title: The Coupling of Peripheral Blood Pressure and Ventilatory Responses during Exercise in Young Adults with Cystic Fibrosis.
abstract: OBJECTIVE
  Cystic fibrosis (CF) is commonly recognized as a pulmonary disease associated with reduced airway function. Another primary symptom of CF is low exercise capacity where ventilation and gas-exchange are exacerbated. However, an independent link between pathophysiology of the pulmonary system and abnormal ventilatory and gas-exchange responses during cardiopulmonary exercise testing (CPET) has not been established in CF. Complicating this understanding, accumulating evidence suggests CF demonstrate abnormal peripheral vascular function; although, the clinical implications are unclear. We hypothesized that compared to controls, relative to total work performed (WorkTOT), CF would demonstrate increased ventilation accompanied by augmented systolic blood pressure (SBP) during CPET.
  
  
  METHODS
  16 CF and 23 controls (age: 23±4 vs. 27±4 years, P = 0.11; FEV1%predicted: 73±14 vs. 96±5, P<0.01) participated in CPET. Breath-by-breath oxygen uptake ([Formula: see text]), ventilation ([Formula: see text]), and carbon dioxide output ([Formula: see text]) were measured continuously during incremental 3-min stage step-wise cycle ergometry CPET. SBP was measured via manual sphygmomanometry. Linear regression was used to calculate [Formula: see text] slope from rest to peak-exercise.
  
  
  RESULTS
  Compared to controls, CF performed less WorkTOT during CPET (90±19 vs. 43±14 kJ, respectively, P<0.01). With WorkTOT as a covariate, peak [Formula: see text] (62±8 vs. 90±4 L/min, P = 0.76), [Formula: see text] (1.8±0.3 vs. 2.7±0.1 L/min, P = 0.40), and SBP (144±13 vs. 152±6 mmHg, P = 0.88) were similar between CF and controls, respectively; whereas CF demonstrated increased [Formula: see text] slope (38±4 vs. 28±2, P = 0.02) but lower peak [Formula: see text] versus controls (22±5 vs. 33±4 mL/kg/min, P<0.01). There were modest-to-moderate correlations between peak SBP with [Formula: see text] (r = 0.30), [Formula: see text] (r = 0.70), and [Formula: see text] (r = 0.62) in CF.
  
  
  CONCLUSIONS
  These data suggest that relative to WorkTOT, young adults with mild-to-moderate severity CF demonstrate augmented [Formula: see text] slope accompanied by increased SBP during CPET. Although the underlying mechanisms remain unclear, the coupling of ventilatory inefficiency with increased blood pressure suggest important contributions from peripheral pathophysiology to low exercise capacity in CF.
authors.affiliation: Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America.
authors.forename: Erik H
authors.initials: EH
authors.lastname: Van Iterson
authors.affiliation: Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America.|College of Pharmacy, University of Arizona, 1295 N Martin Ave, Tucson, AZ, United States of America.
authors.forename: Courtney M
authors.initials: CM
authors.lastname: Wheatley
authors.affiliation: College of Pharmacy, University of Arizona, 1295 N Martin Ave, Tucson, AZ, United States of America.|Department of Anesthesiology, Mayo Clinic, Rochester, MN, United States of America.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Baker
authors.affiliation: Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Olson
authors.affiliation: Department of Pediatrics, University of Arizona, 1501 N. Campbell Avenue, Room 3301, Tucson, AZ, United States of America.
authors.forename: Wayne J
authors.initials: WJ
authors.lastname: Morgan
authors.affiliation: College of Pharmacy, University of Arizona, 1295 N Martin Ave, Tucson, AZ, United States of America.|Department of Kinesiology, University of Minnesota, Cooke Hall, 1900 University Ave SE. Minneapolis, MN, United States of America.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Snyder
mesh_terms: D000328:Adult; D001794:Blood Pressure; D003550:Cystic Fibrosis / Q000503:physiopathology*; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D011659:Pulmonary Gas Exchange