Asthma diagnosis and treatmentDosimeter methacholine challenge: Comparison of maximal versus submaximal inhalations
Section snippets
Subjects
Sixteen subjects with asthma, FEV1 ≥65% predicted, and a methacholine PC20 <8 mg/mL (range, 0.28-5.5) by the tidal breathing method11 were studied. The study was approved by the University of Saskatchewan Ethics Committee, and informed signed consent was obtained.
Methacholine challenge methods
Standard 5-breath dosimeter methacholine challenge The standard dosimeter methacholine challenge was performed as outlined by the ATS5 by using a DeVilbiss 646 Nebulizer (Sunrise Medical HHG, Somerset, Pa) and the Micro-Dosimeter (S&M
Results
Sixteen subjects completed the study with no adverse events (Table I). On average, subjects' submaximal inhalation volume was 43.3% (range, 24% to 55%) of their inspiratory capacity above functional residual capacity.
Results are shown in Fig 1. The geometric mean PC20 for the submaximal and full TLC maneuvers were 2.8 mg/mL (95% CI, 1.6-4.9) and 5.2 mg/mL (95% CI, 1.9-13.9), respectively (P = .0216). This represents almost a 2-fold difference between the 2 methods. The 5 subjects with the mildest
Discussion
This study demonstrates that the TLC maneuvers (and breath hold at TLC) during methacholine inhalations inhibit the bronchoconstriction in some subjects with mild AHR. This was observed in 5 of 16 (31%) subjects; these five had the mildest AHR (ie, highest PC20), yet all had current asthma, and 4 of the 5 required inhaled corticosteroids for control. Thus we observed a significant number of false-negative methacholine inhalation tests in subjects with mild AHR, the range in which diagnostic
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2022, International Journal of PharmaceuticsCitation Excerpt :It is to the best of our knowledge the first time an inhalation-synchronized dog dosing system has been developed. The system design was inspired by the precision dosing dosimeter systems used in clinical bronchial challenge tests (Todd et al., 2004; Nieminen et al., 1988; Jõgi et al., 1994; Alkins et al., 2002; Bins et al., 2020; Barranco et al., 2009) and cough challenge tests (Kelsall et al., 2009; Morice et al., 2007; Sumner et al., 2013) or clinical studies dosing drugs (Laasonen et al., 1993; Patel et al., 2018; Werkström et al., 2016; Bjermer et al., 2015). At the start of each inhalation the monitored inhalation flow automatically triggers a precise dose of drug to be delivered in a very short nebulized pulse.
Guidelines for methacholine provocation testing
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