HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Keith S. Naunheim Larry R. Kaiser Joseph E. Bavaria Stephen R. Hazelrigg Mitchell J. Magee Rodney J. Landreneau Robert J. Keenan Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Naunheim, K. S. Articles by Keller, C. A. Search for Related Content PubMed PubMed Citation Articles by Naunheim, K. S. Articles by Keller, C. A.

Ann Thorac Surg 1999;68:2026-2031
© 1999 The Society of Thoracic Surgeons

---

Original Articles: General Thoracic

Long-term survival after thoracoscopic lung volume reduction: a multiinstitutional review

^a Division of Cardiothoracic Surgery, Saint Louis University, St. Louis, Missouri, USA
^b Division of Cardiothoracic Surgery, Southern Illinois University, Springfield, Illinois, USA
^c Division of Cardiothoracic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
^d Division of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
^e Division of Cardiothoracic Surgery, Allegheny University, Pittsburgh, Pennsylvania, USA
^f COR Specialty Associates of North Texas, Dallas, Texas, USA

Address reprint requests to Dr Naunheim, Department of Surgery, Saint Louis University Health Sciences Center, 3635 Vista Ave at Grand Blvd, PO Box 15250, St. Louis, MO 63110-0250
e-mail: naunheim{at}slu.edu

Presented at the Thirty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 25–27, 1999.

Abstract

Background. It has been suggested that bilateral thoracoscopic lung volume reduction (BTLVR) yields significantly better long-term survival than unilateral thoracoscopic lung volume reduction (UTLVR).

Methods. All perioperative data were collected at the time of the procedure. Follow-up data were obtained during office visits or by telephone.

Results. A total of 673 patients underwent thoracoscopic LVR: 343 had either simultaneous or staged BTLVR and 330, UTLVR. As of July 1998, follow-up was available on 667 (99%) of the 673 patients with a mean follow-up of 24.3 months. The patients in the BTLVR group were significantly younger (62.6 ± 8.0 years versus 65.4 ± 8.1 years; p < 0.0001), had a higher preoperative arterial oxygen tension (69.7 ± 12 mm Hg versus 65.3 ± 11 mm Hg; p < 0.0001), and had a superior preoperative 6-minute walk performance (279.9 ± 93.6 m [933 ± 312 feet] versus 244.5 ± 101.4 m [815 ± 338 feet] p < 0.0001). There was no difference in the operative mortality rate between the two groups (UTLVR, 5.1%, and BTLVR, 7%). Actuarial survival rates for the UTLVR group at 1 year, 2 years, and 3 years were 86%, 75%, and 69%, respectively versus 90%, 81%, and 74%, respectively, for the BTLVR group (p = not significant).

Conclusions. Contrary to previous reports, survival after BTLVR was not superior to that after UTLVR even though the former group appeared to have a lower risk preoperatively because of younger age, higher arterial oxygen tension, more advantageous anatomy, and better functional status. Despite thoracoscopic LVR, the actuarial mortality rate approached 30% at 3 years, and this calls into question whether this procedure offers any survival advantage to patients with end-stage emphysema.

Although most reports on lung volume reduction (LVR) demonstrate superior improvement in spirometric results for bilateral LVR procedures compared with unilateral procedures, results are variable when indices of dyspnea relief, oxygenation, functional capacity, and survival are examined. One 1996 report [1] suggested that patients undergoing unilateral thoracoscopic LVR (UTLVR) have significantly decreased survival compared with those having bilateral thoracoscopic LVR (BTLVR). Another study [2] reported nearly identical survival for UTLVR and BTLVR procedures, although the number of patients examined in both groups was small. Although it is likely that the greatest probable benefit of LVR is palliation of symptoms of end-stage emphysema, improvement in length of survival of patients with this terminal disease would be a major finding supporting wider application. In fact, one of the primary statistical end points for the National Heart, Lung, and Blood Institute–sponsored National Emphysema Treatment Trial is long-term survival. To investigate more thoroughly the issue of long-term survival and causes of death in patients undergoing LVR procedures, we undertook a retrospective multicenter review.

Material and methods

A retrospective multicenter study was instituted to evaluate the effect of unilateral and bilateral LVR on long-term survival and causes of death. Questionnaires were sent to the five participating centers (Allegheny University, Saint Louis University, Southern Illinois University, University of Pennsylvania, and University of Pittsburgh) regarding patients who had undergone either UTLVR or BTLVR for end-stage emphysema. A sample of the questionnaire is shown in the Appendix. Only patients undergoing LVR through a thoracoscopic approach were included. Patients with giant bullae were not included in this study.

Patient selection criteria were similar among the centers and have been described in previous publications [3–6]. In summary, patients chosen had both radiographic and spirometric criteria for the diagnosis of end-stage emphysema. Inclusive criteria consisted of evidence of severe airflow obstruction with forced expiratory volume in 1 second in the range of 15% to 35% of predicted and a residual volume usually in excess of 200% of predicted as measured by body plethysmography. The chest roentgenograms and computed tomographic scans had to demonstrate emphysematous changes and hyperinflation. Quantitative ventilation/perfusion lung scanning was performed to identify variable areas of perfusion within the lung fields. The ideal patient was considered to have heterogeneous disease with focal zones of hypoventilated and hypoperfused lung, most commonly in the lung apices. However, several institutions did perform LVR on patients with more diffuse disease. Exclusion criteria included age older than 80 years, tobacco usage within 3 months prior to evaluation, resting arterial carbon dioxide tension greater than 55 mm Hg, pulmonary artery systolic pressure higher than 50 mm Hg, major obesity (> 1.25 ideal body weight) or cachexia (< 0.75 ideal body weight), ventilator dependence, and radiographic, clinical, or spirometric evidence of chronic bronchitis, bronchiectasis, or bronchospasm. All patients were referred for 6 weeks of preoperative pulmonary rehabilitation, although not all of them were able to successfully complete the course.

Data regarding demographic characteristics (age and sex), etiology of emphysema (smoking and -1-antitrypsin), and distribution (homogeneous versus heterogeneous) of emphysema were recorded. Spirometric data included absolute and percent predicted functional vital capacity, absolute and predicted forced expiratory volume in one second, and both absolute and predicted residual volume as determined by plethysmography. Variables assessing oxygenation included room air, blood gases, and patient-reported supplemental oxygen requirements (none, with exercise or sleeping, or always). Functional capacity was determined using the standardized 6-minute walk test and maximum oxygen consumption as measured by formal cardiopulmonary exercise tests.

Hospital morbidity and mortality were recorded. Operative mortality was defined as any death within 30 days after operation or any death that occurred during hospitalization either within the acute care facility or in a ventilatory or rehabilitation facility prior to discharge home. Prolonged air leak was defined as an air leak that persisted for greater than 7 days. Other recorded morbidity included pneumonia, gastrointestinal complications, tracheostomy, arrhythmia, reoperation for bleeding, acute myocardial infarction, cerebrovascular accident, and utilization of a Heimlich valve at discharge. Information was also obtained regarding the site to which the patient was discharged (home, long-term ventilatory facility, skilled nursing facility, or rehabilitation center).

Follow-up data were collected either at the time of clinic visit or by telephone interview. All data were obtained by thoracic specialty nurses familiar with LVR. Data were analyzed using Stat View for Windows (Version 4.53; Abacus Concepts Inc, Berkeley, CA). Statistical analysis consisted of an unpaired Student t test for continuous variables and a ² contingency table for discrete variables. Data are shown as the mean ± one standard deviation. Actuarial survival was calculated using the method of Kaplan and Meier and statistical comparisons, using a Mantel-Cox analysis. The survival graphs depict survival at 6-month intervals and error bars indicate ± one standard error. A p value of less than 0.05 was considered significant. Patients who underwent staged unilateral procedures were included in the bilateral group. Calculation of the incidence of complications and the length of stay for these patients was additive for the two hospitalizations, and survival was calculated from the date of the first operation.

Results

Preoperative profile
Between February 1993 and July 1998, 673 patients underwent thoracoscopic LVR at one of the five participating institutions. Three hundred thirty patients underwent UTLVR (83, left lung, and 247, right lung) and 343 patients, BTLVR. The majority in the BTLVR group underwent simultaneous reduction of both lungs during a single operation, but 72 patients underwent a staged procedure with an interval between procedures of 1 month to 43 months (mean interval, 9.5 months).

Preoperative patient characteristics for both groups are noted in Tables 1 and 2. There were significant differences between the UTLVR and BTLVR groups preoperatively. The patients in the UTLVR group were older (65.4 ± 8.1 years versus 62.6 ± 8 years; p < 0.0001) and more hypoxic (arterial oxygen tension, 65.3 ± 11 mm Hg versus 69.7 ± 12 mm Hg; p < 0.0001) than those in the BTLVR group. The increased incidence of hypoxemia is corroborated by the higher oxygen requirement in the UTLVR group (66% versus 58%), a difference that approached significance (p = 0.09). In view of this more severe hypoxemia, it is not surprising that the 6-minute walk distance was also lower in the UTLVR group (248.5 ± 103.1 m [815 ± 338 feet] versus 284.6 ± 95.2 m [933 ± 312 feet]; p < 0.0001). Homogeneous or diffuse emphysema, thought to be a less favorable distribution for LVR procedures, was found in a higher percentage of patients in the UTLVR group (46% versus 32%; p < 0.001). Finally, at each institution, the vast majority of early thoracoscopic LVR procedures were unilateral; they were performed in the first 1 year to 2 years of the investigator’s experience. Thus, any negative effects of a learning curve were more likely to occur in the UTLVR group, as the bilateral procedures were performed later after surgeons and pulmonologists had gained experience in the care of these patients.

Long-term survival
The length of follow-up ranged from 1 month to 62 months with a mean follow-up of 24.3 months. The actuarial survival for both groups is depicted in Figure 1. The UTLVR cohort had 1-year, 2-year, and 3-year survival rates of 86%, 75%, and 69%, respectively, and the BTLVR group, 90%, 81%, and 74%, respectively (p = not significant). The causes of late death are shown in Table 5. Pulmonary problems (pneumonia and progressive respiratory failure) were the most common cause of late death; they accounted for 53% (41/77) of the late deaths in the UTLVR group and 61% (26/43) in the BTLVR group (p = not significant).

View larger version (17K): [in this window] [in a new window]   Fig 1. Actuarial survival curves after unilateral thoracoscopic lung volume reduction (UTLVR) and bilateral thoracoscopic lung volume reduction. Error bars represent one standard error.

There are many unanswered issues regarding LVR, including duration of effect, optimal approach, patient selection, cost to benefit ratio, and effect on long-term survival. One of the most controversial issues has been survival. It has been suggested that LVR may lead to longer survival of patients with end-stage emphysema, but because of its relative novelty and continual evolution, there is little factual evidence either supporting or contradicting this hypothesis. The issue of survival is critical if a cost to benefit analysis of the procedure is to be done. Although patients with end-stage emphysema are severely impaired functionally, they often enjoy a fairly prolonged survival with slow progression of disease until a final event such as pneumonia. A LVR procedure carries with it a finite immediate operative mortality rate of 5% to 10% and will deprive this minority of patients of continued survival. Whether or not the improvement in dyspnea and functional capacity of survivors will outweigh this human cost will depend not only on the incidence of early death but also on the length of survival of those patients who do well after the procedure. Thus, survival is a key factor in determining the overall value of LVR to this population, and it is actually one of the primary end points in the ongoing National Emphysema Treatment Trial sponsored by the National Heart, Lung, and Blood Institute.

Only a few publications [1–5] have reported early to midterm survival figures for patients undergoing an LVR procedure. Cooper and co-workers [4] found that actuarial survival declined to 92% and remained constant at this plateau out to 3 years. Their report seemed somewhat optimistic, and a subsequent study by the same group [5] provided 1-year, 2-year, and 3-year survival rates of 89%, 85%, and 83%, respectively.

McKenna and associates [1] also examined midterm survival statistics and were the first to compare results for bilateral and unilateral LVR. They found that unilateral LVR is inferior, as it carries a significantly decreased survival rate at 1 year compared with BTLVR (5% versus 17%; p < 0.01). The group also reported that the unilateral procedure provides inadequate improvement compared with the bilateral procedure and that progressive respiratory failure is more likely to occur.

In all, four groups [1–4] have reported single-institution results of both unilateral and bilateral LVR. If each group had found that the bilateral approach produced significantly better improvements in spirometry, dyspnea, exercise capacity, and oxygenation, we might logically expect a better survival curve as well. However, when their findings regarding these four variables are examined, their conclusions are somewhat varied:

1. Spirometry: Virtually all investigators reported that the improvement in forced expiratory volume in 1 second is significantly greater (by about 50% to 60%) with the bilateral as opposed to the unilateral approach. Similarly, reductions in residual volume are greater for patients having a bilateral procedure.
   
2. Dyspnea relief: Although subjective relief of dyspnea has been shown to correlate with improvement in spirometry [6, 7], the investigators directly comparing results of unilateral and bilateral procedures had mixed results. McKenna and colleagues [1] noted significantly better relief of dyspnea in the bilateral cohort, whereas Argenziano and co-workers [2] reported comparable improvement in the unilateral group. Neither Cooper and associates [4] nor Kotloff and colleagues [3] reported comparisons.
   
3. Functional improvement: The majority of the investigators assessed this using the 6-minute walk test. Whereas Kotloff’s group [3] noted a significantly greater improvement in the 6-minute walk for patients having a bilateral LVR procedure (16% versus 19%), Argenziano and colleagues [2] found no significant discrepancy.
   
4. Oxygenation: The report of Cooper and associates [4] suggested that the increase in arterial oxygen tension after unilateral and bilateral LVR is essentially identical. Arterial blood gas information is not reported by the other three groups [1–3].
   

Consistent findings of improvement in all the variables might lead one to believe that survival would be improved; however, the contradictory nature of these reports raises the question whether or not any survival advantage could or should be expected.

Our results do not confirm the findings of McKenna and associates [1] regarding survival. Despite the fact that our UTLVR group appeared to have a higher-risk profile (increased age, decreased arterial oxygen tension, lower exercise capacity, more homogeneous disease, and learning curve), there was no significant difference between the two groups in regard to operative mortality or late death at 1 year, 2 years, or 3 years. Also, we did not notice an increase in the incidence of death from respiratory causes, either at the time of operation or throughout the 3-year follow-up. We did notice an increased incidence of early respiratory morbidity during hospitalization with BTLVR, as evidenced by an increased incidence of pneumonia; however, the incidence of need of tracheostomy and discharge to a ventilatory facility was nearly identical between the two groups, a finding suggesting no lasting respiratory sequelae.

The question remains: Will the LVR procedure increase survival compared with medical management? It is difficult to find an appropriate group of medically managed patients to compare with our groups in terms of survival. The Nocturnal Oxygen Therapy Trial [8] reported a 64% 3-year survival rate for medically managed oxygen-dependent patients with chronic obstructive pulmonary disease, but comparison with this cohort is probably not valid. Not only is it a historical control representing medical management techniques two decades old, it is also a less highly selected cohort than the LVR group reported by Meyers and colleagues [5] would have been. They followed 22 patients who were formally accepted as LVR candidates but were unable to undergo the operation because Medicare refused coverage. The 3-year survival rate in the "medical" group was 64% compared with our overall 72% 3-year rate.

Although this incremental increase in survival appears encouraging, no definitive conclusions can be drawn at this time. When UTLVR was first performed, the strategy was to eventually undertake bilateral LVR but in a staged fashion [6]. When improved spirometric results and superior survival rates were reported by McKenna and associates [1], nearly all thoracoscopic surgeons proceeded to a bilateral simultaneous approach. However, Brenner and co-workers [9] recently reported an interesting comparison of the rate of decline of spirometric values after bilateral (simultaneous) and unilateral LVR. They found that although short-term incremental improvement after bilateral LVR procedures was superior to the improvement after a unilateral operation, the long-term rate of decline in forced expiratory volume in 1 second was greater in the bilateral group than the unilateral group. These findings call into question the optimal strategy for obtaining the best and most durable improvement. Could staged unilateral LVR procedures separated in time by 2 or 3 years provide a longer period of improvement in dyspnea relief, functional status, or both than a bilateral simultaneous approach? No data exist at this point to answer this question. However, it is important not to assume that preliminary data obtained to date have definitely determined the optimal operative strategy.

In summary, our study suggests that there is no significant difference in the incidence or cause of operative mortality and late death when UTLVR and BTLVR are compared. Further analysis of data regarding spirometry, oxygenation, functional status, and subjective improvement (eg, quality of life and dyspnea relief) will have to be directly compared and analyzed to make a definitive statement regarding advantages of one procedure over another. At present, unilateral LVR certainly remains an excellent alternative for patients with unilateral disease or patients with a prior history of a thoracotomy, empyema, or pleurodesis.

Appendix

Sample of questionnaire

Initials: Age: Sex: Date of operation: Center: Height: Weight: Race: Procedure: Left, right, or bilateral Work status: Alpha-1-antitrypsin syndrome: Preoperative steroids: Dose Postoperative steroids: Dose Preoperative oxygen: Postoperative oxygen: FVC actual: Preop, 6, 12, 18, and 24 months FVC % predicted: Preop, 6, 12, 18, and 24 months FEV1 actual: Preop 6, 12, 18, and 24 months FEV1 % predicted:Preop 6, 12, 18, and 24 months RV actual: Preop, 6, 12, 18, and 24 months RV % predicted: Preop, 6, 12, 18, and 24 months PaO2: Preop, 6, 12, 18, and 24 months VO2: Preop, 6, 12, 18, and 24 months Six-minute walk: Preop, 6, 12, 18, and 24 months Preoperative disease Upper lobe heterogeneous Lower lobe heterogeneous Homogeneous Complications: Postoperative complications Myocardial infarction Cerebrovascular accident Pneumonia Tracheostomy Bleeding (reop) GI complications Arrhythmia Air leak (Air leak duration) Heimlich at discharge (Heimlich duration) Operative mortality: Length of stay: Discharged to: Date of follow-up: Status: Cause of death: Interval hospitalization: Pneumonia or exacerbation: How many: Date:

FVL = functional vital capacity; GI = gastrointestinal; PaO₂ = arterial oxygen tension; RV = residual volume; VO₂ = oxygen consumption.

References

1. McKenna R.J., Jr, Brenner M., Fischel R.J., Gelb A.F. Should lung volume reduction for emphysema be unilateral or bilateral?. J Thorac Cardiovasc Surg 1996;112:1331-1338.[Abstract/Free Full Text]
2. Argenziano M., Thomashow B., Jellen P.A., et al. Functional comparison of unilateral versus bilateral lung volume reduction surgery. Ann Thorac Surg 1997;64:321-327.[Abstract/Free Full Text]
3. Kotloff R.M., Tino G., Palevsky H.I., et al. Comparison of short-term functional outcomes following unilateral and bilateral lung volume reduction surgery. Chest 1998;113:890-895.[Abstract/Free Full Text]
4. Cooper J.D., Patterson G.A., Sundaresan R.S., et al. Results of 150 consecutive bilateral lung volume reduction procedures in patients with severe emphysema. J Thorac Cardiovasc Surg 1996;112:1319-1329.[Abstract/Free Full Text]
5. Meyers B.F., Yusen R.D., Lefrak S.S., et al. Outcome of Medicare patients with emphysema selected for, but denied, a lung volume reduction operation. Ann Thorac Surg 1998;66:331-336.[Abstract/Free Full Text]
6. Keller C.A., Ruppel G., Hibbett A., Osterloh J., Naunheim K.S. Thoracoscopic lung volume reduction surgery reduces dyspnea and improves exercise capacity in patients with emphysema. Am J Respir Crit Care Med 1997;156:60-67.[Abstract/Free Full Text]
7. Brenner M., McKenna R.J., Gelb A.F., et al. Dyspnea response following bilateral thoracoscopic staple lung volume reduction surgery. Chest 1997;112:916-923.[Abstract/Free Full Text]
8. Nocturnal Oxygen Therapy Trial Group. Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive pulmonary disease. Ann Intern Med 1980;93:391-398.
9. Brenner M., McKenna R.J., Jr, Gelb A.F., Fischel R.J., Wilson A.F. Rate of FEV₁ change following lung volume reduction surgery. Chest 1998;113:652-659.[Abstract/Free Full Text]

This article has been cited by other articles:

				A. Shaw Genetics of postoperative complications following thoracic surgery. Seminars in Cardiothoracic and Vascular Anesthesia, December 1, 2006; 10(4): 327 - 345. [Abstract] [PDF]

				F. Venuta and G. Bognolo Surgery for emphysema. BMJ, February 18, 2006; 332(7538): 375 - 376. [Full Text] [PDF]

				A. Palla, M. Desideri, G. Rossi, G. Bardi, D. Mazzantini, A. Mussi, and C. Giuntini Elective Surgery for Giant Bullous Emphysema: A 5-Year Clinical and Functional Follow-up Chest, October 1, 2005; 128(4): 2043 - 2050. [Abstract] [Full Text] [PDF]

				T. C. Mineo, E. Pompeo, D. Mineo, P. Rogliani, C. Leonardis, and I. Nofroni Results of unilateral lung volume reduction surgery in patients with distinct heterogeneity of emphysema between lungs J. Thorac. Cardiovasc. Surg., January 1, 2005; 129(1): 73 - 79. [Abstract] [Full Text] [PDF]

				M. Brenner, N. M. Hanna, R. Mina-Araghi, A. F. Gelb, R. J. McKenna Jr, and H. Colt Innovative Approaches to Lung Volume Reduction for Emphysema Chest, July 1, 2004; 126(1): 238 - 248. [Abstract] [Full Text] [PDF]

				A. M. Ciccone, B. F. Meyers, T. J. Guthrie, G. E. Davis, R. D. Yusen, S. S. Lefrak, G. A. Patterson, and J. D. Cooper Long-term outcome of bilateral lung volume reduction in 250 consecutive patients with emphysema J. Thorac. Cardiovasc. Surg., March 1, 2003; 125(3): 513 - 525. [Abstract] [Full Text] [PDF]

				K. E.A. Burns, R. J. Keenan, W. F. Grgurich, J. D. Manzetti, and M. A. Zenati Outcomes of lung volume reduction surgery followed by lung transplantation: a matched cohort study Ann. Thorac. Surg., May 1, 2002; 73(5): 1587 - 1593. [Abstract] [Full Text] [PDF]

				E. Pompeo and T. C. Mineo Long-term outcome of staged versus one-stage bilateral thoracoscopic reduction pneumoplasty Eur. J. Cardiothorac. Surg., April 1, 2002; 21(4): 627 - 633. [Abstract] [Full Text] [PDF]

				T. Fujimoto, H. Teschler, L. Hillejan, G. Zaboura, and G. Stamatis Long-term results of lung volume reduction surgery Eur. J. Cardiothorac. Surg., March 1, 2002; 21(3): 483 - 488. [Abstract] [Full Text] [PDF]

				T. Geiser, B. Schwizer, T. Krueger, M. Gugger, V. I. Hof, M. Dusmet, J.-W. Fitting, and H.-B. Ris Outcome after unilateral lung volume reduction surgery in patients with severe emphysema Eur. J. Cardiothorac. Surg., October 1, 2001; 20(4): 674 - 678. [Abstract] [Full Text] [PDF]

				A. F. GELB, R. J. McKENNA Jr., M. BRENNER, J. D. EPSTEIN, and N. ZAMEL Lung Function 5 yr after Lung Volume Reduction Surgery for Emphysema Am. J. Respir. Crit. Care Med., June 1, 2001; 163(7): 1562 - 1566. [Abstract] [Full Text] [PDF]

				A. F. Gelb, R. J. McKenna Jr, and M. Brenner Expanding Knowledge of Lung Volume Reduction Chest, May 1, 2001; 119(5): 1300 - 1303. [Full Text] [PDF]

				K. S. Naunheim, S. R. Hazelrigg, L. R. Kaiser, R. J. Keenan, J. E. Bavaria, R. J. Landreneau, J. Osterloh, and C. A. Keller Risk analysis for thoracoscopic lung volume reduction: a multi-institutional experience Eur. J. Cardiothorac. Surg., June 1, 2000; 17(6): 673 - 679. [Abstract] [Full Text] [PDF]

				G. A. Lowdermilk, R. J. Keenan, R. J. Landreneau, S. R. Hazelrigg, J. E. Bavaria, L. R. Kaiser, C. A. Keller, and K. S. Naunheim Comparison of clinical results for unilateral and bilateral thoracoscopic lung volume reduction Ann. Thorac. Surg., June 1, 2000; 69(6): 1670 - 1674. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Keith S. Naunheim Larry R. Kaiser Joseph E. Bavaria Stephen R. Hazelrigg Mitchell J. Magee Rodney J. Landreneau Robert J. Keenan Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Naunheim, K. S. Articles by Keller, C. A. Search for Related Content PubMed PubMed Citation Articles by Naunheim, K. S. Articles by Keller, C. A.