pneumonia%20-%20community-acquired%20(pediatric)
PNEUMONIA - COMMUNITY-ACQUIRED (PEDIATRIC)
Community-acquired pneumonia is the presence of signs and symptoms of lower respiratory tract infection acquired outside of the hospital.
The most common bacterial cause of childhood pneumonia is Streptococcus pneumoniae. It usually causes about 1/3 of radiographically-confirmed pneumonia in children <2 years of age.
Viruses commonly affects children <1 year of age than those aged > 2 years, respiratory syncytial viruses (RSV) being the most frequently detected virus.
Mixed infection may occur in 8-40% of community-acquired pneumonia cases.

Diagnosis

  • Diagnosis of community-acquired pneumonia (CAP) is primarily based on history & physical findings (eg signs & symptoms of respiratory distress, fever)
    • Laboratory & radiographic exams may aid in the diagnosis of severe cases or in patients who failed to show clinical improvement after initiation of antibiotic therapy

Assessment

  • Necessary to identify patients who may be effectively treated as outpatient & who may need hospitalization
  • Patient’s history, presentation & physical examination are the major determinants of the severity of illness & appropriate site of care
  • Severity should be based on patient’s overall clinical appearance & behavior (eg degree of alertness & eagerness to feed)

    Infants

    Older Children

    Mild to Moderate CAP

    Severe CAP

    Mild to Moderate CAP

    Severe CAP

    Temperature

    <38.5 °C

    >38.5 °C

    <38.5 °C

    >38.5 °C

    Resp rate

    <50 breaths/minute

    >70 breaths/minute

    <50 breaths/minute

    >50 breaths/minute

    Breathing effort

    • Mild chest recession
    • Moderate-severe chest recession
    • Nasal flaring
    • Cyanosis
    • Intermittent apnea
    • Grunting
    • Mild breathlessness
    • Severe difficulty in breathing
    • Nasal flaring
    • Cyanosis
    • Grunting

    Other features

    • Taking full feeds
    • Not feeding
    • Increased heart rate
    • Capillary refill time ≥2 seconds
    • No vomiting
    • W/ signs of dehydration
    • Increased heart rate
    • Capillary refill time ≥2 seconds
    Modified from: Harris M, Clark J, Coote N, et al, on behalf of the British Thoracic Society Standards of Care Committee. British Thoracic Society guidelines for the management of community acquired pneumonia in children: update 2011. Thorax. 2011;66(2):ii16.

History

  • Patient’s age, immunization status
    • Age is a good predictor of the causative agent
      • Viruses are often linked in up to 50% of pneumonia in young children
      • S pneumoniae followed by atypical pneumonia (eg Mycoplasma & Chlamydia) is the most likely pathogen in older children w/ pneumonia of bacterial origin
    • Immunization status is important because children fully immunized against Haemophilus influenza type B & S pneumoniae are less likely to be infected w/ these pathogens
  • Symptoms may include fever, difficulty in breathing, cough, chest or abdominal pain w/ or w/o vomiting, headache
    • Patients w/ cough or difficulty of breathing w/ either lower chest indrawing, nasal flaring, or grunting are considered to have severe pneumonia
    • Patients w/ cough or difficulty of breathing w/ either cyanosis, severe respiratory distress, inability to drink or vomits everything, or lethargy, unconsciousness, convulsions have very severe pneumonia
  • Should also take note of the season of the year, daycare attendance, exposure to tobacco smoke or infectious diseases (eg tuberculosis), history of travel, or coexisting illnesses (eg cardiac or pulmonary disorders, immunodeficiencies, neuromuscular diseases)

Physical Examination

  • Combination of clinical findings are more predictive in diagnosing community-acquired pneumonia (CAP)
  • Check for temperature
    • Fever in viral pneumonia is generally lower than in bacterial pneumonia
  • Respiratory rate (RR)
    • Study shows significant correlation between RR & oxygen saturation
    • Less sensitive & specific in the first 3 days of illness
    • Criteria for tachypnea based on age as defined by World Health Organization (WHO):
      • ≥60 breaths/minute in <2 months old
      • ≥50 breaths/minute in 2-11 months old
      • ≥40 breaths/minute in 1-5 years old
      • >20 breaths/minute in ≥5 years old
    • Tachypnea may be a marker for respiratory distress &/or hypoxemia but may also be secondary to fever, dehydration or concurrent metabolic acidosis
  • Respiratory signs may include intercostal, subcostal, or suprasternal retractions, nasal flaring, crackles or wheezing on auscultation
    • Decreased breath sounds, scattered crackles, or rhonchi are usually heard over the affected lung field in the early course of illness
    • Dullness on percussion & decreased breath sounds are usually appreciated when increased consolidation & complication develops

Laboratory Tests

  • May not be necessary in uncomplicated pneumonia
Microbiology
  • Aids in determining the causative agent to provide a narrow-spectrum antimicrobial therapy that targets a specific bacteria or virus
  • Blood culture is not routinely done in a nontoxic, fully immunized children w/ community-acquired pneumonia (CAP)
    • Recommended in patients requiring hospitalization for presumed moderate to severe bacterial CAP, specifically those w/ complicated pneumonia
    • Should also be performed in outpatients who do not show clinical improvement & in those w/ progressive symptoms or clinical deterioration even after starting the antibiotic therapy
    • Follow-up blood culture is necessary to document resolution of bacteremia caused by S aureus, regardless of patient’s clinical status
  • Sputum Gram stain & culture is recommended in hospitalized older children & adolescents w/ more severe disease or in those in whom outpatient therapy has failed
Tests for Viral Pathogens
  • Tests that are specific & sensitive to rapidly identify influenza virus & other respiratory viruses should be done to evaluate children w/ CAP
    • Positive influenza test will guide appropriate antiviral agents to be used in both inpatient & outpatient settings, & may also decrease the need for additional diagnostic studies & antimicrobial use
Tests for Atypical Bacteria
  • School-aged children & adolescents presenting w/ signs & symptoms of possible M pneumoniae should be tested to identify the appropriate antibiotic to use
    • However, no single currently available test (eg culture, cold agglutinating antibodies, serology & molecular-based methods) offers the sensitivity & specificity desired in a clinically relevant time frame

Ancillary Diagnostic Tests

  • Complete blood count (CBC) provides evaluation of white blood cells & determines presence of anemia or thrombocytopenia which may guide antimicrobial intervention & identify presence of hemolytic-uremic syndrome, a rare complication of pneumococcal pneumonia
  • Acute-phase reactants [eg peripheral white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) concentration, procalcitonin concentration] should not be routinely done in fully immunized patients w/ CAP
    • May provide useful information in managing patients requiring hospitalization or those w/ complications
    • May be helpful in assessing patient’s response to therapy in conjunction w/ clinical findings
  • Pulse oximetry gives an estimate of arterial oxygenation in a non-invasive manner
    • More directly relevant in evaluating severity of disease in CAP
    • Should be done in all children w/ pneumonia & suspected hypoxemia
      • Presence of hypoxemia will determine the diagnostic tests needed & if hospitalization is warranted
      • Hypoxemia is a well established determinant for poor outcome in children & infants w/ systemic disease
    • Usually monitored continuously in a child w/ increased work of breathing or significant distress especially if the patient has a decreased level of activity or agitation

Imaging


Chest X-ray
  • Not necessary to confirm suspected community-acquired pneumonia (CAP) in outpatient setting since diagnosis of CAP is strongly suspected based on clinical findings
    • Cannot differentiate viral from bacterial CAP nor among different possible bacterial pathogens
  • Postero-anterior (PA) or lateral chest x-rays are indicated in patients w/ suspected or documented hypoxemia or significant respiratory distress, & in patients who did not respond to initial antibiotic therapy to confirm presence of possible complications (eg parapneumonic effusions, necrotizing pneumonia, pneumothorax)
    • Also recommended in hospitalized patients to determine the presence, size & character of parenchymal infiltrates, & to document possible complications
  • Daily chest x-ray is not required in stable patients w/ pneumonia complicated by parapneumonic effusion after chest tube placement or after video-assisted thoracoscopic surgery (VATS)
  • Follow-up chest X-ray should not be done routinely in patient who improved uneventfully from CAP but is recommended in patients who do not show clinical improvement & in those w/ progressive symptoms or clinical deterioration w/in 48-72 hours after starting the antibiotic therapy
    • Should also be obtained in patients w/ complicated pneumonia who has worsening respiratory distress or clinical instability or in those who are consistently febrile even after 48-72 hours of antibiotic use
    • Recommended after 4-6 weeks in patients w/ recurrent pneumonia in the same lobe & in patients w/ lobar collapse at first chest x-ray w/ suspicion of an anatomic anomaly, chest mass, or foreign body aspiration

Other Imaging Studies

  • Chest ultrasound is the imaging study of choice to assess pleural fluid loculations
    • Chest ultrasound has no ionizing radiation; hence, considered a safer imaging procedure than CT
    • May be used as a guide in percutaneous needle aspiration for direct culture of infected lung tissue, chest tubing or thoracentesis
  • Computed tomography (CT) may also be used to confirm the presence of pleural fluid
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