Reference ranges of peripheral-muscle oxygenation in term neonates delivered by Caesarean section during immediate transition after birth

Aim: To establish reference ranges of peripheral-muscle regional oxygen saturation (prSO₂) and peripheral fractional tissue oxygen extraction (pFTOE) during the first 15 min after birth in stable term neonates.

Methods: Secondary outcome parameters of prospective observational studies in healthy term neonates delivered by Caesarean section were analysed. prSO₂ was measured on the right forearm using the INVOS 5100C monitor. pFTOE was calculated out of prSO₂ and arterial oxygen saturation (SpO₂). Centile charts (10th-90th) of prSO₂ and pFTOE were defined during the first 15 min after birth.

Results: Three-hundred-five term neonates with a mean gestational age and birth weight of 39.0 ± 0.9 weeks and 3321 ± 454 g, respectively, were included. The 50th centiles of prSO₂ were 39% (minute two), 52% (minute five), 71% (minute 10), and 73% (minute 15). The 50th centiles of pFTOE were 0.529 (minute two), 0.378 (minute five), 0.237 (minute 10), and 0.231 (minute 15).

Conclusion: Reference ranges of prSO₂ and pFTOE were established for term neonates delivered by Caesarean section during the immediate transition after birth. These reference ranges increase knowledge of physiological processes taking place immediately after birth and are necessary for possible future clinical applications.