title: Lung deflation and oxygen pulse in COPD: results from the NETT randomized trial.
abstract: BACKGROUND
  In COPD patients, hyperinflation impairs cardiac function. We examined whether lung deflation improves oxygen pulse, a surrogate marker of stroke volume.
  
  
  METHODS
  In 129 NETT patients with cardiopulmonary exercise testing (CPET) and arterial blood gases (ABG substudy), hyperinflation was assessed with residual volume to total lung capacity ratio (RV/TLC), and cardiac function with oxygen pulse (O(2) pulse=VO(2)/HR) at baseline and 6 months. Medical and surgical patients were divided into "deflators" and "non-deflators" based on change in RV/TLC from baseline (∆RV/TLC). We defined deflation as the ∆RV/TLC experienced by 75% of surgical patients. We examined changes in O(2) pulse at peak and similar (iso-work) exercise. Findings were validated in 718 patients who underwent CPET without ABGs.
  
  
  RESULTS
  In the ABG substudy, surgical and medical deflators improved their RV/TLC and peak O(2) pulse (median ∆RV/TLC -18.0% vs. -9.3%, p=0.0003; median ∆O(2) pulse 13.6% vs. 1.8%, p=0.12). Surgical deflators also improved iso-work O(2) pulse (0.53 mL/beat, p=0.04 at 20 W). In the validation cohort, surgical deflators experienced a greater improvement in peak O(2) pulse than medical deflators (mean 18.9% vs. 1.1%). In surgical deflators improvements in O(2) pulse at rest and during unloaded pedaling (0.32 mL/beat, p<0.0001 and 0.47 mL/beat, p<0.0001, respectively) corresponded with significant reductions in HR and improvements in VO(2). On multivariate analysis, deflators were 88% more likely than non-deflators to have an improvement in O(2) pulse (OR 1.88, 95% CI 1.30-2.72, p=0.0008).
  
  
  CONCLUSIONS
  In COPD, decreased hyperinflation through lung volume reduction is associated with improved O(2) pulse.
authors.affiliation: Pulmonary and Critical Care Division, Brigham and Women's Hospital, Boston, MA 02115, USA. ccome@partners.org
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Come
authors.forename: Miguel J
authors.initials: MJ
authors.lastname: Divo
authors.forename: Raúl
authors.initials: R
authors.lastname: San José Estépar
authors.forename: Frank C
authors.initials: FC
authors.lastname: Sciurba
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Criner
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Marchetti
authors.forename: Steven M
authors.initials: SM
authors.lastname: Scharf
authors.forename: Zab
authors.initials: Z
authors.lastname: Mosenifar
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Keller
authors.forename: Omar A
authors.initials: OA
authors.lastname: Minai
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.forename: MeiLan K
authors.initials: MK
authors.lastname: Han
authors.forename: John J
authors.initials: JJ
authors.lastname: Reilly
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D015331:Cohort Studies; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption; D011013:Pneumonectomy; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D013318:Stroke Volume; D014109:Total Lung Capacity