title: The global peripheral chemoreflex drive in patients with systemic sclerosis: a rebreathing and exercise study.
abstract: BACKGROUND
  Exercise intolerance (EI) in systemic sclerosis (SSc) is difficult to manage by the clinician. The peripheral chemoreflex drive compensates for metabolic acidosis during exercise and may be related to EI.
  
  
  OBJECTIVE
  To assess the global peripheral chemoreflex drive (GPCD) in patients with SSc at rest and during exercise.
  
  
  METHODS
  Consecutively tested SSc patients (n = 49) were evaluated by pulmonary function tests, carbon dioxide (CO2) rebreathing studies and non-invasive cardiopulmonary exercise testing (CPET). Results of their CO2 rebreathing tests were compared with those of controls (n = 32). Respiratory compensation for metabolic acidosis during CPET was defined by the occurrence of a sharp increase in minute ventilation (VdotE) and the ventilatory equivalent for CO2 (V'E and V'CO2) at the end of the isocapnic buffer phase. Euoxic (eVHR) and hyperoxic (hVHR) ventilatory responses to hypercapnia were measured and its difference (eVHR - hVHR) was considered to reflect the GPCD.
  
  
  RESULTS
  In 45 patients with SSc, CPET results showed respiratory compensation at the occurrence of metabolic acidosis. eVHR - hVHR in patients with diffuse cutaneous SSc (dcSSc) differed significantly from that in patients with limited cutaneous SSc (lcSSc) and from that in controls (0.47 ± 0.38 (dcSSc) vs. 0.90 ± 0.77 (lcSSc) and 0.90 ± 0.49 (controls) l/min/mmHg; P = 0.04 and P = 0.03, respectively).
  
  
  CONCLUSIONS
  Respiratory compensation for metabolic acidosis occurred in all patients. However, the GPCD was diminished in dcSSc patients, suggesting an altered control of breathing. Its assessment may help the clinician to better understand reported EI and exertional dyspnea in dcSSc patients.
authors.affiliation: From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands m.k.ninaber@lumc.nl.
authors.forename: M K
authors.initials: MK
authors.lastname: Ninaber
authors.affiliation: From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands.
authors.forename: W B G J
authors.initials: WB
authors.lastname: Hamersma
authors.affiliation: From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Schouffoer
authors.affiliation: From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands.
authors.forename: E F A
authors.initials: EF
authors.lastname: van 't Wout
authors.affiliation: From the Department of Pulmonology, Department of Rheumatology, Leiden University Medical Center, Leiden and Department of Rheumatology, HAGA Hospital The Hague, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Stolk
mesh_terms: D000138:Acidosis / Q000209:etiology / Q000503:physiopathology; D000368:Aged; D016022:Case-Control Studies; D002628:Chemoreceptor Cells / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012018:Reflex / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods; D012595:Scleroderma, Systemic / Q000150:complications / Q000503:physiopathology*