Transcript Fluid, Electrolyte and Acid-Base 10-07

Alterations in Fluid,
Electrolyte and
Acid-Base Balance
Ball & Bindler
Donna Hills EdD APN
Pediatric Differences
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ECF/ICF ratio varies with age
Neonates and infants have proportionately
larger ECF vol
Infants: high daily fluid requirement with
little fluid reserve; this makes the infant
vulnerable to dehydration.
Distribution of Water
Fluid Loss; Infants and <2yr.
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excretion is via the urine, feces, lungs and
skin
have greater daily fluid loss than older child
more dependent upon adequate intake
greater about of skin surface (BSA),
therefore greater insensible loss.
respiratory and metabolic rates are higher
therefore, dehydrate more rapidly
FIGURE 23–2 The newborn and infant have a high percentage of body weight comprised of water,
especially extracellular fluid, which is lost from the body easily. Note the small stomach size which
limits ability to rehydrate quickly.
Jane W. Ball and Ruth C. Bindler
Child Health Nursing: Partnering with Children & Families
© 2006 by Pearson Education, Inc.
Upper Saddle River, New Jersey 07458
All rights reserved.
Mechanism to Restore balance
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kidney: conserves water, regulates
electrolyte excretion
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<2yr kidneys immature
less able to conserve or excrete water and
solutes effectively
greater risk for acid/base imbalances
Fluid Volume Imbalances
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Dehydration: loss of ECF fluid and sodium.
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Caused by: vomiting, diarrhea, hemorrhage,
burns, NG suction.
Manifested by wt loss, poor skin turgor, dry
mucous memb., VS changes, sunken fontanel
Fluid overload: excess ECF fluid and excess
interstitial fluid volume with edema.
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Causes: fluid overload, CHF.
Manifested by wt.gain, puffy face and extremities,
enlarged liver.
Nursing Considerations
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How can the nurse determine if the child is
mildly dehydrated vs moderately
dehydrated?
Mild Dehydration: by history.
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hard to detect because the child may be
alert, have moist mucous membranes and
normal skin turgor.
Wt loss may be up to 5% of body weight.
The infant might be irritable; the older child
might be thirsty
vital signs will probably be normal
Capillary refill will most likely be normal
Urine output may be normal or sl less
Moderate Dehydration
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dry mucous membranes; delayed cap refill
>2 sec; Wt loss 6-9% of body weight
irritable, lethargic, unable to play, restless
decreased urinary output: <1ml/kg/hr; dark
urine with SG > 1.015 (in child >2yr)
Sunken fontanel
HR increased, BP decreased. Postural vital
signs
Severe Dehydration
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wt loss > 10% body weight
lethargic/comatose
rapid weak pulse with BP low or
undetectable; RR variable and labored.
dry mucous membranes/parched; sunken
fontanel
decr or absent urinary output.
Cap refill >4sec
Types of Dehydration and Sodium
Loss
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Sodium may be:
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Low
High
Or normal
Isotonic Dehydration or Isonatremic
Dehydration
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Loss of sodium and water are in proportion
Most of fluid lost is from extracellular component
Serum sodium is normal (130-150mEq/L) Harriet
Lane Handbook, 2000.
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Most practitioners consider below 135 and above 148 a
more conservative parameter.
Most common form of dehydration in young children from
vomiting and diarrhea.
Hypotonic or Hyponatremic
Dehydration
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Greater loss of sodium than water
Serum sodium below normal
Compensatory shift of fluids from extracellular to
intracellular makes extracellular dehydration
worse.
Caused by severe and prolonged vomiting and
diarrhea, burns, renal disease. Also by treatment
of dehydration with IV fluids without electrolytes.
Hypertonic or Hypernatremic
Dehydration
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Greater loss of water than sodium
Serum sodium is elevated
Compensatory shift from intracellular to
extracellular which masks the severity of
water loss (dehydration) delaying signs and
symptoms until condition is quite serious.
Caused by concentrated IV fluids or tube
feedings.
Rotavirus
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Common viral form of diarrhea
All ages but 3 mo-2yrs most common
Fecal/oral route
Virus remains active;
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10 days on hard, dry surfaces
4 hrs on human hands
1 wk on wet areas
Rotavirus (cont.)
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Incubation period 1-3 days
Symptoms: mild/mod fever, stomach ache,
frequent watery stools (20/day)
Treatment: prevention! Hand washing and
isolation of the infected child.
Fluid rehydration for diarrhea, advanced to
bland diet for older children
Breast milk for the infant who BF
Clinical Management for
Dehydration
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Blood may be drawn to assess electrolytes,
BUN and Creatinine levels
an IV may be placed the same time
Oral Rehydration Solution is the treatment
of choice for mild-moderate dehydration
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1-3 tsp of ORS every 10-15min to start (even if
vomits some)
50ml/Kg/Hr is the goal for rehydration.
Why are drinks high in glucose
avoided during rehydration?
Answer to why high glucose drinks are
avoided:
Recommended foods during
rehydration progression:
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starches, cooked fruits & vegetables,
soups, yogurt, formula, breast milk.
BRAT diet used to be recommended, but
recent research has shown no difference
than return to normal diet with some
attention to lactose containing foods,
depending upon the child’s response.
IV Therapy
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Used for severe dehydration or in the child
who will not/cannot tolerate ORS
Half 24hr maintenance plus replacement
given within first 6-8hr (in ER) to rapidly
expand the intravascular space. Usually a
normal saline bolus.
slower IV rate for the remainder of the first
24hrs
nurse records IV vol infused hourly
Rehydration and IV solution
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Why is the child initially rehydrated with a
normal saline bolus and not an IV solution
with potassium?
Answer to rehydration and IV solution
question:
Calculation of intravenous fluid
needs: maintenance
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see pg 735 B&B, Box 23-5.
For the 1st 10 Kg, replace at 100ml/Kg
for the second 10 Kg, replace at 50ml/Kg
for >20kg, replace at 20ml/Kg
Example of Maintenance Fluid
Calculation
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Your patient is a 10 yr old weighing 35 Kg.
You want to determine this patient’s 24hr
maintenance fluid needs:
for the first 10 Kg give 100ml/Kg = 1000ml
for the second 10 Kg:
50ml/Kg = 500ml
for the remaining 15 Kg (35-20Kg) , replace
at 20 ml/Kg = 20 (15) = 300ml
100 + 500+ 300= 1800ml/day.
How much fluid should this patient get
per hour?
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1800 ml / 24 hrs = 75 ml/hr.
Therefore, if the patient were NPO and not
taking in fluids from any other source, the IV
should be running at 75ml/hr.
If there is a deficit that also needs to be
replaced, the IV rate may be slightly higher
for a defined period of time.
If the patient is receiving fluids from other
sources, these need to be accounted as well
Practice Problems for Calculating 24hr
Fluid Maintenance and the hourly IV rate
for:
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A 9 yr old patient who weighs 20 Kg.
A 6 mo old baby who weighs 8 Kg
An 24mo old toddler who weighs 18 Kg
A 3 yr old preschooler who weighs 28 Kg
An 18 yr old who weighs 50 Kg
Answers for 24hr Fluid Calc.
Fluid Overload:Edema
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Incr capillary blood flow: inflammation,
infection
venous congestion: ECF excess, R sided
heart failure, muscle paralysis.
Incr albumin excess: Nephrotic Syndrome
Decr albumin synthesis: Kwashiorkor, liver
cirrhosis
incr capillary permeability: inflam/ burns
blocked lymphatic drainage: tumors/surg.
Clinical Assessment/Management
of Edema
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assess dependent limbs if ambu or sacrum
is lying
ascites; periorbital edema; rings too tight
pitting edema for degree of swelling
daily wt and strick I and O
elevation/change position Q2hr/ protect skin
against breakdown
distraction to deal with discomfort and
limitations of edema.
Electrolyte Imbalances
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Electrolytes usually gained and lost in
relatively equal amounts to maintain
balance
Imbalance caused by:
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Abnormal route of loss (vomiting/diarrhea) can
disturb electrolyte balance
Disproportionate IV supplementation
Disease states: renal dis.
Hypernatremia
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Excess serum sodium in relation to water
Causes:
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Too concentrated infant formula
Not enough water intake
Clinical manif: thirst, lethary, confusion
Seizures occur when rapid or is severe.
SG concentrated 1.020-1.030
Lab test: serum sodium
Treatment: hypotonic IV solution
Hyponatremia
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Excess water in relation to serum sodium
Most common sodium imbalance in
children
Causes:
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Infants vulnerable to water intoxication:dilute
form, excess pool water, poorly developed thirst
mech so cont to drink and can’t excrete excess
water.
Hyponatremia (cont)
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Clinical manif: decreased level of
consciousness d/t swelling of brain cells.
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Anorexia, headache, muscle weakness,
decreased DTR’s, lethargy, confusion or coma.
Seizures occur when rapid or severe.
SG dilute: 1.000-1.010
Lab tests: serum sodium
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ADH level and 24hr urine to r/o DI.
Treatment: hypertonic solution.
Hyperkalemia
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Excess serum potassium
Causes:
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excess K intake from IV overload, blood
transfusion, rapid cell death (hemolytic crisis,
large tumor destruction from chemo rx, massive
trauma, metabolic acidosis from prolonged
diarrhea and in DM when insulin levels are low
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Insulin drives K back into the cells
decreased K loss from Renal insufficiency
Hyperkalemia (cont)
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Clinical manif: all are related to muscle dysfunction:
hyperactivitiy of GI smooth muscle: intestinal cramping and
diarrhea.
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Weak skeletal muscles
Lethargy
Cardiac arrhythmias (tachycardia, prolonged QRS, peaked T
waves: also AV block and VTach).
Lab test: serum potassium
Treatment: correct underlying condition (take K out of the IV)
dialysis (peritoneal or hemo), Kayexalate (po or enema), K
wasting diuretics, IV calcium, bicarbonate, insulin and glucose.
Low potassium diet.
Hypokalemia
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Decreased serum potassium
Causes: diarrhea and vomiting, ingestion of
large amts black licorice, diuretics, osmotic
diuresis (glucose in urine as in DM), NPO
without K replacement in IV, NG Sx,
bulimia, insulin.
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Also in nephrotic syndrome, cirrhosis, Cushing
Syndrome, CHF (to be covered elsewhere)
Hypokalemia (cont)
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Clinical manif: muscle dysfunction
Slowed GI smooth muscle resulting in abdominal
distention, constipation and paralytic ileus
Skeletal muscles are weak; may effect respiratory
muscles
Cardiac arrhythmias: hypokalemia potentiates
Digitoxin Toxicity.
Lab test: serum potassium
Treatment: oral and/or IV potassium, diet rich in K.
Hypercalcemia
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Excess calcium
Needs vit D for efficient absorption; most of Ca is
stored in the bones.
Causes: bone tumors that cause bone
destruction, chemo rx release Ca from the bones;
immobilization causes loss from the bones
(usually excreted) but if kidneys can’t clear it,
hypercalcemia results, increased intake (milkalkali syndrome).
Hypercalcemia (cont)
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Clinical manif: Ca imbalances alter neuromuscular
irritability with non-specific symptoms
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Constipation, anorexia, N/V, fatigue, skeletal muscle
weakness, confusion, lethargy.
Renal calculi, cardiac arrhythmias
HyperCa increases Na and K excretion leading to polyuria
and polydipsia.
Rx: serum Ca, Ionized Ca, fluids, Lasix, steroids, dialysis.
Hypocalcemia
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Decreased serum calcium
Causes: decreased intake of Ca and/or Vit D
(adolescents are vulnerable d/t fad diets and the
deficit cannot be made up later, increasing risk for
osteoporosis).
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Limited exposure to sunlight, premature infants and dark
skinned people at increased risk to inadeq. Vit D and
therefore decreased Ca absorption.
Parathyroid dysfunction, multiple transfusion (Citrate
binds Calcium), steatorrhea (as in pancreatitis and Cystic
Fibrosis) binds Calcium in the stool.
Hypocalcemia (cont)
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Clinical Manif:acute situation related to increased
muscular excitability: tetany. +Chvostek’s Sx, +
Trousseau’s Sx.
In children: Twitching, cramping, tingling around
the mouth or fingers, carpal/pedal spasms.
In infants: tremors, muscle twitches, brief tonicclonic seizures, CHF.
Laryngospasm, seizures and cardiac arrhythmias
in severe situations.
Hypocalcemia (cont 2)
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In children and adolescents, chronic
hypocalcemia more common, manif. By
spontaneous fractures.
Lab tests: serum Ca; bone density study
Rx: oral and/or IV Ca, Ca rich diet
Hypermagnesemia
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Excess in Mg.
Imbalances characterized by
neuromuscular irritability
Causes: impaired renal function, Mag
Sulfate given perinatally to treat eclampsia,
increased use of laxatives, enemas,
antacids, IV fluid additives.
Hypermagnesemia (cont)
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Clinical Manif: decreased muscle irritability,
hypotension, bradycardia, drowsiness,
lethargy, weak or absent DTR’s.
Rx: increase fluids, diuretics, dialysis.
Hypomagnesemia
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Decreased serum Mg.
Stored in cells and bones
Causes: prolonged NPO without
replacement, chronic malnutrition, chronic
diarrhea, short bowel syndrome,
malabsorption syndromes, steatorrhea,
multiple transfusions, prolonged NG Sx,
some medications.
Hypomagnesemia (cont)
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Clinical manif: increased neuromuscular
excitability (tetany). Hyperactive reflexes,
skeletal muscle cramps, twitching, tremors,
cardiac arrhythmias, seizures.
Lab: serum Mg along with Ca and K.
Rx: po/IV Magnesium admin and treating
underlying cause of imbalance.
Critical Thinking: Clinical Evaluation
of Fluid and Electrolyte Imbalance
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B & B p. 757
How can you evaluate children
appropriately for fluid and electrolyte
imbalance without thinking through the
clinical manifestations of every possible
disorder, one after the other?
Answer to Critical Thinking:
Acid Base Balance
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normal arterial blood pH: 7.35-7.43 (in
general)
Acidosis < 7.35 : too much acid
Alkalotic > 7.43 : too little acid
pCO2 reflects carbonic acid status: 40 +- 5
HCO3- reflects metabolic acid status:
24 +- 4
Respiratory Acidosis
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caused by decr respir effort
build up of CO2 in the blood
pH decr or normal; pCO2 incr.
Symptoms manifested: confusion, lethargy,
HA, incr ICP, coma, tachycardia,
arrhythmias
Management of Respiratory
Acidosis
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Incr ventilatory rate
give O2
intubate
adm NaHCO3
Clinical Conditions that cause
Respir Acidosis
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conditions associated with decreased
respiratory drive, impaired gas
exchange/air trapping, ie:
head trauma, general anesthesia, drug
overdose, brain tumor, sleep apnea,
mechanical under ventilation, asthma,
croup/epiglottitis, CF, atelectasis, MD,
pneumothorax.
Respiratory Alkalosis
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caused by hyperventilation
CO2 is being blown off
pH incr : pCo2 decr
Symptoms: dizziness, confusion,
neuromuscular irritability, paresthesias in
extremities and circumoral, muscle
cramping, carpal or pedal spasms.
Management of Resp. Alkalosis
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First determine if oxygenation is adequate,
if not, you don’t want to slow the RR.
Determine the cause and correct it:
Causes of hypervent: hypoxemia, anxiety,
pain, fever, ASA toxicity,
meningitis/encephalitis, Gram - sepsis,
mechanical overventilation.
Ipecac is no longer recommended for
treatment of ingestions.
Metabolic Acidosis
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caused by a loss of bicarbonate (HCO3)
therefore, is an incr of acids in the blood
pH decr or moving towards normal
pCo2 decr ; HCO3 decr
Symptoms: Kussmaul respirations = incr
rate and depth as compensation
(hyperventilation/acetone breath),
confusion, hypotension, tissue hypoxia,
cardiac arrhythmias, pulmonary edema.
Management of Metabolic Acidosis
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Identify and treat underlying cause
In severe case may give IV NaHCO3 to incr
pH, or insulin/glucose.
Causes of MA for gain of acid: ingestion of
ASA, antifreeze, oliguria, RF, HAL, DKA,
starvation or ETOH KA, lactic acidosis
(tissue hypoxia).
Loss of HCO3: maple syrup urine disease,
diarrhea, RF.
Metabolic Alkalosis
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caused by loss of H+ or HCO3 retention
HCO3 incr with probable incr in pH, incr
pCO2.
Symptoms:weak, dizzy, muscle cramps,
twitching, tremors, slow shallow resp.,
disorientation, seizures.
Management of Metabolic Alkalosis
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correct underlying cause; facilitate renal
excretion of HCO3.
admin NS, K+ if hypokalemic, replace loss
of fluids, prec for Sz, monitor I and O and
electrolytes
Causes: prolonged vomiting, ingestion of lg
quantities of bicarb, antacids, loss of NG
fluids, hypokalemia from prolonged diuretic
use, multiple blood transfusion with citrate.
ABG Basic (Uncompensated)
Analysis
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Resp Acidosis: low pH and high PaCO2
Resp Alkalosis: incr pH and low PaCO2
Metab Acidosis: low pH and nl PaCo2;
decr HCO3
Metab Alkalosis: high pH; nl PaCO2 ; high
HCO3
ABG Analysis with Compensation
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Resp Acidosis: HCO3 will incr, pH will
approach nl; PaCO2 will still be increased
Resp Alkalosis: HCO3 will decr, pH will
approach nl; PaCO2 will still be decreased
Metab Acidosis: PaCO2 will decr, pH will
approach nl; HCO3 will still be decreased
Metab Alkalosis: PaCO2 will incr, pH will
approach nl; HCO3 will still be increased
Examples of ABG:
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pH 7.35-7.43 PaCO2 35-45 HCO3 20-28
= Norms
pH 7.33
PaCO2 52
HCO3 26
pH 7.48
PaCO2 32
HCO3 24
pH 7.28
PaCO2 37
HCO3 18
pH 7. 45
PaCO2 38 HCO3 32