Buttressing the Staple Line in Lung Volume Reduction Surgery: A Randomized Three-Center Study

Buttressing the Staple Line in Lung Volume Reduction Surgery: A Randomized Three-Center Study Uz Stammberger, MD, Walter Klepetko, MD, Georgios Stamatis, MD, Jürg Hamacher, MD, Ralph A. Schmid, MD, Wilfried Wisser, MD, Ludger Hillerjan, MD, and Walter Weder, MD Division of Thoracic Surgery and Pulmonary Division, University Hospital, Zürich, Switzerland, Division of Cardio-thoracic Surgery, University Hospital, Vienna, Austria, and Division of Thoracic Surgery, Ruhrlandklinik, Essen, Germany Background. The intention of buttressing the staple line in lung volume reduction surgery is to reduce air leaks and to shorten the hospital stay. A randomized three-center study was carried out to test this hypothesis. Methods. Sixty-five patients with a mean age of 59.2 1.2 years underwent bilateral lung volume reduction surgery by video-assisted thoracoscopy using endoscopic staplers (ET 45B; Ethicon Endo-Surgery, Cincinnati, OH) either without or with bovine pericardium for buttressing (Peri-Strips Dry; Bio-Vascular, Inc, Saint Paul, MN). There were no differences between the control and treatment groups in lung function, degree of dyspnea, and arterial blood gases before and 3 months after LVRS. Results. Seven patients (3 in the treatment group) needed a reoperation because of persistent air leak. The median duration of air leaks was shorter in the treatment group (0.0 day [range, 0 to 28 days versus 4 days [range, 0 to 27 days); p < 0.001), confirmed by a shorter median drainage time in this group (5 days [range, 1 to 35 days] versus 7.5 days [range, 2 to 29 days); p 0.045). Hospital stay was comparable between the two groups (9.5 days [range, 6 to 44 days] versus 12.0 days [range, 5 to 46 days]; p 0.14). Conclusions. Buttressing the staple line significantly shortens the duration of air leaks and the drainage time. As hospital stay did not differ significantly between the two groups, cost-effectiveness may depend on the local situation. (Ann Thorac Surg 2000;70:1820 5) 2000 by The Society of Thoracic Surgeons Presented at the Thirty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 31 Feb 2, 2000. Address reprint requests to Dr Weder, Department of Surgery, University Hospital, CH-8091 Zürich, Switzerland; e-mail: walter.weder@chi.usz.ch. Lung volume reduction surgery (LVRS) reduces dyspnea and improves lung function and quality of life in select patients with advanced pulmonary emphysema [1 6]. Initial results using different laser techniques were unsatisfactory [5]. Therefore, stapled lung volume reduction became the technique of choice [1, 2, 4, 7, 8]. A major problem after volume reduction procedures is the occurrence of persistent air leaks. Because Cooper and associates [7, 9] observed favorable results in LVRS using stapling devices armed with strips of bovine pericardium, it was suggested that buttressing the staple lines with either biological [9, 10] or synthetic materials such as Teflon [11] and polydioxanone [12] would reduce air leaks and shorten hospital stay. At present, the data from only one randomized study of unilateral LVRS have been published [10]. To evaluate the effect of buttressing the staple lines on the postoperative course in bilateral LVRS, a randomized three-center study was carried out. Patients underwent LVRS by video-assisted thoracoscopy using endoscopic stapling devices (ET 45B; Ethicon Endo-Surgery, Cincinnati, OH) either without (control group) or with (treatment group) bovine pericardium (Peri-Strips Dry; Bio- Vascular, Inc, Saint Paul, MN). The effectiveness of buttressing the staple lines was evaluated by comparing the incidence and the duration of air leaks, the drainage time, the hospital stay, the short-term functional outcome, and the complications between the two groups. Material and Methods Seventy-four consecutive patients (27 women) with severe emphysema underwent bilateral LVRS by videoassisted thoracoscopy at the three institutions between 1997 and 1998. Inclusion and exclusion criteria were the same in the three centers according to the study protocol and previously published guidelines [13]. Nine patients were excluded from further analysis for various reasons. Severe adhesions were found in 5 patients and necessitated conversion to a thoracotomy on one site. Two patients in the control group died on postoperative day 3 of septic multiorgan failure or cerebrovascular infarction; neither death was considered attributable to surgical technique. In 1 patient, thoracoscopic LVRS was performed only unilaterally because of severe adhesions, and 1 patient underwent unilateral resection because the morphology was preponderantly unilateral emphysema. Therefore, the postoperative course of 65 patients (42 2000 by The Society of Thoracic Surgeons 0003-4975/00/$20.00 Published by Elsevier Science Inc PII S0003-4975(00)01903-2

Ann Thorac Surg STAMMBERGER ET AL 2000;70:1820 5 BUTTRESSED STAPLERS IN LVRS 1821 men, 23 women) with a mean age at operation of 59.2 1.2 years (range, 38 to 79 years) was analyzed. Six of them, 3 in each group, had homozygous 1 -antiprotease deficiency (ZZ). All 65 study patients (32 in the treatment group, 33 in the control group) were severely symptomatic with a mean modified Medical Research Council dyspnea score of 3.4 0.08. They had severe airflow obstruction with a mean forced expiratory volume in one second of 0.76 0.027 L (27% 0.81% predicted), a mean total lung capacity of 8.30 0.18 L (139% 2.0% predicted), a mean residual volume of 5.79 0.15 L (286% 7.6% predicted), and a mean residual volume to total lung capacity ratio of 0.70 0.01. Twenty-nine patients (45%) received oxygen supplementation for at least 12 hours per day (13 in the control group, 16 in the treatment group). Only 6 patients had a preoperative resting arterial oxygen tension of 55 mm Hg or less (4 in the control group, 2 in the treatment group). Oral steroids in a dose of 10 mg/d or more were used by 29 patients (45%) during the last 8 months (16 in the control group, 13 in the treatment group). All patients consented to be enrolled in a prospective study on outcome after LVRS, which was approved by each hospital s ethical committee. No systematic pulmonary rehabilitation was performed before or after operation. Clinical and Functional Evaluation Preoperative patient evaluation consisted of medical history and extensive clinical workup, pulmonary function testing, rating of dyspnea, chest radiography, chest computed tomography, and perfusion scintigraphy of the lung. At the 3-month follow-up, pulmonary function, gas analysis at rest, and dyspnea were assessed. Dyspnea was rated according to the American Thoracic Society modified Medical Research Council dyspnea score [14]. The patient describes his or her degree of dyspnea by grading with an integer from 0 to 4. Zero means breathlessness only with strenuous exercise, and 4 means the patient is unable to leave the house or is breathless while dressing. Pulmonary function testing was performed after inhalation of two puffs of salbutamol (albuterol in the United States), adhering to standard criteria [15, 16], with standardized body plethysmographs (Fenyves & Gut, Bodelshausen, Germany; Sensor Medics Autobox plethysmograph, Yorba Linda, CA). Reference values were those of the European Community for Steel and Coal [15]. Arterial blood gas values were determined with the patient at rest while breathing room air in an upright sitting position. Blood gas analysis was performed after withdrawal of about 1 ml of blood from the radial artery with a powder preheparinized syringe. The sample was analyzed within 2 minutes after puncture. Emphysema was scored on preoperative chest computed tomography as either homogeneous, intermediately heterogeneous, or markedly heterogeneous according to a previously validated classification [17]. Adhesion were rated intraoperatively as not present, small and easy to release, large but without parenchymal lesions after resection, or large with parenchymal lesions in the remaining lung. Postoperative air leakage on the ventilator was assessed at a respiratory peak pressure set to a maximum of 30 cm H 2 O and was rated as either less than 10%, 10% to 30%, or more than 30% of tidal volume on the ventilator. Persistent air leakage in the postoperative course was assessed during ward rounds in the morning and evening. Chest tubes were removed independently on each side within 24 hours after air leaks stopped. Hospital stay was counted starting on day 1 after the operation until discharge either to a stationary rehabilitation program or home. Randomization One day before the procedure, the patient was randomized to either the treatment group, in which buttressed stapling devices were applied, or the control group, in which the same kind of stapling devices were used without buttressing. Patients older than 65 years and patients younger than that were randomized independently. Patients with homozygous 1 -antiprotease deficiency were randomized as a separate group. Surgical Technique Surgical lung volume reduction was performed bilaterally by video-assisted thoracoscopy as previously described [8, 18]. The most damaged zones of lung parenchyma, target areas for resection, were identified on computed tomographic scans and perfusion scintigrams and resected using endoscopic staplers (ET 45B; Ethicon Endo-Surgery). According to randomization, the staplers were either buttressed with Peri-Strips Dry (Bio- Vascular, Inc) or not buttressed. In patients without target areas (homogeneous emphysema morphology type), the resection was performed mostly in the upper lobes. A cumulative lung volume of approximately 20% to 30% on each side was resected. Two chest tubes (Charrière 24) were placed on each side and connected to a chest tube drainage system with suction of 10 cm H 2 O. Patients were extubated in the operating room. After discontinuation of hemorrhagic secretion, chest tubes were connected to Heimlich valves [19], and suction was applied only in patients with symptomatic pneumothorax. The last drainage tube was removed if no air leak was observed for 24 hours. Peri-Strips Dry were provided without costs to the three study centers by the local representative of Bio- Vascular, Inc. There was no financial support from the company. Data Analysis Results were expressed as the mean the standard error of the mean, the median, and the range. The data were not normally distributed and skewed to the left. For comparison of the two groups, the Mann-Whitney U test (ordinal scale) was used. Again the data were not normally distributed. The 2 test was performed to detect

1822 STAMMBERGER ET AL Ann Thorac Surg BUTTRESSED STAPLERS IN LVRS 2000;70:1820 5 Table 1. Preoperative and Postoperative Pulmonary Function Test Results, Arterial Blood Gas Analyses, and Modified Medical Research Council Dyspnea Score a,b FEV 1 TLC Time of Measurement L % Predicted RV (% Predicted) L % Predicted RV/TLC PaO 2 (mm Hg) PaCO 2 (mm Hg) Dyspnea Score Preoperative Treatment group 0.77 0.04 27 1.1 287 10.6 8.15 0.22 139 2.9 0.71 0.01 65.3 1.3 40.1 0.76 3.34 0.12 Control group 0.76 0.04 27 1.2 284 10.9 8.45 0.29 138 2.8 0.68 0.01 64.2 1.4 41.3 1.1 3.50 0.10 Postoperative Treatment group 1.09 0.06 c 38 2.0 c 205 9.3 c 7.08 0.21 d 122 2.8 e 0.58 0.02 c 70.2 1.6 e 37.8 0.76 d 1.67 0.10 c Control group 1.15 0.06 c 41 1.9 c 187 9.4 c 7.14 0.24 e 116 2.2 c 0.54 0.02 c 70.7 1.4 d 37.1 0.67 c 1.69 0.12 c a Data are shown as the mean the standard error of the mean. b There were no significant differences between groups in any variable either before or after operation. c Significance: p 0.001 versus preoperative value. d Significance: p 0.05 versus preoperative value. e Significance: p 0.01 versus preoperative value. FEV 1 forced expiratory volume in 1 second; PaCO 2 arterial carbon dioxide tension; PaO 2 arterial oxygen tension; RV residual volume; TLC total lung capacity. differences in proportions between groups. For comparison of preoperative and postoperative pulmonary function and blood gas analysis between groups, analysis of variance was applied. Data were analyzed using the STATISTICA 4.5 software (StatSoft, Tulsa, OK). A p value of less than or equal to 0.05 was considered significant. Results Comparison of Lung Function, Arterial Blood Gases, and Dyspnea Pulmonary function tests, arterial blood gas analysis, and degree of dyspnea did not differ between the two groups either before or after the procedure (Table 1). In both groups, significant improvements after LVRS were observed. Morphological Grading of Emphysema In the treatment group, 5 patients had homogeneous, 3 had intermediately heterogeneous, and 19 had markedly heterogeneous emphysema morphology as assessed by chest computed tomographic scans. In the control group, 7 patients had homogeneous, 8 had intermediate, and 18 had heterogeneous emphysema morphology ( p 0.66). Adhesions and Site of Resection No adhesions were seen in 14 patients in the treatment group and 9 in the control group, whereas mild adhesions were observed in 12 patients and 14 patients, respectively. Large adhesion without parenchymal lesions in the remaining lung after resection were observed in 5 patients in the treatment group and 10 patients in the control group. One patient in the treatment group had severe adhesions with parenchymal lesion of the lung after resection. Group differences were not significant ( p 0.19). In the majority of patients in both groups, the resection involved the upper lobe (Table 2). Cartridges In the treatment group, a mean of 14.7 0.64 cartridges (median number, 15 cartridges; range, 8 to 24 cartridges) were used per procedure, including the cartridge delivered with the stapler. In the control group, a mean of 16.1 0.77 cartridges (median number, 16 cartridges; range, 10 to 26 cartridges) were fired ( p 0.20). Technical Problems In 3 patients in the treatment group, the Peri-Strips Dry detached from the stapler before it was fired. No other technical problems related to the stapling devices occurred. Intraoperative Air Leak During Ventilation The majority of patients in both groups had an intraoperative air leak of less than 10%, as measured by the inspiration/expiration difference on the ventilator set to a respiratory peak pressure of a maximum of 30 cm H 2 O. In the treatment group, 1 patient had an air leak of 10% to 30% and 1, of more than 30%. In the control group, 4 patients had an inspiration/expiration difference of 10% to 30% and 1 patient, of more than 30% ( p 0.53). Duration of Operation and Extubation Mean duration of operation was 100.1 7.4 minutes (median duration, 85.0 minutes; range, 50 to 215 minutes) in the treatment group and 100.4 7.1 (median duration, 105.0 minutes; range, 40 to 177 minutes) in the control group ( p 0.92). In two centers, patients were extubated in the operating room and in one center, in the recovery room but within 4 hours after the end of the operation. However, 3 patients in the control group were extubated after the fourth postoperative hour, but within 24 hours. There Table 2. Area of Resection Area Treatment Group Control Group Left Right Left Right Upper lobe 28 27 22 24 Middle lobe/lingula 10 13 10 12 Lower lobe 12 9 12 11

Ann Thorac Surg STAMMBERGER ET AL 2000;70:1820 5 BUTTRESSED STAPLERS IN LVRS 1823 Table 3. Presence and Duration of Air Leaks, Drainage Time, and Hospital Stay a Variable Treatment Group Control Group p Value Air leaks Present 25 (39) 51 (77) 0.001 Absent 39 (61) 15 (23) Air leak duration (d) 2.5 0.7 (0; 0 28) 5.2 0.75 (4; 0 27) 0.002 Drainage time (d) 7.6 1.3 (5; 1 35) 9.7 1.2 (7.5; 2 29) 0.045 Hospital stay (d) 12.7 1.4 (9.5; 6 44) 15.7 1.8 (12; 5 46) 0.14 a Data are shown as the mean the standard error of the mean with the median and the range in parentheses except for air leaks, where the numbers in parentheses are percentages. were no differences in patient or operative variables, eg, intraoperative air leak during ventilation, drainage time, technical problems, or confounding disease between these patients and the remaining study population, and the later course was uneventful in these 3 patients. Postoperative Complications The two main complications in the postoperative course were persistent air leaks and the development of pneumothorax (n 12, 5 in the treatment group and 7 in the control group), which led to reoperation in 7 patients [3 in the treatment group]. Other complications included pneumonia (n 2), exacerbation of chronic obstructive pulmonary disease (n 1), and atelectasis of the middle lobe (n 1), which responded to adequate physical therapy. Air Leaks After Operation Because the occurrence of air leaks on one side is not dependent on the other side, data from both sides were recorded, and two values were entered for each patient in the analysis in Table 3. Thus, there were 66 entries for the control group and 64 for the treatment group. Duration of Air Leaks, Drainage Time, and Hospital Stay The duration of air leaks on each individual side was recorded as just mentioned. However, the total drainage time can depend more on the longest duration of any air leak regardless of side. In the treatment group, the mean longest duration on both sides together was 3.9 1.25 days (median time, 1.0 day; range, 0 to 28 days) compared with 7.1 1.19 days (median time 5.0 days; range, 0 to 27 days ( p 0.002) in the control group (see Table 3). The interval until removal of the last chest tube was significantly shorter in the treatment group (see Table 3). The cumulated analysis treating each side independently, which may not be relevant for clinical practice, reveals similar results: 5.8 0.74 days (median time, 4 days; range, 1 to 35 days) versus 8.0 0.78 days (median time, 8 days; range, 2 to 29 days) ( p 0.001). The reduction in chest tube time did not translate into a significantly shorter hospital stay in the treatment group (see Table 3). Comment The main finding of this prospective, randomized threecenter study was a significantly shorter duration of postoperative air leaks and a resulting significantly shorter drainage time in patients who underwent buttressed procedures. These results are corroborated by a significant decrease in the incidence of initial air leakage from 77% to 39%. A trend toward a shorter hospital stay in the treatment group was noted. Whereas nearly all surgeons performing LVRS with the use of buttressed stapling devices claim a significant reduction in air leaks, only a few attempts have been made to prove this hypothesis. A randomized two-center study by Hazelrigg and colleagues [10] involving 123 patients undergoing unilateral thoracoscopic LVRS showed a significant decrease in the duration of postoperative air leaks, earlier chest tube removal, and a shorter hospital stay in patients receiving bovine pericardial strips on staple lines than in patients without such buttressing. The incidence of postoperative infections was identical, as were the total hospital charges because costs for the pericardial sleeves offset the saving in hospitalization days. Another randomized study by Santambrogio and coworkers [20] involved 60 patients. The patient population was younger (mean age, about 46 years) than in our study or that of Hazelrigg and associates [10], and preoperative pulmonary function tests are lacking. It is assumed that in most of these patients, a bullectomy rather than lung volume reduction was performed. A trend toward a reduced duration of air leaks was noted, but significance was observed only in the comparison of the two subgroups with the highest radiological emphysema score. Operation time was significantly longer when the strips were tied to the stapling device, whereas in our study, the operation time was virtually the same. This is probably due to the faster process of gluing the strips to the stapler. In both these studies [10, 20], a thoracoscopic approach was used. Venuta and colleagues [21] performed open lobectomies for lung cancer in 30 patients using a stapler with bovine pericardium, a stapler alone, or cautery, clamps, and silk ties for completion of the interlobar fissure. No difference regarding duration of air leaks was

1824 STAMMBERGER ET AL Ann Thorac Surg BUTTRESSED STAPLERS IN LVRS 2000;70:1820 5 observed between the last group and patients having operation without a buttressed stapling device, but bovine pericardium significantly decreased the duration of air leaks. These results leave no doubt as to the effectiveness of buttressing the staple lines. However, bovine pericardium is expensive. A study by Fischel and McKenna [22] compared the use of bovine pericardium with that of bovine collagen in bilateral thoracoscopic LVRS. The mean interval until chest tube removal was 8.6 7.2 days for bovine pericardium and 10.7 8.7 days for bovine collagen ( p 0.16). The authors concluded that the cheaper material might be a valid alternative. It is possible that a different statistical analysis, taking into account the fact that data were not normally distributed, might have been able to substantiate the trend toward a reduction in chest tube time in patients receiving bovine pericardium. New surgical techniques try to reduce the incidence of air leaks without the need of expensive bovine pericardium. Venuta and coworkers [23] presented a technique to create a pleural tent after thoracoscopic lung volume reduction. A modification of this technique uses the parietal pleural tent to cover the stapling line [24]. Swanson and colleagues [25] performed no-cut thoracoscopic lung plication in 32 patients, and only 4 of them had prolonged air leak of longer than 7 days. The authors concluded that lung plication is an alternative technique for LVRS. These techniques may be useful in specific instances, but to date, they have not gained widespread acceptance, and comparative trials have not been carried out. The issue of biocompatibility needs to be considered with any prosthetic material [26]. Currently, little information is available regarding host reaction in lung resection procedures. In experimental cardiac applications in rodents, use of bovine pericardium was associated with calcification, extensive inflammatory reactions, and formation of fibrosis [27]. In patients undergoing lung transplantation after LVRS, many surgeons have observed that adhesions are more dense if bovine pericardium was used [8]. Therefore, bovine pericardium should be used selectively in younger patients who may be transplant candidates in the future. In this prospective three-center study, a significantly decreased occurrence of initial air leakage resulted in a shorter duration of air leaks and a shorter drainage time in patients receiving buttressed stapler lines. Complications, infectious and others, were the same in both groups, and improvements in postoperative lung function, arterial blood gases, and dyspnea were equal in both groups. Only a trend toward a reduced hospital stay was observed in the treatment group, and therefore, cost-effectiveness may depend on the local situation. Supported by grant 3200-043358;95.1 from the Swiss National Science Fund and by a grant from the Zürich Lung League. References 1. Cooper JD, Lefrak SS. Lung-reduction surgery: 5 years on. Lancet 1999;353(Suppl 1):SI26 I27. 2. Hamacher J, Bloch KE, Stammberger U, et al. Two years outcome of lung volume reduction surgery in different morphologic emphysema types. Ann Thorac Surg 1999;68: 1792 8. 3. Wisser W, Tschernko EM, Wanke T, et al. Functional improvements in ventilatory mechanics after lung volume reduction surgery for homogeneous emphysema. Eur J Cardio-thorac Surg 1997;12:525 30. 4. Teschler H, Thompson AB, Stamatis G. Short- and long-term functional results after lung volume reduction surgery for severe emphysema. Eur Respir J 1999;13:1170 6. 5. McKenna RJ Jr, Brenner M, Gelb AF, et al. A randomized, prospective trial of stapled lung reduction versus laser bullectomy for diffuse emphysema. J Thorac Cardiovasc Surg 1996;111:317 22. 6. Bingisser R, Zollinger A, Hauser M, et al. Bilateral volume reduction surgery for diffuse pulmonary emphysema by video-assisted thoracoscopy. J Thorac Cardiovasc Surg 1996; 112:875 82. 7. Cooper JD, Trulock EP, Triantafillou AN, et al. Bilateral pneumectomy (volume reduction) for chronic obstructive pulmonary disease. J Thorac Cardiovasc Surg 1995;109: 106 19. 8. Klepetko W. Surgical aspects and techniques of lung volume reduction surgery for severe emphysema. Eur Respir J 1999; 13:919 25. 9. Cooper JD. Technique to reduce air leaks after resection of emphysematous lung. Ann Thorac Surg 1994;57:1038 9. 10. Hazelrigg SR, Boley TM, Naunheim KS, et al. Effect of bovine pericardial strips on air leak after stapled pulmonary resection. Ann Thorac Surg 1997;63:1573 5. 11. Roberson LD, Netherland DE, Dhillon R, Heath BJ. Air leaks after surgical stapling in lung resection: a comparison between stapling alone and stapling with staple-line reinforcement materials in a canine model. J Thorac Cardiovasc Surg 1998;116:353 4. 12. Juettner FM, Kohek P, Pinter H, Klepp G, Friehs G. Reinforced staple line in severely emphysematous lungs. J Thorac Cardiovasc Surg 1989;97:362 3. 13. Russi EW, Stammberger U, Weder W. Lung volume reduction surgery for emphysema. Eur Respir J 1997;10:208 18. 14. Surveillance for respiratory hazards in the occupational setting. American Thoracic Society. Am Rev Respir Dis 1982; 126:952 6. 15. Quanjer PH, Tammeling GJ, Cotes JE, Pederson OF, Peslin R, Yernault JC. Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official statement of the European Respiratory Society. Eur Respir J 1993;16(Suppl):5 40. 16. Standardization of spirometry 1987 update. American Thoracic Society. Am Rev Respir Dis 1987;136:1285 98. 17. Weder W, Thurnheer R, Stammberger U, Bürge M, Russi EW, Bloch KE. Radiologic emphysema morphology is associated with outcome after surgical lung volume reduction. Ann Thorac Surg 1997;64:313 20. 18. Stammberger U, Thurnheer R, Bloch KE, et al. Thoracoscopic bilateral lung volume reduction for diffuse pulmonary emphysema. Eur J Cardiothorac Surg 1997;11:1005 10. 19. Heimlich HJ. Valve drainage of the pleural cavity. Dis Chest 1968;53:282 6. 20. Santambrogio L, Nosotti M, Baisi A, Bellaviti N, Pavoni G, Rosso L. Buttressing staple lines with bovine pericardium in lung resection for bullous emphysema. Scand Cardiovasc J 1998;32:297 9. 21. Venuta F, Rendina EA, De Giacomo T, et al. Technique to reduce air leaks after pulmonary lobectomy. Eur J Cardiothorac Surg 1998;13:361 4.

Ann Thorac Surg STAMMBERGER ET AL 2000;70:0000 0000 BUTTRESSED STAPLERS IN LVRS 1825 22. Fischel RJ, McKenna RJ Jr. Bovine pericardium versus bovine collagen to buttress staples for lung reduction operations. Ann Thorac Surg 1998;65:217 9. 23. Venuta F, De Giacomo T, Rendina EA, Ricci C, Coloni GF. Thoracoscopic pleural tent. Ann Thorac Surg 1998;66:1833 4. 24. Busetto A, Moretti R, Barbaresco S, Fontana P, Pagan V. Extrapleural bullectomy or lung volume reduction: air tight surgery for emphysema without strip-patch. Acta Chir Hung 1999;38:15 7. 25. Swanson SJ, Mentzer SJ, DeCamp MM Jr, et al. No-cut thoracoscopic lung plication: a new technique for lung volume reduction surgery. J Am Coll Surg 1997;185:25 32. 26. Vaughn CC, Wolner E, Dahan M, et al. Prevention of air leaks after pulmonary wedge resection. Ann Thorac Surg 1997;63:864 6. 27. Dahm M, Lyman WD, Schwell AB, Factor SM, Frater RW. Immunogenicity of glutaraldehyde-tanned bovine pericardium. J Thorac Cardiovasc Surg 1990;99:1082 90. DISCUSSION DR SCOTT J. SWANSON (Boston, MA): I greatly enjoyed your presentation, and I have two questions for you. First, have you considered an autologous buttressing technique? My colleagues and I have used it in about 50 patients. Our results show that it compares favorably with your data, and it does not have the extra costs. Second, how do you decide between bovine and Gore-Tex buttressing? DR STAMMBERGER: In answer to your first question, at our center, we do not, for example, form a pleural tent and use this to buttress the stapling lines. It might be an alternative in some patients, but in our opinion, this could prolong the operation time. As for your second question, we have no experience with Gore-Tex or other synthetic materials. DR PETER GOLDSTRAW (London, England): Did any of your patients leave the hospital with drains in place? DR STAMMBERGER: No. This might explain why the hospital stay was not significantly different between the two groups. Patients are usually discharged home and not to a rehabilitation center or somewhere else where they can be sent with drains in place. DR JOSEPH B. SHRAGER (Philadelphia, PA): I am surprised that you had only 1 day of air leak in the treatment group but the chest tubes remained in for a mean of 5 days. In my experience, patients having volume reduction do not leak a lot of fluid, particularly those with a thoracoscopic procedure, and for that reason, I wonder why you could not remove the chest tubes sooner. Doing so might have made your ultimate data on length of stay reach significance. DR STAMMBERGER: As noted in the presentation, data were not normally distributed and skewed to the left. Therefore, the median and the range rather than the mean were shown. The mean duration for air leaks in the treatment group was longer than 1 day (3.9 1.25 days).