title: Decreased Hypercapnic Ventilatory Response in Long-Term Lung Transplant Recipients is Associated with Exercise Impairment.
abstract: Bilateral lung transplantation results in complete denervation of the lung and might impair hypercapnic ventilatory response (HCVR). However, experimental and clinical findings are scarce and conflicting. Therefore, this study investigated the relationship between HCVR and exercise capacity after long-term bilateral lung transplantation.
  
  
  
  This cross-sectional analysis enrolled 46 bilateral lung transplant recipients between October 2011 and July 2012 who underwent cardiopulmonary exercise testing to evaluate maximum workload, and carbon dioxide (CO2) rebreathing. CO2 rebreathing was also evaluated in 35 control subjects.
  
  
  
  In lung transplant recipients age was 54 ± 11 years, body mass index (BMI) 25.4 ± 4.1 kg/m(2), and time after transplantation 4.5 ± 2.5 years (range 9 months to 10 years). Controls were aged 41 ± 12 years and had a BMI of 24.9 ± 4.0 kg/m(2). There were significant differences between lung transplant recipients and controls in forced expiratory volume in 1 s (76 ± 22 vs. 94 ± 12 % predicted, p < 0.001) and inspiratory vital capacity (91 ± 20 vs. 105 ± 14 % predicted, p = 0.001). Blood gases did not differ significantly in patients versus controls. HCVR in lung transplant recipients was 1.44 ± 1.07 L/min/mmHg compared with 2.09 ± 1.14 L/min/mmHg in controls (p = 0.001). Exercise capacity in lung transplant recipients (73 ± 24 W) was 49 % predicted. Linear regression analysis showed that exercise capacity was significantly associated with HCVR. A 1 L/min/mmHg decrease in HCVR decreased exercise capacity by 50 W.
  
  
  
  HCVR is reduced in long-term bilateral lung transplant recipients and this might explain the observed impairment of exercise capacity.
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany. manuela.scherer@rlk.uk-essen.de.
authors.forename: Manuela J
authors.initials: MJ
authors.lastname: Scherer
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Weinreich
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Bjoern E
authors.initials: BE
authors.lastname: Kleibrink
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rabis
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, West German Heart Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Kamler
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Teschler
authors.affiliation: Department of Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany.|Department of Pneumology, St. Vinzenz Hospital Braunschweig, Brunswick, Germany.
authors.forename: Urte
authors.initials: U
authors.lastname: Sommerwerck
mesh_terms: D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D016040:Lung Transplantation; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014797:Vital Capacity
chemical_list: D002245:Carbon Dioxide
keywords: Control of breathing; Hypercapnic respiratory drive; Lung transplantation