ACUTE EFFECTS OF BILATERAL LUNG-VOLUME REDUCTION SURGERY ON LUNG AND CHEST-WALL MECHANICAL-PROPERTIES

Study objectives: To characterize acute changes in the dynamic, passiv e mechanical propel-ties of the lungs and chest wall, elastance (E) an d resistance (R), caused by lung volume reduction surgery (LVRS). Desi gn: Prospective data collection. Patients: Nine anesthetized/paralyzed patients with severe emphysema, Interventions: Bilateral LVRS. Measur ements and results: From measurements of airway and esophageal. pressu res and flow during mechanical ventilation throughout the physiologic range of breathing frequency (f) and tidal volume (VT), E and R of the total respiratory system (Ers and Rrs), lungs (EL and RL), and chest wall (Ecw and Rcw) immediately before and after LVRS were calculated. After surgery, Ers, EL, Rrs, and RL were all greatly increased at each combination off and VT (p<0.05). Ecw and Rcw showed no consistent cha nges (p>0.05),The increases in EL were greatest in those patients with the lowest residual volumes, highest FEV, values, and highest maximum voluntary ventilations measured 3 months preoperatively (p<0,05); the increases in RL were greatest in those patients with the lowest preop erative residual volumes (p<0,05). The largest increases in RL mere in those patients with the largest decreases in residual volume and tota l lung capacity, measured 3 months postoperatively, caused by LVRS (p< 0.05). Conclusion: Acute effects of LVRS are large increases in lung e lastic tension and resistance; these increases need to be considered i n immediate postoperative care, and can be predicted roughly from resu lts of preoperative pulmonary function tests.