RESUMO
BACKGROUND: Peripheral oxygen saturation (SpO(2)) measured by pulse oximetry is widely used in clinical practice, but its fluctuations over the course of the 24 h of a day have not been explored at length. Recently, we reported that children hospitalized due to non-cardiopulmonary causes had a circadian variation in SpO(2). This finding needed to be corroborated in healthy children, which is the objective of the present study. PATIENTS AND METHODS: Healthy children residing in a state foster home were studied with pulse oximetry every 2h for 24h. RESULTS: Eighty two children were included in the study, ranging in age from one month to 6.5 years (average ± standard error of 3.06 ± 0.16 years), with a weight-for-length/height percentile of 65.5 ± 2.9. In 65 (79.3%) children, the SpO(2) levels followed a sinusoidal curve suggesting circadian rhythm. The total group of sinusoidal curves in this population had a mesor of 95.10 ± 0.08% SpO(2), period of 21.05 ± 0.54 h (in 53.8% of these children, the period was between 20 and 28 h). The maximum SpO(2) was reached at 3:14 pm ± 16 min, and the minimum at 5:16 am ± 48 min. When the 24 h were divided into four periods, it was demonstrated that the highest SpO(2) levels were reached between 2 pm and 8 pm. CONCLUSIONS: In this population of clinically healthy children, there was a circadian variation in pulse oximetry, with maximum values in the late afternoon and minimal values in the early morning.
