Infants and small children have different proportions of body water and body fat than do adults (Figure 15-1), and the water needs and water losses of the infant, per unit of body weight, are greater. In children younger than 2 years of age, the surface area is particularly important in fluid and electrolyte balance because more water is lost through the skin than through the kidneys. The surface area of the infant is two to three times greater than that of the adult in proportion to body volume or body weight. Metabolic rate and heat production are also two to three times greater in infants per kilogram of body weight. This produces more waste products, which must be diluted to be excreted. It also stimulates respiration, which causes greater evaporation through the lungs. Compared with adults, children younger than 2 years of age have a greater percentage of body water contained in the extracellular compartment.

FIGURE 15-1 Average body weight composition. Water (particularly extracellular water) makes up a larger percentage of an infant’s total body weight than an adult’s. Because extracellular water is lost first when water loss occurs in illness, trauma, or environmental stress, the infant is extremely susceptible to fluid and electrolyte imbalances.

Fluid turnover is rapid, and dehydration occurs more quickly in infants than in adults. The infant cannot survive as long as the adult can in the presence of continued water depletion. A sick infant does not adapt as rapidly to shifts in intake and output because the kidneys lack maturity. Their kidneys are less able to concentrate urine and require more water than an adult’s kidneys to excrete a given amount of solute. Disturbances of the gastrointestinal tract frequently lead to vomiting and diarrhea (discussed in Chapter 14). Electrolyte balance depends on fluid balance and cardiovascular, renal, adrenal, pituitary, parathyroid, and pulmonary regulatory mechanisms. Many of these mechanisms are maturing in the developing child and are unable to react to full capacity under the stress of illness.

In order to understand fluid balance and imbalance in children, it is important to understand fluid volume requirements. Box 15-1 refers to the daily maintenance fluid requirements for children.

Box 15-1 Daily Maintenance Fluid Requirements

1. Calculate weight of child in kilograms:

Weight of child (in pounds)Divided by 2.2 lb/kg=Weight in kilograms

2. Allow 100 ml/kg for first 10 kg.

3. Allow 50 ml/kg for second 10 kg.

4. Allow 20 ml/kg for remainder of weight in kilograms.

5. Divide total amount by 24 hours to obtain rate in milliliters per hour.

Fluid Imbalance

Dehydration

When a person is in good health, fluid intake and output balance and homeostasis (a uniform state) exist. This is accomplished by appropriate shifts of fluids and electrolytes across cellular membranes and by elimination of those products of metabolism that are no longer needed or that are in excess. The volume of blood plasma and interstitial and intracellular fluid (ICF) remains relatively constant. Dehydration occurs whenever fluid output exceeds fluid intake, regardless of the cause. The degree of dehydration and the symptoms are discussed in Box 15-2.

Box 15-2 Clinical Signs of Dehydration in an Infant

Mild Dehydration (up to 5% weight loss)

Vital signs are normal

Alert and thirsty

Turgor is normal

Capillary refill time is normal

Anterior fontanel is normal

Tears are present

Slight oliguria

Moderate Dehydration (6% to 9% weight loss)

Heart rate and respiratory rate are increased

Blood pressure is normal or slightly decreased

Behavior: restless or irritable

Marked thirst

Turgor shows tenting

Capillary refill time is 2 to 3 seconds

Lips and mucous membranes of the mouth are dry

Anterior fontanel is sunken

Tears are absent

Oliguria

Severe Dehydration (10% and greater weight loss)

Heart rate and respiratory rate are increased

Blood pressure is normal or slightly decreased

Behavior: lethargic or comatose

Turgor shows severe tenting

Capillary refill time is greater than 3 seconds

Skin is cold and clammy

Cyanosis may be present

Mucous membranes are extremely dry

Anterior fontanel is severely sunken

Tears are absent

Severe oliguria

Nursing Brief

Output in infants is determined by weighing the wet diaper (urine or liquid stool), subtracting the weight of a comparable dry diaper, and recording the difference. It is important to monitor both intake and output when a child is dehydrated or can potentially become dehydrated.

Disorders of fluids and electrolytes (sodium [Na], potassium [K], calcium [Ca], and magnesium [Mg]) are more complex in children who are growing. A newborn infant’s total weight is approximately 78% water, compared with 60% in adults. This varies with the amount of fat. Also, the daily turnover of water in an infant is equal to almost 24% of total body water, compared with about 6% in adults. An infant’s body surface in comparison with weight is three times that of the older child; therefore the infant is subject to greater evaporation of water from the skin. The younger the child, the higher the metabolic rate and the more unstable the heat-regulating mechanisms. (Elevations in temperature are also higher, increasing the rate of water loss.) Rapid respirations speed up this process, and when diarrhea is present (see Chapter 14), additional fluid is lost in the stools. Immaturity of the kidneys impairs the infant’s ability to conserve water. Preterm and newborn infants are also more susceptible to dehydration from variations in room temperature and humidity. Cessation of intake alone can result in significant depletion. When this is coupled with higher fluid losses, life-threatening deficits can occur in a few hours.

Problems of fluid and electrolyte disturbance require evaluation of the type and severity of dehydration, clinical observation of the child, and chemical analysis of the blood. Types of dehydration are classified as follows according to the amount of serum sodium: isotonic (the child has lost equal amounts of fluids and electrolytes), hypotonic (the child has lost more electrolytes than fluids), and hypertonic (the child has lost more fluids than electrolytes). These classifications are important because each form of dehydration is associated with different relative losses from intracellular fluid (ICF) and extracellular fluid (ECF) compartments, and each requires certain modifications in treatment. Maintenance therapy replaces normal water and electrolyte losses, and deficit therapy restores preexisting body fluid and electrolyte deficiencies. The replacement of a deficit may take several days, and the deficit continues unless adequate maintenance therapy is also provided. The physician calculates the volume of fluids to be administered through the use of various formulas on the basis of caloric expenditures because daily physiologic water losses are directly proportional to caloric expenditure. The child’s temperature and activity (coma, restlessness) must also be considered. Basal calories are determined by the weight of the child. Volume is calculated on a 24-hour basis. Isotonic dehydration is the most common form in children. Signs of isotonic, hypertonic, and hypotonic dehydration are discussed in Table 15-1.

Table 15-1

Signs of Isotonic, Hypertonic, and Hypotonic Dehydration

	SIGNS OF DEHYDRATION
BODY RESPONSES	ISOTONIC	HYPOTONIC	HYPERTONIC
Level of consciousness	Irritable to lethargic	Lethargic to coma	Lethargic, hyperirritable with stimulation
Skin turgor	Diminished turgor, feels dry	Diminished to absent turgor; “tenting”	Fair turgor, feels thickened, “doughy”
Skin temperature	Cold	Cold	Cold to hot
Eyes	Sunken	Sunken	Sunken
Tearing and salivation	Absent or decreased	Absent or decreased	Absent or decreased
Mucous membranes	Dry	Dry to slightly moist	Parched
Fontanel	Sunken	Sunken	Sunken
Body temperature	Afebrile to febrile	Afebrile to febrile	Afebrile to febrile
Respiration and pulse	Rapid	Rapid	Rapid
Blood pressure	Normal to low	Normal to low	Very low

Adjustments in fluid therapy are made constantly, according to the condition of the child. The higher daily exchange of water that occurs in child leaves less volume reserve with dehydration. Shock (hypovolemia) is the greatest threat to life in isotonic dehydration. The electrolyte content of oral fluids is particularly significant in the care of infants and small children with disorders of fluid balance and those receiving infusions. Commercially prepared electrolyte solutions are available by bottle; however, the nurse should ascertain whether they are to be given freely or by physician’s order only. Children with hypotonic dehydration—that is, excess water with sodium electrolyte depletion—are at risk for water intoxication. This can also occur if tap water enemas are given to small children. Loss of potassium occurs in almost all states of dehydration. Replacement potassium is administered only after normal urinary excretion is established.

Renal System

The renal system includes the kidneys, ureters, bladder, urethra, and the renal arteries and veins. The primary functions of the urinary system includes waste excretion; maintaining homeostasis with fluid, electrolyte, and acid-base balance; and hormonal function (production of renin for blood pressure regulation, production of erythropoietin, and metabolism of vitamin D). The kidneys function normally at birth but are not fully developed. There is also a decrease in the ability to concentrate urine and to cope with fluid imbalances. As discussed in Chapter 5, the infant should void within the first 24 to 48 hours after birth. Urine output increases as the child ages and is monitored closely in children with renal conditions.

Nursing Brief

The rule of thumb for urine output is 2 mL/kg/hr for an infant and 0.5 to 1 mL/kg/hr for a child.

Urinary Tract Infection

Urinary tract infections (UTIs) are caused by bacterial invasion of the upper urinary tract (kidney and ureters) or lower urinary tract (bladder and urethra). Genitourinary anatomy is reviewed in Figure 15-2. They generally occur in children between 2 and 6 years of age, unless a structural anomaly is the cause. Urinary tract infections are more commonly found in girls because the distance infectious organisms need to travel to enter the bladder is considerably shorter than in boys. Boys have a much longer urethra.

FIGURE 15-2 Anatomy of the genitourinary system.

Several factors contribute to the incidence of UTIs in children. These include congenital malformations of the urinary tract and conditions resulting in urinary stasis (such as ignoring the urge to urinate or neurogenic bladder in children with conditions such as myelomeningocele). In affected infant boys, the incidence is higher in uncircumcised infants. Mechanical factors such as tight diapers or underwear, chemical irritation from bubble bath, inflammatory conditions of the external perineal area, and pinworms all contribute to UTIs. Although UTI in young girls is not uncommon, repeated UTIs can suggest possible sexual abuse.

Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is a primary contributing factor to UTIs. As urine fills the bladder or as the bladder contracts during voiding, the opening to the ureter is normally occluded. With VUR, a malfunctioning valve at the junction of the ureter and bladder allows urine to reflux upward into the ureters toward the kidney (Figure 15-3). This allows bacteria in the urine to be carried upward, possibly all the way into the kidney. This can cause pyelonephritis and renal damage. In addition, the urine can return to the bladder, creating a residual that becomes a medium for bacterial growth or infection. VUR is graded I to V (1 to 5), with grade V involving a gross dilation of the ureter and pelvis and calyces of the kidney. Diagnosis is generally made after ultrasound and a voiding cystourethrography (VCUG). During a VCUG, contrast medium is injected into the bladder through a urethral catheter; radiographs are taken before, during, and after voiding. This procedure visualizes the bladder outline and urethra, and it identifies reflux and other structural complications. All children (1 to 10 years of age) are treated initially with antimicrobial prophylaxis. At the end of 1 year, if VUR is not resolved, endoscopy therapy is recommended for children with lower grades of reflux. Open surgery is used if endoscopy is unsuccessful; it may also be used from the outset if children have higher grades of reflux (Greenbaum and Mesrobian, 2006).

Signs and Symptoms

Signs of UTIs in infants and young children are easily missed. The child exhibits poor feeding, fussiness, delayed growth, foul-smelling urine, and incontinence (in a child who has been previously trained). Unexplained fever in infants may be caused by a UTI, and this should be considered when no other source for the fever is found. Many adolescent girls exhibit classic signs of UTI (frequency, urgency, pain on urination, blood in the urine) after the first episode of sexual intercourse. High fever, chills, flank pain, and abdominal pain can indicate kidney infection (pyelonephritis).

Urinary tract infection is diagnosed with urine culture. The specimen is obtained with a clean midstream urine collection in potty-trained children or with catheterization or suprapubic aspiration in infants and untrained children. The culture shows organism growth; usually colony growth exceeding 100,000 of a single organism is diagnostic from a midstream specimen. Escherichia coli and other gram-negative organisms are frequently the cause. Antimicrobial sensitivities determine the treatment. Blood, protein, and white blood cell casts might be found in the urine. A complete renal workup to detect urinary tract abnormalities includes ultrasonography, VCUG and radionuclide cystography, renal nucleotide scans, and CT or MRI.

Treatment and Nursing Care

Treatment of a UTI with older children is a 7- to 14-day course of an appropriate antimicrobial, generally sulfamethoxazole/trimethoprim (Bactrim, Septra). Penicillins, cephalosporins, and nitrofurantoin may also be ordered. Children who do not improve within 2 days of starting antimicrobials for UTI should be reevaluated with ultrasound and VCUG. Nurses need to teach proper hygiene (no bubble baths or irritating diaper wipes; wiping from front to back).

It is important to explain procedures using terms with which the child is familiar. If a catheterized urine sample is necessary, the nurse needs to reassure the child that the tube does not harm the body but helps find out what is wrong. Practice relaxation breathing exercises with the child before inserting the catheter, and encourage the child to sing or breathe slowly as the tube is being inserted. Sphincter relaxation decreases the amount of discomfort the child might experience.

Other preventive measures include wearing cotton underwear, adequate fluid intake, encouraging children to not put off going to the bathroom when needed, investigating and treating signs of intestinal parasites (pinworms), and avoiding bubble baths. Acidification of the urine with cranberry juice may be helpful. Some clinicians may recommend drinking cranberry juice to help prevent urinary tract infections. Sexually active girls should urinate after sexual intercourse. If urine specimens are obtained at home, teach the parent to bring the specimen immediately to the laboratory. If the parent is unable to get to the laboratory within 30 minutes, the specimen should be refrigerated.

Acute (Poststreptococcal) Glomerulonephritis

Acute glomerulonephritis (AGN) occurs as an immune reaction (antigen-antibody) to an infection in the body. The most common of the noninfectious renal diseases in childhood is acute poststreptococcal glomerulonephritis. The infection is generally caused by a Group A beta-hemolytic streptococci infecting the throat or the skin. It may appear after the child has had scarlet fever or skin infections (impetigo). The body’s immune mechanisms appear to be important in its development. Antibodies produced to fight the invading organisms react against the glomerular tissue. Glomerulonephritis is the most common form of nephritis in children and occurs most frequently in boys between 3 and 7 years of age. It has a seasonal incidence, with peaks in winter and spring. Both kidneys are affected.

The nephron is the working unit of the kidneys. Nephrons number in the millions. Within the bulb of each nephron lies a cluster of capillaries known as the glomerulus. It is these structures that are affected, as the name of the disease implies. They become inflamed and sometimes blocked, permitting red blood cells and protein, which are normally retained, to enter the urine. Sodium and fluid are retained, leading to edema and oliguria (decreased urine output). The kidneys become pale and slightly enlarged.

The prognosis is excellent. Children with mild cases of the disease may recover within 10 to 14 days. Children with protracted cases may show urinary changes for as long as a year but have complete recovery. Chronic nephritis is seen in a small number of children; renal failure can result from this.These severe complications, plus hypertensive changes, necessitate careful observation and care of each child.

Signs and Symptoms

Symptoms range from mild to severe. From 1 to 2 weeks after a streptococcal infection has occurred in the child, the mother may notice that the urine is smoky brown in color or bloody. This is frightening to the mother and child; medical advice is immediately sought by most parents. Periorbital edema (mild swelling about the eyes) may also be present in the morning, and the edema spreads to the abdomen and extremities as the day progresses. The child may have fatigue, headache, abdominal discomfort, and vomiting. After an initial acute phase, the child spontaneously diureses and the symptoms begin to abate. Blood and protein can be found in the urine for several weeks.

Urinary output is decreased. Protein, red blood cells, white blood cells, and casts may be found on examination. The BUN level can be elevated, as can the serum creatinine and erythrocyte sedimentation rates. The serum complement level is usually reduced. For a definitive diagnosis, it may be necessary to have positive confirmation of a streptococcal infection, either with culture or with antibody titer. Mild-to-severe hypertension may be seen. Complications such as renal and cardiac failure and encephalopathy may also occur.

Treatment and Nursing Care

Although the child may feel well, activity should be limited until gross hematuria subsides. The urine should be examined regularly. Every effort should be made to prevent the child from becoming overtired, chilled, or exposed to infection. Because renal function is impaired, there is a danger of accumulation of nitrogenous wastes and sodium in the body. A low-sodium diet may be ordered. Parents need to be educated by the dietitian on this diet. Protein restriction is not usually necessary. Fluid restriction may be necessary for some children. Furosemide (Lasix) may be given if significant edema and fluid overload are present and renal failure is not severe (Hockenberry and Wilson, 2007). Penicillin is given if the streptococcal infection persists, but it usually does not alter the course of the disease. Recurrent glomerulonephritis is rare.

The nurse should try to make the period of bed rest as pleasant as possible by providing quiet diversions. When the child is allowed up, the nurse observes him or her frequently for signs of fatigue. The child should be protected from contact with persons with infections.

The child’s vital signs are taken regularly, preferably with the same apparatus. A rise in blood pressure is reported immediately. Between readings, the nurse should be alert for symptoms such as headache, drowsiness, vomiting, and blurring of vision. If any of these are noticed, the child is returned to bed and the crib sides or rails are raised. Because seizures can occur, someone should remain with the child until medication is given. Hypotensive drugs, including short-acting calcium channel blockers such as nifedipine, may be ordered by the physician. Parameters for administration are specific. These reduce the blood pressure rapidly, and the cerebral symptoms subside. If cardiac failure is evidenced with an ECG or chest radiograph, sedation, oxygen, and digitalis may be necessary.

The nurse accurately records the child’s daily weight, fluid intake, and urine output. Fluids may be restricted, especially if the urinary output is scant. In this circumstance, the physician orders the oral intake allowed; for example, 650 mL daily. This must be distributed throughout the 24-hour period. Each shift should know the specific amount of fluids the child is to receive for that shift so that an excess amount is not given. The greater amounts of fluid are allotted to the day shift, when thirst is more pronounced and when the child is awake. The individual needs of the child should be observed and incorporated into the day’s events. Persistent anuria (suppression of urine formation) may necessitate dialysis.

Although glomerulonephritis is generally benign, it can be a source of anguish for parents and child. If the child is treated at home, the parents must be creative if he or she has restricted activity orders. They must understand the importance of continued medical supervision because follow-up urine and blood tests are necessary to ensure that the disease has been eradicated.

Nephrotic Syndrome (Nephrosis)

Nephrotic syndrome refers to a number of different types of kidney conditions that are distinguished by the presence of marked amounts of protein in the urine. Minimal change nephrotic syndrome, idiopathic nephrosis, in which the cause is seldom determined, is discussed here because it is the most common type seen in early childhood. Table 15-2 compares poststreptococcal glomerulonephritis and nephrotic syndrome.

Table 15-2

Comparison of (Poststreptococcal) Glomerulonephritis and (Minimal Change) Nephrotic Syndrome

MANIFESTATIONS	APSGN	MINIMAL CHANGE NEPHROTIC SYNDROME
Streptococcal antibody titers	Elevated	Normal
BP	Elevated	Normal or decreased
Edema	Periorbital and peripheral	Generalized, severe
Circulatory congestion	Common	Absent
Proteinuria	Mild to moderate	Massive
Hematuria	Gross to microscopic	Microscopic or none
BUN and serum creatinine	Elevated	Normal
Serum potassium levels	Normal or increased	Normal
Serum protein levels	Minimal reduction	Markedly decreased
Serum lipid levels	Normal	Elevated
Peak age at onset	3-7 yr	2-7 yr
Recurrence	Uncommon	Common

Data modified from Hockenberry, M., Wilson, D., Winkelstein, M., et al. (2007). Wong’s nursing care of infants and children (8th ed.). St. Louis: Mosby.

The glomeruli, the working units of the kidneys that filter the blood, become damaged and allow albumin and other proteins to enter the urine. Proteinuria is massive. There is a fall in the level of protein in the blood, termed hypoproteinemia, and a rise in cholesterol content, termed hyperlipidemia.

Nephrosis is more frequently seen in boys than in girls and is seen most often in toddlers and preschoolers. The prognosis for children with nephrosis is usually positive. Most children have repeated relapses until the disease resolves itself. Children with types other than minimal change nephrotic syndrome do not have as good a prognosis. They may have renal failure develop and need dialysis or transplantation.