Changes in breath sound power spectra during experimental oleic acid-induced lung injury in pigs.
To evaluate the effect of acute lung injury on the frequency spectra of breath sounds, we made serial acoustic recordings from nondependent, midlung and dependent regions of both lungs in ten 35- to 45-kg anesthetized, intubated, and mechanically ventilated pigs during development of acute lung injury induced with intravenous oleic acid in prone or supine position. Oleic acid injections rapidly produced severe derangements in the gas exchange and mechanical properties of the lung, with an average increase in venous admixture from 16 ± 12 to 62 ± 16% (P < 0.01), and a reduction in dynamic respiratory system compliance from 25 ± 4 to 14 ± 4 ml/cmH2O (P < 0.01). A concomitant increase in sound power was seen in all lung regions (P < 0.05), predominantly in frequencies 150-800 Hz. The deterioration in gas exchange and lung mechanics correlated best with concurrent spectral changes in the nondependent lung regions. Acute lung injury increases the power of breath sounds likely secondary to redistribution of ventilation from collapsed to aerated parts of the lung and improved sound transmission in dependent, consolidated areas.
Department of Anesthesiology, H. Lee Moffitt Cancer Center, Tampa, Florida;
Jukka
J
Räsänen
Michael E
ME
Nemergut
Noam
N
Gavriely
D055371:Acute Lung Injury / Q000139:chemically induced* / Q000503:physiopathology*; D000818:Animals; D008168:Lung / Q000502:physiology / Q000503:physiopathology; D019301:Oleic Acid / Q000009:adverse effects*; D016684:Prone Position / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology; D012135:Respiratory Sounds / Q000503:physiopathology*; D016683:Supine Position / Q000502:physiology; D013552:Swine
D019301:Oleic Acid
acoustics; acute lung injury; respiratory sounds