Pediatric emergency medicine trisk 2297 2297
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (102.8 KB, 1 trang )
The goal of treatment is the prompt recognition of osteomyelitis in the febrile child with bone pain. The clinical
team should consider advanced imaging by MRI to evaluate for contiguous infections.
Clinical Considerations
Clinical recognition: As the most common bones involved are the femur and tibia, limp is a common presentation.
The multiplicity of bones that may be involved leads to a wide spectrum of chief complaints. Vertebral
osteomyelitis manifests as backache, torticollis, or stiff neck, and involvement of the mandible causes painful
mastication. Infection of the pelvis is particularly elusive and may masquerade as appendicitis, septic hip,
neoplasm, or UTI. Infants with osteomyelitis localize the symptoms less well than older children. Initially,
irritability may be the only complaint.
Fever is seen in 70% to 80% of children with osteomyelitis. The infant with a long bone infection often
manifests pseudoparalysis, an unwillingness to move the extremity. Movement may also be decreased in the older
child, but to a lesser degree. Point tenderness is seen commonly in osteomyelitis; however, it is nonspecific, as it is
found in other conditions, such as trauma, may be difficult to discern in the struggling infant, and does not always
occur early in the course of the infection. Percussion of a bone at a point remote from the site of an osteomyelitis
may elicit pain in the area of infection. When purulent material ruptures through the cortex from a subperiosteal
abscess, diffuse local erythema and edema appear. This finding occurs often in infants, but late in the course, and is
confined primarily to children in the first 3 years of life (before the cortex thickens sufficiently to contain the
inflammatory exudate).
Triage considerations: Any child with fever and a focal bone pain should be evaluated for osteomyelitis.
Associated tachycardia and/or hypotension can imply sepsis and would require fluid resuscitation.
Clinical assessment: Bone biopsy cultures are positive in approximately 60% of children with acute
hematogenous osteomyelitis, and blood cultures are positive in 50% of cases. The ESR and CRP are the most
consistent abnormal laboratory studies and can be used to monitor response to therapy. Plain radiographs of the
affected extremity should be obtained, although they are often normal early in the disease course. Within 3 to 10
days, some radiographic anomalies become evident: muscle edema will obliterate the lucent planes separating
muscle groups. Visualization of bony destruction requires loss of over 40% of the bony matrix, and is a finding
uncommon prior to 10 to 14 days. MRI is used to evaluate for drainable fluid collections (e.g., subperiosteal
abscess or pyomyositis), and the most common finding on MRI in children with osteomyelitis is bone marrow
edema. In the era of MRSA, many centers have noted that some children with osteomyelitis have infected deep
venous thromboses (DVTs) in the adjacent blood vessels. MRI also allows for evaluation of DVTs (which appear
as flow voids). Recognition of DVTs is important, as it could alter antibiotic therapy (e.g., make it more likely to
select a bactericidal antibiotic as opposed to a bacteriostatic drug) and would prompt anticoagulation.
Management: In contrast to septic arthritis, well-appearing children with suspected osteomyelitis do not require
immediate parenteral antibiotic therapy. If a child has age-appropriate vital signs, is previously healthy, and there is
a low likelihood of osteomyelitis, blood cultures and an MRI can be obtained while the child is observed off of
antibiotics. As blood cultures will be positive in only one-half of children, identification of an organism from bone
biopsy is critical. The clinician should immediately contact orthopedic surgery or interventional radiology about
culturing the infected bone prior to initiation of antibiotics in these patients. However, antibiotics should not be
withheld if the child becomes or is toxic-appearing or immunocompromised. Empiric therapy should target S.
aureus. The selection of vancomycin over clindamycin depends upon local antibiotic susceptibility patterns and
any prior culture results available for the child. Nafcillin is a more bactericidal drug for MSSA than vancomycin or
clindamycin and change to a beta-lactam antibiotic (nafcillin or cefazolin) should occur if the child is known to
have MSSA. Coverage should be expanded beyond staphylococcal coverage in immunocompromised children,
children in whom other pathogens have been cultured in the past, and for septic children. Standard precautions
should be used.
Necrotizing Fasciitis
Fasciitis is cellulitis extending to deeper tissues, such as fascia and muscle, but not to bones or joints. The most
common causes in the modern era are GAS and S. aureus. Widespread use of the varicella vaccine has decreased
the incidence of necrotizing fasciitis, where GAS could complicate varicella infection. The family may report that
the lesion is rapidly progressive. Fasciitis can be differentiated from cellulitis by pain out of proportion to
examination findings and more systemic signs; toxic appearance, high fever, tachycardia, and hypotension are
more common. In some cases of anaerobic fasciitis, subcutaneous crepitance may be noted. Patients generally have
