Sports Medicine: Just the Facts

CHAPTER 23 • EXERCISE-INDUCED ASTHMA TESTING 135

23 EXERCISE-INDUCED ASTHMA

TESTING

Major Fred H Brennan, Jr, DO

EXERCISE-INDUCED ASTHMA TESTING

EPIDEMIOLOGY

• Exercise-induced asthma(EIA) is a common medical
  condition that affects at least 10 to 15% of athletes
  (Eliasson, Phillips, and Rajagopal, 1992).


• Respiratory symptoms alone are insensitive in pre-
  dicting bronchospasm in athletes (Holzer, 2002).


• Common respiratory symptoms suggestive of asthma
  (coughing, wheezing etc.) have only a 60–70% posi-
  tive predictive value for EIA (Rundell et al, 2001;
  Rice et al, 1985).

INDICATIONS FOR EIA TESTING

• An athlete with signs or symptoms suggestive of exer-
  cise-induced asthma


• An athlete with known chronic asthma may be tested
  for an exercise-triggering event.


• An athlete with exertional dyspnea, once cardiac eti-
  ologies have been clinically and/or diagnostically
  eliminated.

CONTRAINDICATIONS FOR EIA TESTING

• Active or recent pulmonary infection within past
  30 days


• Ongoing or recent exacerbation of asthma


• Known allergy to methacholine (methacholine chal-
  lenge)


• An athlete using inhaled corticosteroids may still be
  tested; however, the provocation test may be falsely
  negative in up to 50% of patients (Anderson et al,
  2001; Waalkans et al, 1993).

EIA PROVOCATIVE TESTING

EXERCISE CHALLENGE

•A baseline pulmonary function test(PFT) should be
performed and results recorded prior to this provoca-
tive test.

• The sensitivity and specificity of this test for identify-
  ing EIA in athletes is approximately 65% (Eliasson,
  Phillips, and Rajagopal, 1992; Avital, 2000).


• The challenge should be sport-specific and conducted
  in the environment in which athletes most commonly
  experience their symptoms (Brennan, Jr, 2001).


• An exercise challenge may be used as a first-line diag-
  nostic study.

CONDUCTING ANEXERCISECHALLENGE

• Allow athletes to stretch but do not allow them to
  exercise or warm up prior to the challenge. A warm-
  up period may result in a false negative result.


• Obtain a baseline PFT or peak expiratory flow rate
  (PEFR). Record FEV1 and FEF 25-75, or PEFR.


• The sport-specific exercise should be conducted for
  8–10 min at a heart rate of 85–90% maximum calcu-
  lated heart rate (220 – age in years =calculated max-
  imum heart rate).


• After 10 min of exercise allow a 1-min rest. Check
  PFT or PEFR three times and record the best result.


• Repeat these at 3, 5, 10, 15 and 20 min post termina-
  tion of the exercise challenge.
  •A decrease of >10% in the FEV1 or PEFR, and/or a
  decrease in FEF 25–75 of >20% are diagnostic for EIA
  (Mannix, Manfredi, and Farber, 1999; Provost, et al,
  1996).

METHACHOLINE CHALLENGE

• Methacholine stimulates muscarinic receptors located
  in the airway smooth muscle (Lin et al, 1991).


• The sensitivity of this test is estimated to be 55% and
  up to 100% specific (Eliasson, Phillips, and Rajagopal,
  1992).


• The positive predictive value may be as high as 100%,
  with a negative predictive value of 61% (Holzer, 2002).

CONDUCTING THEMETHACHOLINECHALLENGE

• Obtain a baseline PFT. Record the best FEV1.


• Solutions of methacholine are prepared in the fol-
  lowing concentrations: 0.025, 0.25, 2.5, 10, and
  25 mg/mL.


• The athlete inhales five breaths of the lowest concen-
  tration solution via nebulizer. A PFT is performed
  3 min post inhalation of the methacholine.


• The concentration of methacholine solution is increased
  to the next highest concentration and a PFT performed
  3 min post inhalation.


• This provocative test is concluded and considered
  positive if there is a decline in the FEV1 of at least