Table 1.

Results from the principal component analysis of respiratory and sleep variables.

	Component
	Sleep fragmentation	Hypoxemia
Number of arousals associated with a respiratory event	0.92	0.16
Number of stage transitions from NREM1 and wakefulness	0.81	−0.05
Apnea-hypopnea index, events/h	0.73	0.41
Micro-arousal index, events/h	0.64	0.52
Inverted minimum oxygen saturation, %	0.22	0.81
Inverted mean oxygen saturation, %	−0.02	0.82
3 % oxygen desaturation index, events/h	0.57	0.66
Accounted variance, %	40.5	31.9

NREM1: stage 1 of non rapid-eye movement sleep.