Detection of porcine oleic acid-induced acute lung  injury using pulmonary acoustics

Räsänen, Jukka; Gavriely, Noam

doi:10.1152/japplphysiol.01238.2001

Cited by 21 publications

(14 citation statements)

References 14 publications

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“…It is also in accord with the experimental evidence that the attenuation of sound introduced to the lung decreases when the lung is made edematous (4,13,15) and the well-known clinical observation that an increase in transmission of high-frequency sound occurs, giving rise to auscultatory signs such as "whispering pectriloquy" when the lung is consolidated in the presence of pneumonia (19). Furthermore, the strong frequency dependence of normalized attenuation indicates that the increase in attenuation with inflation at high frequencies is an intrinsic property of the lung tissue and not simply a manifestation of increased distance traveled by the sound waves.…”

Section: Discussionsupporting

confidence: 87%

“…A key aspect of our study design was to introduce sound directly to the lung surface, rather than via the airway, the route of entry for sound in most earlier studies using isolated lungs (8,17) or using intact animals (4,15) and humans (1,6,10). Although studies utilizing airway entry of sound report that lung inflation has an effect on the velocity of sound from its point of entry at the airway opening to the surface of the lung or chest wall, interpretation of results requires assumptions about the pathway that sound takes through the respiratory system (1,8).…”

Section: Critique Of Methodsmentioning

confidence: 99%

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Velocity and attenuation of sound in the isolated fetal lung as it is expanded with air

Berger¹,

Skuza²,

Ramsden³

et al. 2005

Journal of Applied Physiology

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. Velocity and attenuation of sound in the isolated fetal lung as it is expanded with air. J Appl Physiol 98: 2235-2241, 2005. First published February 3, 2005 doi:10.1152/japplphysiol.00683.2004We measured the velocity and attenuation of audible sound in the isolated lung of the near-term fetal sheep to test the hypothesis that the acoustic properties of the lung provide a measure of the volume of gas it contains. We introduced pseudorandom noise (bandwidth 70 Hz-7 kHz) to one side of the lung and recorded the noise transmitted to the surface immediately opposite, starting with the lung containing only fetal lung liquid and making measurements after stepwise inflation with air until a leak developed. The velocity of sound in the lung fell rapidly from 187 Ϯ 28.2 to 87 Ϯ 3.7 m/s as lung density fell from 0.93 Ϯ 0.01 to 0.75 Ϯ 0.01 g/ml (lung density ϭ lung weight/gas volume plus lung tissue volume). For technical reasons, no estimate of velocity could be made before the first air injection. Thereafter, as lung density fell to 0.35 Ϯ 0.01 g/ml, there was a further decline in velocity to 69.6 Ϯ 4.6 m/s. High-frequency sound was attenuated as lung density decreased from 1.0 to 0.5 g/ml, with little change thereafter down to a density of 0.35 Ϯ 0.01 g/ml. We conclude that both the velocity of audible sound through the lung and the degree to which high-frequency sound is attenuated in the lung provide information on the degree of inflation of the isolated fetal lung, particularly at high lung densities. If studies of sound transmission through the lung in the intact organism were to confirm these findings, the acoustic properties of the lung could provide a means for monitoring lung aeration during mechanical ventilation of newborn infants. fetal lamb; lung expansion; lung density; velocity of sound; sound attenuation IN A STUDY THAT HAS PROVEN highly influential, Rice (16) estimated the velocity of sound in the parenchyma of the excised horse lung by measuring the time it took for a sound impulse to travel between two points on the pleural surface of the lung. He reported that inflation of the lung with air causes the velocity of sound passing through the parenchyma to increase from ϳ30 m/s at a low gas volume to ϳ60 m/s with the lung maximally inflated. He further demonstrated that, when the lung was inflated with helium or sulfur hexafluoride, for which the free-field sound speeds are 970 and 140 m/s, respectively, there was little change in the measured velocity, from which he concluded that sound introduced at the pleural surface travels as longitudinal waves through the bulk of the parenchyma and not along the airways. His analysis indicated that average lung density and gas stiffness (compliance; approximately constant for diatomic gases) are the important

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Section: Discussionsupporting

confidence: 87%

Section: Critique Of Methodsmentioning

confidence: 99%

Velocity and attenuation of sound in the isolated fetal lung as it is expanded with air

Berger¹,

Skuza²,

Ramsden³

et al. 2005

Journal of Applied Physiology

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“…One possible option may be to compute the ratio between sound and flow. Alternatively, a different approach based on the injection of a known sound and recording of the sound transmitted to the chest wall [46,47] may be applied, but this method may be less practical in critical care.…”

Section: Discussionmentioning

confidence: 99%

Computerized Lung Acoustic Monitoring Can Help to Differentiate between Various Chest Radiographic Densities in Critically Ill Patients

Lev

Glickman²,

Kagan

et al. 2010

Respiration

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Background: Complementary bedside lung monitoring modalities are often sought in order to assist in the differentiation between several lung opacities in the intensive care unit (ICU). Objectives: To evaluate the use of computerized lung acoustic monitoring as a complementary approach in the differentiation between various chest radiographic densities in critically ill patients. Methods: Lung vibration intensity was assessed in 82 intensive care patients using vibration response imaging. Patients were classified according to their primary findings on chest radiography (CXR): consolidation (n = 35), congestion (n = 10), pleural effusion (n = 15), atelectasis/hypoinflation (n = 10) and normal findings (n = 12). Sixty patients were mechanically ventilated and 22 patients were spontaneously breathing. Results: Significantly elevated vibration intensity was detected in patients with consolidation, as opposed to pleural effusion, atelectasis and normal CXR (p < 0.01, Mann-Whitney U test). Vibration intensity was also increased for congestion, but this increase was not significant. The positive predictive value of CXR lung opacity in combination with increased vibration intensity to detect consolidations and/or congestions was 95% (20/21). Furthermore, vibration intensity was significantly higher in mechanically ventilated patients compared to spontaneously breathing patients (p = 0.001, Mann-Whitney U test). Differences related to gender, age and body position were not significant. Conclusions: Computerized lung acoustic monitoring at the bedside was found to be a useful, readily available, noninvasive, adjunctive tool in the differentiation between various CXR densities in critically ill patients.

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“…(23) One group of authors (24) measured the wet-to-dry weight ratio in pigs and observed that this ratio increased significantly in the group that received OA, compared with the control group, which suggests worsening of compliance. Using forced oscillation, the authors of another study (25) demonstrated an increase in airway opening pressure, although without stabilization for up to 140 min. The principal events responsible for the increase in compliance are the accumulation of liquid in the alveolar and interstitial space and the increase in surface tension.…”

Section: Resultsmentioning

confidence: 98%

Estabilidade do modelo animal de lesão pulmonar aguda induzida por ácido oleico

Gaio

Silva

Brito³

et al. 2009

J. bras. pneumol.

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Objective: To evaluate the stability of hemodynamic, respiratory and gas exchange variables in an animal model of oleic acid-induced acute lung injury. Methods: This was an experimental study involving 10 mongrel dogs. The variables were measured at baseline, as well as at 30, 60, 90 and 120 min after the administration of oleic acid. In order to analyze repeated measurements, linear and quadratic effects were tested. Mixed linear models with diversified variance and covariance structures were used, depending on the variable studied. Results: We found that mean arterial blood pressure stabilized at 30 min, as did heart rate, pulmonary arterial pressure and pulmonary capillary pressure at 60 min. Respiratory rate, tidal volume, minute volume and respiratory work stabilized at 30 min. Regarding gas exchange variables, PaO 2 , PaO 2 /FiO 2 ratio and pulmonary shunt fraction stabilized at 30 min. The remaining variables maintained a continuous rise or fall. Conclusions: This oleic acid-induced acute lung injury model is stable for some of the variables tested, although stabilization occurs at different times. The respiratory and gas exchange variables stabilized at 30 min, whereas the hemodynamic variables stabilized at 60 min. Keywords:Respiratory distress syndrome, adult; Models, animal; Statistical analysis. ResumoObjetivo: Avaliar a estabilidade das variáveis hemodinâmicas, da mecânica respiratória e de troca gasosa do modelo animal de lesão pulmonar aguda induzida por ácido oleico. Métodos: Trata-se de um estudo experimental no qual foram utilizados 10 cães de raça indeterminada. As variáveis foram aferidas inicialmente e em 30, 60, 90 e 120 min após a administração do ácido oleico. Para analisar as medidas repetidas, foram testados efeitos lineares e quadráticos e foram utilizados ajustes de modelos lineares mistos com estruturas de variâncias e covariâncias diversificadas, dependendo da variável analisada. Resultados: Observamos estabilidade da pressão arterial média aos 30 min, assim como da frequência cardíaca, da pressão arterial pulmonar e da pressão de capilar pulmonar aos 60 min. Frequência respiratória, volume corrente, volume minuto e trabalho respiratório estabilizaram aos 30 min. Quanto às variáveis de troca gasosa, PaO 2 , relação PaO 2 /FiO 2 e fração de shunt pulmonar estabilizaram-se aos 30 min. As demais variáveis mantiveram-se em ascensão ou queda contínuas. Conclusões: O modelo de lesão pulmonar aguda induzida por ácido oleico é estável para algumas das variáveis testadas; porém, a estabilização se dá em momentos diferentes. As variáveis da mecânica respiratória e de troca gasosa estabilizaram em 30 min, e as hemodinâmicas, em 60 min.Descritores: Síndrome do desconforto respiratório do adulto; Modelos animais; Análise estatística. *Study carried out in the

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Detection of porcine oleic acid-induced acute lung injury using pulmonary acoustics

Cited by 21 publications

References 14 publications

Velocity and attenuation of sound in the isolated fetal lung as it is expanded with air

Velocity and attenuation of sound in the isolated fetal lung as it is expanded with air

Computerized Lung Acoustic Monitoring Can Help to Differentiate between Various Chest Radiographic Densities in Critically Ill Patients

Estabilidade do modelo animal de lesão pulmonar aguda induzida por ácido oleico

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