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Alterations in Fluid, Electrolyte and Acid-Base Balance Ball & Bindler Donna Hills EdD APN
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
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:
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: (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 ( mEq/L) Harriet Lane Handbook, 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 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 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 = 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
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 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: 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 study Rx: 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.
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: (in general) Acidosis < 7.35 : too much acid Alkalotic > 7.43 : too little acid pCO2 reflects carbonic acid status: HCO3- reflects metabolic acid status:
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