The Influence of Lung Volume Reduction Surgery on Ventilatory Mechanics in Patients Suffering from Severe Chronic Obstructive Pulmonary Disease

Recently, lung volume reduction ([LVR] removal of about 20% of lung volume), has been performed to treat severe emphysema.Little is known, however, about the mechanism and time course of functional improvement, and the reasons that such patients can be tracheally extubated very early. Therefore, we studied changes in ventilatory mechanics in 12 patients after LVR. Measurements of work of breathing (WOB), intrinsic positive end-expiratory pressure (PEEPi), dynamic compliance (Cdyn), and mean airway resistance (Rawm) were performed the day before surgery, early postoperatively, and 1 and 3 mo after surgery. All measurements were performed on tracheally extubated patients, simultaneously assessing esophageal pressure via esophageal balloon catheter and air flow via tightly adjusted mask. Standard spirometry was assessed preoperatively and 1 and 3 mo postoperatively. The patients presented with forced expiratory volume in 1 s (FEV1) of 670 +/- 50 mL and pathological values of WOB and PEEPi. All patients were successfully tracheally extubated within 5 h postoperatively. Immediately thereafter, a marked and sustained decrease in WOB, PEEPi, and Rawm was noted, as well as an increase in Cdyn. Ventilatory mechanics improved immediately after LVR, probably due to decompression of lung tissue, thereby enabling successful tracheal extubation.(Anesth Analg 1996;83:996-1001)