Pathological respiratory consequences
are hypoxia manifested by a drop in oxygen saturation below 80% (Figure
17.1) and hypercapnia. Pathological cardiovascular changes are bradycardia
manifested by a 20% drop below baseline (Figure 17.1), tachycardia, arrhythmia,
asystole, and arterial hypotension or hypertension. Pathological neurological
findings are lethargy, seizures, and hypotonia.
Figure 17.1.— Central apnea (cessation of airflow at the nose and mouth, and absence of thoracic and abdominal movements). Sleep stage: quiet sleep (tracé alternant and regular respiration), bradycardia, and desaturation.
Periodic breathing (Figure 17.2) refers to respiratory pauses lasting from 3 to 10 seconds without pathological consequences, interrupted by at least5periodsofnormalbreathing lasting less than 5 seconds each. Periodic breathing is abnormal if it occupies more than 3% of the recording time in a fullterm infant.