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. 2017 Sep 29;4:162. doi: 10.3389/fvets.2017.00162

Figure 2.

Figure 2

Schematics of the modeling of gas movements. During the denitrogenation phase, xenon flow was turned off. Then xenon flow was started at 10 L min−1. As fR was six breaths per minute during the experiment 10 L/6 = 1.67 L of xenon were delivered from the bottle into the machine for each breath. Just before the first breath, as the total volume of the machine was 28 L, the total percentage of xenon in the machine was 1.67 L/28 L = 5.96%. So, when the horse breathed xenon for the first time, as the tidal volume (TV) was 6 L, the horse breathed 6 L × 5.96% = 0.36 L of xenon (Vol Xe insp). The horse’s consumption was assumed to be 0.1 L kg−1 h−1 (= 0.142 L per breath). The new percentage of xenon in the horse’s lungs was then the amount breathed in less the amount consumed, divided by the total volume of the lungs (FRC + TV) so (0.36 − 0.142)/(20 + 6) = 0.84%. Then, as the horse breathed out 6 L containing 0.84% of xenon back into the machine, 6 L × 0.84% = 0.05 L of xenon were expired back into the machine (Vol Xe exp).