Reference values for respiratory events in overnight polygraphy from infants aged 1 and 3months

We aimed to determine reference values for respiratory indices in polygraphies (PGs) performed in infants aged 1 and 3months.

Healthy full-term neonates were recruited on the maternity ward. They were followed up by overnight PG at the age of 1month and again at the age of 3months. Indices of respiratory events, such as apneas, hypopneas, and percentage of periodic breathing were determined in each PG. Interpretation of PGs was performed blinded to the subject's data and the time of measurement. PG indices at 1 and 3months of age were compared.

PG recordings were obtained for 37 healthy infants (22 boys). At the age of 1month, the median (minimum-maximum) central, obstructive, and mixed apnea index was 5.5 (0.9-44.3), 0.8 (0.1-6.7), and 0.3 (0-1.2), respectively. The same figures at the age of 3months were 4.1 (1.2-27.3), 0.8 (0-2.3), and 0.1 (0-0.8), respectively. Mixed obstructive apnea-hypopnea index (MOAHI) was 1.5 (0.2-7.0) and 0.9 (0.2-4.4) at the first and second measurements, respectively (P=.017). Only 1.2% of central apneas lasted longer than 20s. Periodic breathing was present in more than 90% of subjects studied.

The infants in our study aged ⩽3months had respiratory event indices that were different from older children or adults. MOAHI showed a significant decrease during the first 3months after birth. We recommend that scoring of PG in infants of 3months or younger should consider age-specific reference values.