Taylor Terence E, Holmes Martin S, Sulaiman Imran, Costello Richard W, Reilly Richard B
1 Trinity Centre for Bioengineering, Trinity College Dublin , Dublin, Ireland .
2 School of Engineering, Trinity College Dublin , Dublin, Ireland .
J Aerosol Med Pulm Drug Deliv. 2016 Oct;29(5):439-446. doi: 10.1089/jamp.2015.1276. Epub 2016 Feb 9.
The efficacy of drug delivery from inhalers is very much dependent on the user's peak inspiratory flow rate (PIFR). Current methods to measure PIFR in inhalers are based on subjective checklists. There is a lack of methods currently available to objectively remotely monitor PIFR in pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). In this study, for the first time, non-contact acoustic methods were employed to estimate PIFR through three commonly used inhalers (Diskus™ DPI, Turbuhaler™ DPI, and Evohaler™ pMDI) with the aim of applying these methods to remotely monitor inhaler inhalation technique in future clinical applications.
Each inhaler was placed inside an airtight container connected to a spirometer to measure PIFR. A high quality microphone was placed 5 cm from the mouthpiece of the inhalers to record inhalation sounds. Over 2000 inhaler inhalation sounds were recorded from 11 healthy participants. A range of temporal and spectral acoustic features from the inhalation sounds were correlated with PIFR. The variation of acoustic features and the repeatability of the inhalation acoustic spectral profile were investigated to further characterize inhaler inhalation sounds and to determine the reliability of acoustics to estimate PIFR.
All acoustic features were significantly correlated with PIFR (p < 0.001). The mean power of the inhalation sound generated the most consistent correlation across all inhalers [R = 0.77 (Diskus™), R = 0.7 (Turbuhaler™), R = 0.75 (Evohaler™)]. Acoustic features generated low variation and the spectral profile of inhalation sounds was repeatable regardless of flow rate, suggesting that acoustic methods are a reliable method of estimating PIFR.
The methods presented in this study may be employed in a wearable monitoring device in future applications to measure inhaler PIFR. Objective monitoring of PIFR in inhalers may help patients improve their inhaler inhalation technique and therefore may be of significant clinical benefit to both patients and clinicians.
吸入器的药物递送效果在很大程度上取决于使用者的最大吸气流速（PIFR）。目前测量吸入器中PIFR的方法基于主观检查表。目前缺乏可用于客观远程监测压力定量吸入器（pMDIs）和干粉吸入器（DPIs）中PIFR的方法。在本研究中，首次采用非接触声学方法通过三种常用吸入器（Diskus™ DPI、Turbuhaler™ DPI和Evohaler™ pMDI）来估计PIFR，目的是将这些方法应用于未来临床应用中远程监测吸入器吸入技术。
将每个吸入器放置在连接到肺活量计的气密容器内以测量PIFR。在距吸入器吸嘴5厘米处放置一个高质量麦克风以记录吸入声音。从11名健康参与者中记录了超过2000次吸入器吸入声音。将吸入声音的一系列时间和频谱声学特征与PIFR相关联。研究声学特征的变化以及吸入声谱轮廓的可重复性，以进一步表征吸入器吸入声音并确定声学估计PIFR的可靠性。
所有声学特征均与PIFR显著相关（p < 0.001）。吸入声音的平均功率在所有吸入器中产生了最一致的相关性[R = 0.77（Diskus™），R = 0.7（Turbuhaler™），R = 0.75（Evohaler™）]。声学特征变化较小，且无论流速如何，吸入声音的频谱轮廓都是可重复的，这表明声学方法是估计PIFR的可靠方法。
本研究中提出的方法可在未来应用中用于可穿戴监测设备以测量吸入器PIFR。对吸入器中PIFR的客观监测可能有助于患者改善其吸入器吸入技术，因此可能对患者和临床医生都具有重大临床益处。
