title: Reduced dynamic hyperinflation after LVRS is associated with improved exercise tolerance.
abstract: BACKGROUND
  Dynamic hyperinflation (DH) after lung volume reduction surgery (LVRS) has not been well studied. It is not known if reductions in DH correlate with improvements in exercise performance post-LVRS.
  
  
  METHODS
  Forty-two upper-lobe predominant emphysema patients who underwent LVRS were analyzed. Inspiratory capacity was measured every 2 min during symptom-limited cardiopulmonary exercise test (CPET) and end-expiratory lung volumes (EELV) were calculated. The main measure of DH was EELV/TLC ratio matched at metabolic isotimes (based on the post-rehabilitation VCO2max).
  
  
  RESULTS
  Patients had very severe airflow obstruction (FEV1 28.3 ± 7.0% predicted), were hyperinflated (TLC 125 ± 17% predicted) and gas trapped (RV 198 ± 39% predicted). Compared to the post-rehab baseline, dynamic hyperinflation (EELV/TLC) was significantly reduced after LVRS at 6, 12, 24, and 36 months. There were also increases in inspiratory reserve volume at matched isotimes after surgery. Patients adopted a slower, deeper breathing pattern during exercise after LVRS, which strongly correlated to reductions in DH. There were significant correlations between reductions in DH (EELV/TLC @50% VCO2max) and improvements in 6 min walk distance (Pearson r = -0.411, p = 0.02, n = 33) and maximal watts on CPET (Spearman r = -0.536, p = 0.001, n = 33) when comparing post-rehabilitation and 6 month post-LVRS values.
  
  
  CONCLUSIONS
  Dynamic hyperinflation during exercise was reduced after LVRS (up to 3 years) and there was a strong association between alterations in breathing pattern and reduced DH after LVRS. This is the first study to demonstrate that reductions in DH correlated with improved exercise performance following LVRS.
authors.affiliation: Louisiana State University Health Sciences Center, New Orleans, LA, United States. Electronic address: mlammi@lsuhsc.edu.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Lammi
authors.affiliation: Temple University School of Medicine, Philadelphia, PA, United States.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Marchetti
authors.affiliation: Temple University School of Medicine, Philadelphia, PA, United States.
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Criner
mesh_terms: D000368:Aged; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011013:Pneumonectomy / Q000379:methods; D011656:Pulmonary Emphysema / Q000601:surgery*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D014109:Total Lung Capacity / Q000502:physiology
keywords: COPD; Cardiopulmonary exercise testing; Dynamic hyperinflation; LVRS