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A Model Analysis of Arterial Oxygen Desaturation during Apnea in Preterm Infants
Figure 6
Impact of metabolic O2 consumption (
) on 
.
Panel (A) shows the effect of doubling 
on arterial (
) and mixed venous (
) O2 during apnea; (i) 10 ml min−1kg−1, (ii) 20 ml min−1kg−1 with cardiac compensation (CC), and (iii) 20 ml min−1kg−1 with no CC (nCC). Note that with CC, increased 
, from (i) to (ii), elevated 
uniformly at all levels of 
during both stages 1 and 2; note that the level of 
at the inflection point (shown by short black lines) is unchanged. With nCC (iii), increased 
caused a reduced resting 
and lower 
inflection, and greater 
during stage 1, compared to (ii). (B) Sensitivity of 
to changes in 
. Note that with increased 
: a uniform increase in 
occurred with CC, and a more-than-proportional increase was seen with nCC; 
is elevated in both cases, but more so with nCC; a uniform increase in 
is shown regardless of CC. n = ‘normal’ values; S1, stage 1 slope; S2, stage 2 slope.
doi: https://doi.org/10.1371/journal.pcbi.1000588.g006