Pulmonary air trapping during two-lung and one-lung ventilation

Objective: Evaluation of the magnitude of pulmonary air trapping during rou tine thoracic surgery and single-lung transplantation. Design: Prospective study on consecutive patients. Setting: Single institution, university hospital. Participants: Sixteen patients with no or moderate obstructive lung disease undergoing routine thoracic surgery (group 1), six patients with severe em physema (group 2), and six patients with severe fibrosis (group 3) undergoi ng single-lung transplantation. Interventions: Occlusion maneuver timed at the end of expiration to measure auto-positive end-expiratory pressure (auto-PEEP) and trapped volume (Delt a FRC). The maneuver was performed during two-lung ventilation in supine (2 LV supine) and lateral decubitus (2LV lateral) positions and during one-lun g ventilation (OLV) in lateral decubitus position. At the same time, airway pressures and PaO2 measurements were performed. Measurements and Main Results: In group 1, consistent values of auto-PEEP a nd Delta FRC occurred only during OLV: 4.8 +/- 2.5 cm H2O and 109 +/- 61 mt (mean+/- standard deviation). In group 2, auto-PEEP and Delta FRC values w ere 11.7 +/- 6.9 cm H2O and 355 +/- 125 mt during 2LV supine, 8.8 +/- 5.7 c m H2O and 320 +/- 122 mt during 2LV lateral, and 15.9 +/- 3.9 cm H2O and 28 4 +/- 45 mt during OLV. In group 3, pulmonary air trapping was low. For the three groups together, auto-PEEP and Delta FRC (p < 0.0001) related invers ely to the ratio of forced expired volume in 1 second (FEV1) to forced vita l capacity (FVC) expressed in percent (FEV1/FVC%) during OLV, In contrast, there was no correlation between PaO2 and auto-PEEP or Delta FRC. Conclusion: Pulmonary air trapping must be suspected in patients with no or moderate obstructive lung disease during OLV and in those with severe obst ructive disease as soon as 2LV is initiated. Copyright (C) 1999 by W.B. Sau nders Company.