Pneumothorax detection using pulmonary acoustic transmission measurements

Abstract

Pneumothorax is a common clinical condition that can be life threatening. The current standard of diagnosis includes radiographic procedures that can be costly and may not always be readily available or reliable. The objective of this study was to investigate the hypothesis that pneumothorax causes detectable pathognomonic changes in pulmonary acoustic transmission. An animal model was developed whereby 15 mongrel dogs were anaesthetised, intubated and mechanically ventilated. A thoracoscopic trocar was placed into the pleural space for the introduction of air and confirmation of a approximately 30% pneumothorax by direct visualisation. Broadband acoustic signals were introduced into the endotracheal tube, while transmitted waves were measured at the chest surface. Pneumothorax was found consistently to lower the pulmonary acoustic transmission in the 200-1200 Hz frequency band, whereas smaller transmission changes occurred at lower frequencies (p< 0.0001, sign test). The ratio of acoustic energy between low-(< 220 Hz) and high-(550-770 Hz) frequency bands was significantly different in the control and pneumothorax states (p < 0.0001, sign test). This implies that pneumothoraces can be reliably detected using pulmonary acoustic transmission measurements in the current animal model. Further studies are needed to investigate the feasibility of using this technique in humans.

Pneumothorax detection using computerised analysis of breath sounds

“…Another acquisition of breath sounds was then performed. Note that the number of animals used in this study was lower than in our earlier study (MANSY et al, 2002). This difference is because more realistic estimates of the low variability were obtained from the first study, which allowed the use of a smaller number of subjects in the current study.…”

“…An electronic stethoscope* measured the breath sounds in the fight mid-clavicular line at the level of the third rib. Following breath sound acquisition in the baseline state, a 30% PTX was created and confirmed with a thoracoscope (MANsY et al, 2002). Another acquisition of breath sounds was then performed.…”

A comprehensive computational model of sound transmission through the porcine lung

“…[3][4][5][6] Indeed simultaneous, multi-sensor auscultation methods have been developed to "map" sounds on the thoracic surface by several groups. 5,[7][8][9][10][11] Also recently the phase contrast-based technique known as magnetic resonance elastography (MRE) has been applied to the lungs in pilot studies with limited success.…”

Environmental sound research as it stands today

“…Machine listening applications can be geared toward the analysis of specific sounds such as use automatic classification of heart beats [140], respiratory sounds [141], indoor appliance sounds [139] or the sounds of automobiles [142]. Certainly, devices which could perform reliable identification of environmental sounds could be very useful in security applications, noise monitoring and assisted living situations.…”