THE LACK OF A ROLE FOR SALINE SOLUTION INHALATION IN BRONCHOPROVOCATION CHALLENGE

The purpose of this study was to look prospectively at the practice of prefacing methacholine bronchoprovocation challenge (BPC) with diluen t challenge using physiologic saline solution (NaCl) as the diluent. W e wished to determine whether NaCl challenge added to the safety or di agnostic accuracy of BPC. We studied 108 consecutive patients undergoi ng methacholine BPC. We determined (1) the FEV1 response of all patien ts to the inhalation of NaCl (the difference between the FEV1 before N aCl and the FEV1 after NaCl), and (2) the correlation between the resp onse to saline solution and bronchial hyperresponsiveness (BHR) measur ed using methacholine. Paired Student's t testing demonstrated a small but significant difference between the values for FEV, before and aft er NaCl for the group as a whole (n = 108; mean change, - 0.9 +/- 4 pe rcent [+/- SD]; p = 0.023). When the mean changes in the FEV, after Na Cl for the group with increased BHR (BHR +) (n = 62; mean, - 1.1 +/- 4 .9 percent) and the group with no increase in BHR (BHR -) (n = 46; mea n, - 0.6 +/- 2.4 percent) were contrasted, there was no significant di fference between the two groups (p = 0.46). Only 4 of 108 patients had a drop in FEV1 of 10 percent or more after NaCl, with the greatest dr op being 16 percent. All four patients were BHR(divided-by), 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 exp ense to BPC without increasing the safety or yield of BPC. We suggest that NaCl challenge can be omitted from the standard performance of BP C.