title: Dynamic vs. fixed bag filling: impact on cardiac output rebreathing protocol.
abstract: The purpose of this study was to compare the repeatability (2.77 multiplied by the within-subject SD)between two different rebreathing protocols on cardiac output ( ˙Q ), pulmonary diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), and pulmonary capillary blood volume (Vc). This study compared two bag volume protocols [Fixed Bag Volume (FBV) = bag volume fixed at 60% of forced vital capacity; Dynamic Bag Volume (DBV) = bag volume matched to tidal volume at each stage of exercise].Ten females (age = 27±8 yrs; ˙VO2, (peak)=2.5±0.6 L/min had measurements at rest (12%), 52%, 88%, and 100% of ˙VO2, (peak) on two study days. Neither the slope nor intercept of ˙Q vs. ˙VO2 were different between either bag volume protocols. The slope of DLCO vs. ˙Q was the same but the intercept was higher for the FBV protocol. The bag volume affected the slope and the intercept between DLNO vs. ˙Q (p < 0.05).The mean repeatability was similar between both protocols for ˙Q (2.0 vs. 2.3 L/min) and DLCO (3.8 vs.5.9 mL/min/mmHg), regardless of exercise intensity. Increasing exercise intensity made the measurement error worse for Vc and DLNO (p ≤ 0.06). Measurement error was lower for Vc when using the FBV protocol (p = 0.02). Also, the pattern of bag volume used during rebreathing maneuvers affected the relation between DLNO vs. ˙Q more than it affected DLCO vs. ˙Q , or Vc vs. ˙Q. Additionally, the FBV protocol provided less measurement error for Vc compared to the DBV protocol [corrected].
authors.affiliation: Department of Obstetrics, Gynecology and Women's Health, School of Medicine, Saint Louis University, Saint Mary's Health Center, Saint Louis MO 63117, USA. zavorsky@slu.edu
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Zavorsky
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Beck
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Cass
authors.forename: Raul
authors.initials: R
authors.lastname: Artal
authors.forename: Peter D
authors.initials: PD
authors.lastname: Wagner
mesh_terms: D000328:Adult; D002248:Carbon Monoxide / Q000097:blood; D002302:Cardiac Output / Q000502:physiology*; D015444:Exercise; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D011653:Pulmonary Diffusing Capacity; D012044:Regression Analysis; D012129:Respiratory Function Tests / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology*; D012146:Rest; D055815:Young Adult
chemical_list: D009569:Nitric Oxide; D002248:Carbon Monoxide; D010100:Oxygen