Respiratory Therapy Blog

Worldwide somewhere between 5% and 10% of all newborns require some form of resuscitation. There continues to be questions about how much oxygen should be used during neonatal resuscitation. Despite over 50 years experience of oxygen therapy in neonates, the use of oxygen in neonates, especially premature neonates is not well understood. We still don’t fully understand the effects oxygen or saturation levels on retinopathy of prematurity, growth, brain, lung and other organs in respect to gestational age, time or onset and duration of specific oxygen or saturation levels.

A meta-analysis by Davis, Tan, et al. (1) showed a reduction in mortality in neonates resuscitation was started with room air compared to 100% oxygen. Saugstad, Ramji, et al. (2) did a follow-up of survivors resuscitated with room air and 100% oxygen at 2 years of age and found no differences in neurological sequelae. We also know that oxygen supplementation can be harmful because O₂ free radicals are involved in the pathogenesis of many neonatal diseases. Pulse oximetry has been advocated to be used to adjust O₂ supplementation.

In the April 2007 issue of the Journal of Pediatrics, Mariani, Dik, Ezquer et al. (3) looked at the physiological changes in pre- and post-ductal SpO₂ levels in healthy neonates during the first few minutes after birth. They studied 110 neonates with a gestational age > 37 weeks. As soon as possible after clamping of the neonate’s cord, oximetry sensors (with Masimo signal extraction technology) were placed on the right hand and on one foot to record the pre- and post-ductal saturation levels. Oxygen saturation levels were up to 15 minutes after birth or until the pre-ductal saturation was greater than 90%. The resident who attended each delivery was unaware of the SpO₂ levels and the AAP/AHA Neonatal Resuscitation Program protocol was followed if needed.

Pre- and post-ductal O₂ saturation both increased gradually after birth but the levels were significantly different during the first 15 minutes after birth. At 5 minutes of birth the median pre-ductal saturation level was 90% (84-94) and the median post-ductal saturation level was 82% (76-89). The mean time to achieve a pre-ductal SpO₂ level of 90% was 5.5 minutes. None of the infants required admission to the neonatal intensive care unit.

[Figure. Pre- and post-ductal SpO₂ levels during the first 15 minutes after birth (median) Post-ductal SpO₂ levels were significantly lower than pre-ductal SpO₂ levels at 3, 4, 5, 10, and 15 minutes.](3)

The significant difference in pre-ductal and post-ductal oxygen saturation levels during the first 15 minutes after birth is probably due to a high pulmonary artery pressure and right-to-left shunting through the ductus arterious.

As some physicians have suggested, monitoring of oxygen saturation by pulse oximetry may help in infants requiring resuscitation to avoid exposure to high oxygen concentrations by varying supplemental oxygen levels. This study helps gives some insight to what may be the desired range of oxygen saturation levels in newborn infants. More studies are still needed though to understand the physiologic adaptations of the newborn and the rational of the use of supplemental oxygen especially in the most vulnerable premature infants.

A number of NICUs in Canada will very soon be participating in the Canadian Oxygen Trial (Efficacy and safety of targeting lower arterial oxygen saturations to reduce oxygen toxicity and oxidative stress in very preterm infants: the Canadian Oxygen Trial); a multi-centre, double blind, randomized controlled trial to look at the different effects of two different oxygen saturations in extremely pre-term infants. This study plans to look at whether lowering oxygen levels to target a SpO₂ of 85-89% compared with 91-95% in infants born at gestational ages of 23 to 28 weeks increases the probability of survival to a corrected age of 18 months without severe neurosensory disability. This study plans to include about 1200 patients in the next 2.5 years.

Hopefully in the near future we will continue to get a better understanding of this extremely important and urgent issue in our neonatal patients.

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(1) Davis PG, Tan A, O’Donnell CP, Schulze A. Resuscitation of newborn infants with 100% oxygen or air: a systematic review and meta-analysis. Lancet 2004;364:1329-33.

(2) Saugstad O, Ramji S, Irani S, El-Meneza S, et al. Resuscitation of newborn infants with 21% or 100% oxygen: follow-up at 18 to 24 months. Pediatrics 2003;112:296-300.

(3) Mariani G, Dik PB, Ezquer A, Aquirre A, et al. Pre-ductal and Post-ductal Oxygen Saturation in Healthy Term Neonates after Birth. J Pediatrics 2007 Apr;150(4):418-21.