Open AccessValidity, reliability and minimum detectable change of COSMED K5 portable gas exchange system in breath-by-breath mode
Author(s) -
Laura Guidetti,
Marco Meucci,
Francesco Bolletta,
Gian Pietro Emerenziani,
Maria Chiara Gallotta,
Carlo Baldari
Publication year - 2018
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0209925
Subject(s) - intraclass correlation , limits of agreement , reliability (semiconductor) , statistics , reproducibility , linear regression , mathematics , mean absolute percentage error , medicine , nuclear medicine , physics , mean squared error , thermodynamics , power (physics)
Purpose This study aimed to examine the validity, reliability and minimum detectable change (MDC) of the Cosmed K5 in breath by breath (BxB) mode, against VacuMed metabolic simulator. Intra and inter-units reliability was also assessed. Methods Fourteen metabolic rates (from 0.9 to 4 L.min-1) were reproduced by a VacuMed system and pulmonary ventilation (VE), oxygen consumption (VO 2 ) and carbon dioxide production (VCO 2 ) were measured by two different K5 units. Validity was assessed by ordinary least products (OLP) regression analysis, Bland-Altman plots, intraclass correlation coefficients (ICC), mean percentage differences, technical errors (TE) and MDC for VE, VO 2 , and VCO 2 . Intra- and inter-K5 reliability was evaluated by absolute percentage differences between measurements (MAPE), ICCs, TE, and MDC. Results Validity analysis from OLP regression data and Bland- Altman plots indicated high agreement between K5 and simulator. ICC values were excellent for all variables (>0.99). Mean percentage differences in VE (-0.50%, p = 0.11), VO 2 (-0.04%, p = 0.80), and VCO 2 (-1.03%, p = 0.09) showed no significant bias. The technical error (TE) ranged from 0.73% to 1.34% (VE and VCO 2 respectively). MDC were lower than 4% (VE = 2.0%, VO 2 = 3.8%, VCO 2 = 3.7%). The intra and inter K5 reliability assessment reveled excellent ICCs (>0.99), MAPE <2% (no significant differences between trials), TE < or around 1%, MDC