ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

Test Procedure

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Next and Remaining Doses of Methacholine Steps

If the FEV 1 falls less than 20% from the post-diluent value, empty the nebulizer by shaking excess solution into wastebasket or sink. Withdraw 2 ml or appropriate amount of the starting dose of methacho- line, and place it in the same nebulizer used for the diluent. With nose clip in place, aerosolize the methacholine using the same nebulizer used for diluent. Start timer. Perform post-methacholine spirometry at 30 and 90 seconds after nebuli- zation is completed. Obtain an acceptable quality FEV 1 at each time point. As noted above, obtaining a full FVC is not required if FEV 1 is the only outcome. If abbreviated expiratory time is used, care should be taken to assure the inspiration is complete. Perform no more than 3 or 4 test ma- neuvers after each dose. In order to keep the cumulative effect of metha- choline relatively constant, the time interval between the commencement of two serial concentrations is important and should be kept constant at 5 minutes. At each dose, report the highest FEV 1 from acceptable test maneuvers. If the highest post-methacholine FEV 1 falls less than 20% from the post- diluent value go to next step (next highest concentration of methacholine). If the highest post-methacholine FEV 1 falls more than 20% from the post- diluent FEV 1 or the highest concentration has been administered, give no further methacholine, note signs and symptoms, and administer an inhaled bronchodilator. , administer a bronchodilator (e.g., 0.5 ml of albuterol in 1 ml of normal saline by small volume nebulizer, or 2 puffs from a metered dose inhaler). Wait 5–10 minutes and repeat PF tests. If the post-bronchodilator FEV 1 ≥ 90% of the highest pre-challenge FEV 1 , the patient can leave the laboratory. If the post-bronchodilator FEV 1 < 90% of the highest pre-challenge FEV 1 or the patient is symptomatic, administer a second bronchodilator or ipratropium bromide treatment and repeat PF tests after a waiting period of 10 minutes. If the post-bronchodilator FEV 1 is still < 90% of the highest baseline, no- tify ordering physician before letting patient leave the laboratory. If the highest post-methacholine FEV 1 from the post-diluent FEV 1 from any dose falls 20% or more

Bronchodilator Administration

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