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Ann Thorac Surg 2000;69:1670-1674
© 2000 The Society of Thoracic Surgeons

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Original articles: General thoracic

Comparison of clinical results for unilateral and bilateral thoracoscopic lung volume reduction

^a Division of Cardiothoracic Surgery, Saint Louis University, St. Louis, Missouri, USA
^b Division of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
^c Division of Cardiothoracic Surgery, Allegheny University, Pittsburgh, Pennsylvania, USA
^d Division of Cardiothoracic Surgery, Southern Illinois University, Springfield, Illinois, USA
^e Division of Cardiothoracic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, 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: naunheks{at}slu.edu

Presented at the Forty-sixth Annual Meeting of the Southern Thoracic Surgical Association, San Juan, Puerto Rico, Nov 4–6, 1999.

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. It is widely believed that bilateral thoracoscopic lung volume reduction (BTLVR) yields superior results when compared with unilateral thoracoscopic lung volume reduction (UTLVR) with regard to spirometry, functional capacity, oxygenation and quality of life results.

Methods. To address these issues, we compared the results of patients undergoing UTLVR (N = 338 patients) and BTLVR (N = 344 patients) from 1993 to 1998 at five institutions. Follow-up data were available on 671 patients (98.4%) between 6 and 12 months after surgery, and a patient self-assessment was obtained at a mean of 24 months.

Results. It was found that BTLVR provides superior improvement in measured postoperative percent change in FEV₁ (L) (UTLVR 23.3% ± 55.3 vs BTLVR 33% ± 41, p = 0.04), FVC(L) (10.5% ± 31.6 vs 20.3% ± 34.3, p = 0.002) and RV(L) (-13% ± -22 vs -22% ± 17.9, p = 0.015). BTLVR also provides a slight improvement over UTLVR in patient’s perception regarding improved quality of life (UTLVR 79% vs BTLVR 88%, p = 0.03) and dyspnea relief (71% vs 61%, p = 0.03). There was no difference in mean changes in PO₂ (mm Hg) (UTLV 4.5 ± 12.3 vs BTLVR 4.9 ± 13.3, p = NS), 6-minute walk (UTLVR 26% ± 66.1 vs BTLVR 31% ± 59.6, p = NS) or decreased oxygen utilization (UTLVR 78% vs BTLVR 74%, p = NS).

Conclusions. These data suggest that both UTLVR and BTLVR yield significant improvement, but the results of BTLVR seem to be superior with regard to spirometry, lung volumes, and quality of life.

	Introduction

Top Abstract Introduction Material and methods Results Comment References

 
Thoracoscopic lung volume reduction was initially performed unilaterally by most surgeons with the intent of proceeding in a staged fashion with a contralateral thoracoscopic lung volume reduction at an interval of weeks to months after the first procedure. However, it was not long before simultaneous bilateral thoracoscopic lung volume reduction (BTLVR) was performed. Early reports suggest that, when compared with unilateral thoracoscopic lung volume reduction (URLVR), patients undergoing BTLVR enjoyed a significantly greater increment in forced expiratory volume in 1 second (FEV₁) and a greater freedom from oxygen supplementation [1]. However, these results were somewhat controversial, as other investigators performing open bilateral LVR identified the same significant advantage with regard to spirometric improvement but failed to show any significant improvement in arterial oxygenation or exercise capacity [2, 3]. To address these issues, we attempted to examine and analyze the results of several institutions that have performed both UTLVR and BTLVR to determine whether there is a significant advantage to one specific procedure with regard to spirometry, oxygenation, functional capacity, and quality of life.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
A retrospective multicenter study was undertaken to evaluate the effect of UTLVR and BTLVR on perioperative change in spirometry, oxygenation, exercise capacity, and patient-assessed quality of life. Questionnaires were sent to the five participating centers (Allegheny University, St. Louis University, Southern Illinois University, University of Pennsylvania, and University of Pittsburgh) regarding patients who had undergone either unilateral or bilateral thoracoscopic lung volume reduction for end-stage emphysema. A sample questionnaire has been previously published [4].

Only patients undergoing LVR through a thoracoscopic approach were included. Patients with giant bullae were specifically excluded from the study. Patients undergoing lung volume reduction on both sides using staged unilateral procedures were relegated to the BTLVR group. Preoperative pulmonary rehabilitation was attempted in all patients 6 weeks before surgery, although not all patients were able to successfully complete the course.

Selection criteria were based on similar previous publications by the authors. Patients selected to undergo surgery had spirometric and radiographic evidence of end-stage emphysema. The chest x-rays and CT scans demonstrated emphysematous changes. Quantitative ventilation perfusion scanning was performed to identify areas of relative ischemia within the lung fields. Spirometric inclusion criteria consisted of severe air flow obstruction with an FEV₁ in the range of 15% to 35% of predicted and the residual volume in excess of 200% predicted, as measured by body plethysmography.

General exclusion criteria were age more than 80 years, resting PCO₂ greater than 55 mm Hg, pulmonary artery systolic pressure greater than 50 mm Hg, significant obesity (> 1.25 ideal body weight) or cachexia (< 0.75 ideal body weight), tobacco use within 3 months before evaluation, ventilator dependency, and radiographic or clinical evidence of chronic bronchitis, bronchiectasis, or bronchospasm.

Data regarding demographic characteristics (age, gender), etiology of emphysema (smoking, ₁-antitrypsin), and distribution of disease (homogeneous vs heterogeneous) were recorded. Heterogeneous disease is defined as emphysema that predominantly affects one location or region of the lung with less severe emphysema in the remaining lung. The perfusion scan demonstrated focal hypoperfusion in one area. Homogeneous disease is emphysema spread diffusely throughout the lung as demonstrated by both CT and perfusion scans. These assessments were qualitative and were made by the investigators at each institution. Spirometric data included both absolute and percent predicted values for functional vital capacity (FVC), forced expiratory volume in one second (FEV₁), and residual volume (RV) as determined by plethysmography. Room air blood gases were used to determine partial oxygen pressure (PO₂) and patients were asked about supplemental oxygen. Functional capacity was determined using a standardized 6-minute walk test and a maximum oxygen consumption as measured by a formal cardiopulmonary exercise test.

Follow-up testing was performed between 6 and 12 months postoperatively. Follow-up data on quality of life was collected by telephone interview or at the time of clinic visit. Data were analyzed using the STATView for Windows Version 5.01 (SAS Institute, Inc, Cary, NC). Statistical analysis consisted of paired or unpaired Student’s t tests for continuous variables and a ² contingency table or Fisher’s exact test for discrete variables. Data are expressed as the mean plus or minus one standard deviation. A p value of less than 0.05 was considered to be significant

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Thoracoscopic LVR was performed on 682 patients (415 male, 267 female) at one of five participating institutions between February 1993 and July 1998. Patient age ranged from 36 to 87 years (mean, 64 years). In 344 patients BTLVR was undertaken, whereas in 338 patients unilateral thoracoscopic lung volume reduction (253 right lung, 85 left lung) was performed. The majority of the BTLVR patients underwent simultaneous reduction of both lungs during a single operation; however, 72 patients underwent a staged procedure with an interval of 1 to 43 months between procedures (mean, 9.5 months). Only the results after the second procedure are reported.

Preoperative patient characteristics for both groups are noted (Table 1). There were significant clinical differences between the bilateral and unilateral patients. Unilateral patients were more hypoxic (PO₂, 65.3 ± 11 vs 69.7 ± 12, p < 0.0001) and were older (65.4 ± 8.1 years, vs 62.6 ± 8 years, p < 0.0001). This higher incidence of hypoxemia was corroborated by a higher supplemental oxygen requirement in the unilateral group (66% vs 58%), a difference that approached significance (p = 0.09). The 6-minute walk distance was also lower in the unilateral group (815 ± 338 vs 933 ± 312, p < 0.0001.). Unilateral patients had a higher percentage of diffuse or homogenous emphysema (46% vs 32%, p < 0.001).

Aggregate preoperative and postoperative measurements are shown for both groups in Tables 2 and 3. Both procedures showed statistically significant improvement in all measurements except · VO₂ (mL/min/kg). Postoperative differences between UTLVR and BTLVR are illustrated as percent change and are shown in Table 4. Statistically significant differences were found in FVC (L), FVC (% predicted), FEV₁, FEV₁ (% predicted), RV(L), RV(% predicted). Quality of life evaluation showed the bilateral group to have a significant improvement in quality of life and feeling better than before surgery (Table 5). There was no difference in opinion as to whether these patients would have the operation again or the decrease in oxygen utilization and related rehospitalizations.

The mean values for percent change reflect superior results in the BTLVR group with regard to actual and predicted spirometric results (FVC, FEV, and RV). It is interesting to note, however, that the overall improvement in PO₂ and 6-minute walk were similar in the two groups, suggesting relatively equal functional improvement.

Attempts were made to contact each patient in person or by phone: to inquire regarding their self-assessment of heath. The patients were asked five questions concerning their postoperative quality of life status: (1) Did the operation improve your overall quality of life? (2) Are you breathing better now than before the operation? (3) If you had it to do over again, would you have the operation? (4) Have you decreased your oxygen use since the operation? (5) Have you had a respiratory-related hospitalization since the operation?

The answers for the two groups are compared in Table 5. The BTLVR group self-reported a higher incidence of improved quality of life and dyspnea relief. There were no significant differences in the other variables.

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
When thoracoscopic lung volume reduction was first undertaken, it was performed unilaterally with the intention to proceed with contralateral lung reduction in a staged fashion. Soon afterward McKenna and colleagues [1] reported that patients undergoing UTLVR had significantly reduced 1-year survival compared with that of BTLVR patients. The analyzed data from 166 consecutive patients undergoing either UTLVR or BTLVR and noted no difference in operative mortality or morbidity between the groups. Oxygen dependence was eliminated in 68% of the BTLVR cohort in comparison with 36% of UTLVR patients (p < 0.01); BTLVR also produced significantly greater improvements in measured spirometry. After this report, most of the surgical investigators switched to a BTLVR approach. It was not only the data of McKenna and colleagues, however, but also the data of other investigators that suggested that bilateral procedures produced spirometric improvement superior to that of unilateral procedures [5].

However, there have also been some contradictory results published. Argenziano and coworkers [3] reported similar dyspnea relief when comparing unilateral LVR (both thoracoscopic and open) to bilateral (open) LVR. They also noted no advantage when 6-minute walk results were compared. Our own initial report [6] on UTLVR demonstrated increments in PO₂ and 6-minute walk results similar to those reported by Cooper and colleagues [2] with an open bilateral approach.

We undertook this analysis in an attempt to sort out these controversial issues to determine whether either the unilateral or bilateral thoracoscopic lung volume reduction could be demonstrated to yield superior results in all facets of clinical outcome. Surprisingly, the results appear mixed. Performance of BTLVR seems to yield superior results with regard to improvements in FEV₁, FVC, and RV. This correlates with a greater frequency of quality of life improvement as self-reported by patients. However, there appears to be no corresponding improvement in PO₂, oxygen use, or functional capacity. Although on the surface these results seem somewhat contradictory, there may be some physiologic explanation, as yet unrecognized, that may reconcile and explain these findings.

Do the results suggest that BTLVR is the optimal strategy and should be performed in all candidates? Certainly indications for UTLVR remain, including the likelihood of unilateral pleural adhesions or symphysis secondary to empyema, pleurodesis, or prior thoracotomy. Our results would suggest that such patients can and should undergo UTLVR with a reasonable expectation of significant clinical improvement.

There is also the question of operative risk. Although McKenna and colleagues [1] state that the operative mortality was virtually identical in the UTLVR and BTLVR cohorts, not all investigators agree. Our own previous report [7] demonstrated that the bilateral thoracoscopic approach was an independent risk factor for operative mortality. Cooper and colleagues [8] have also commented that their unilateral mortality is less than half of that found in their bilateral open lung volume reduction patients. It may be that there is a subset of elderly high-risk patients who would be better served with a unilateral procedure that minimizes operative morbidity yet provides for improved clinical outcome.

Finally, the issue of the continued decline in pulmonary function after lung volume reduction has been raised. Brenner and coworkers recently reported an interesting comparison of the rate of decline of spirometric values after bilateral (simultaneous) and unilateral lung volume reduction [9]. They found that although short-term incremental improvement after bilateral LVR procedures was superior to that after a unilateral operation, the long-term rate of decline in FEV₁ was greater in the bilateral group than the unilateral group. These findings call into question the optimal strategy for obtaining the 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 or functional status than a bilateral simultaneous approach? Further data regarding progressive postoperative deterioration of lung function will have to be obtained to confirm or refute this theory. It is important to realize that we do not currently have adequate data to determine the optimal operative strategy for all patients.

We recognize that there are limitations inherent in this study. The two patient cohorts are not perfectly matched in that the UTLVR patients were older, had more homogeneous disease, lower PO₂ levels, and inferior 6-minute walk scores. Perhaps some of these patients had disease so far advanced that they had little hope of improvement regardless of the procedure performed. It is also of note that the UTLVR patients were operated on early in each investigator’s experience, thus providing, perhaps, a negative "learning curve" effect. Probably the most significant limitation is the incomplete following achieved with this retrospective approach. Nearly one-third of the patients had no follow-up spirometry, one-half were missing the postoperative 6-minute walk, and two-thirds had no postoperative arterial blood gas for comparison. Although missing patients were fairly evenly distributed in the bilateral and unilateral groups, the potential for inappropriate conclusions exists if the missing patients are clinically skewed toward poor results in one group or the other. Also, the possibility exists that the missing patients were so dissatisfied or disabled that they chose not to return to follow-up. This would result in an artificially "rosy" clinical outcome in the patients reported.

As with many such studies, our report raises more questions then it answers. Does dyspnea relief correlate more with spirometric changes then with exercise capacity or oxygen levels? Is BTLVR the optimal strategy for all patients? Should staged UTLVR be considered as an alternative in fragile high-risk patients? Hopefully, the randomized trials currently underway in the United States, the United Kingdom, and Canada will help answer some of these questions allow us to understand better the physiology of emphysema and lung volume reduction operation, thereby helping us to find the right answers.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. McKenna R.I., 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. 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]
3. Argenziano M., Thomashow B., Jellen P.A., et al. Functional comparison of unilateral versus bilateral long volume reduction surgery. Ann Thorac Surg 1997;64:321-327.[Abstract/Free Full Text]
4. Naunheim K.S., Kaiser G.R., Bavaria J.E., et al. Long term survival following thoracoscopic lung volume reduction. Ann Thorac Surg 1999;68:2026-2031.[Abstract/Free Full Text]
5. Krucylak P.E., Keller C.A., Naunheim K.S. Current status of thoracoscopic lung volume reduction. World J Surg 1999;23:1148-1155.[Medline]
6. Naunheim K.S., Keller C.A., Krucylak P.E., Singh A., Ruppel G., Osterloh J.F. Unilateral video-assisted thoracic surgical lung reduction. Ann Thorac Surg 1996;61:1092-1098.[Abstract/Free Full Text]
7. Naunheim KS, Hazelrigg SR, Kaiser LR, et al. Risk analysis for thoracoscopic lung volume reduction: a multi-institutional experience. Eur J Cardiothorac Surg 2000; (in press).
8. Cooper J.D., Naunheim K.S., Kaiser O.R., Bavaria J.E., et al. Long-term survival following thoracoscopic lung volume reduction. A multi-institutional experience. Ann Thorac Surg 1999;68:2026-2031.
9. Brenner M., McKenna R.J., Gelb A.T., Fischel R.J., Wilson A.F. Rate of FEV, change following lung volume. Chest 1998;113:652-659.[Abstract/Free Full Text]

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