Lung volume reduction surgery: preoperative functional predictors for postoperative outcome

Abstract

Approximately 20% of patients undergoing lung volume reduction surgery (LVRS) exhibit no functional improvement postoperatively. Therefore, we examined whether variables characterizing ventilatory mechanics before LVRS could serve as predictors for outcome. In 32 patients undergoing LVRS, lung function, dyspnea score, and ventilatory mechanics were assessed preoperatively and 3 mo after LVRS. Ventilatory mechanics were characterized by total resistive work of breathing (WOB), mean airway resistance (Rawm), and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn). Calculations of WOB, Rawm, and PEEPi,dyn were made from measurements of airflow, volume, and esophageal pressure. Preoperative PEEPi,dyn correlated well with the increase in forced expiratory volume percent predicted (r = 0.75; P < 0.0001) and the decrease in dyspnea score (r = -0.74; P < 0.0001) after LVRS. Rawm and WOB showed inferior correlation compared with PEEPi,dyn. The examination of distinct threshold values for WOB, Rawm, and PEEPi,dyn with respect to predicting improvement resulted in a sensitivity of 93% and specificity of 88% for a cutoff point of preoperative PEEPi,dyn > or =5 cm H2O. Preoperative PEEPi,dyn correlated well with improvement in forced expiratory volume and dyspnea score after LVRS. Thus, preoperative assessment of PEEPi,dyn could improve risk to benefit stratification before LVRS.

Implications: We examined the preoperative ventilatory mechanics of patients with emphysema undergoing lung volume reduction surgery with respect to their value in predicting outcome. Preoperative intrinsic positive end-expiratory pressure correlated well with the increase in forced expiratory volume in 1 s after surgery. Thus, this variable seems promising for improved patient selection.