Preoperative Severity of Emphysema Predictive of Improvement After Lung Volume Reduction Surgery: Use of CT Morphometry

doi:10.1378/chest.118.5.1240

Chest

Volume 118, Issue 5, November 2000, Pages 1240-1247

https://doi.org/10.1378/chest.118.5.1240 Get rights and content

Study objective

To determine how the volume andseverity of emphysema measured by CT morphometry (CTM) before and afterlung volume reduction surgery (LVRS) relates to the functional statusof patients after LVRS.

Design

A histologicallyvalidated CT algorithm was used to quantify the volume and severity ofemphysema in 35 patients before and after LVRS: total lung volume(TLV), normal lung volume (< 6.0 mL gas per gram of tissue), volumeof mild/moderate emphysema (ME; 6.0 to 10.2 mL gas per gram of tissue),volume of severe emphysema (> 10.2 mL gas per gram of tissue),surface area/volume (SA/V; meters squared per milliliter), and surfacearea (SA; meters squared). Outcome parameters included maximalcardiopulmonary exercise (CPX) performance in 21 patients and routinepulmonary function in all patients. We hypothesized that baseline CTMparameters predict response to LVRS and that the change in theseparameters may offer insight into mechanisms of improvement.

Patients and intervention

Thirty-five patients withsevere emphysema who had successful LVRS.

Results

Thesignificant decrease in TLV following LVRS was entirely accounted forby a decrease in severe emphysema. The SA/V and the SA both increasedsignificantly following LVRS. The change in maximal CPX in wattsfollowing surgery correlated significantly with baseline values ofsevere emphysema (r = 0.60), which was collinear withTLV, and SA/V. The change in diffusing capacity of the lung for carbonmonoxide revealed a significant positive linear relationship withpreoperative severe emphysema (r = 0.37) and anegative relationship with ME (r = −0.37). Change inwatts revealed a strong relationship with changes in severe emphysema(r = −0.75) and weaker but significant relationshipswith change in TLV, ME, SA/V, and SA. Other measures of pulmonaryfunction revealed significant albeit less dominant relationships withbaseline CTM and change in these indexes.

Conclusion

Using CTM, we have identified a close relationship between baselinesevere emphysema, or change in severe emphysema, and the improvement inCPX after LVRS. These observations support a potential role of CTM infuture clinical trials for predicting responders to LVRS andidentifying mechanisms of improvement.

Section snippets

Patient Selection

The procedures used in this study were approved by theInstitutional Review Board of the University of Pittsburgh MedicalCenter. All of the patients signed informed consent forms that allowedthe use of physiologic data, CT scans, and the surgically resectedtissue. Patient selection criteria have been publishedelsewhere.³ CT was obtained on all patients and was usedto identify surgically accessible emphysematous lesions and to excludepatients with diffuse disease using standard visual assessment.

Patient Characteristics and Physiologic Response to LVRS

Patient characteristics and physiologic indexes before and afterLVRS for the total group of 35 patients (group T) are shown in Table 1. At 3 months after surgery, group T demonstrated statisticallysignificant improvement in FVC, FEV₁, RV, TLC,and functional residual capacity (FRC), but no significant changes werefound in the Dlco.

In group E, physiologic variables responded similarly to group Tfollowing surgery. The characteristics and maximal cycle ergometrywatts before and after LVRS of the

Discussion

LVRS for end-stage emphysema was introduced > 40 yearsago.¹ The physiologic basis for the surgery wassound,¹⁵ and while it was shown to improve airwayconductance postoperatively,¹⁶ this change wastransient¹⁷ and the mortality was high.²Several articles have rekindled interest in the procedure and reportimprovement in physiologic parameters such asFEV₁, FVC, FRC, RV, TLC,⁴¹⁰¹⁸ andlung elastic recoil,³¹⁹²⁰ as well as lower surgicaloperative mortality. Other fundamental physiologic changes

ACKNOWLEDGMENT

The authors wish to express our sincere thanks toLaurie Silfies, who coordinated the data analysis, ClaudeLavalleée who prepared the manuscript, William Slivka, whoconducted the physiologic testing, William Bradford Rogers, who helpedin many important ways to get this study completed, and a specialthanks to Dr. Carl Fuhrman, for his thoughtful suggestions.

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This application of quantitative CT helps in selecting candidates for lung volume reduction surgery (LVRS) and provides insights into the mechanisms of improvement after LVRS. In a subgroup of 21 patients with severe COPD who underwent LVRS, postoperative changes in FEV1 and maximal exercise capacity correlated with extent of preoperative emphysema of the whole lung [60,62,63] and the upper [62], and upper-rind regions of the lungs [60]. The volume reduction in regions with severe emphysema [63] or with confluent emphysema [62] has been cited as a mechanism of improvement after LVRS.
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: Supported by a grant from the George H. Love research fund.

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Chest

Clinical InvestigationsSurgeryPreoperative Severity of Emphysema Predictive of Improvement After Lung Volume Reduction Surgery: Use of CT Morphometry

Study objective

Design

Patients and intervention

Results

Conclusion

Section snippets

Patient Selection

Patient Characteristics and Physiologic Response to LVRS

Discussion

ACKNOWLEDGMENT

Chest

Clin Chest Med

Med Clin North Am

Chest

Chest

Chest

Clin Chest Med

Chest

Lancet

Chest

Surgical treatment of pulmonary emphysema

Am Surg

The surgical approach to pulmonary emphysema

Dis Chest

Improvement in pulmonary function and elastic recoil after lung-reduction surgery for diffuse emphysema

N Engl J Med

Bilateral pneumectomy (volume reduction) for chronic obstructive pulmonary disease

J Thorac Cardiovasc Surg

Pulmonary emphysema: subjective visual grading versus objective quantification with macroscopic morphometry and thin section CT densitometry

Radiology

Pulmonary emphysema: comparison of preoperative quantitative CT and physiologic index values with clinical outcome after lung-volume reduction surgery

Radiology

Clinical Investigations
Surgery
Preoperative Severity of Emphysema Predictive of Improvement After Lung Volume Reduction Surgery: Use of CT Morphometry