Chest
Volume 110, Issue 1, July 1996, Pages 18-27
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Clinical Investigations: Lung Volume Reduction Surgery
Mechanisms of Relief of Exertional Breathlessness Following Unilateral Bullectomy and Lung Volume Reduction Surgery in Emphysema

https://doi.org/10.1378/chest.110.1.18Get rights and content

Study objective

To explore mechanisms of relief of exertional breathlessness following surgery to reduce thoracic gas volume in patients with emphysema.

Materials and methods

We studied 8 patients with emphysema (FEV1=39±3% predicted; residual volume [RV]=234 ± 12% predicted; mean±SEM) who were severely breathless despite optimal pharmacotherapy and who underwent unilateral bullectomy for giant bullae (greater than one third hemithorax); 4 of these also had ipsilateral lung reduction (pneumectomy). Pulmonary function and cycle exercise performance (n=6) were evaluated before and 13 ± 3 weeks after surgery. Chronic breathlessness was measured with the Baseline Dyspnea Index and the Medical Research Council dyspnea scale. Exertional breathlessness was measured using Borg ratings at a standardized work rate (BorgSTD).

Results

FEV1, FVC, and maximal inspiratory pressures increased postsurgery by 29 ± 7% (p<0.05), 24 ± 10% (p=0.06), and 39 ± 12% (p<0.01), respectively. Plethysmographic total lung capacity, RV, and functional residual capacity fell by 14±2%, 30±4%, and 18±3%, respectively (p<0.001). All measures of chronic breathlessness improved significantly (p<0.05). During exercise at a standardized work rate, BorgSTD fell 45% (p<0.05), end-expiratory lung volume (EELV) fell 22% (p<0.01), and breathing frequency (F) fell 25% (p=0.08). By multiple stepwise regression analysis, 99% (p=0.007) of the variance in symptom relief (ABorgSTD) was explained by the combination of decreased ratio of the end-expiratory lung volume to total lung capacity, decreased F, and diminished mechanical constraints on tidal volume (tidal volume to vital capacity ratio).

Conclusion

Reduced exertional breathlessness at a given workload after volume reduction surgery was attributed to a combination of reduced thoracic hyperinflation, reduced F, and reduced mechanical constraints on lung volume expansion.

Section snippets

Subjects

Eight consecutive patients (Table 1) with clinically stable, severe emphysema10 and disabling chronic exertional breathlessness participated in the study after providing informed consent. Selection criteria for surgery (bullectomy and pneumectomy) included the following: (1) unilateral large well-demarcated bullae (> one third hemithorax); (2) anatomic emphysema and visible compression of adjacent lung tissue on CT scan of the thorax; (3) severe breathlessness despite optimization of

RESULTS

Serious complications were encountered in the early postoperative period in only 1 patient who developed pneumonia and required prolonged (6 weeks) treatment in the ICU. This patient eventually made a full recovery. Persistent air leaks (3 to 7 days) were encountered in 3 of the patients. Follow-up evaluations of breathlessness, pulmonary function, and exercise performance were conducted 13±3 weeks after surgery. Two subjects were operated on before completing their presurgery exercise test;

DISCUSSION

Surgery effectively ameliorated activity-related breathlessness as measured by self-rated and observerrated questionnaires, and by standardized Borg ratings during cycle ergometry. The magnitude of benefit was substantial and comparable with that achieved by an 8-week exercise reconditioning program in patients with similar baseline pathophysiologic derangements.24 In general, our results are in keeping with the few previous studies that have used validated instruments to measure exertional

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