Figure 2.

Individual data of the cerebral metabolic rate of oxygen (CMRO₂) at baseline (BL), the onset of apnea (Onset), the first involuntary breathing movement (IBM), and immediately at apnea end (End), for the normal apnea (NM; top panel), apnea following 5 min of hyperventilation (HV; middle panel), and apnea following 15 min of 100% O₂ hyperventilation (HX; bottom panel). Compared to baseline, there was an average ∼24% reduction in CMRO₂ at the end of the NM apnea, no significant change at the end of the HV apnea, and an ∼44% reduction at the end of the HX apnea.