Algorithms, modelling and (V) over dotO(2) kinetics

作者：Carlo Capelli^*; Michela Cautero; Silvia Pogliaghi

来源：European Journal of Applied Physiology, 2011, 111(3): 331-342.

DOI：10.1007/s00421-010-1396-8

• Breath-by-breath gas exchange
• Lung gas stores variation
• Lung volume variation
• O-2 uptake kinetics

This article summarises the pros and cons of different algorithms developed for estimating breath-by-breath (B-by-B) alveolar O-2 transfer ((V) over dotO(2A)) in humans. (V) over dotO(2A) is the difference between O-2 uptake at the mouth and changes in alveolar O2 stores (Delta(V) over dotO(2s)), which for any given breath, are equal to the alveolar volume change at constant F-AO2[(F-AiO2 Delta V-Ai)] plus the O-2 alveolar fraction change at constant volume [VAi-1(F-Ai - F-Ai-(1))(O2)], where VAi-1 is the alveolar volume at the beginning of a breath. Therefore, (V) over dotO(2A) can be determined B-by-B provided that VAi-1 is: (a) set equal to the subject's functional residual capacity (algorithm of Auchincloss, A) or to zero; (b) measured (optoelectronic plethysmography, OEP); (c) selected according to a procedure that minimises B-by-B variability (algorithm of Busso and Robbins, BR). Alternatively, the respiratory cycle can be redefined as the time between equal FO2 in two subsequent breaths (algorithm of Gronlund, G), making any assumption of VAi-1 unnecessary. All the above methods allow an unbiased estimate of (V) over dotO(2) at steady state, albeit with different precision. Yet the algorithms "per se" affect the parameters describing the B-by-B kinetics during exercise transitions. Among these approaches, BR and G, by increasing the signal-to-noise ratio of the measurements, reduce the number of exercise repetitions necessary to study (V) over dotO(2) kinetics, compared to A approach. OEP and G (though technically challenging and conceptually still debated), thanks to their ability to track Delta VO2s changes during the early phase of exercise transitions, appear rather promising for investigating B-by-B gas exchange.

• 出版日期2011-3