Alterations in Fluid, Electrolyte and

Acid-Base Balance

Pediatric Differences 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. 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. BindlerChild Health Nursing: Partnering with Children & Families

© 2006 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

Mechanism to Restore balance kidney: conserves water, regulates

electrolyte excretion <2yr kidneys immature less able to conserve or excrete water and

solutes effectively greater risk for acid/base imbalances Will use the SG norm: 1.005-1.015

Fluid Volume Imbalances Dehydration: loss of ECF fluid and sodium.

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. Causes: fluid overload, CHF. Manifested by wt.gain, puffy face and extremities,

enlarged liver.

Nursing Considerations How can the nurse determine if the child is

mildly dehydrated vs moderately dehydrated?

Mild Dehydration: by history. 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 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 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

Sodium may be: Low High Or normal

Isotonic Dehydration or Isonatremic Dehydration 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. Most practitioners consider below 135 and above 148 a

more conservative parameter (138-148) Most common form of dehydration in young children from

vomiting and diarrhea.

Hypotonic or Hyponatremic Dehydration 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 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

Common viral form of diarrhea All ages but 3 mo-2yrs most common Fecal/oral route Virus remains active;

10 days on hard, dry surfaces 4 hrs on human hands 1 wk on wet areas

Rotavirus (cont.)

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 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 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: 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 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 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:

Which of the following IV solutions replaces Sodium?

D5 W Lactated Ringers Normal Saline D5 ½ NS

Answer: All but D5 W

See IV solutions table B & B p. 733

Calculation of intravenous fluid needs: maintenance 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 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 1000 + 500+ 300= 1800ml/day.

How much fluid should this patient get per hour? 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:

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 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 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 Electrolytes usually gained and lost in

relatively equal amounts to maintain balance

Imbalance caused by: Abnormal route of loss (vomiting/diarrhea) can

disturb electrolyte balance Disproportionate IV supplementation Disease states: renal dis.

Hypernatremia Excess serum sodium in relation to water Causes:

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 Excess water in relation to serum sodium Most common sodium imbalance in

children Causes:

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) Clinical manif: decreased level of

consciousness d/t swelling of brain cells. Anorexia, headache, muscle weakness,

decreased DTR’s, lethargy, confusion or coma. Seizures occur when rapid or severe. SG dilute: 1.000-1.0005 Lab tests: serum sodium

Treatment: hypertonic solution.

Hyperkalemia Excess serum potassium Causes:

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

Insulin drives K back into the cells decreased K loss from Renal insufficiency

Hyperkalemia (cont) Clinical manif: all are related to muscle dysfunction:

hyperactivitiy of GI smooth muscle: intestinal cramping and diarrhea. 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 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. Also in nephrotic syndrome, cirrhosis, Cushing

Syndrome, CHF (to be covered elsewhere)

Hypokalemia (cont) 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 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 (milk-alkali syndrome).

Hypercalcemia (cont) Clinical manif: Ca imbalances alter neuromuscular

irritability with non-specific symptoms 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 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). 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) 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 tonic-clonic seizures, CHF.

Laryngospasm, seizures and cardiac arrhythmias in severe situations.

Hypocalcemia (cont 2) In children and adolescents, chronic

hypocalcemia more common, manif. By spontaneous fractures.Lab tests: serum Ca; bone density studyRx: oral and/or IV Ca, Ca rich diet

Hypermagnesemia 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) Clinical Manif: decreased muscle irritability,

hypotension, bradycardia, drowsiness, lethargy, weak or absent DTR’s.

Rx: increase fluids, diuretics, dialysis.

Hypomagnesemia 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) 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

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:

Fluid and Electrolyte Worksheet Use the fluid and electrolyte worksheet to

help review some of the major concepts of fluid and electrolyte imbalance.

Acid Base Balance 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 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 Incr ventilatory rate give O2 intubate adm NaHCO3

Clinical Conditions that cause Respir Acidosis 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 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 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 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

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 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 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 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 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: 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