EPS1.03 feasibility of obtaining submaximal outcomes in people with advanced cystic fibrosis lung disease undergoing cardiopulmonary exercise testing

Urquhart, D.S, Burns, P. and Jamieson, P. , CPET in CF Study Group (2024) EPS1.03 feasibility of obtaining submaximal outcomes in people with advanced cystic fibrosis lung disease undergoing cardiopulmonary exercise testing. Journal of Cystic Fibrosis, 23 (Suppl. 1), S34-S35. (doi:10.1016/S1569-1993(24)00213-3).

Abstract

Objectives: cardiopulmonary exercise testing (CPET) in people with advanced cystic fibrosis lung disease (pwACFLD) may be challenging due to the marked reduction in exercise performance, aswell as concerns about patient safety. Submaximal, relatively effort independent tests to obtain information on performance up to and beyond the first ventilatory threshold [VT1, herein referred to as anaerobic threshold (AT)] might therefore be clinically and prognostically useful for pwACFLD.

Methods: in a retrospective, multicentre study, CPET data were sought from CF centres for pwACFLD (FEV1 ≤40% predicted). Various measures were extracted from data analysis including, pulmonary oxygen uptake (VO2) at the AT, breathing reserve index at the AT (BRIAT), and the slope of the minute ventilation to carbon dioxide production ratio (VE/VCO2-slope). CPET data were analysed independently by two experienced CPET operators (PJ, PBu). Mean bias and limits of agreement (95% confidence interval) and intraclass-correlation coefficients (ICC) using a two-way mixed effects model were calculated for inter-observer agreement.

Results: of 174 pwACFLD, CPET raw data were available for 101; with 89 tests being of sufficient quality for analysis (see Table 1 for patient characteristics). In 72/89 (81%), AT could be confidently identified by both operators. Inter-observer agreement was acceptable for VO2 at the AT, BRIAT and the VE/VCO2-slope with ICCs indicating strong to excellent agreement between operators (Table 2).

Conclusion: identification of the AT is possible in most pwACFLD. We found strong to excellent inter-observer agreement with acceptable limits of agreement especially for the VE/VCO2-slope, despite these being measures reliant on reporter selection. Our data demonstrate that meaningful submaximal CPET data can be obtained in most pwACFLD.

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Contributors

Author: Z.L. Saynor

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