Figure 4. Evolution of haemoglobin oxygen saturation in response to a cyclic change in FIO₂.

Traces from a representative animal. Saturation was assessed during four consecutive cycles of 60 s during which the hypoxic phase was progressively lengthened (15, 20, 30 and 40 s). The red line corresponds to FIO₂ in the inspired air, the black line to the transcutaneous measurement of haemoglobin oxygen saturation of the animal. Latency (1); time to peak (2) and amplitude of change in saturation (3).