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Pediatric Dehydration

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Pediatric Dehydration

ACHIEVING*A*FLUID*BALANCE

Recognizing EARLY SIGNS of dehydration in infants and children can be a matter of LIFE AND DEATH

By Nita Kumar, MSN, RN

Nurses have long recognized the importance of maintaining fluid and electrolyte balance. Florence Nightingale wrote of the benefits of giving patients beef tea, and today we know a major benefit of bouillon is its high sodium content, which helps increase extracellular fluid volume. Continued research has further shown that beef tea may in fact have too much sodium and better products are now available that are more beneficial and safe to use even in children with dehydration (see Table 1).

Being alert for developing dehydration is an important aspect of caring for infants and children. Dehydration often is characterized as mild, moderate or severe. In children, dehydration usually is attributable to vomiting or an acute viral or bacterial diarrhea.

 

FLUID BALANCE

Fluid balance refers to total body water, which stays constant with consistent distribution among the main fluid compartments. Water and electrolytes are equally important. Children and infants present unique problems in managing fluids and electrolytes. In a healthy state, premature infants are approximately 90 percent water; newborns, 70 percent-80 percent water; a 3-year-old child is 60 percent water; and an adult is approximately 90 percent water.

An infant may exchange half his extracellular fluid daily, whereas an adult may exchange only one-sixth in the same period. Compared to an older child, a premature infant has almost five times as much body surface area in relation to its weight; the newborn has three times the body surface area. This increase in body surface area increases insensible water losses, which in turn makes infants more susceptible to dehydration than older children and adults. A child's fluid requirements are listed in Table 2.

 

ELECTROLYTE OVERVIEW

To effectively monitor infants and children, the nurse needs a basic knowledge of important electrolytes and signs and symptoms of imbalances. Table 3 presents normal fluid expenditures. The most crucial electrolytes for all cell life are K+, Na+ and Cl-. Another electrolyte to closely monitor is Ca+. Although not an electrolyte, serum glucose plays an important role in the hemodynamic monitoring of the pediatric patient.

 

BASAL METABOLIC RATE

The BMR, or basal metabolic rate, for infants and children is higher than for adults because of larger body surface area in relation to the mass of active tissue. BMR is higher in infants to support growth. Infants expend 100 calories per kilogram of body weight and adults expend 40 calories per kilogram. Infant kidneys are also not mature enough to concentrate urine efficiently. Thus, the infant needs more water to excrete a given amount of solute.

Insensible water losses may increase as much as 50-70 mL for each degree Celsius above normal body temperature in an infant. Fever increases insensible water losses by about 0.42 mL/kg/degree Celsius for each degree above 37 degrees C. Radiant heat warmers and phototherapy lights can also increase fluid losses.

Increased respiratory rate in infants and children (> 60-80 breaths per minute) when they are sick (for example with respiratory syncytial virus can also contribute to increased insensible water losses, resulting in severe dehydration (see Table 4).

For each 1 percent weight loss, 10 mL/kg of fluid have been lost. For example, if a child weighing 10 kg lost 12 percent body weight, the child lost 1200 mL of fluid (12 percent x 10 mL percent x 10 kg). Weight loss of 1 kg is approximately equivalent to body fluid loss in the amount of 1 L.

 

ASSESSMENT

Good assessment skills will help the nurse recognize subtle clues before an infant or child gets into serious fluid and electrolyte problems. Assessing physical data, the results of lab tests, body weight and intake and output are important aspects of care to monitor.

The following are signs of a dehydrated child:

* decrease in extracellular fluid volume leading to decrease in peripheral circulation;

* change in skin color to pale or gray;

* decreased capillary refill;

* dry skin turgor;

* decrease in tear production;

* vasoconstriction of small arterioles to keep blood flow going to vital organs, resulting in cool extremities, even if the child is febrile;

* decrease in saliva, dry lips and nares, cracked membranes, and tongue may become red, rough, dry and wrinkled;

* increase in pulse rate (>160 bpm for infants and >120 bpm for children) resulting from hypovolemia;

* fluid deficit causing mild metabolic; acidosis; and

* hyperventilation, resulting in increased insensible fluid losses.

Blood pressure is the last vital sign to show changes and should not be relied on as an assessment indicator of dehydration. Fontanels of infants will be depressed with a moderate fluid deficit.

 

REHYDRATION

IV fluids remain a treatment of choice for volume deficit in severely dehydrated children as well as adults. Oral solutions are successful in treating children with isotonic, hypotonic or hypertonic dehydration. Vomiting is not a contraindication. A child who is vomiting should be given frequent, small doses of oral rehydration solutions. Alternating an IV solution with a low-sodium fluid, such as water, breast milk, lactose-free formula or half-strength lactose containing formula, is an effective treatment plan.

Signs of moderate dehydration plus one or more of the following: rapid thready pulse, cyanosis, rapid breathing, delayed capillary refill, lethargy or coma, necessitate the need for IV rehydration therapy. Isotonic solutions such as Ringer's Lactate or 0.9 percent saline can be administered IV or intraosseous (IO) at a rate of 40 mL/kg/h until pulse and state of consciousness return to normal, then 50-100 mL/kg of oral rehydration solutions (ORS) based on remaining degree of dehydration.

Replacement of ongoing stool losses and vomitus may be done with ORS, 10 mL/kg for each diarrheal stool and 5 mL/kg for each episode of vomitus. While parenteral access is being sought, nasogastric infusion of ORS may be begun at 30 cc/kg/hr, provided airway protective reflexes remain intact.

Maintenance requirements include giving enough water and electrolytes to prevent deterioration of body stores (see Table 5). When short-term (2-3 days) parenteral therapy is given, enough calories are given to blunt hunger and inhibit protein breakdown and ketosis. In general, all intravenous fluids should have at least 5 percent glucose. Reasonable initial approximations for maintenance needs are 3 mEq Na+/100 kcal and 2.5 mEq K+/100 kcal.

Corrections are also made for temperatures above 38 degrees C. For every degree (centigrade) of temperature, fluid needs increase by 12.5 percent. A fever of 39 degrees C would require maintenance fluid to be increased by 25 percent.

 

REFEEDING

As soon as possible, children can be given breast milk with added libitum, full-strength formula, complex carbohydrates (rice, wheat, potatoes, bread, cereals), lean meats (chicken), yogurts, fruits and vegetables. Avoid foods that are high in fats or simple sugars and avoid highly restrictive diets (i.e., the BRAT diet).

NEW RESEARCH

Frozen oral hydration (FS) has been studied as an alternative to conventional solution (CS) of enteral fluids. Results show that children with mild or moderate dehydration are more likely to tolerate FS than CS. Conventional solution failures crossed over to FS had a greater tolerance rate than the reverse.

 

CONCLUSIONS

Accurate assessment of the degree of dehydration in children is important in helping make decisions on which children should receive oral vs. intravenous hydration, the length of treatment, and the need for prolonged observation or hospitalization. Laboratory tests alone cannot reliably assess mild to moderate dehydration in children due to various factors and should be used as an adjunctive tool only. Oral rehydration solutions should be the mainstay therapy for mildly to moderately dehydrated children. Rapid intravenous rehydration therapy offers an alternative modality that ultimately may offer more efficient and cost-effective management for the moderately to severely dehydrated child. *

Resources

Burkhart, D. (1999, December). Management of acute gastroenteritis in children. American Family Physician, 60(9).

Fann, B. (1998). Fluid and electrolyte balance in the pediatric patient. J Intravenous Nurs, 21(3).

Halperin, M.L., & Goldstein, M.B. (1999). Fluid, electrolyte, and acid-base physiology: A problem-based approach (3rd ed.). Philadelphia: W.B. Saunders.

Liebelt, E. (1998). Clinical and laboratory evaluation and management of children with vomiting, diarrhea, and dehydration. Current Opinions in Pediatrics, 10, 461-469.

Narchi, H. (1998). Serum bicarbonate and dehydration severity in gastroenteritis. Arch Dis Child, 78, 70-71.

Santucci, K., et. al. (1998). Frozen oral hydration as an alternative to conventional enteral fluids. Arch Pediatr Adolesc Med, 152.

 

Nita Kumar is employed at Moses Cone Health System in Greensboro, NC. She is an educator in staff education and also works in the neonatal intensive care unit.

TYPES OF DEHYDRATION

Type of Dehydration Serum Sodium Value (Normal 135-145 mEq/L)

ISOTONIC 130-150 mEq/L

Isotonic Dehydration (Isonatremic): Electrolyte and water deficits are approximately equal. This is the most common dehydration in children and may be life threatening. The child with isotonic dehydration has signs and symptoms characteristic of hypovolemic shock.

HYPERTONIC 150-160 mEq/L

 

Hypertonic Dehydration (Hypernatremic): This is caused by water losses that are greater than electrolyte losses or large electrolyte intake. Gastroenteritis, vomiting and diarrhea in children usually leads to this. Burns, high fever, diabetes insipidus, aggressive diuresis and diabetic ketoacidosis also my produce fluid loss that is more than sodium loss.

HYPOTONIC <130 mEq/L

Hypotonic Dehydration (Hyponatremia): Electrolyte losses are greater than water losses. Hypotonic dehydration also presents with signs and symptoms of hypovolemia.




     

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