Exercise Challenge Test in 3-6 Years Old Asthmatic Children
Condition: Asthma
MeSH terms: Asthma
Study type: Observational

Summary: 
      Vigorous exercise is known to cause transient bronchoconstriction in school children with
      asthma, many of whom initially have normal lung function at rest. The presence and extent of
      this phenomena in early childhood is difficult to recognize, because exercise induced
      bronchoconstriction (EIB) may not limit the child's performance and the child may fail to
      notice the symptoms until taking part in organized or competitive sport. Conversely, as
      children do participate in vigorous activities all day long, severe EIB may provoke a crucial
      disabling condition in the child.

      In school children the exercise challenge test (ECT) is a well standardized test and is used
      to make a diagnosis of asthma because it is able to discriminate between asthma and other
      chronic breathing illnesses of childhood and is also used to determine the effectiveness and
      optimal dosages of medications prescribed to prevent EIB.

      The test includes is a controlled run on a motor-driven treadmill followed by scheduled
      multiple spirometry maneuvers. This procedure was never been tested and may not be suitable
      for the preschool age.

      In this study we assumed that a free-run test which combined with measurements of duplicate
      spirometry-sets would be the most convenient way to test young children.

      The aims of this study are a) to examine the feasibility of a free-run protocol (according to
      the ATS/ERS recomendations), followed by duplicate spirometry measurements in early
      childhood.

      b) to explore the existence of exercise induced bronchoconstriction in young children (age
      3-6 years old) with respiratory symptoms.
    

Detailed description: 
      Method:

      The children are to come in comfortable clothes and running shoes, having consumed no more
      than a light meal and having had pulmonary medications withdrawn as described above. A
      parent, a pediatric pulmonary physician and a technician is present throughout the test. Each
      child undergoes a physical examination to exclude evidence of wheeze, and baseline spirometry
      was performed. The children are asked to run freely back and forth (without a nose-clip) in a
      50m long corridor next to the pulmonary laboratory. The target is to achieve 6 minutes of
      "free run" to increase hart-rate to 80% in the maximum for at least 4 minutes according to
      ATS/ERS recommendations for exercise challenge test in older children [1]. An adult
      (parent/technician/ physician) will run with the child to encourage him/her to continue
      running. Heart-rate and O2-saturation is monitored continuously throughout the run using a
      portable mobile pulse-oximeter monitor (Nonin medical, INC, model 2500, Minneapolis, USA).

      Spirometry is measured according to the recommendations for preschool children [2], with a
      commercial ZAN100 Spirometer situated in the pediatric pulmonary laboratory, by a skilled
      technician. Measurements are performed in the standing position, without nose-clip (for
      comfort of the child) until two consecutive technically acceptable curves are achieved. After
      the free-run, spiroetmry is measured in duplicate sets at 1, 3, 5, 10 and 20 minutes
      post-exercise [1]. The better of the two curves is selected as the representative value at
      each interval, but differences between the two values of FEV1 has to be <5%. The following
      signs are monitored by the pulmonologist: wheeze and prolonged expiration on auscultation
      over the trachea and two zones of both lungs (upper front and lower back). Cough, shortness
      of breath, or perceived breathlessness within 20 minutes after the run were noted.

      Analysis: Technically acceptable spirometry maneuvers are analyzed. Baseline values are first
      compared to the spirometry values with relation to height derived from the indices in 109
      healthy children in our previous study [3].

      Following exercise, best spirometry values for each interval are compared to baseline values.
      Exercise response was defined as the greatest decrease in FEV1 expressed as a percentage of
      the baseline values. A bronchoconstriction response to exercise is considered as positive
      when the FEV1 decrease from baseline was greater than 13% [4]. Student's paired t-test is
      used for comparison of data between each spirometry index and the calculated values for
      healthy children. A value of p<0.05 was considered significant.

      References:

        1. Guidelines for Methacholine and Exercise Challenge Testing 1999. The official statements
           of the American Thoracic Society, adopted by the ATS board of directors, 1999. Am J
           Respir Crit. Care Med 2000;161:309-329.

        2. Aurora P, Stocks J, Oliver C, Saunders C, Castle R, Chaziparasidis G, Bush A; London
           Cystic Fibrosis Collaboration. Quality control for spirometry in preschool children with
           and without lung disease. Am J Respir Crit Care Med 2004; 169:1152-1159.

        3. Vilozni D, Barak A, Efrati O, Augarten A, Springer C, Yahav Y, Bentur L. The role of
           computer games in measuring spirometry in healthy and "asthmatic" preschool children.
           Chest. 2005; 128:1146-115.

        4. Godfrey S, Springer C, Bar-Yishay E, Avital A. Cut-off points defining normal and
           asthmatic bronchial reactivity to exercise and inhalation challenges in children and
           young adults. Eur Respir J. 1999; 14:659-66.
    

Intervention name(s): Exercise chalenge test
Intervention type(s): Procedure
Time perspective: Other
Keywords: Exercise-induced asthma,; early childhood;; spirometry,; exercise challenge; Data from preschool children who were referred to the Pediatric; Pulmonary Clinic over a 1-year period were recruited