Fever is the most common chief complaint of children presenting
to the ED, and accounts for approximately 30% of pediatric
outpatient visits. Emergency providers evaluating febrile children
must differentiate mildly ill from seriously ill children, a challenge
that may be compounded when nonspecific symptoms or no focus of
infection are apparent, especially in the neonate and infant. The
extent of the diagnostic workup and the initiation of appropriate
management must be determined. Many factors, such as clinical assessment,
physical examination findings, age of the patient, immunization
status, and height of the fever, influence evaluation and management
Fever is a symptom of underlying disease, which
may be due to acute processes secondary to infection, or more chronic
processes, such as rheumatologic or oncologic diseases. The focus
of this chapter is the management of a neonate, infant, or child
(Table 113-1) with acute fever who is at
risk for serious bacterial illness (SBI). SBI
is bacterial infection in neonates, infants, and young children
with high morbidity and mortality if not properly treated.
Table 113-1 Pediatric Age
| Save Table
Table 113-1 Pediatric Age
|Neonate||Birth to 28 d of age*|
|Infant||29 d to 1 y of age|
|Child||>1 y of age|
Fever is defined as a
rise in core body temperature associated with a resetting of the
body’s thermostat. This thermostat is located in the preoptic
region of the anterior hypothalamus. Exogenous fever-producing substances
(pyrogens), such as bacteria, bacterial endotoxin, antigen-antibody
complexes, yeast, viruses, and etiocholanolone, may stimulate the formation
and release of endogenous pyrogens. Endogenous pyrogens are produced
by neutrophils, monocytes, hepatic Kupffer cells, splenic sinusoidal
cells, alveolar macrophages, and peritoneal lining cells, and are
believed to induce the synthesis of prostaglandins in the hypothalamus.
Endogenous pyrogens include interleukin-1, interleukin-6, and tumor
necrosis factor.1 The body’s thermostat
is then reset at a higher setting, and the patient, whose own temperature
is below that of the body’s thermostat, experiences chills.
Peripheral vasoconstriction, shivering, central pooling, and behavioral
activity (e.g., putting on a sweater or drinking hot tea) lead to
an increase in body temperature.
Any elevation in temperature above normal is considered a fever,
but the threshold for concerning fever varies with the age group
and is related to the ability of signs and symptoms to identify
the underlying cause of fever. Acute fever is fever for <7 days. In
the neonate or infant <2 to 3 months of age, the threshold for
concerning fever is 38°C (100.4°F); in infants and children 3 to
36 months old, the threshold is 39°C (102.2°F). In children
>36 months old, the definition of significant fever is not fixed because
most children >36 months old should demonstrate signs or symptoms
of the underlying cause. In children with developmental delay or
mental retardation, with limited ability to demonstrate specific
signs and symptoms, the cause of fever may be difficult to determine,
and more testing is often necessary.
Oral temperatures are generally 0.6°C (1°F) lower than rectal
temperatures, and axillary temperatures are 0.6°C (1°F) lower than
oral temperatures. Temperatures taken with infrared thermometers
that scan the tympanic membrane are of variable reliability and
reproducibility.2 Body temperature normally varies
from morning to evening with the body’s circadian rhythm.
The degree of variation, which is greater in young women and small
children, is approximately 1.1°C (2°F).
Fever is treated with acetaminophen or ibuprofen. The dosage
of acetaminophen is 15 milligrams/kg/dose (maximum
daily dose, 80 milligrams/kg) every 4 to 6 hours, up to
five times/day. Acetaminophen can be given PO or PR. The
dosage of ibuprofen is 10 milligrams/kg/dose (maximum
daily dose, 40 milligrams/kg) every 6 to 8 hours.
Infants ≤3 months of age, and especially neonates, are relatively
immunosuppressed. Neonates and young infants demonstrate decreased
opsonin activity, decreased macrophage and neutrophil function,
and bone marrow exhaustion.3 Infants and
children demonstrate a poor immunoglobulin G antibody response to
encapsulated bacteria until 24 months of age. Immune development
is a continuum and improves as the child matures. Therefore, the
age of the patient and the virulence of the bacteria are considerations
for the evaluation of fever in children and the identification of SBI.
The most common maniffestations of SBI in children are discussed:
urinary tract infection (UTI), bacteremia and sepsis, pneumonia
and sinusitis, and meningitis.
Overall, the most common SBI is UTI with or without pyelonephritis (see Chapter 126, Urinary Tract Infection in Infants and Children). Among young children presenting to EDs with
fever and no obvious source of infection, between 3% and
8% have UTI.4 The overall incidence of
UTI is 5% in children between 2 months and 2 years old.5 For
children between 1 and 2 years of age, the incidence of UTI in girls
is up to 8%, but in uncircumcised boys, it is 1.9%.
Uncircumcised boys have a rate of UTI 5 to 20 times greater than
circumcised boys. The presence of fever ≥39°C (102.2°F) and
a urine suggestive of infection indicate renal parenchymal involvement,
or pyelonephritis. After 2 years of age, UTI remains a frequent
bacterial cause of fever in girls but is more commonly associated
with urinary symptoms.
Escherichia coli and other gram-negative rod
bacteria are the most common causative organisms, although gram-positive
organisms comprise a significant minority in older boys and in children
with underlying medical conditions such as neurogenic bladder. UTIs
may not produce symptoms other than fever, so routinely obtain a
urinalysis and culture in the evaluation of the febrile neonate
or infant without other source.
The ideally obtained urine specimen for a child in diapers has
traditionally been by urethral catheterization or suprapubic aspiration.
In children with labial adhesions or phimosis, a bag collection
specimen may be ...