Respiratory mechanics and surfactant in the acute respiratory distress syndrome.
Clin Exp Pharmacol Physiol
; 25(11): 955-63, 1998 Nov.
Article
em En
| MEDLINE
| ID: mdl-9807672
ABSTRACT
1. Although abnormalities in pulmonary surfactant were initially implicated in the pathogenesis of the acute respiratory distress syndrome (ARDS) 30 years ago, most subsequent research has focused on mediators of the parenchymal acute lung injury (ALI) and the associated increase in alveolocapillary permeability. 2. Surfactant is essential for normal breathing and the severity of ALI correlates with surfactant dysfunction and abnormalities in surfactant composition; however, no relationship has been shown with respiratory system compliance. In neonates and most animal models, respiratory system compliance will directly reflect the elastic properties of the lung. However, the greater vertical height of the chest wall in adults, in combination with the increase in lung density due to ALI, results in dependent collapse of alveoli. Because simple, global measurement of compliance is strongly influenced by the volume of aerated lung, alternative measures of respiratory mechanics may reflect surfactant dysfunction. 3. Using a dynamic, volume-dependent model of respiratory mechanics to indirectly reflect this heterogeneous inflation, we have found direct relationships with surfactant composition in patients with ARDS. A failure of surfactant to increase surface tension in large alveoli may also explain why lung overdistension occurs at relatively low pressures. Furthermore, surfactant dysfunction will exaggerate heterogeneous lung inflation, augmenting regional overinflation, and is essential for ALI secondary to repetitive opening and closing of alveoli during tidal ventilation. 4. Ventilation-induced ALI has also been shown to result in massive increases in pro-inflammatory cytokines within the lung. Because ALI itself fails to compartmentalize cytokines, with spillover into the systemic circulation resulting in distant organ dysfunction, surfactant dysfunction may have widespread implications.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Síndrome do Desconforto Respiratório
/
Surfactantes Pulmonares
/
Mecânica Respiratória
Limite:
Adult
/
Animals
/
Humans
Idioma:
En
Revista:
Clin Exp Pharmacol Physiol
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Austrália