The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

USE OF CORTICOSTEROIDS AT THE TIME OF METHACHOLINE CHALLENGE TESTING

Jeffrey M. Haynes RRT RPFT, Eric S. Lindquist RRT CPFT, Elizabeth L. Sweeney CRT. Pulmonary Function Laboratory, St. Joseph Hospital, Nashua, New Hampshire.

Background: While it is recommended that patients not use non steroid asthma medications for 8-48 hours (depending on the drug) before methacholine challenge testing (MCT) because of their ability to reduce airway responsiveness, there are no recommendations for withholding corticosteroids (CS) prior to MCT.1 It is our experience that many patients receive the same instructions for withholding CS prior to MCT as they do for short acting bronchodilators; however, the effect of CS on the provocative concentration of methacholine producing a 20% decrease in forced expiratory volume in the first second (PC20) may last much longer than non steroid medications. Therefore, the use of CS near the timing of MCT may elevate PC202 and perhaps result in a false negative MCT. Since CS are being used earlier in the treatment of asthma and even suspected asthma, we sought to examine how many patients were presenting for MCT while being treated with systemic CS (SCS), inhaled CS (ICS), and nasal CS (NCS).3

Methods:
6-month retrospective chart review of all patients undergoing MCT at our institution. The types of respiratory medications patients take and the timing of their last dose are routinely documented by the pulmonary function technologist for physician review when interpreting MCT data. Patients who had used SCS, ICS, or NCS within 1 week of testing were regarded as patients being treated with CS at the time of MCT.

RESULTS:
89 patient charts were reviewed. 27 (30%) patients were being treated with CS at the time of MCT. 15 (16.8%) were taking ICS, 17 (19%) were taking NCS, and no patients were being treated with SCS. 5 (5.6%) patients were being treated with both ICS and NCS. The mean time interval of the last dose of CS before MCT was 2.25 days (range: 0-7 days). Of the patients treated with CS, 15 (56%) had a PC20 < 16 mg/mL and 12 (44%) had a PC20 > 16 mg/mL. No patients treated with CS who had a PC20 > 16 mg/mL returned to our institution for repeat MCT following a discontinuance of CS treatment.

Conclusions:
Many patients are treated with CS at the time of MCT. In these patients, PC20 may be elevated by CS treatment, which has the potential to produce a false negative MCT. Repeat MCT following the discontinuance of CS treatment should be considered if the clinical suspicion for asthma is high despite a PC20 > 16 mg/mL during CS treatment. Further investigation is needed regarding the proper time interval for withholding CS prior to MCT.

References:


1. Crapo RO, Casaburi R, Coates AL, Enright PL, Hankinson JL, Irvin CG, et al. Guidelines for methacholine and exercise challenge testing-1999. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, July 1999. Am J Respir Crit Care 2000:161(1):309-329.

2. Lim S, Jatakanon A, John M, Gilbey T, O'Connor BJ, Chung KF, Barnes PJ. Effect of inhaled budesonide on lung function and airway inflammation. Assessment by various inflammatory markers in mild asthma. Am J Respir Crit Care Med. 1999;159(1):22-30.

3. Watson WT, Becker AB, Simons FE. Treatment of allergic rhinitis with intranasal corticosteroids in patients with mild asthma: effect on lower airway responsiveness. J Allergy Clin Immunol. 1993;91(1 Pt 1):97-101.

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