| Author | Message | ||
     Juerg Senior Member Username: Juerg Post Number: 2521 Registered: 04-2006 |
More and more clients are interested in the PhysioFlow. One of the most common question is Validation. First of all would be the question back. Validating with what. 1. Is an echo ever used during a workout or what other technique is actually used and if , how where they validated. In rest the Physio Flow is validated with all the " traditional " ideas. teh question is how a echo really show real values once you know how it is done and if you know the error level. One part we see with the physio Flow in sport is , that it is very very repeatable and therefor we are at the same level as with the lactate Pro as we use trends to see changes caused by certain interventions. Here a small abstract to see, what I mean with " Validation" and with what . At least teh readings will be very consistence and no matter , who is reading the Physio Flow info all will read the same end results. : Estimating Left Ventricular Ejection Fraction from Two-Dimensional Echocardiograms: Visual and Computer-Processed Interpretations MAYLENE WONG M.D. 1 , 2 , STEVEN BRUCE M.D. 1 , DAVID JOSEPH M.D. 1 HARRY LIVELY M.D. 1 1 Cardiology Section, Medical Service, West Los Angeles Veterans Affairs Medical Center, and Department of Medicine, Center for Health Sciences, University of California, Los Angeles Correspondence to 2 Cardiology Section (WlllE), West Los Angeles VAMC, Los Angeles, CA 90073. Fax (213)-824–6681. Copyright 1991 Blackwell Publishing Ltd KEYWORDS digital echocardiography • ejection fraction • intraobserver errors ABSTRACT Digital echocardiography makes computer-processed estimates of ejection fraction feasible for clinical use but increases physician reading time. The practicabilities were examined by three novice fellows and four experienced attendings. Ejection fraction was visually estimated from playback of videotape or cine-loop displays. Ejection fraction was also estimated from single tracings of endocardium, digitized and applied to biplane Simpson's rule, and expressed in whole units. Differences between fellows' and attendings' visual estimates were close to 0 ± 6.4 median standard deviation. The 95% confidence intervals for reproducing visual and computer-processed ejection fractions ranged from 15% to 46% of mean ejection fraction; for comparing the two methods, from 7% to 36%. Intraobserver reading errors varied widely and with one observer, systematically, and were independent of experience, but dependent on the quality of signals. Computer-processed readings of ejection fraction should be reserved for images of reasonable quality and for confirming visually estimated ejection fractions between the lower limits of normal (45%-50%) to moderately severely depressed (25%-30%), when accuracy is clinically relevant or when a serial change is at the confidence limits of the reader and needs verification. (ECHOCARDIOGRAPHY, Volume 8, January 1991) " | ||
| Juerg Senior Member Username: Juerg Post Number: 2586 Registered: 04-2006 |
Eur J Appl Physiol. 2005 Jun;94(3):228-34. Epub 2005 May 26. Reliability of peak VO(2) and maximal cardiac output assessed using thoracic bioimpedance in children. Welsman J, Bywater K, Farr C, Welford D, Armstrong N. Children's Health and Exercise Research Centre, University of Exeter, Heavitree Road, Exeter, EX1 2LU, UK. j.r.welsman@ex.ac.uk Abstract The purpose of this study was to evaluate the reliability of a thoracic electrical bioimpedance based device (PhysioFlow) for the determination of cardiac output and stroke volume during exercise at peak oxygen uptake (peak VO(2) in children. The reliability of peak VO(2) is also reported. Eleven boys and nine girls aged 10-11 years completed a cycle ergometer test to voluntary exhaustion on three occasions each 1 week apart. Peak VO(2) was determined and cardiac output and stroke volume at peak VO(2) were measured using a thoracic bioelectrical impedance device (PhysioFlow). The reliability of peak VO(2) cardiac output and stroke volume were determined initially from pairwise comparisons and subsequently across all three trials analysed together through calculation of typical error and intraclass correlation. The pairwise comparisons revealed no consistent bias across tests for all three measures and there was no evidence of non-uniform errors (heteroscedasticity). When three trials were analysed together typical error expressed as a coefficient of variation was 4.1% for peak VO(2) 9.3% for cardiac output and 9.3% for stroke volume. Results analysed by sex revealed no consistent differences. The PhysioFlow method allows non-invasive, beat-to-beat determination of cardiac output and stroke volume which is feasible for measurements during maximal exercise in children. The reliability of the PhysioFlow falls between that demonstrated for Doppler echocardiography (5%) and CO(2) rebreathing (12%) at maximal exercise but combines the significant advantages of portability, lower expense and requires less technical expertise to obtain reliable results. | ||
| Juerg Senior Member Username: Juerg Post Number: 2613 Registered: 04-2006 |
Now here is a way they assess CO ( Cardiac output ) n a so called state of the art fascility. Now you see why we have a smile when they ask us about Validation ? "Cardiac Output Testing On a subsequent visit, cardiac output was estimated at rest and during cycle ergometer exercise by using the acetylene (C2H2) rebreathing technique as described previously (21). Briefly, subjects rebreathed 8-10 breaths from a rubber bag initially containing a mixture of 0.7% C2H2, 40% O2, 10% He, and balance N2. Cardiac output was computed by using the equations outlined by Triebwasser et al. (31). Cardiac output was measured while the subject rested on the bike seat and during steady-state, submaximal work rates (typically 70 and 140 W for women; 70, 140, and 210 W for men). Resting trials were conducted three to four times, with the two closest values used for averaging. During each submaximal power output, HR and O2 were monitored for 2-4 min until steady state was achieved, followed by cardiac output measurements at ~4 and 7 min of exercise. When two cardiac output values differed by >10%, the bout was repeated a second time after a short rest period. In most cases, this approach provided at least three values for averaging at each submaximal power output." |