Objective predictors of response for staple versus laser emphysematous lung reduction

Lung volume reduction surgery for emphysema: What the radiologist needs to know

Imaging plays a pivotal role in the selection of patients for the surgical treatment of emphysema. In this article, the imaging features of emphysema are reviewed along with the surgical options for treatment. Particular emphasis is given to lung volume reduction surgery as this technique has gained wide acceptance within the thoracic surgical community in recent years. Radiologists need to have an understanding of which patients may be potentially suitable for this technique.

Lung volume reduction surgery as a bridge to lung transplantation

Lung volume reduction surgery (LVRS) improves lung function, exercise capacity, and quality of life in patients with advanced emphysema. In some patients with emphysema who are candidates for lung transplantation, LVRS is an alternative treatment option to lung transplantation, or may be used as a bridge to lung transplantation. Generally accepted criteria for LVRS include severe non-reversible airflow obstruction due to emphysema associated with significant evidence of lung hyperinflation and air trapping. Both high resolution computed tomography (CT) scan of the chest and quantitative ventilation/perfusion scan are used to identify lung regions with severe emphysema which would be used as targets for lung resection. Bilateral LVRS is the preferred surgical approach compared with the unilateral procedure because of better functional outcome. Lung transplantation is the preferred surgical treatment in patients with emphysema with alpha1 antitrypsin deficiency and in patients with very severe disease who have homogeneous emphysema pattern on CT scan of the chest or very low diffusion capacity.

[Body mass, dyspnea, and quality of life as success predictors in emphysema surgery for reduction of pulmonary volume]

OBJECTIVES

Lung volume reduction surgery has recently been proposed as a palliative treatment for advanced emphysema. Some patients improve and others remains the same, being debated at this time the factors that predict improvement. The purpose of this work is to find predictive factors for positive response in patients operated with this surgery.

MATERIAL AND METHODS

Patients with positive response (7 patients) and patients without positive response (5 patients) have been compared in our series of lung volume reduction surgery (12 patients). Positive response to surgery was defined as Delta FEV1 > or = 15%, dyspnea transitional index (Mahler scale) > or = 3, and improvement in the scoring surgery of quality of life for chronic respiratory disease questionnaire (Guyatt and Güell) > or = 1.5 3 months after the surgery. Basal values of FEV1, FEF50/FIF50%, hyperinsufflation degree, heterogeneity, PaO2, PaCO2, type of surgery, body mass index (BMI), dyspnea basal index (DBI) and quality of life questionnaire score (QLQS).

RESULTS

Patients without and with positive response were different only because their baseline BMI, DBI and QLQS were lower. Other parameters studied (although the population was rather homogeneous) did not show significant differences between the two groups.

CONCLUSIONS

Patients with higher subjective problems (dyspnea and quality of life) and more malnourished are those with less benefit from surgery for pulmonary volume reduction.

Small airway morphometry and improvement in pulmonary function after lung volume reduction surgery

We examined small airway morphometry from resected lung specimens in 25 patients with severe emphysema undergoing lung volume reduction surgery (LVRS) and correlated their pathologic findings to changes in FEV(1) 6 months after LVRS. Patients were classified into two groups: responders had a more than 12% and a more than 200-ml change in FEV(1) at 6 months, and nonresponders had 12% or less and/or 200 ml or less change in FEV(1). Epithelial height (EH) and perimeters and areas of peribronchial smooth muscle, epithelium, and subepithelial space were measured quantitatively. The degrees of interstitial fibrosis, vascular sclerosis, goblet cell hyperplasia, squamous metaplasia, chronic inflammation, peribronchial fibrosis, and bullous disease were assessed semiquantitatively. Despite similar baseline characteristics, nonresponders had a greater EH (0.045 vs. 0.035 mm, p = 0.025), greater EH adjusted for basement membrane perimeter (0.040 vs. 0.011, p = 0.016), greater epithelial area adjusted for basement membrane area (0.561 vs. 0.499, p = 0.040), and less bullous disease (1.7 vs. 2.6, p = 0.011) compared with responders. We found a linear relationship between percentage change in FEV(1) and bullous disease and inverse relationships between percentage change in FEV(1) and interstitial fibrosis, goblet cell hyperplasia, peribronchial fibrosis, and vascular sclerosis. We conclude that small airway morphometry and lung histopathology in patients with severe emphysema have an important influence on changes in FEV(1) 6 months after LVRS.

Patient selection for lung volume reduction surgery

LVRS represents a valid surgical option for a limited number of patients who have symptomatic emphysema. The results of recent controlled studies have provided a realistic view of LVRS outcomes and yielded a validated algorithm for selection of optimal candidates for surgery. Furthermore, the NETT has provided simultaneously collected cost data that have provided a unique view of the costs and benefits of LVRS in patients who have advanced emphysema. Additional data collection will better define the long-term benefits of such surgical intervention in patients who have COPD.

Patient selection for lung volume reduction surgery: is outcome predictable?

Patient selection for lung volume reduction surgery (LVRS) relies on sound physiologic concepts and experience from large case series. LVRS should be considered in severely symptomatic emphysema with marked airflow obstruction and hyperinflation despite optimal medical management, and in the absence of major comorbidities associated with excessive perioperative risks. Qualitative estimation of functional benefit from LVRS in suitable candidates has been based on functional criteria (e.g., high inspiratory conductance, high residual volume/total lung capacity ratio), on heterogeneity of emphysema assessed by computed tomography (CT) or perfusion scans, and on severity of emphysema assessed by CT or impaired diffusing capacity. Selection strategies relying on such criteria have provided favorable functional results at a low mortality, but further validation of potential outcome predictors in prospective trials is needed.

Improvement in spirometry following lung volume reduction surgery: application of a physiologic model

According to a previously published theoretical model of emphysema, the ratio of RV to TLC (RV/TLC) reflects the size mismatch between the hyperinflated lungs in the disease and the surrounding chest. The model suggests that RV/TLC is an important predictor of improvement in FVC and that increased FVC is an important determinant of increased FEV(1) after lung volume reduction surgery (LVRS). We tested these predictions in 13 patients undergoing LVRS, in whom we made detailed measurements of lung mechanics. Using stepwise regression, we found that RV/TLC was the only preoperative independent predictor of the increase in FVC. Seventy percent of the increase in FEV(1) was attributable to increased FVC, with the remainder due to increased FEV(1)/FVC. In a separate group of 78 LVRS patients evaluated with standard preoperative pulmonary function tests, RV/TLC again was found to correlate with the increase in FVC, and changes in FEV(1) were also due largely to changes in FVC. However, RV/TLC was not predictive of the increase in FEV(1) among the group of 78 patients, because FEV(1)/FVC in patients with a low preoperative RV/TLC often increased despite little change in FVC. These findings support the proposed mechanism for increased FVC following LVRS. They also illustrate the limitations of the model, and suggest further hypotheses for selecting patients who may benefit from surgery.

Lung volume reduction surgery in emphysema: a systematic review

The aim of this study was to systematically review the literature regarding the safety and efficacy of lung volume reduction surgery (LVRS) in patients with emphysema. Studies on LVRS to August 2000 were identified using MEDLINE, Embase, Current Contents, and the Cochrane Library. Human studies of patients with upper, lower or diffuse distributions of emphysema were included. All types of bullous emphysema were excluded. A surgeon and researcher independently assessed the retrieved articles for their inclusion in the review. When LVRS was compared with medical management, at 2 years LVRS was associated with a higher FEV1 and at least equivalent survival. The use of staple excision of selected areas of lung appeared to be more efficacious than laser ablation. There is insufficient evidence to show preference for median sternotomy or videoscopically assisted thoracotomy, as the more safe and efficacious procedure. In highly selected patients with emphysema LVRS is deemed an acceptable treatment. To fully evaluate the safety and efficacy of LVRS, outcomes beyond 2 years must be included. The results of prospective randomized trials between medical management and LVRS, now in progress, are essential before a final assessment can be made.

Short-term and long-term outcomes after bilateral lung volume reduction surgery : prediction by quantitative CT

OBJECTIVES

To evaluate selection criteria and duration of benefit for patients undergoing lung volume reduction surgery (LVRS).

METHODS

Eighty-nine consecutive patients with severe emphysema who underwent bilateral LVRS were prospectively followed up for up to 3 years. Patients underwent preoperative pulmonary function testing, 6-min walk, chest CT, and answered a baseline dyspnea questionnaire. CT scans in 65 patients were analyzed for emphysema extent and distribution using the percentage of emphysema in the lung, percentage of normal lower lung, and the CT emphysema ratio (CTR, an index of the craniocaudal distribution of emphysema). All patients underwent at least 6 weeks of pulmonary rehabilitation prior to surgery. Outcome measures were FEV(1), 6-min walk distance, and transitional dyspnea index (TDI).

RESULTS

Compared to baseline, FEV(1) was significantly increased at 3, 6, 12, 18, 24, and 36 months after surgery (p < or = 0.008). The 6-min walk distance increased from 871 feet (baseline) to 1,110 feet (3 months), 1,214 feet (6 months), 1,326 feet (12 months), 1,342 feet (18 months), 1,371 feet (24 months), and 1,390 feet (36 months) after surgery. Despite a decline in FEV(1) over time, 6-min walk distance was preserved. Dyspnea as measured by TDI improved at 3, 6, 12, 18, 24, and 36 months after surgery. A high CTR was the best predictor of a 12% increase over baseline and an absolute increase of 200 mL in FEV(1), although with a low area under the receiver operating characteristic curve. In addition, the sensitivity and negative predictive value of the CTR were limited. No radiographic or physiologic predictor was able to consistently predict a successful increase in walk distance or TDI.

CONCLUSION

LVRS improves pulmonary function, decreases dyspnea, and enhances exercise capacity in many patients with severe emphysema, although improvement wanes 36 months after surgery.

Lung volume reduction surgery for emphysema

Over the past decades, extensive literature has been published regarding surgical therapies for advanced COPD. Lung-volume reduction surgery would be an option for a significantly larger number of patients than classic bullectomy or lung transplantation. Unfortunately, the initial enthusiasm has been tempered by major questions regarding the optimal surgical approach, safety, firm selection criteria, and confirmation of long-term benefits. In fact, the long-term follow-up reported in patients undergoing classical bullectomy should serve to caution against unbridled enthusiasm for the indiscriminate application of LVRS. Those with the worst long-term outcome despite favourable short-term improvements after bullectomy have consistently been those with the lowest pulmonary function and significant emphysema in the remaining lung who appear remarkably similar to those being evaluated for LVRS. With this in mind, the National Heart, Lung and Blood Institute partnered with the Health Care Finance Administration to establish a multicenter, prospective, randomized study of intensive medical management, including pulmonary rehabilitation versus the same plus bilateral (by MS or VATS), known as the National Emphysema Treatment Trial. The primary objectives are to determine whether LVRS improves survival and exercise capacity. The secondary objectives will examine effects on pulmonary function and HRQL, compare surgical techniques, examine selection criteria for optimal response, identify criteria to determine those who are at prohibitive surgical risk, and examine long-term cost effectiveness. It is hoped that data collected from this novel, multicenter collaboration will place the role of LVRS in a clearer perspective for the physician caring for patients with advanced emphysema.

Patient selection for lung volume reduction surgery: An objective model based on prior clinical decisions and quantitative CT analysis

OBJECTIVES

We used whole-lung quantitative CT analysis (QCT)-an objective method of evaluating emphysema severity and distribution based on measurement of lung density-to determine whether subjective selection criteria for lung volume reduction surgery are applied consistently and to model the patient selection process, and assessed the relationship of the model to postoperative outcome.

DESIGN

Logistic regression analysis using QCT indexes of emphysema and preoperative physiologic test results as the independent variables, and the decision to operate as the dependent variable.

SETTING

University hospital.

PATIENTS

Seventy patients selected for bilateral lung volume reduction surgery and 32 otherwise operable patients excluded from surgery based on subjective assessment of emphysema morphology on chest radiography, CT, and perfusion scintigraphy.

INTERVENTION

Bilateral lung volume reduction surgery in the selected group.

MEASUREMENTS AND RESULTS

Emphysema in patients selected for surgery was more severe overall and in the upper lungs by multiple QCT indexes (p < 0.01, unpaired two-tailed t test). Physiologic abnormalities were slightly more severe in selected patients (p < 0.05, unpaired two-tailed t test). The range of many QCT and physiologic values overlapped considerably between the selected and excluded groups. The percent severe emphysema (<- 960 Hounsfield units [HU]), upper/lower lung emphysema ratio (- 900 HU threshold), and residual volume were the key variables in the model predicting selection decisions (model r(2) = 0.48; p < 0.0001). The model correctly predicted selection decisions in 87% of all cases, 91% of the selected group, and 78% of the excluded group. Surgical patients with a higher model-derived probability of selection had greater postoperative improvement in FEV(1) and 6-min walk distance.

CONCLUSIONS

Radiologic selection criteria are applied consistently to the majority of patients. QCT features are strongly associated with selection decisions, are related to outcome, and may help improve consistency and confidence in patient selection.

Survival after unilateral versus bilateral lung volume reduction surgery for emphysema

OBJECTIVE

Bilateral staple lung volume reduction surgery (LVRS) immediately improves pulmonary function and dyspnea symptoms in patients with advanced heterogeneous emphysema to a greater degree than do unilateral procedures. However, the long-term outcome after these surgical procedures needs to be critically evaluated. We compare 2-year survival of patients who underwent unilateral versus bilateral video-assisted LVRS in a large cohort treated by a single surgical group.

METHODS

The cases of all 260 patients who underwent video-assisted thoracoscopic stapled LVRS from April 1994 to March 1996 were analyzed to compare results after unilateral versus bilateral procedures. Overall survival was calculated by Kaplan-Meier methods; Cox proportional hazard methods were used to adjust for patient heterogeneity and baseline differences between groups.

RESULTS

Overall survival at 2 years was 86.4% (95% CI 80. 9%-91.8%) after bilateral LVRS versus 72.6% (95% CI 64.2%-81.2%) after unilateral LVRS (P =.001 for overall survival comparison). Improved survival after bilateral LVRS was seen among high- and low-risk subgroups as well. Average follow-up time was 28.5 months (range, 6 days to 46.6 months) for the bilateral LVRS group and 29.3 months (range, 6 days to 45.0 months) for the unilateral LVRS patients.

CONCLUSIONS

Comparison of unilateral versus bilateral thoracoscopic LVRS procedures for the treatment of emphysema reveals that bilateral LVRS by video-assisted thoracoscopy resulted in better overall survival at 2-year follow-up than did unilateral LVRS. This survival study, together with other studies demonstrating improved lung function after bilateral LVRS, suggests that bilateral surgery appears to be the procedure of choice for patients undergoing LVRS for most eligible patients with severe heterogeneous emphysema.

Radiologic evaluation of emphysema for lung volume reduction surgery

Lung volume reduction surgery has created an opportunity for the advanced imaging of emphysema. Patients with CT or perfusion scintigraphy demonstrating an upper- or lower-lobe-predominant pattern of emphysema have better patient outcomes after LVRS than patients with emphysema diffusely or homogeneously distributed throughout the lungs. Some patients with diffuse or homogeneous emphysema may demonstrate improvement in function or dyspnea after surgery, but the magnitude of the improvement seen is less than in patients with heterogeneous emphysema, and the duration of benefit is not known. An ongoing, multicenter National Heart, Lung, and Blood Institute (NHLBI)/Health Care Financing Association (HCFA) sponsored trial of LVRS aims to determine whether LVRS together with maximal medical therapy and pulmonary rehabilitation improves patient outcomes compared with maximal medical therapy and pulmonary rehabilitation alone. This study will address the duration of clinical benefit and the cost-effectiveness of LVRS.

Surgical treatment of chronic obstructive pulmonary disease

Over the past several decades, a number of surgical techniques have been developed for the treatment of chronic obstructive pulmonary disease. Many of these procedures have been abandoned because of lack of efficacy and/or high morbidity and mortality. At the present time, lung transplantation, reduction pneumoplasty for giant bullous emphysema, and lung volume reduction surgery are being performed in a number of centers. Data concerning the effectiveness of these procedures is accumulating and will ultimately need careful analysis to determine long-term outcomes in this group of patients.

Survival following bilateral staple lung volume reduction surgery for emphysema

STUDY OBJECTIVES

Despite numerous reports of short-term response to lung volume reduction surgery (LVRS) for treatment of emphysema, to our knowledge, longer-term survival has not been reported. We describe survival following LVRS in a large cohort of 256 patients treated with bilateral staple LVRS (n = 236 video-assisted thoracic surgery [VATS] approaches, n = 20 median sternotomy) by a single group of physicians over a 3 1/2-year period from April 1994 to November 1997.

DESIGN

Prospective survival study. Overall survival, survival stratified by preoperative presentation, and acute postoperative response were investigated using Kaplan-Meier methods. The simultaneous effects of preoperative predictors and postoperative response variables on survival were examined using a Cox proportional hazards model.

SETTING

Community hospital and university medical center.

PATIENTS

We studied 256 consecutive patients with severe emphysema treated with LVRS.

INTERVENTIONS

Bilateral staple LVRS by VATS.

MEASUREMENTS AND RESULTS

Overall survival information was known with certainty for 246 of 256 patients as of February 1, 1998. Median follow-up time was 623 days (range, 0 to 1,545 days). Mean FEV1 was 0.635L+/-0.015 L preoperatively and rose to 1.068L+/-0.029 L postoperatively. By standard analysis methods (missing patients censored at the time of last contact), 1-year survival was 85+/-2.3% compared with 83+/-2.4% 1-year survival with "worst case" analytic methods (assuming all missing patients died). Two-year survival averaged 81+/-2.7% by standard analysis vs 76+/-2.9% by worst case evaluation. Survival was significantly better for patients who were younger (< or = 70 years old, p = 0.02) and with higher baseline FEV1 (> 0.5, p < 0.03) and PO2 (> 54, p < 0.001). Patients who had greatest short-term improvement in FEV1 following surgery (> 0.56 L increase) also had significantly better longer-term survival following LVRS.

CONCLUSIONS

To our knowledge, this is the first longer-term survival analysis of a large series of patients who underwent bilateral staple LVRS for emphysema. Substantial long-term mortality is seen, particularly within identifiable high-risk subgroups. Careful comparison to comparably matched control patients will be needed to definitively assess the benefits and risks of LVRS. This study suggests that prospective, controlled trials may need to stratify patient randomization based on preoperative risk factors to obtain meaningful results.

Role of lung perfusion scintigraphy in relation to chest computed tomography and pulmonary function in the evaluation of candidates for lung volume reduction surgery

Lung perfusion scintigraphy is employed to evaluate patients with severe emphysema who are candidates for lung volume reduction surgery (LVRS). Our purpose was to investigate the role of scintigraphy in relation to chest computed tomography (CT) and lung function in this setting. Six observers blinded to clinical data retrospectively scored preoperative scintigrams of 70 patients undergoing bilateral video-assisted LVRS according to the distribution of lung perfusion as homogeneous, intermediately heterogeneous, or markedly heterogeneous. Heterogeneity of emphysema distribution was also assessed by chest CT. Dyspnea and pulmonary function were measured preoperatively and 3 mo postoperatively. In 42 patients with markedly heterogeneous, in 18 with intermediately heterogeneous, and in 10 with homogeneous perfusion, mean (+/- SE) FEV1 increased by 57 +/- 8% (p < 0.0001), 38 +/- 9% (p < 0.001), and 23 +/- 9% (p = NS) (p = NS for intergroup comparisons). In a multiple regression analysis, functional improvement after LVRS was more closely correlated with preoperative hyperinflation and the degree of emphysema heterogeneity estimated by chest CT than with the degree of perfusion heterogeneity assessed by scintigraphy. In 16 of 22 patients with homogeneous emphysema distribution in the chest CT scintigraphy revealed intermediately or markedly heterogeneous perfusion. We conclude that lung perfusion scintigraphy has a limited role in prediction of outcome, but it may help to identify target areas for resection in LVRS candidates with homogeneous CT morphology.

Lung volume reduction surgery for emphysema: out on a limb without a NETT

Lung volume reduction surgery (LVRS) has recently been rediscovered and offers the potential of improving the quality of life of patients with advanced emphysema. In this article, we discuss the historical and contemporary versions of LVRS. Although initial enthusiasm has been substantial, existing data seem insufficient to demonstrate the safety and efficacy of the procedure in comparison with conventional medical therapy. Fundamental questions remain regarding the long-term effects of an operation versus medical therapy, the optimal selection criteria, the best measures of efficacy, the mechanisms of improvement, the cost-effectiveness of the procedure, and the optimal surgical technique. Until such questions are answered, advising patients about the best management their emphysema will be difficult. The National Emphysema Treatment Trial will address many of these issues and should be embraced by both health-care providers and patients.

Serial lung function and elastic recoil 2 years after lung volume reduction surgery for emphysema

STUDY OBJECTIVE

To evaluate serial lung function studies, including elastic recoil, in patients with severe emphysema who undergo lung volume reduction surgery (LVRS). To determine mechanism(s) responsible for changes in airflow limitation.

METHODS

We studied 12 (10 male) patients aged 68+/-9 years (mean+/-SD) 6 to 12 months prior to and at 6-month intervals for 2 years after thoracoscopic bilateral LVRS for emphysema.

RESULTS

At 2 years post-LVRS, relief of dyspnea remained improved in 10 of 12 patients, and partial or full-time oxygen dependency was eliminated in 2 of 7 patients. There was significant reduction in total lung capacity (TLC) compared with pre-LVRS baseline, 7.8+/-0.6 L (mean+/-SEM) (133+/-5% predicted) vs 8.6+/-0.6 L (144+/-5% predicted) (p=0.003); functional residual capacity, 5.6+/-0.5 L (157+/-9% predicted) vs 6.7+/-0.5 L (185+/-10% predicted) (p=0.001); and residual volume, 4.9+/-0.5 L (210+/-16% predicted) vs 6.0+/-0.5 L (260+/-13% predicted) (p=0.000). Increases were noted in FEV1, 0.88+/-0.08 L (37+/-6% predicted) vs 0.72+/-0.05 L (29+/-3% predicted) (p=0.02); diffusing capacity, 8.5+/-1.0 mL/min/mm Hg (43+/-3% predicted) vs 4.2+/-0.7 mL/min/mm Hg (18+/-3% predicted) (p=0.001); static lung elastic recoil pressure at TLC (Pstat), 13.7+/-0.5 cm H2O vs 11.3+/-0.6 cm H2O (p=0.008); and maximum oxygen consumption, 8.7+/-0.8 mL/min/kg vs 6.9+/-1.5 mL/min/kg (p=0.03). Increase in FEV1 correlated with the increase in TLC Pstat/TLC (r=0.75, p=0.03), but not with any baseline parameter.

CONCLUSION

Two years post-LVRS, there is variable clinical and physiologic improvement that does not correlate with any baseline parameter. Increased lung elastic recoil appears to be the primary mechanism for improved airflow limitation.

Lung volume reduction surgery and airflow limitation

Interest has recently been renewed in lung volume reduction surgery (LVRS) for end-stage emphysema. However, numerous questions about its role in the treatment of emphysema remain, including the clinical characteristics of optimal candidates and its mechanism of improvement in pulmonary function. In this report, we develop a mathematical analysis and graphic depiction of the mechanism of improvement in expiratory airflow and vital capacity. This analysis is based on consideration of the interaction between lung function and respiratory muscle function. We also reexamine previously published pulmonary mechanics in patients with alpha1-antitrypsin deficiency, chronic obstructive pulmonary disease, and asthma. We find a major determinant of airflow limitation common to these diseases is the ratio of residual volume to total lung capacity (RV/TLC). Moreover, RV/TLC is found to be the single most important determinant of the improvement in pulmonary function after LVRS. Regardless of the specific underlying lung disease, the impairment of airflow is due primarily to mismatch between the sizes of the lung and the chest wall, and the effects of LVRS are almost exclusively due to improvement of that match. This analysis can be used to develop testable hypotheses to guide patient selection for this procedure.

Bovine pericardium versus bovine collagen to buttress staples for lung reduction operations

BACKGROUND

Air leaks after stapled lung volume reduction operations for emphysema remain the most common postoperative complication. Cooper developed the use of bovine pericardium buttress for the staple lines in an attempt to decrease the occurrence of prolonged postoperative air leaks. However, the materials cost for a bilateral procedure may add $3,000 to $4,000 to the cost of the operation. We undertook this study to evaluate the efficacy of a less expensive buttress.

METHODS

Fifty-seven patients underwent a bilateral thoracoscopic stapled operation with bovine pericardium (Peri-Strips) on one side and bovine collagen (INSTAT) on the contralateral side to buttress the staples.

RESULTS

The average time to chest tube removal was 8.6 +/- 7.2 days for Peri-Strips and 10.7 +/- 8.7 days for INSTAT (p = 0.16). No significant differences were seen when right-sided and left-sided application were considered separately (p = 0.12).

CONCLUSIONS

Peri-Strips or INSTAT for buttressing staple lines in thoracoscopic stapled bilateral lung volume reduction operations were equally effective. Materials cost savings of up to 80% per case can be realized by using the less expensive but equally effective INSTAT for buttressing staple lines.