title: Pneumothorax effects on pulmonary acoustic transmission.
abstract: Pneumothorax (PTX) is an abnormal accumulation of air between the lung and the chest wall. It is a relatively common and potentially life-threatening condition encountered in patients who are critically ill or have experienced trauma. Auscultatory signs of PTX include decreased breath sounds during the physical examination. The objective of this exploratory study was to investigate the changes in sound transmission in the thorax due to PTX in humans. Nineteen human subjects who underwent video-assisted thoracic surgery, during which lung collapse is a normal part of the surgery, participated in the study. After subjects were intubated and mechanically ventilated, sounds were introduced into their airways via an endotracheal tube. Sounds were then measured over the chest surface before and after lung collapse. PTX caused small changes in acoustic transmission for frequencies below 400 Hz. A larger decrease in sound transmission was observed from 400 to 600 Hz, possibly due to the stronger acoustic transmission blocking of the pleural air. At frequencies above 1 kHz, the sound waves became weaker and so did their changes with PTX. The study elucidated some of the possible mechanisms of sound propagation changes with PTX. Sound transmission measurement was able to distinguish between baseline and PTX states in this small patient group. Future studies are needed to evaluate this technique in a wider population.
authors.affiliation: Department of Mechanical and Aerospace Engineering and Department of Pediatrics, University of Central Florida, Orlando, Florida; hansen.mansy@ucf.edu.
authors.forename: Hansen A
authors.initials: HA
authors.lastname: Mansy
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Rush Medical College, Chicago, Illinois;
authors.forename: Robert A
authors.initials: RA
authors.lastname: Balk
authors.affiliation: Department of Cardiovascular-Thoracic Surgery, Rush Medical College, Chicago, Illinois;
authors.forename: William H
authors.initials: WH
authors.lastname: Warren
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois; and.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Royston
authors.affiliation: Department of Mechanical Engineering, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Zoujun
authors.initials: Z
authors.lastname: Dai
authors.affiliation: Department of Mechanical Engineering, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Ying
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Department of Mechanical and Aerospace Engineering and Department of Pediatrics, University of Central Florida, Orlando, Florida;
authors.forename: Richard H
authors.initials: RH
authors.lastname: Sandler
mesh_terms: D065638:Absorption, Radiation; D001314:Auscultation / Q000379:methods*; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011030:Pneumothorax / Q000175:diagnosis* / Q000503:physiopathology*; D012135:Respiratory Sounds; D012542:Scattering, Radiation; D013016:Sound; D013018:Sound Spectrography
keywords: acoustic; pneumothorax; transmission