[Pulse Oximetry Values in Preterm infants at 34-36 weeks postmenstrual age]

Pulse oximetry (SpO2) is essential for guiding oxygen therapy in preterm infants. Data on SpO2 values before discharge are limited.

To establish SpO2 values in asymptomatic premature infants at 34, 35, and 36 weeks of postmenstrual age (PMA).

Longitudinal, multicen ter study carried out from May 2018 to May 2019 in three neonatal intensive care units in Santiago, Chile (altitude 579 m) which included premature infants born ≤ 32 weeks of gestational age, healthy, with clinical stability, and without respiratory morbidity at the moment of the study or until dis charge. The following parameters were analyzed: mean accumulated SpO2 and SD, minimum SpO2 value, SpO2 time percentage < 90%, SpO2 time percentage < 80%, DI4, and DI80. Continuous over night SpO2 was obtained with Masimo Radical-7 or Rad-8 (USA), mean artifact-free-recording-time (AFRT) ≥ 6 hours.

101 SpO2 recordings were registered in 44, 33, and 24 studies at 34, 35, and 36 weeks of PMA, respectively, from 62 preterm infants, twenty-eight (45%) were male, median gestational age at birth 30 weeks (range 26-32), and median birth weight 1480 g (range 785-2700g). Oximetry variables were mean AFRT (± SD) 8.6 (± 1.5) hours; median mean SpO2 96.9% (range 93.3-99.3%); median minimum SpO2 74% (range 51-89%); median time of SpO2 < 90% 2% (range 0-10.6%); median time of SpO2 < 80% 0.1% (range 0-1.3%); median desaturation event ≥ 4% (DI4) within ≥ 10 seconds per hour sampled 15 (range 3.5-62.5); and median desaturation event <80% (DI80) 0.58 (range 0-10.8). We found no differences in SpO2 values between the different PMA wee ks.

We described SpO2 values in very preterm infants, asymptomatic at 34-36 PMA weeks. These values could be used as a reference for guiding oxygen therapy.