Respiratory sounds : Advances beyond the stethoscope

We describe a microfabricated airway system integrated with computerized air–liquid two-phase microfluidics that enables on-chip engineering of human airway epithelia and precise reproduction of physiologic or pathologic liquid plug flows found in the respiratory system. Using this device, we demonstrate cellular-level lung injury under flow conditions that cause symptoms characteristic of a wide range of pulmonary diseases. Specifically, propagation and rupture of liquid plugs that simulate surfactant-deficient reopening of closed airways lead to significant injury of small airway epithelial cells by generating deleterious fluid mechanical stresses. We also show that the explosive pressure waves produced by plug rupture enable detection of the mechanical cellular injury as crackling sounds.

https://www.pnas.org/content/pnas/104/48/18886.full.pdf

Acoustically detectable cellular-level lung injury induced by fluid mechanical stresses in microfluidic airway systems.

Neural classification of lung sounds using wavelet coefficients.

Each stage in the life cycle of coal-extraction, transport, processing, and combustion-generates a waste stream and carries multiple hazards for health and the environment. These costs are external to the coal industry and are thus often considered "externalities." We estimate that the life cycle effects of coal and the waste stream generated are costing the U.S. public a third to over one-half of a trillion dollars annually. Many of these so-called externalities are, moreover, cumulative. Accounting for the damages conservatively doubles to triples the price of electricity from coal per kWh generated, making wind, solar, and other forms of nonfossil fuel power generation, along with investments in efficiency and electricity conservation methods, economically competitive. We focus on Appalachia, though coal is mined in other regions of the United States and is burned throughout the world.

/pdf/full-cost-accounting-for-the-life-cycle-of-coal-57ukx6bckn.pdf

Full cost accounting for the life cycle of coal.

Background Active sodium absorption is the dominant mechanism of ion transport in airway epithelium, but its role in pulmonary physiology and airway host defense is unknown. To address this question, we studied the function of airway epithelial cells and determined the frequency of pulmonary symptoms in patients with systemic pseudohypoaldosteronism, a salt-losing disorder caused by loss-of-function mutations in the genes for the epithelial sodium channel. Methods In nine patients 1.5 to 22 years of age who had systemic pseudohypoaldosteronism, we tested for mutations in the genes for the epithelial sodium channel, estimated the rate of sodium transport in the airway, determined the volume and ion composition of airway surface liquid, reviewed clinical features, collected laboratory data pertinent to pulmonary function, and, in three adults, measured mucociliary clearance. Results The patients with systemic pseudohypoaldosteronism had loss-of-function mutations in the genes for the epithelial sodium-chann...

/pdf/pulmonary-epithelial-sodium-channel-dysfunction-and-excess-3ag3vqxl0g.pdf

Pulmonary epithelial sodium-channel dysfunction and excess airway liquid in pseudohypoaldosteronism

Acoustic imaging of the human chest.

Context.— The effectiveness of glucocorticoids for patients with croup is well established but it remains uncertain which glucocorticoid regimen is most effective. Objective.— To determine the effectiveness of 3 glucocorticoid regimens in patients with croup. Design.— Randomized controlled trial with parallel design. Setting.— Emergency departments of 2 Canadian pediatric tertiary care hospitals. Participants.— Children with a clinical syndrome consistent with croup, aged 3 months to 5 years, with a croup score of 2 or greater following at least 15 minutes of mist therapy. Interventions.— Oral dexamethasone, 0.6 mg/kg, and nebulized placebo; oral

https://jamanetwork.com/journals/jama/articlepdf/187570/joc80358.pdf

Nebulized Budesonide and Oral Dexamethasone for Treatment of Croup: A Randomized Controlled Trial

Breath sounds were recorded in normal and asthmatic children over the chest and trachea. The power spectra of the sounds were analyzed for peaks of high amplitude and high frequency as indications of wheezing. The percent of inspiration and expiration spent wheezing was used as an indication of the severity of bronchial obstruction. Wheezing was found to be strongly dependent upon air flow, and generally followed the changes in pulmonary function as indicated by the forced expiratory volume at 1 s (FEV1). The trachea was found to be a better location for analyzing wheezes than the lung.

Automated Spectral Characterization of Wheezing in Asthmatic Children

A simple, non-invasive acoustical method is developed to detect respiratory phases in relationship to swallows without the direct measurement of airflow. In 21 healthy subjects (4-51 years) breath sounds are recorded at the trachea and at five different recording locations at the chest wall, with simultaneous recording of airflow by a pneumotachograph. The chest signal with the greatest inspiratory-expiratory power difference ('best location') is either in the mid-clavicular line in the second interspace on the left or third interspace on the right. Using the 'best location' on the chest wall and the tracheal signal, a phase detection algorithm is developed and achieves 100% accuracy in the estimation of respiratory phases without using the measured airflow signal. Thus, acoustically monitoring breaths and swallows holds promise as a non-invasive and reliable assessment tool in the study of swallowing dysfunction.

Hans Pasterkamp

Papers

Respiratory sounds : Advances beyond the stethoscope

Acoustic imaging of the human chest.

Nebulized Budesonide and Oral Dexamethasone for Treatment of Croup: A Randomized Controlled Trial

Automated Spectral Characterization of Wheezing in Asthmatic Children

Computerised acoustical respiratory phase detection without airflow measurement.