Pediatric Reactive Airway Disease Workup

Updated: Feb 23, 2016
  • Author: Eric S Chin, MD; Chief Editor: Kirsten A Bechtel, MD  more...
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Workup

Laboratory Studies

A complete blood count (CBC) may be indicated for a suspected viral infection (lymphocytosis, leukopenia), parasitic infection (eosinophilia), or hemosiderosis.

An arterial blood gas (ABG) determination should be performed for any patient in status asthmaticus to check for hypoxia, hypercarbia, or acidosis; alternatively, a venous blood gas measurement can be used to assess for hypercarbia and acidosis and combined with pulse oximetry monitoring.

An assessment of electrolyte levels may reveal hypokalemia in patients who are using albuterol.

Although theophylline is prescribed less frequently, a theophylline level is useful for those on the drug.

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Imaging Studies

Routine radiography does not need to be part of the initial routine evaluation of asthma. [14]

Consider chest radiography if increased temperature, absence of family history of asthma, and the presence of localized wheezes or rales.

  • Hyperinflation
  • Peribronchial thickening
  • Atelectasis
  • Radiographs may provide evidence of foreign body, associated vascular anomalies, cardiac enlargement, pulmonary hypertension, infiltrates, or masses.
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Other Tests

See the list below:

  • All chronically wheezing infants and children with chronic asthma should have a sweat chloride test for cystic fibrosis at a subsequent primary care provider (PCP) visit or during inpatient evaluation.
  • A tuberculosis skin test may be indicated if significant risk factors exist.
  • Allergy testing
  • Exercise tolerance testing
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Procedures

Procedures include the following:

  • Spirometry (decreased forced expiratory volume in one second [FEV 1])
    • Bedside spirometry is the primary procedure for children with RAD who are older than 5 years.
    • Patients with decreased FEV1 require further evaluation and treatment.
  • A barium swallow may be indicated to determine any esophageal, pulmonary, or vascular pathology, particularly a tracheoesophageal fistula.
  • Bronchoscopy (rarely indicated) (see Table 1 below)
  • Peak expiratory flow (PEF) is the most common form of pulmonary function test monitoring. Record the best of 3 attempts. Possible life-threatening asthma exacerbation with PEF predicted of less than 30%; severe exacerbation, with less than 50%; and moderate exacerbation, with less than 80%.

Peak flow rates are described in the table below.

Table 1. Peak Flow Rates in Liters per Minute [15] (Open Table in a new window)

Height in



Inches



Average



Rate



Range* Height in



Inches



Average



Rate



Range*
40 150 110-190 56 330 240-420
41 160 115-205 57 340 240-420
42 170 120-220 58 360 260-460
43 180 130-220 59 375 270-480
44 190 135-245 60 390 280-500
45 200 145-255 61 400 290-510
46 210 150-270 62 415 300-530
47 220 160-280 63 430 310-550
48 230 165-295 64 445 320-570
49 240 175-305 65 460 330-590
50 250 180-320 66 480 345-615
51 260 190-330 67 500 360-640
52 270 195-345 68 515 370-660
53 280 200-360 69 530 380-680
54 300 215-385 70 550 395-705
55 315 225-405 71 570 410-730
*Includes 95% of white males aged 7-20 years.



Derived and adapted from J Pediatr 1979;95:192-6.



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