Fluid and Electrolytes
Alteration in Fluid and Electrolyte Status Lecture notes
Developmental and Biological Variances
Infants younger than 6 weeks do not produce tears.
In an infant a sunken fontanel may indicate dehydration.
Infants are dependant on others to meet their fluid needs.
Infants have limited ability to dilute and concentrate urine.
Developmental and Biological
The small the child, the greater the proportion of body water to weight and proportion of extracellular fluid to intracellular fluid.
Infants have a larger proportional surface are of the GI tract than adults.
Infants have a greater body surface area and higher metabolic rate than adults.
Water Balance
Regulated by Anti-diuretic Hormone ADH.
Acts on kidney tubules to reabsorb water.
The young infant is highly susceptible to dehydration.
Increased Water Needs
Fever
Vomiting and Diarrhea
High-output in renal failure
Diabetes insipidus
Burns
Shock
Tachypnea
Decreased Water Needs
Congestive Heart Failure
Mechanical Ventilation
Renal failure
Head trauma / meningitis
General Appearance
How does the child look?
Skin:
• Temperature
• Dry skin and mucous membranes
• Poor turgor, tenting, dough-like feel
• Sunken eyeballs; no tears
• Pale, ashen, cyanotic nail beds or mucous membranes.
• Delayed capillary refill > 3 seconds
Loss of Skin Elasticity
Cardiovascular
Pulse rate change:
Note rate and quality: rapid, weak, or thready
Bounding or arrhythmias
Tachycardia #1 sign that something is wrong
Increased HR may be first subtle sign of hypovolemia
Blood Pressure
Note increase or decrease (remember it takes a 25% decrease in fluid or blood volume for change to occur)
Respiratory
Change in rate or quality
Dehydration or hypovolemia
Tachypnea
Apnea
Deep shallow respirations
Fluid overload
Moist breath sounds
Cough
Diagnostic Tests
Make sure free flowing specimen is obtained, a hemolyzed or clotted specimen may give false values.
Hemoglobin and Hematocrit
Measures hemoglobin, the main component of erythrocytes, which is the vehicle for transporting oxygen.
Hgb and hct will be increased in extracellular fluid volume loss.
Hgb and hct will be decreased in extracellular fluid volume excess.
Electrolytes
Electrolytes account for approximately 95% of the solute molecules in body water.
Sodium Na+ is the predominant extracellular cation.
Potassium K+ is the predominant intracellular cation.
Potassium
High or low values can lead to cardiac arrest.
With adequate kidney function excess potassium is excreted in the kidneys.
If kidneys are not functioning, the potassium will accumulate in the intravascular fluid
Potassium
Adults: 3.5 to 5.3 mEq /L
Child: 3.5 to 5.5 mEq / L
Infant: 3.6 to 5.8 mEq / L
Panic Values:
<> 7.0 mEq / L
Hyperkalemia
Defined as potassium level above 5.0 mEq / L
Significant dysrhythmias and cardiac arrest may result when potassium levels arise above 6.0 mEq/L
Adequate intake of fluids to insure excretion of potassium through the kidneys.
CM: Hyperkalemia
Nausea
Irregular heart rate
Pulse slow / irregular
Causes of Hyperkalemia
Acute renal failure
Chronic renal failure
Glomerulonephritis
Diagnostic tests:
Serum potassium
ECG
Bradycardia
Heart block
Ventricular fibrillation
Hypokalemia
Potassium level below 3.5 mEq / L
Before administering make sure child is producing urine.
A child on potassium wasting diuretics is at risk – Lasix
CM: Hypokalemia
Neuromuscular manifestations are: neck flop, diminished bowel sounds, truncal weakness, limb weakness, lethargy, and abdominal distention.
Causes of Hypokalemia
Vomiting / diarrhea
Malnutrition / starvation
Stress due to trauma from injury or surgery.
Gastric suction / intestinal fistula
Potassium wasting diuretics
Ingestion of large amounts of ASA
Foods high in potassium
Apricots, bananas, oranges, pomegranates, prunes
Baked potato with skin, spinach, tomato, lima beans, squash
Milk and yogurt
Pork, veal and fish
Monitor Potassium Levels
Sodium
Sodium is the most abundant cation and chief base of the blood.
The primary function is to chemically maintain osmotic pressure and acid-base balance and to transmit nerve impulses.
Normal values: 135 to 148 mEq / L
Hyponatremia
Reflects an abnormal rate of sodium to water and is defined as a serum sodium concentration less than 135 mEq/L.
Results from retention of water secondary to impairment in free water excretion.
Pathophysiology
When sodium levels drop in the fluids outside the cells, water will sweep into the cells in an attempt to balance the concentration of salt outside the cells.
Cells will swell as the result of the excess water.
Brain cells cannot accommodate – symptoms of hyponatremia result from brain swelling
Diagnosis
10 to 15% of patients
Vomiting, diarrhea, or excessive sweating
Vital Signs: BP (orthostatic), skin turgor, mucous membrane appearance, jugular vein distention, edema
Lab values
History of oral intake of low-electrolyte or electrolyte free fluids
Early Manifestations
Anorexia, nausea, lethargy and apathy
More advanced symptoms: disorientation, agitation, seizures, depressed reflexes, focal neurological deficits
Severe: coma and seizures: sodium concentration less than 120 mEq/L
Medical Management
Normal saline given as resuscitative fluid
May need to reduce the fluid rate to 75% of maintenance
Supplemental oxygen
Water and salt restrictions
Hypernatremia
Serum sodium greater than 150 mEq/L is caused by conditions that produce an excessive gain of sodium or excessive loss of water that is greater than the loss of sodium.
Clinical Pearl
Most infant with severe dehydration have a history of lethargy, listlessness, and decreased responsiveness; those with hypernatremia dehydration tend to be irritable and fussy.
Hypernatremia
Inadequate fluid intake – 75%
Gastrointestinal losses – 44%
Occurs primarily in infants with diarrhea dehydration
Diabetes insipidus was major reason for excessive urinary output
Loss from high fever, environmental temperatures and hyperventilation
Primary Sodium Excess
Improperly mixed formula or re-hydration solution
Ingestion of sea water
Hypertonic saline IV
High breast milk sodium
Primary Water Deficit
Diabetes Insipidus
Diabetes Mellitus
Gastroenteritis (water loss greater than solute loss)
Inadequate breast feeding
Withholding of water: handicapped
Increased insensible loss – premature infant
Treatment Modalities
Intraosseous Therapy
Central Venous Catheter
Total Parental Nutrition
TPN Therapy
TPN provides complete nutrition for children who cannot consume sufficient nutrients through gastrointestinal tact to meet and sustain metabolic requirements.
TPN solutions provide protein, carbohydrates, electrolytes, vitamins, minerals, trace elements and fats.
Complications of TPN
Sepsis: infection
Liver dysfunction
Respiratory distress from too –rapid infusion of fluids
TPN: care reminder
caREminder:
The TPN infusion rate should remain fairly constant to avoid glucose overload. The infusion rate should never be abruptly increased or decreased.
Dehydration
General Assessment
Loss of weight
Level of consciousness
Alert to irritable
Restless to lethargic
Lethargic to coma
Skin Turgor
In moderate dehydration the skin may have a doughy texture and appearance.
In severe dehydration the more typical “tenting” of skin is observed.
Skin Turgor
Urine Output
Normal urine output is 1-2 mL/kg/hr
In mild dehydration urine output may be low – parent may report decrease in voiding
Moderate dehydration urine output would be low and concentrated (oliguric) with elevated specific gravity.
Severe dehydration would by (anuric) very low – very concentrated urine with high S.G.
Vital Signs
The heart rate is the most sensitive indicator of dehydration / hypovolemia.
HR will be elevated in an attempt to compensate for fluid loss.
Blood pressure will only drop as child is severely dehydrated (>10%).
Treatment of Mild to Moderate
ORT – oral re-hydration therapy
50 ml / kg every 4 hours
Increase to 100 ml / kg every 4 hours
Non carbonated soda, jell-o, fruit juices or tea.
Commercially prepared solutions are the best.
Re-hydration Therapy
Increase po fluids if diarrhea increases.
Give po fluids slowly if vomiting.
Stop ORT when hydration status is normal
Start on BRAT diet
Bananas
Rice
Applesauce
Toast
Teaching / Parent Instruction
Call PMD
If diarrhea or vomiting increases
No improvement seen in child’s hydration status.
Child appears worse.
Child will not take fluids.
NO URINE OUTPUT
Moderate to Severe Dehydration
Fluid replacement
Isotonic fluids initially:
Normal Saline 0.9%
Followed by: Dextrose 5% in.45 NS
Potassium is added only after child has voided.
Nursing Interventions
Assess child’s hydration status
Accurate intake and output
Daily weights
most accurate way to monitor fluid levels
Hourly monitoring of IV rate and site of infusion.
Increase fluids if increase in vomiting or diarrhea.
Decrease fluids when taking po fluids or signs of edema.
Care Reminder
A severely dehydrated child will need more than maintenance to replace lost fluids. 1 ½ to 2 times maintenance.
Adding potassium to IV solution.
Never add in cases of oliguria / anuria
• Urine output less than 0.5 mg/kg/hour
Never give IV push
Double check dosage
Over hydration
Occurs when child receives more IV fluids that needed for maintenance.
In pre-existing conditions such as meningitis, head trauma, kidney shutdown, nephrotic syndrome, congestive heart failure, or pulmonary congestion.
Signs and Symptoms
Tachypnea
Dyspnea
Cough
Moist breath sounds
Weight gain from edema
Jugular vein distention
Safety Precautions
Use small bags of fluid or buretrol to control fluid volume.
Check IV solution infusion against physician orders.
Always use infusion pump so that the rate can be programmed and monitored.
Even mechanical pumps can fail, so check the intravenous bag and rate frequently.
Record IV rate q hour
Acid – Base Imbalances
Acidosis:
Respiratory acidosis is too much carbonic acid in body.
Metabolic Acidosis is too much metabolic acid.
Alkalosis.
Respiratory alkalosis is too little carbonic acid.
Metabolic alkalosis is too little metabolic acid.
Respiratory Acidosis
Caused by the accumulation of carbon dioxide in the blood.
Acute respiratory acidosis can lead to tachycardia and cardiac arrhythmias.
Causes of Respiratory Acidosis
Any factor that interferes with the ability of the lungs to excrete carbon dioxide can cause respiratory acidosis.
Aspiration, spasm of airway, laryngeal edema, epiglottitis, croup, pulmonary edema, cystic fibrosis, and Bronchopulmonary dysplasia.
Sedation overdose, head injury, or sleep apnea.
Medical Management
Correction of underlying cause.
Bronchodilators: asthma
Antibiotics: infection
Mechanical ventilation
Decreasing sedative use.
Respiratory Alkalosis
Occurs when the blood contains too little carbon dioxide.
Excess carbon dioxide loss is caused by hyperventilation.
Causes of hyperventilation
Hypoxemia
Anxiety
Pain
Fever
Salicylate poisoning: ASA
Meningitis
Over-ventilation
Management
Stress management if caused by hyperventilation.
Pain control.
Adjust ventilation rate.
Treat underlying disease process.
Metabolic Acidosis
Caused by an imbalance in production and excretion of acid or by excess loss of bicarbonate.
Causes:
Gain in acid: ingestion of acids, oliguria, starvation (anorexia), DKA or diabetic ketoacidosis, tissue hypoxia.
Loss of bicarbonate:
diarrhea, intestinal or pancreatic fistula, or renal anomaly.
Ingestion of large doses of Aspirin
Management
Treat and identify underlying cause.
IV sodium bicarbonate in severe cases.
Assess rate and depth of respirations and level of consciousness.
Metabolic Alkalosis
A gain in bicarbonate or a loss of metabolic acid can cause metabolic alkalosis.
Causes:
Gain in bicarbonate:
Ingestion of baking soda or antacids.
Loss of acid:
Vomiting, nasogastric suctioning, diuretics massive blood transfusion
Clinical Manifestations
Hypertonicity or tetany
Management: Correct the underlying condition
