Vargas Mario H, Heyaime-Lalane Jorge, Pérez-Rodríguez Liliana, Zúñiga-Vázquez Guillermo, Furuya María Elena Y
Unidad de Investigación Médica en Enfermedades Respiratorias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, México.
Rev Invest Clin. 2008 Jul-Aug;60(4):303-10.
Pulse oximetry is a simple and non-invasive procedure widely used nowadays in the clinical practice. However, it is unclear if SpO2 values are constant throughout the 24 hours of the day or have periodic fluctuations. In the present study we evaluated if progressive day-night variations of SpO, values occur in children.
Pulse oximetry (Nonin 2500) was carried out approximately every 2 hours during a 24-hours period in pediatric patients hospitalized due to different diseases but without acute or chronic respiratory diseases. Measurements were analyzed through the cosinor method (sinusoidal curve fitting).
A total of 131 patients (23 days to 16 years old) were studied. A sinusoidal fitting of the SpO2 values was accomplished in 84.7% of children. According to these curves, maximal SpO2 values occurred in the late afternoon [4:53 PM (3:49-5:32 PM), median (quartile 1-quartile 3)], while minimal values appeared in the first hours of the day [3:06 AM (2:12-4:08 AM)]. This pattern was the same in sleeping or awake children. More than half of these sinusoidal curves had a period near to 24 hours (between 20 and 28 hours). An additional finding was that maximal and minimal SpO2 values diminished with age (approximately 0.15 and approximately 0.13% SpO2 per year, respectively). In children less than six years old 5th percentile of SpO2 values were 93.8% in the late afternoon and 89.8% in the early hours of the day, while corresponding figures for older children were 91.0% and 88.5%, respectively.
Our results suggested that, regardless of the sleep influence, in most children the SpO2 follows a progressive fluctuation during a 24-hours cycle, a pattern which is suggestive of a circadian rhythm. A prospective study in healthy children is warranted.
脉搏血氧饱和度测定是一种简单且无创的检查方法，如今在临床实践中广泛应用。然而，尚不清楚血氧饱和度（SpO₂）值在一天24小时内是否恒定，还是存在周期性波动。在本研究中，我们评估了儿童的SpO₂值是否存在昼夜渐进性变化。
对因各种疾病住院但无急慢性呼吸系统疾病的儿科患者，在24小时内大约每2小时进行一次脉搏血氧饱和度测定（使用Nonin 2500）。通过余弦分析法（正弦曲线拟合）对测量结果进行分析。
共研究了131例患者（年龄在23天至16岁之间）。84.7%的儿童完成了SpO₂值的正弦曲线拟合。根据这些曲线，SpO₂最大值出现在下午晚些时候[下午4:53（四分位间距为下午3:49 - 5:32），中位数（四分位间距1 - 四分位间距3）]，而最小值出现在一天的最初几个小时[凌晨3:06（凌晨2:12 - 4:08）]。睡眠或清醒儿童的这种模式相同。超过一半的这些正弦曲线周期接近24小时（20至28小时之间）。另一个发现是，SpO₂最大值和最小值随年龄减小（分别约为每年降低0.15% SpO₂和约0.13% SpO₂）。在6岁以下儿童中，下午晚些时候SpO₂值的第5百分位数为93.8%，凌晨时分则为89.8%，而年龄较大儿童的相应数字分别为91.0%和88.5%。
我们的结果表明，无论睡眠的影响如何，大多数儿童的SpO₂在24小时周期内呈渐进性波动，这种模式提示存在昼夜节律。有必要对健康儿童进行前瞻性研究。
