Mapping Sound Propagation Through the Human Lung for Better Diagnosis

Overview

This study investigates the propagation of sound from a source in the chest to the chest wall. The methodology of the study will be to place a sound source at a known location in the chest and measure the acoustic response on the posterior chest wall with an acoustic sensor array. The sound source will be created by playing sound down the working channel of a bronchoscope and located anatomically using direct imaging. Subjects will be selected for the study by asking patients undergoing a bronchoscopy procedure whether they would be willing to take part in the experiment in addition to their standard procedure. Procedures will take place in the Bronchoscopy Unit at Addenbrooke's hospital in Cambridge. The Unit runs regional speciality clinics in severe chronic obstructive pulmonary disease, asthma, lung cancer, bronchomalacia and interstitial lung disease and has a nationally significant interventional bronchoscopy service. A subsidiary part of the study (Part A) will collect sound recordings from healthy volunteers and patients with common respiratory diseases using the same acoustic sensor array. This is to create a database of lung sounds and quantify inter-subject variability. The study will last approximately 30 months.

The study has two parts, A and B. Both parts are observational studies of the sounds heard at the chest as recorded by an acoustic array. In Part A, healthy volunteers and patients at Addenbrooke's hospital will have the chest sounds at their back recorded using an electronic-stethoscope array. This will be done in a single session lasting approximately 30 minutes. 50 healthy volunteers and 100 patients will be included. In Part B, 50 patients undergoing a bronchoscopy at Addenbrooke's hospital will have their bronchoscopy extended by 5-10 minutes so that sounds can be played through the working channel of the bronchoscope and recorded by a microphone array at the posterior chest. Part B will investigate 25 patients with structurally 'normal' lungs (for example patients with Chronic Cough) (Part B(i)), and 25 patients with lung disease that has resulted in an 'abnormal' lung structure (Part B(ii)). The consultant bronchoscopist will assign the patient to the relevant group based on information from their medical history and their CT scan. For Part B of the study an existing CT scan is an inclusion criterion. CT scans will not be carried out specifically for this study.