Characterization of patient inhaler inhalation sounds using non-contact and tracheal microphones. (18th October 2016)

• Record Type: Journal Article
• Authors: Taylor, Terence E; De Looze, Céline; MacHale, Philippa; Holmes, Martin S; Sulaiman, Imran; Costello, Richard W; Reilly, Richard B
• Is Part Of: Biomedical physics & engineering express. Volume 2:Number 5(2016)
• Publication Date: 2016-10-18
• Subjects: acoustics -- inhaler -- inhalation -- breath sounds -- signal processing -- asthma -- COPD; Medical physics -- Periodicals; Biophysics -- Periodicals; Biomedical engineering -- Periodicals; Medical sciences -- Periodicals; 610.153
• DOI: 10.1088/2057-1976/2/5/055021
• Languages: English
• ISSNs: 2057-1976

Abstract

Abstract: The dose delivery from dry powder inhalers is dependent on user inhalation technique, particularly the peak inspiratory flow rate (PIFR). Non-contact acoustic methods have recently been employed to objectively measure PIFR during inhaler use. This study aimed to further inhaler acoustics research by extracting acoustic features from inhaler inhalation sounds using non-contact and tracheal microphones and correlating these features with PIFR. This study also investigated the repeatability of the position of the peaks and troughs of the inhaler inhalation power spectral density (PSD) profile across patients. The effects of PIFR, inhalation duration, age, gender, body mass index (BMI) and lung function on the PSD profile were also investigated. Fifty three patients (asthma ( n = 26), COPD ( n = 14) and other respiratory conditions ( n = 13), such as obstructive sleep apnea and chronic cough) were recruited for this study. Each patient was asked to inhale at maximal flow rate through a Diskus™ inhaler while non-contact (5 cm from the inhaler mouthpiece) and tracheal microphones recorded the inhalation sounds. A gold standard measurement of PIFR of inhaler inhalations was also measured simultaneously using a spirometer. It was observed that the Shannon entropy ( H ) of inhalation sounds generated the strongest correlation with PIFR in the non-contact recordings ( R 2 = 0.82, p < 0.001). The average power ( P ave ) of inhalation sounds generated the strongest correlation with PIFR in the tracheal recordings ( R 2 = 0.29, p < 0.001). It was found that the position of peaks and troughs in the PSD profile of inhaler inhalations were more repeatable at an intra-patient level ( p < 0.001) and that PIFR, inhalation duration and age had weak significant effects on the inhalation PSD profile ( p < 0.01). Non-contact acoustic methods show promising opportunities to objectively monitor patient inhalation technique and respiratory health remotely which may greatly benefit both patients and healthcare professionals.