PURPOSE:Bronchial vasoconstriction has been reported in asthmatics within 30–60 min of inhaled corticosteroid, without spirometric improvement. Impulse Oscillometry (IOS) is noninvasive, unobtrusive and more sensitive than spirometry. Accordingly, we measured respiratory mechanics with IOS in four (preliminary results) asthmatics for the first 5 hours after mometasone furoate DPI (MF) administration, and on two subsequent days.
METHODS:Steroid-naïve adult asthmatics (FEV1 = 75% predicted) randomly allocated to daily treatment with 440 mcg MF were tested at baseline by IOS (6 replicates) to provide low frequency reactance (AX, an index of small airways impairment), and two maximal forced expirations within 5% were obtained. MF was administered and IOS tests repeated 30, 60, 90, 120 and 300 min later, with spirometry at 120 and 300 min only. Patients returned for IOS and spirometry testing on the next two mornings.
RESULTS:Preliminary results show IOS AX decreased 21, 42, 39, 38, and 34% at 30 (p=0.06), 60 (p=0.03), 90 (p<0.03), 120 (p=0.03), and 300 min (p<0.04) respectively. On day 2, AX was 56% below baseline (p=0.01); on day 3, AX was 49% below baseline (p=0.02). FEV1 improved from 75.3% predicted at baseline to 84.4% at 120 min (p < 0.02), 80.5% at 300 min (p=0.055), 89.4% (p=0.02) on day 2 and 84.7% (p=0.04) on day 3.
CONCLUSION:We conclude that improved airway function is measureable by IOS 1 hr after initiation of MF 440 mcg. Spirometry improved at 2 hrs; and both IOS and spirometry improved subsequently. These changes are consistent with the previously described time course of bronchial vasoconstriction; and significantly augmented over the subsequent 48 hrs.
CLINICAL IMPLICATIONS:Improved lung function may occur much sooner than hitherto assumed in asthmatic patients when first given MF. Earlier clinical followup may benefit patient care.
DISCLOSURE:Michael Goldman, Grant monies (from industry related sources) Schering-Plough; No Product/Research Disclosure Information