Esophageal pressure as an estimate of average pleural pressure with lung or chest distortion in rats

Abstract: Pressure–volume curves of the lungs and chest wall require knowledge of an effective ‘average’ pleural pressure (Pplav), and are usually estimated using esophageal pressure as Pl es–V and Pwes–V curves. Such estimates could be misleading when Ppl becomes spatially non-uniform with lung lavage or shape distortion of the chest. We therefore measured Pl es–V and Pwes–V curves in conditions causing spatial non-uniformity of Ppl in rats. Pl es–V curves of normal lungs were unchanged by chest removal. Lung lavage depressed PLes–V but not Pwes–V curves to lower volumes, and chest removal after lavage increased volumes at PL≥15cmH2O by relieving distortion of the mechanically heterogeneous lungs. Chest wall distortion by ribcage compression or abdominal distension depressed Pwes–V curves and Pl es–V curves of normal lungs only at Pl ≥3cmH2O. In conclusion, Pes reflects Pplav with normal and mechanically heterogeneous lungs. With chest wall distortion and dependent deformation of the normal lung, changes of Pl es–V curves are qualitatively consistent with greater work of inflation. [Copyright &y& Elsevier]