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Fluid and Electrolyte Imbalances in Children

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    Learning Objectives:  
                                                                                                                
  1. Describe the physiological characteristics in infants that affect adjustments to alterations in fluid and electrolyte balance.
  2. Discuss factors that may result in acid-base imbalances in children.
  3. Outline a nursing plan to maintain fluid and electrolyte balance in a child with diarrhea.
  4. Describe the various degrees of dehydration and how to assess for these  children.
  5. Differentiate between isotonic, hypotonic and hypertonic dehydration in children.
  6. Discuss the therapy of oral rehydration and the nursing management involved.

You have studied adults for most of the year.  When you are caring for children, especially infants and young children, it is important to be aware that there are some significant differences in their ability to maintain fluid and electrolyte balance.   Look at the following chart to see what those differences are and their clinical implications.

Differences Clinical Implications
Immature Kidneys - Infants and young children are unable to to concentrate or dilute urine as well as adults and also unable to conserve or excrete sodium as well. Infants are more likely to become dehydrated more quickly.  Given an episode of gastroenteritis, their bodies do not conserve fluid well and the loss of intake and increased output produce exaggerated effects.  On the other hand, children who are given an overload of fluid are also unable to compensate well and can easily get into cardiac overload.
Surface Area - An infant has a greater surface area to body mass than an adult therefore insensible loss (sweating) can be greater.  Metabolism is also greater because of the larger mass of active tissue. Infants with fevers will have greater fluid loss from sweating than older children.  During a fever the infant's metabolism will also climb which will increase the fluid loss through the respiratory system. Children are prone to illnesses that involve fluid losses and fevers.
Metabolic Rate - Infants generally have a high metabolic rate which makes replacement of water and electrolytes and important issue. Given an already high metabolism, the addition of illness (fever,  infection) casues the to produce increased wastes via metabolism. The immature kidneys may have difficulty filtering large amounts of wastes.
Total Body Water - Proportionately, infants and small children have greater percentages of body water which is replaced by fat and muscle in the older child/adult.  Until about the age of 2, one-half of the total body water (TBW) is extracellular.  Infants and children are prone to illnesses that increase water losses. 
Intake and Output - Children take in and exrete a larger amount of fluid proportionately than an older child.   Because the daily exchange of ECF is high in the infant, there is little fluid reserve. Dehydration during vomiting or diarrhea happens quickly because there is a smaller reserve of fluid in the infant.

Illnesses that produce fluid and electrolyte losses in children

Diarrhea
Diarrhea can causes dehydration, electrolyte imbalances and metabolic acidosis.   Infants and young children are more prone to the deleterious effects of diarrhea than older chidlren.  This is most likely due to their immature systems..  There are many causes for diarrhea which inlcude bacterial, viral and parasitic pathogens.   We also know that antibiotics, ear infections, respiratory infections and urinary tract infections are also associated with diarrhea.  Remember infants are generally at high risk for ear infections due to the shape and angles of their eustachian tube. They are also exposed to viral and bacterial infections with siblings and at daycare.   Diarrhea also occurs in areas of inadequate sanitation, crowding, poor water sources and areas where contaminated milk is served.

  • Rotavirus - is one type of virus that causes diarrhea, especially in young children.   It is commonly characterized by explosive, green, watery, foul smelling diarrhea.   It is a common cause of diarrhea in the child care setting.  Rotavirus infection usually occurs during the winter months.  Some children have no symptoms of rotavirus infection while others may have severe vomiting, watery diarrhea and fever.   Rotavirus is highly contagious via direct contact with the virus (fecal-oral).   Often, another child or adult touches a surface that has been contaminated and then touches his or her mouth. The daycare setting with multiple diaper changes and natural child - child contact increases the possibility of group illness.

Vomiting
Vomiting is common in childhood (especially related to minor GI viral infections) and becomes a problem when adequate intake of fluid and electrolytes does not accompany the illness.  Causes of vomiting are diagnosed by the history of the espisodes, color/amount/character of the vomitus, and pain involved. 

Assessing for Dehydration
Table 28-7
is an excellent source for learning the signs and symptoms of dehydration in an infant or young child. Areas for you to concentrate are:

  • Progression of symptoms from mild to moderate dehydration
  • Physical assessment of each of the symptoms

Types of Dehydration and Clinical Implications

Type of Dehydration Clinical Implications
Isotonic Dehydration - electrolyte and water losses happen in equal proportions .
Most common type of dehydration
The greatest threat to the child is hypovolemic shock because most of the fluid loss is from the extracellular compartment.  Treatment would be IV fluids
Hypotonic dehydration - greater electrolyte deficit than water deficit.  This can happen with diuretic therapy, renal failure, presence of antidiurtetic hormone or excessive tube drainage, bleeding, vomiting and diarrhea.   Fluid shifts to the intracellular spaces rapidly and the body perceives itself to be in shock much faster than with isotonic dehydration Causes:
*Giving children large amounts of electrolyte free solution (water) to replace diarrhea.
*Giving IV solutions without Na+ to the patient who is NPO
*Tap water enemas
*Children with cystic fibrosis who secrete large amount of Na+ in their sweat
Hypertonic dehydration - greater water loss than electrolyte loss *Most dangerous because shock symptoms are less apparent.  Yet fluid deficit is occuring.  Seizures and neurological imbalances can occur.
Causes:
*When insensible loss from the skin ans repsiratory tract is high
*Any clinical condition that depletes the body of water

Estimating Fluid Requirements
In caring for children with fluid and electrolyte imbalances, you will need to monitor their intake and output carefully.  How do you know when "encouraging" fluids, how much is fair, good or excellent?  Why are IV rates set at 17 cc/hour or 42 cc/hr? 

One such way to estimate body fluid requirements is using the following formula.

Body Weight Volume of maintenance fluid
Child weighing 1 - 10 kg Needs 100cc/kg
Child weighing 11 - 20 kg Needs 1,000 cc + 50cc/kg over 10 kg
Child weighing greater than 20 kg Needs 1,500 cc + 20cc/kg over 20 kg

Therefore, a child weighing 5 kg. would need 100 X 5 = 500cc/24 hours 
A child weighing 15 kg would need 1000 + (50cc X 5kg) = 1000 + 250 = 1250cc/24 hours  
A child weighing 24 kg would need 1500 + (4kg X 20cc) = 1500 + 80 = 1580cc/24 hours

Can you figure out how much IV fluid the child would get each hour if the child were NPO?
Or how many bottles/cups of fluid the child needs that is not NPO?

Oral Rehydration
Remember, children who are not experiencing illness tend to drink enough or respond to thirst cues adequately to prevent themselves from becoming dehydrated. Illnesses that tend to make children more prone to dehydration include:

                   Fevers
                   Cystic fibrosis
(increased respiratory effort, increased metabolism, increased mucous production)
                   Vomiting
                   Diarhhea
                   Poorly controlled diabetes
(polyuria).

Oral rehydration is recommended for mild to moderate dehydration.  The goal of oral rehydration is to gradually increase fluids starting with very small amounts.  This allows the child to get used to the fluids and decreases the chance of vomiting.  Withholding fluids and food for 24 hours is no longer recommended.  We now know that infants and small children dehydrate too rapidly to encourage the withholding of fluids.  But remember, replacement is with small amounts - amounts that can get absorbed even before reaching the stomach so as not to stimulate vomiting.
Fluids used to orally rehydrate children are electrolyte based.  A few common guidelines to follow are:

  • Use of an oral rehydration solution like Pedialyte is the best
  • Ongoing stool losses should be replaced 1:1 with an oral rehydration solution
  • Children who are vomiting can be given 5-10cc every 1-5 minutes so that fluids can be absorbed without stimulating vomiting
  • NO LONGER RECOMMENDED
    1. BRAT diet (banana, rice, applesauce and toast) - little nutritional value, high carbohydrate and low in electrolytes
    :2. Pop,  jello, fruit juices - high carbohydrate, low nutritional value and high osmolality
    3. Caffeinated drinks - have a mild diuretic affect