Static pressure-volume curves and effect of positive end-expiratory pressure on gas exchange in adult respiratory distress syndrome

• Published in: Critical care medicine Vol. 11; no. 8; p. 591
• Main Authors: Holzapfel, L, Robert, D, Perrin, F, Blanc, P L, Palmier, B, Guerin, C
• Format: Journal Article
• Language: English
• Published: United States 01.08.1983
• Subjects: Adolescent; Adult; Aged; Carbon Dioxide - blood; Child; Female; Functional Residual Capacity; Humans; Hydrogen-Ion Concentration; Intermittent Positive-Pressure Ventilation; Male; Middle Aged; Oxygen - blood; Positive-Pressure Respiration; Pressure; Pulmonary Edema - physiopathology; Pulmonary Fibrosis - physiopathology; Pulmonary Gas Exchange; Respiratory Distress Syndrome, Adult - physiopathology; Respiratory Distress Syndrome, Adult - therapy
• ISSN: 0090-3493
• DOI: 10.1097/00003246-198308000-00002

Fifteen patients with adult respiratory distress syndrome (ARDS) were studied: 11 in the early stage of ARDS (group 1); 4 in the late stage (group 2). The inspiratory and expiratory static pressure-volume (P-V) curves of the respiratory system were compared to the pulmonary shunt (Qsp/Qt) when PEEP was increased; cardiac output was kept constant. In group 1 patients, we found that a concavity on the P-V curves was associated with an abrupt decrease in Qsp/Qt when PEEP was increased; the concavity on the expiratory curve was correlated with the change in Qsp/Qt but not the concavity on the inspiratory curve. In group 2 patients, the P-V curves were found rectilinear and Qsp/Qt was not abruptly decreased when PEEP was increased. Expiratory P-V curve can be used to determine: first, whether a patient should be ventilated with PEEP; second, the PEEP level which can be set on the respirator. In group 1 patients, when PEEP was set to a value corresponding to the inflexion point, i.e., the point of departure from the exponential shape (mean value 14.6 +/- 2.8 cm H2O), Qsp/Qt compared to zero PEEP was abruptly decreased to 87.6 +/- 6%; further increase in PEEP had little advantage.