The intention of this study was to direct the eye prospectively at the practice of prefacing methacholine bronchoprovocation challenge (BPC) with diluent challenge using physiologic saline solution (NaCl) as the diluent.

The intention of this study was to direct the eye prospectively at the practice of prefacing methacholine bronchoprovocation challenge (BPC) with diluent challenge using physiologic saline solution (NaCl) as the diluent. We wished to determine whether NaCl challenge added to the safety or diagnostic accuracy of BPC We studied 108 consecutive patients undergoing methacholine BPC We determined (1) the [FEVsub1] reply of all patients to the inhalation of NaCl (the difference between the [FEVsub1] before NaCl and the [FEVsub1] after NaCl), and (2) the correlation between the reply to saline solution and bronchial hyperresponsiveness (BHR) measured using methacholine. Paired Student's t testing demonstrated a small further significant difference between the values for [FEVsub1] before and after NaCl FOR THE cluster as a whole (n = 108; mean change, - 09 [+ or -] 4 percent [+ or -] SD]; p = 0023) When the mean changes in the [FEVsub1] after NaCl for the assign places to with increased BHR (BHR +) (n = 62; mean, - 11 [+ or -] 49 percent) and the dispose with no increase in BHR (BHR -) (n = 46; mean, -06 [+ or-] 24 percent) were contrasted, there was no significant difference between the brace groups (p = 0.46). and nothing else 4 of 108 patients had a least bit in [FEV.sub.1] of 10 percent or more after NaCl, with the greatest globule being 16 percent. All four patients were BHR [divided by] if it be not that none had marked BHR. For the BHR + arrange there was no correlation between replication to saline solution and posterior response to methacholine (r = 002) We deduce that saline solution challenge adds time and outlay to BPC without increasing the safety or yield of BPC We put in mind of that NaCl challenge can be omitted from the standard performance of BPC

BHR = bronchial hyperresponsiveness; BHR + = increased BHR; BHR - = no increase in BHR; BPC = bronchoprovocation challenge; PC20 = provocative concentration causing 20 percent least bit in [FEV.sub.1]

It is standard practice to preface bronchoprovocation challenge (BPC) with an inhalational challenge using a diluent.[1-8] The diluent used is almost always physiologic saline solution (NaCl), with or without guards and preservatives.[1-8] The [FEV.sub.1], after NaCl is then used as the baseline [FEVsub1] against which following responses to the challenge unsalable article are measured. After having followed this standard practice for many years, we realized that we had none seen a marked response (ie, >20 percent decrease in the [FEVsub1]) to NaCl and bad none had to discontinue a cogitation because of the response to NaCl. We also questioned the rationale of eliminating any answer elicited by diluent from a investigation designed to detect nonspecific bronchial hyperresponsiveness (BHR) (as oppos to antigen-specific BHR) We therefore undertook a prospective contemplation of all patients undergoing BPC in our laboratory to examine the relationship between answer to NaCl and subsequent rejoinder to methacholine.

MATERIALS AND METHODS

each BPC performed in our laboratory from June 8 1990 until Aug 27 1991 was included in the contemplation Data collection included the [FEVsub1] before NaCl, the [FEVsub1] after NaCl, the extrapolated concentration of methacholine at which a 20 percent very little in [FEV.sub.1], occurred (PC20), and the maximal ear-ring in [FEV.sub.1], induced by the BPC

in the greatest degree spirometric values were obtained with a Sensormedics 2100 spirometer. A scarcely any studies were performed on Sensormedics 2130 Sensormedics 2200 and Sensormedics 6200 spirometers. Computer software was uniform for all a whole s The tested solutions were aerosolized using a nebulizer (DeVilbiss 646) with press togethered air at 8 L/min. The output of the ten nebulizers used for the application of mind were measured. The mean output was 027 ml/min (range, 026 to 028 ml/min).

Initially, three forced vital capacity maneuvers which met the criteria of the American Thoracic Society were obtained.[9] (A clip was placed in succession the nose for all spirometric maneuvers and during inhalation of all challenge solutions.) The highest [FEVsub1] obtained was used as the initial baseline. Patients with an initial [FEVsub1] of les than 70 percent of predicted and patients receiving medications known to affect BHR were exclud from BPC[10] The methacholine BPC was performed according to the tidal turn method of Hargreave et al.[2-4,11] Each patient inhaled plain NaCl, the diluent used for the methacholine, for 2 min followed by dint of repeat forced maneuvers. The percent change in [FEVsub1] after NaCl was recorded for each patient, but all patients went forward to receive methacholine there was no value for [FEVsub1] after NaCl which preclud following study; however, the [FEV.sub.1], after NaCl was used as the fresh baseline [FEV.sub.1], for the BPC After the inhalation of NaCl, dilutions of methacholine in NaCl were delivered in sequentially higher concentrations (0125 mg/ml 025 mg/ml 05 mg/ml 1 mg/ml 2 mg/ ml 4 mg/ml and 8 mg/ml) The same following of concentrations was used regardless of the replication to NaCl. Each concentration was inhaled for 2 min, with spirometry obtained 1 min after the conclusion of that dose. The BPC was terminated when a ear-ring of at least 20 percent in [FEVsub1] bad occurr or after the highest concentration had been administered. Patients who did experience a 20 percent or greater fall in [FEVsub1] were subsequently given inhalations of bronchodilator until the [FEVsub1] had answered to within 10 percent of the baseline value.

...