The Lack of a Role for Saline Solution Inhalation in Bronchoprovocation Challenge* Thaddeus C. Bartter, M.D., F.C.C.P.; james Dubois, M.H.A., R.R.T.; and Melvin R. Pratter, M.D., F.C.C.P. The purpose of this study was to look prospectively at the practice of prefacing methacholine bronchoprovocation challenge (BPC) with diluent challenge using physiologic saline solution (NaCl) as the diluent. We wished to deter- mine whether NaCl challenge added to the safety or diagnostic accuracy of BPC. We studied 108 consecutive patients undergoing methacholine BPC. We determined (1) the FEV, response of all patients to the inhalation of NaCl (the difference between the FEV, before NaCI and the FEV, after NaCI), and (2) the correlation between the response to saline solution and bronchial hyperresponsive- ness (BHR) measured using methacholine. Paired Student's t testing demonstrated a small but significant difference between the values for FEV, before and after NaCI for the group as a whole (n= 108; mean change, -0.9±4 percent [±SD]; p=0.023). When the mean changes in the FEV, after NaCl for the group with increased BHR (BHR +) (n = 62; mean, - 1.1 ± 4.9 percent) and the group with no I t is standard practice to preface bronchoprovocation challenge (BPC) with an inhalational challenge using a diluent. t-s The diluent used is almost always physiologic saline solution (NaCl), with or without buffers and preservatives. •-s The FEV 1 after NaCI is then used as the baseline FEV 1 against which subse- quent responses to the challenge drug are measured. After having followed this standard practice for many years, we realized that we had never seen a marked For editorial comment see page 1323 response (ie, >20 percent decrease in the FEV 1 ) to NaCl and had never had to discontinue a study because of the response to NaCl. We also questioned the rationale of eliminating any response elicited by dilu- ent from a study designed to detect nonspecific bronchial hyperresponsiveness (BHR) (as opposed to antigen-specific BHR). We therefore undertook a prospective study of all patients undergoing BPC in our laboratory to examine the relationship between response to NaCl and subsequent response to metha- choline. MATERIALS AND METHODS Every BPC performed in our laboratory from June 8, 1990 until Aug 27, 1991 was included in the study. Data collection included the FEY, before NaCl, the FEY, after NaCl, the extrapolated *From the Division of Pulmonary and Critical Care Medicine, Department of Medicine, Cooper Hospital/University Medical Center, Camden, NJ. Manuscript received December 8, 1992; revision accepted March 10, 1993. increase in BHR (BHR-) (n=46; mean, -0.6±2.4 per- cent) were contrasted, there was no significant difference between the two groups (p=0.46). Only 4 of 108 patients had a drop in FEV, of 10 percent or more after NaCl, with the greatest drop being 16 percent. All four patients were BHR +, but none had marked BHR. For the BHR + group, there was no correlation between response to saline solution and subsequent response to methacholine (r=0.02). We conclude that saline solution challenge adds time and expense to BPC without increasing the safety or yield of BPC. We suggest that NaCI challenge can be omitted from the standard performance of BPC. (Chest 1993; 104:1338-41) BHR =bronchial hyperresponsiveness; BHR + =increased BHR; BHR- =no increase in BHR; BPC = bronchoprovocation challenge; PC20 =provocative concentration causing 20 percent dropinFEV, concentration of methacholine at which a 20 percent drop in FEY, occurred (PC20), and the maximal drop in FEY, induced by the BPC. Most spirometric values were obtained with a Sensormedics 2100 spirometer. A few studies were performed on Sensormedics 2130, Sensormedics 2200, and Sensormedics 6200 spirometers. Computer software was uniform for all systems. The tested solutions were aerosolized using a nebulizer (DeVilbiss 646) with compressed air at 8 Umin . The outputs of the ten nebulizers used for the study were measured. The mean output was 0.27 ml!min (range, 0.26 to 0.28 ml!min). Initially, three forced vital capacity maneuvers which met the criteria of the American Thoracic Society were obtained. • (A clip was placed on the nose for all spirometric maneuvers and during inhalation of all challenge solutions.) The highest FEY, obtained was used as the initial baseline. Patients with an initial FEY, of less than 70 percent of predicted and patients receiving medications known to affect BHR were excluded from BPC. "'The methacholine BPC was performed according to the tidal volume method of Hargreave et al. 2 -'· 11 Each patient inhaled plain NaCI, the diluent used for the methacholine, for 2 min followed by repeat forced maneuvers. The percent change in FEY, after NaCI was recorded for every patient, but all patients went on to receive methacholine; there was no value for FEY, after NaCI which precluded subsequent study; however, the FEY, after NaCI was used as the new baseline FEY, for the BPC. After the inhalation of NaCI, dilutions of methacholine in NaCI were delivered in sequentially higher con- centrations (0.125 mwml, 0.25 mwml, 0.5 mwml, 1 mwml, 2 mw ml, 4 m!Vml, and 8 m!iml). The same sequence of concentrations was used regardless of the response to NaCI. Each concentration was inhaled for 2 min, with spirometry obtained 1 min after the end of that dose. The BPC was terminated when a drop of at least 20 percent in FEY, had occurred or after the highest concentration had been administered. Patients who did experience a 20 percent or greater fall in FEY, were subsequently given inhalations of bronchodilator until the FEY, had returned to within 10 percent of the baseline value. 1338 lack of Role lor Saline Inhalation in Bronc:hopro\loc Challenge (Bartler. Dubois, Pratter)