title: Dynamic lung mechanics in late-stage emphysema before and after lung volume reduction surgery.
abstract: This study evaluated the effects of lung volume reduction surgery (LVRS) on the heterogeneity of lung function in awake, late-stage emphysema patients with measurements taken before and after full recovery from LVRS. We assessed standard clinical measures of lung function and functional heterogeneity in six awake, late-stage emphysema patients before and 6 months after LVRS. Functional heterogeneity was quantified by measuring dynamic inspiratory resistance (R(L)(insp)) and elastance (E(L)(insp)) over a frequency range that included normal breathing ( approximately 0.33-8 Hz). Since LVRS involves targeted resection of emphysematous regions of the lung, we hypothesized that emphysema patients would be functionally more homogeneous post-LVRS. We also compared our measures of functional heterogeneity with indices of anatomic heterogeneity and severity using high-resolution computed tomography (HRCT). After LVRS, 6 min walk distance increased by 22% (940+/-91 versus 1158+/-299, p=0.031) and recoil pressure at TLC increased (9.0+/-2.0 versus 14+/-5, p=0.031), but changes in R(L)(insp) and E(L)(insp) varied greatly between subjects. A measure of anatomic severity quantified using HRCT positively correlated with airway resistance (r(s)=0.89, p=0.048). These results suggest that subjects with more severe disease as assessed by HRCT criteria had reduced overall effective airway caliber consequent to active airway constriction, reduced parenchymal tethering, and/or loss of parallel lung units. Furthermore, LVRS may not necessarily improve lung function via a substantial reduction in mechanical heterogeneity.
authors.affiliation: Department of Biomedical Engineering, Boston University, 44 Cummington St., Boston, MA 02215, United States. achenderson@ucsd.edu <achenderson@ucsd.edu>
authors.forename: A Cortney
authors.initials: AC
authors.lastname: Henderson
authors.forename: Edward P
authors.initials: EP
authors.lastname: Ingenito
authors.forename: Edgardo S
authors.initials: ES
authors.lastname: Salcedo
authors.forename: Marilyn L
authors.initials: ML
authors.lastname: Moy
authors.forename: John J
authors.initials: JJ
authors.lastname: Reilly
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Lutchen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance; D000465:Algorithms; D003627:Data Interpretation, Statistical; D004548:Elasticity; D004646:Emphysema / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology; D015656:Respiratory Mechanics / Q000502:physiology*; D014057:Tomography, X-Ray Computed