The National Emphysema Treatment Trial (NETT) Part II: Lessons learned about lung volume reduction surgery

Abstract

Substantial information regarding the role of lung volume reduction surgery (LVRS) in severe emphysema emanates from the National Emphysema Treatment Trial (NETT). The NETT was not a crossover trial and therefore was able to examine the effects of optimal medical management and LVRS on short- and long-term survival,as well as lung function, exercise performance, and quality of life.The NETT generated multiple insights into the preoperative, perioperative,and postoperative management of patients undergoing thoracotomy; described pain control techniques that were safe and effective; and emphasized the need to address nonpulmonary issues to optimize surgical outcomes. After the NETT, newer investigation has focused on bronchoscopic endobronchial interventions and other techniques less invasive than LVRS to achieve lung reduction.In this review, we summarize what we currently know about the role of LVRS in the treatment of severe emphysema as a result of insights gained from the NETT and provide a brief review of the newer techniques of lung volume reduction.

Figure 1.

Probability of death as a function of the number of months after randomization (Kaplan-Meier estimates). High-risk patients were defined as having an FEV₁ not greater than 20% predicted and either homogeneous emphysema or DL_CO (diffusing capacity for carbon monoxide) not exceeding 20% predicted. Low baseline exercise capacity was defined as a maximal workload at or below the sex-specific 40th percentile (25 W for women and 40 W for men); high exercise capacity was defined as a workload above this threshold. P values were derived by Fisher's exact test for e comparison between groups over a mean follow-up period of 29.2 months. (Reprinted by permission from Reference .)

Figure 2.

Kaplan-Meier estimates of the cumulative probability of death as a function of years postrandomization to lung volume reduction surgery (LVRS) (gray line) or medical therapy (black line) for (a) all patients and (b–d) non–high-risk and upper lobe–predominant subgroups of patients. The P value is from the Fisher's exact test for difference in the proportions of patients who died during the 4.3 years (median) of follow-up. Shown below each graph are the numbers of patients at risk, the Kaplan-Meier probabilities, the ratio of the probabilities (LVRS:Medical), and P value for the difference in these probabilities. This is an intention-to-treat analysis. (a) All patients (n = 1,218). (b) Non–high-risk patients (n = 1078). (c) Upper lobe–predominant and low baseline exercise capacity (n = 290). (d) Upper lobe–predominant and high exercise capacity (n = 419). RR = relative risk. Reprinted by permission from Reference .

Figure 3.

Improvement in exercise capacity (increase in maximal work > 10 W above the patient's postrehabilitation baseline) at 1, 2, and 3 years postrandomization to lung volume reduction surgery (LVRS) (open columns) or medical therapy (solid columns) for (a) all patients and (b–d) non–high-risk and upper lobe–predominant patient subgroups. Shown below each graph are the numbers of patients evaluated, the odds ratio for improvement (LVRS:Medical), and the Fisher's exact P value for difference in proportion improved. Patients who died or who did not complete the assessment were considered not improved. This is an intention-to-treat analysis. (a) All patients (n = 1,218). (b) Non–high-risk patients (n = 1,078). (c) Upper lobe–predominant and low baseline exercise capacity (n = 290). (d) Upper lobe–predominant and high exercise capacity (n = 419). Reprinted by permission from Reference .

Figure 4.

Improvement in health-related quality of life (decrease in St. George's Respiratory Questionnaire total score of >8 units below the patient's postrehabilitation baseline) at 1, 2, 3, 4, and 5 years after randomization to LVRS (open columns) or medical therapy (solid columns) for (a) all patients and (b–d) non–high-risk and upper lobe–predominant subgroups of patients. Shown below each graph are the numbers of patients evaluated, the odds ratio for improvement (LVRS:Medical), and the Fisher's exact P value for difference in proportion improved. Patients who died or who did not complete the assessment were considered not improved. This is an intention-to-treat analysis. (a) All patients (n = 1,218). (b) Non–high-risk patients (n = 1,078). (c) Upper lobe–predominant and low baseline exercise capacity (n = 290). (d) Upper lobe–predominant and high exercise capacity (n = 419). Reprinted by permission from Reference .

Figure 5.

Effect of heterogeneity on endobronchial valve (EBV) response at 6 months. Shown is the effect of heterogeneity on change in (A) FEV₁ and (B) 6-minute walk distance (6MWD) at 6 months after EBV implantation. Percent heterogeneity was the difference in quantitative emphysema score (the proportion of pixels less than −910 Hounsfield units) between EBV-treated and ipsilateral nontreated lobes. In (C), sagittal high-resolution chest computed tomography views with density mask views show low (6%, left) and high heterogeneity (25%, right). Darker areas represent pixels less than −910 Hounsfield units, consistent with emphysema. Reprinted by permission from Reference .