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Lung Elastic Recoil Does Not Correlate With Pulmonary Hemodynamics in Severe Emphysema^*

^* From the Division of Pulmonary and Critical Care Medicine (Dr. Falk), Department of Medicine, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA; the Division of Pulmonary and Critical Care Medicine (Drs. Martin and Criner), Department of Medicine, Temple University School of Medicine, Philadelphia, PA; and Division of Pulmonary and Critical Care Medicine (Dr. Scharf), Department of Medicine, University of Maryland School of Medicine, Baltimore, MD.

Correspondence to: Jeremy A. Falk, MD, 8700 Beverly Blvd, Room 6732, Los Angeles, CA 90048; e-mail: falkja{at}cshs.org

Abstract

Background: It has been postulated that right ventricular (RV) function may improve after lung volume reduction surgery (LVRS) for severe emphysema due to improvement in lung elastic recoil. Improved lung elastic recoil after LVRS is hypothesized to "tether" open extraalveolar vessels, thereby leading to a decrease in pulmonary vascular resistance (PVR) and improved RV function. Whether a relationship exists between static elastic lung recoil and pulmonary hemodynamics in severe emphysema, however, is unknown.

Methods: We prospectively studied 67 patients with severe emphysema (32 women; mean age, 65.3 ± 6.6 years [SD]; mean FEV₁, 0.79 ± 0.25 L) who had hyperinflation (total lung capacity [TLC], 122.5 ± 12.3% of predicted) and gas trapping (residual volume, 209.1 ± 41.1% of predicted), and were referred to the National Emphysema Treatment Trial. Lung elastic recoil was measured both at TLC (coefficient of retraction [CR]) and at functional reserve capacity (CR at functional residual capacity [CRFRC]) in each patient.

Results: CR and CRFRC values were 1.3 ± 0.6 cm H₂O/L and 0.61 ± 0.5 cm H₂O/L, respectively. Hemodynamic measurements revealed a pulmonary artery (PA) systolic pressure of 35.9 ± 8.9 mm Hg, mean PA pressure of 24.8 ± 5.6 mm Hg, and PVR of 174 ± 102 dyne * s * cm^–5. No significant correlations were found between CR and PVR (R = – 0.046, p = 0.71), PA systolic pressure (R = 0.005, p = 0.97), or mean PA pressure (R = – 0.028, p = 0.82). Additionally, no significant correlations were found between CRFRC and PVR (R = – 0.002, p = 0.99), PA systolic pressure (R = – 0.062, p = 0.62), or mean PA pressure (R = – 0.041, p = 0.74).

Conclusions: We conclude there is no correlation between lung elastic recoil and pulmonary hemodynamics in severe emphysema, suggesting that elastic lung recoil is not an important determinant of secondary pulmonary hypertension in this group. Registered with www. clinicaltrials.gov, #NCT00000606 [ClinicalTrials.gov] .

Key Words: compliance • COPD • pulmonary circulation • pulmonary hypertension