Mental status changes
Incontinence
FLUID VOLUME DEFICIT
 What
causes
it?
 What
can you
do?
FLUID VOLUME EXCESS
 What
causes
it?
 What
can you
do?
NURSING INTERVENTIONS

Strict I/O
Intake – oral, IV, tube feedings, retained irrigants
 Output – urine, excess sweating, wound/tube drainage,
vomitus, diarrhea

Urine specific gravity
 Assessment of CV, Resp, Neuro, Skin status
 Daily weight under standardized conditions
 Don’t “catch up” IV fluids
 No water with NG suction, use isotonic saline
 Keep fluids accessible and within reach
 Give warm or cold fluids (not room temperature)

SERUM ELECTROLYTES

Sodium (Na) 135 - 145
 Primarily
responsible for maintaining osmotic pressure
(intracellular and extracellular fluids)
 Increased with fluid deficit
 Decreased with fluid excess

Potassium (K) 3.5 – 5.0




Chloride (Cl) 96 – 106




Works with Na to maintain osmotic pressure
Increased with poor kidney function
Decreased with excessive vomiting or diarrhea
Calcium (Ca) 8.6 – 10.2


Major component of cardiac function
Increased with poor kidney function
Decreased with excessive urination, diarrhea or vomiting
Transmission of nerve impulses, heart and muscle contractions,
blood clotting, formation of teeth and bone
Phosphate (PO4) 2.4 – 4.4

Function of muscle, RBCs, and the nervous system
THE MAGIC FOURS
Electrolyte
Potassium
Chloride
Sodium
pH
CO2
HCO3
Range
3.5 - 5.0
96 - 106
135 - 145
7.35 - 7.45
35 - 45
22 - 26
Magic 4
4
104
140
7.4
40
24
Hematocrit normal is 3 times the hemoglobin
SODIUM (135 - 145)
Major cation of ECF
 Primary determinant of osmolality
 GI tract absorbs sodium from food
 Regulated by kidneys, ADH, aldosterone
 Sodium level reflects the ratio of sodium to
water
 Imbalances are typically associated with fluid
volume problems

HYPERNATREMIA (HIGH SODIUM)
 What
causes
it?
What can you
do?
HYPONATREMIA (LOW SODIUM)
 What
causes
it?
 What
can you
do?
POTASSIUM (3.5 - 5.0)
Major cation of ICF
 Sodium-potassium pump requires magnesium
 Moves into cells during formation of new
tissues and leaves the cell during tissue
breakdown
 Diet is the source of potassium
 Kidneys are primary route of loss

HYPERKALEMIA (HIGH POTASSIUM)
 What
causes
it?
 What
can you
do?
HYPOKALEMIA (LOW POTASSIUM)
 What
causes
it?
 What
can you
do?
CALCIUM (8.6 – 10.2)
Primary source is bones
 Regulated by parathyroid hormone, calcitonin,
and vitamin D
 Affects transmission of nerve impulses, heart
and muscle contractions, blood clotting, and
forming of teeth and bone

HYPERCALCEMIA (HIGH CALCIUM)
 What
causes
it?
 What
are the
symptoms?
 What
can you
do?
HYP0CALCEMIA (LOW CALCIUM)
PHOSPHATE IMBALANCES

Hyperphosphatemia




Cause - renal failure
S/S – calcium deposits in joints, skin, kidneys, eyes;
hypocalcemia, tetany, neuromuscular irritability
Tx – decrease intake of dairy products, good hydration, fix
hypocalcemia
Hypophosphatemia



Cause – malnutrition, malabsorption syndrome, alcohol
withdrawal
S/S – CNS depression, confusion, muscle weakness,
dysrhythmias
Tx – oral supplements (Neutra-Phos), lots of dairy products,
IV phosphate (but this can cause sudden hypocalcemia)
MAGNESIUM IMBALANCES

Hypermagnesemia




Cause – increased intake (ie. MOM, Maalox) with chronic kidney
disease
S/S – lethargy, n/v, loss of DTRs, can have respiratory and
cardiac arrest
Tx – avoid magnesium-containing drugs, IV calcium, increased
fluid intake, may need dialysis
Hypomagnesemia



Cause – prolonged fasting or starvation, chronic alcoholism,
diuretics
S/S – confusion, hyperactive DTRs, tremors, seizures, cardiac
dysrhythmias
Tx – oral supplements, increase green veggies, nuts, bananas,
oranges, peanut butter, chocolate; IV or IM magnesium (if given
too rapidly can cause cardiac or respiratory arrest)
MEDICATIONS

Loop diuretics

Thiazide diuretics

Potassium sparing diuretics

Electrolytes

Kayexolate
ACID BASE BALANCE
REGULATION OF ACID-BASE BALANCE

Buffer system (immediate)
 Primary
regulator
 Won’t work without good functioning respiratory
and renal symptoms

Respiratory system (minutes, max in hours)
 Excretes

CO2 and water
Renal system (2-3 days to max respond)
 Reabsorbs
HCO3
ARTERIAL BLOOD GAS

pH (7.35 – 7.45)

CO2 (35 – 45)

HCO3 (22 – 26)

Base excess (+2 to -2)
If high, metabolic alkalosis
 If low, metabolic acidosis

DETERMINING
ACID–BASE BALANCE
1.
2.
3.
4.
5.
Is pH acid, base or normal?
Is CO2 acid, base or normal?
Is HCO3 acid, base or normal?
Which of the components match?
Is there compensation?
Is non-matching reading abnormal? – partial compensation
Is non-matching reading normal? – no compensation
RESPIRATORY ALKALOSIS
RESPIRATORY ALKALOSIS

Causes




Hyperventilation
Pulmonary disease
High altitudes
Signs/symptoms




Hyperventilation
Feels “light-headed”
Arrhythmias
Anxiety

Treatment







Breathe into paper bag
Rebreather mask
Anti-anxiety medicine
Relaxation techniques
Reduce stimulation
Treat pain/fever
Assess:





Resp rate/depth
HR & BP
Serum K levels
Hydration status
Check for digitalis toxicity
RESPIRATORY ACIDOSIS
RESPIRATORY ACIDOSIS

Causes






CNS depression
Loss of lung surface
Neuromuscular disease
Immobility
Mechanical ventilation

Treatment





Signs/symptoms

Dyspnea
Hypoxia
Drowsiness
Tachycardia
Seizures
Diaphoresis









Turn, cough, deep breathe
Semi-Fowler’s position
Suction
Incentive spirometer
Seizure precautions
Decrease use of sedatives
Bronchodilators
May need ventilator
Assess:



Resp rate/depth
HR & BP
Patiency of airway
METABOLIC ALKALOSIS
METABOLIC ALKALOSIS

Causes






NG suctioning
Prolonged vomiting
Diuretic use
Multiple blood transfusions
CPR (given bicarb)
Signs/symptoms





Dizziness
Dysrhythmias
Convulsions
Confusion
Muscle cramps (late sign)

Treatment






Identify and treat the cause!
IV fluids
Stop giving bicarbonate
Give antiemetics
Give Diamox
Assess:






Resp rate/depth
HR & BP
Serum K levels (usually low)
Hydration status (tend to be
dehydrated)
Check for digitalis toxicity
Parasthesias
METABOLIC ACIDOSIS
METABOLIC ACIDOSIS

Causes






Diabetic ketoacidosis
Renal or liver failure
Severe diarrhea
Vomiting
Starvation
Signs/symptoms





Kussmaul respirations
Hypotension
Arrythmias
Warm to hot ,flushed skin
Confusion

Treatment






Identify and treat the cause!
Administer insulin (if due to
ketoacidosis)
Give antiemetics
IV fluids
IV bicarbonate
Assess:



Renal function (BUN,
creatinine)
Serum K levels (tends to go
up but down once insulin
given)
Hydration status
IV FLUIDS

Isotonic




Hypertonic




3% NS
D51/2NS
D10W
Hypotonic


NS
D5W
LR
1/2NS
Plasma Expanders
CENTRAL VENOUS ACCESS DEVICES

Centrally
inserted
catheters (CVCs)

Peripherally
inserted central
catheters (PICCs)

Implanted
infusion ports
NURSING CARE OF CVADS








Inspect site for redness, edema, warmth, drainage, pain
Dressing change/cleaning with sterile technique using
chlorhexidine (back and forth scrub to generate friction)
Maintain transparent dressing c/d/I
Change injection caps using sterile technique
Teach pt to turn head away from insertion site during
cleaning and cap change
Have patient Valsalva during cap change if unable to
clamp
Use push-pause method to flush (creates turbulence)
Removal of non-tunneled CVCs and PICCs may be done
by a trained nurse (have pt Valsalva as last of catheter is
withdrawn, apply pressure immediately, inspect catheter
tip)