• Zach Rozenbaum, Shafik Khoury, Galit Aviram, Yaniv Gura, Jack Sherez, Avi Man, Jason Shimiaie, Thierry Le Tourneau, Amir Halkin, Simon Biner, Gad Keren, and Yan Topilsky.
• Division of Cardiovascular Diseases and Internal Medicine, Tel Aviv Medical Center, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv Medical Center, Tel Aviv, Israel.
• Chest. 2017 Feb 1; 151 (2): 431-440.

BackgroundDiscriminating circulatory problems with reduced stroke volume (SV) from deconditioning, in which the muscles cannot consume oxygen normally, by gas exchange parameters is difficult.MethodsWe performed combined stress echocardiography (SE) and cardiopulmonary exercise tests (CPET) in 110 patients (20 with normal effort capacity, 54 with attenuated SV response, and 36 with deconditioning) to evaluate multiple hemodynamic parameters and oxygen content difference (A-V.o2 Diff) in four predefined activity levels to assess which of the gas measures may help in the discrimination.ResultsReduced anaerobic threshold (AT), low unchanging peak oxygen pulse, periodic breathing, shallow Δ peak oxygen consumption (V.o2)/Δwork rate (WR) ratio, and high expired volume per unit time/carbon dioxide production (V.e/V.co2) slope were all associated with abnormal SV response (P < .05 for all). The best discriminator was V.e/V.co2 slope to V.o2 ratio (≥ 2.7; area under the curve [AUC], 0.79; P < .0001). The optimal gas exchange model included ΔV.o2/ΔWR < 8.6; V.e/V.co2 slope to peak V.o2 ratio ≥ 2.7, and periodic breathing (AUC of 0.84; P < .0001).ConclusionsThe best single gas exchange parameter to discriminate between circulatory problems and deconditioning is V.e/V.co2 slope to peak V.O2 ratio. Combining it with ΔV.o2/ΔWR and periodic breathing improves the discriminative ability.Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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