Lung volume reduction surgery: Preoperative functional predictors for postoperative outcome

Approximately 20% of patients undergoing lung volume reduction surgery (LVR S) exhibit no functional improvement postoperatively. Therefore, we examine d whether variables characterizing ventilatory mechanics before LVRS could serve as predictors for outcome. In 32 patients undergoing LVRS, lung funct ion, dyspnea score, and ventilatory mechanics were assessed preoperatively and 3 mo after LVRS. Ventilatory mechanics were characterized by total resi stive work of breathing (WOB), mean airway resistance (R-awm), and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn). Calculations of WOE , R-awm, and PEEPi,dyn were made from measurements of airflow, volume, and esophageal pressure. Preoperative PEEPi,dyn correlated well with the increa se 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. R-awm an d WOE showed inferior correlation compared with PEEPi,dyn. The examination of distinct threshold values for WOB, R-awm, 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 greater than or equal to 5 cm H2O. Preoperative PEEPi,dyn correlated well with improvement in forced expiratory volume and dyspnea scorn after LVRS. Thus, preoperative assessme nt of PEEPi,dyn could improve risk to benefit stratification before LVRS. I mplications: We examined the preoperative ventilatory mechanics of patients with emphysema undergoing lung volume reduction surgery with respect to th eir value in predicting outcome. Preoperative intrinsic positive end-expira tory pressure correlated well with the increase in forced expiratory volume in 1 s after surgery. Thus, this variable seems promising for improved pat ient selection.