Accuracy of pulse oximeter readings from probe placement on newborn wrist and ankle

Abstract

Objective:

To compare the accuracy of pulse oximetry oxygen saturation (SpO₂) measured on the wrist compared with the ipsilateral palm, and SpO₂ measured on the ankle compared with the ipsilateral sole.

Study Design:

In this prospective observational study, neonates admitted to the neonatal intensive care unit were enrolled. We recorded SpO₂ (Masimo Radical-7 pulse oximeter) detected at the palm and ipsilateral wrist initially, then at 30 s, and at 1 min, and we repeated the same procedure over the sole and ipsilateral ankle. We recorded the time to obtain the SpO₂ readings from all these sites. Regression analysis was performed to determine the relationship between paired SpO₂ measurements. The mean difference (bias) and standard deviation of the paired SpO₂ differences (precision) were calculated (Bland–Altman plots).

Result:

A total of 150 patients (birth weight 2381±1020 g, gestational age 34.3±4.3 weeks, median postnatal age 3.5 days (25th–75th percentile 1–16 days)) were enrolled. There was a good correlation between SpO₂ measured at the palm versus the wrist (r=0.95, P<0.001 (right); r=0.97, P< 0.001 (left)) and between SpO₂ measured at the sole versus the ankle (r=0.92, P<0.001 (right); r=0.91, P<0.001 (left)). There was also a good agreement between paired SpO₂ measurements from these sites. The bias and precision for SpO₂ at the right palm and right wrist was 0.08±0.94% and for the left palm and left wrist 0.22±0.87%. Similarly, the bias and precision for SpO₂ at the right sole and right ankle was −0.03±0.93% and for the left sole and left ankle was −0.01±0.93%.

Conclusion:

Our results show that the wrist and ankle can be used as alternative sites to measure SpO₂ in newborn infants in place of the routinely used palm or sole.