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Doctoral Thesis
DOI
10.11606/T.5.2009.tde-25062009-113611
Document
Author
Full name
Shari Anne Ahmed El Dash
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Velasco, Irineu Tadeu (President)
Amato, Marcelo Britto Passos
Carvalho, Carlos Roberto Ribeiro de
Negri, Elnara Márcia
Okamoto, Valdelis Novis
Title in Portuguese
Estudo tomográfico de pressões de colapso alveolar e níveis isogravitacionais em pulmões de pacientes com SDRA e LPA
Keywords in Portuguese
Colapso pulmonar
Isogravitacionalidade
Mecânica pulmonar
Respiração artificial
Respiração com pressão positiva
Síndrome do desconforto respiratório do adulto
Tomografia computadorizada por raios X
Abstract in Portuguese
Estudo clínico prospectivo, em 11 pacientes com SARA ou LPA, avaliando o comportamento regional da densidade do tecido pulmonar e do colapso alveolar ao longo dos três eixos do espaço. Foram realizadas tomografias seriadas, após manobra de recrutamento inicial e após níveis de PEEP progressivamente decrescentes. Regressão linear múltipla (R2=0.83) mostrou importante gradiente no eixo gravitacional (p<0.001) e não no sentido céfalo-caudal (p<0.001), nem da direita para a esquerda (p<0.05). Isto corrobora o conceito do pulmão líquido, em que a resultante das pressões exercidas pelo diafragma, estruturas mediastinais e derrames seria transmitida uniformemente pelo tecido pulmonar. Cada um destes níveis isogravitacionais tem uma pressão crítica de fechamento (Pclosing), que é maior do que a pressão superimposta calculada. PEEP tem um efeito homogeneizador sobre o parênquima pulmonar. Dentre os parâmetros clínicos estudados, Pflex mostrou a pior correlação com colapso pulmonar documentado enquanto PO2 e a complacência máxima se mostraram equivalentes.
Title in English
Tomographic study of alveolar collapsing pressures and isogravitational levels and in the lungs of patients with ARDS and/or ALI
Keywords in English
Adult respiratory distress syndrome
Computerized tomography
Isogravitacionality
Lung collapse
Lung mechanics
Mechanical respiration
Positive pressure breathing
Abstract in English
A prospective clinical study performed on 11 patients with ARDS or ALI with the intention of studying the regional behavior of lung tissue density and alveolar collapse along the three spatial axes. An initial recruitment maneuver was followed by multiple semi-complete CT scans at descending levels of PEEP. Multiple linear regression (R2=0.83) showed a gravitational gradient of densities and collapse (p<0.001) and no cephalo-caudal (p<0.001) or right-toleft increase (p<0.05), corroborating the liquid-like behavior of the lung. Pressure exerted by mediastinal structures, chest wall and effusions is transmitted uniformly throughout the lung. PEEP has a homogenizing effect on lung parenchyma. Among commonly used clinical surrogates, Pflex showed the worst correlation with actual lung collapse, while arterial PO2 and compliance were equivalent.
 
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ShariAElDash.pdf (1.15 Mbytes)
Publishing Date
2009-06-29
 
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