title: Portable open-circuit spirometry systems.
abstract: BACKGROUND
  The purpose of this review is to describe the evolution of portable open-circuit spirometry systems, and discuss their validity, reliability, and principles of operation.
  
  
  METHODS
  Eleven devices were selected for review: the Oxylog, Aerosport KB1-C, Cosmed K2, Cosmed K4RQ, Cosmed K4b2, MetaMax I, MetaMax II, Metamax3B/VmaxST, Medgraphics VO2000, Oxycon Mobile I and Oxycon Mobile II. The validity (compared to the Douglas bag method [DBM]) and reliability of each device for measuring VO2 was summarized.
  
  
  RESULTS
  Mean differences in resting measurements of VO2 were within ±0.05 L/min for all devices except one (difference of 0.17 L/min). When compared to the DBM, VO2 differences for all devices ranged from 0.01 L/min to 0.29 L/min during submaximal intensity exercise and from 0.01 L/min to 0.36 L/min during vigorous/maximal intensity. During submaximal and maximal intensities, ICC ranged from 0.66-0.99 and CV ranged from 2.0-14.2%. Of these devices, four used breath-by-breath technology and six used micro-proportional sampling technology. Validity and reliability of devices did not seem to differ between methods of gas collection.
  
  
  CONCLUSIONS
  Of the three commercially available devices in 2015, all were found to be reliable. Two of the three systems (Cosmed K4b2 and Oxycon Mobile II) provided valid estimates of VO2 (mean values within ±0.10 L/min of DBM) during rest, and submaximal and maximal intensities, while the MetaMax3B slightly overestimated VO2, particularly at maximal exercise.
authors: Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville, TN, USA - bwilker8@vols.utk.edu.
authors: Brittany S
authors: BS
authors: Overstreet
authors: Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville, TN, USA.
authors: David R
authors: DR
authors: Bassett
authors: Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville, TN, USA.
authors: Scott E
authors: SE
authors: Crouter
authors: Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville, TN, USA.
authors: Brian C
authors: BC
authors: Rider
authors: Department of Exercise and Sports Science, University of South Carolina Aiken, Aiken, SC, USA.
authors: Brian B
authors: BB
authors: Parr
mesh_terms: D005080:Exercise Test / Q000295:instrumentation; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D015203:Reproducibility of Results; D012119:Respiration; D013147:Spirometry / Q000266:history / Q000295:instrumentation*