Automated detection of the phase III slope during inert gas washout testing

作     者：Stuart-Andrews, Christopher R. Kelly, Vanessa J. Sands, Scott A. Lewis, Angela J. Ellis, Matthew J. Thompson, Bruce R. 

作者机构：Alfred Hosp Dept Allergy Immunol & Resp Med Serv Physiol Melbourne Vic Australia Monash Univ Dept Med Nursing & Hlth Sci Clayton Vic Australia Cooperat Res Council Asthma & Airways Glebe NSW Australia Massachusetts Gen Hosp Dept Med Pulm & Crit Care Unit Boston MA 02114 USA Harvard Univ Sch Med Boston MA USA Monash Univ Ritchie Ctr Baby Hlth Res Monash Inst Med Res Clayton Vic Australia Brigham & Womens Hosp Div Sleep Med Boston MA 02115 USA 

出 版 物：《JOURNAL OF APPLIED PHYSIOLOGY》 (应用生理学杂志)

年 卷 期：2012年第112卷第6期

页      面：1073-1081页

核心收录：

学科分类：0710[理学-生物学] 0403[教育学-体育学] 07[理学] 071003[理学-生理学] 

基　　金：National Health and Medical Research Council of Australia [521808, 486101, 491103] Cooperative Research Centre for Asthma and Airways (CRCAA) American Australian Association American Heart Association 

主　　题：inert gas washout computer algorithm alveolar slope 

摘      要：Stuart-Andrews CR, Kelly VJ, Sands SA, Lewis AJ, Ellis MJ, Thompson BR. Automated detection of the phase III slope during inert gas washout testing. J Appl Physiol 112: 1073-1081, 2012. First published December 15, 2011;doi:10.1152/japplphysiol.00372.2011.-We describe a method to determine the phase III slope for the purpose of calculating indexes of ventilation heterogeneity, S-acin and S-cond, from the multiple breath nitrogen washout test (MBNW). Our automated method applies a recursive, segmented linear regression technique to each breath of the MBNW test and determines the best point of transition, or breakpoint, between each phase of the washout. A sample set of 50 MBNW tests (controls, asthma, and COPD) was used to establish the conditions in which the phase III slope obtained from the automated technique best matched that obtained by two manual interpreters. We then applied our technique to a test set of 30 subjects (with an even number of subjects in each of the above groups) and compared these results against the manual analysis of a third independent manual interpreter. Indexes of ventilation heterogeneity were determined using both methods and compared. The phase III slopes determined by the automatic technique best matched the manual interpreter when the phase III slope was calculated from the phase II-III transition point plus the addition of 50% of the phase II volume to the end of the expiration. Calculation of the indexes S-acin and S-cond showed no overall difference between analysis methods in either S-acin (P = 0.14) or S-cond (P = 0.59) when the set threshold was applied to our automated analysis. Our analysis method provides an alternate means for rapid quantification of the MBNW test, removing operator dependence without alteration in either S-acin or S-cond.