Comments on Oxygen Toxicity and Retinopathy (ROP) in the Premature Infant
Edward F. Bell, MD and Jonathan M. Klein, MD
Peer Review Status: Internally Peer Reviewed
In the newborn period, an infant may require an increased ambient oxygen concentration in order to maintain a normal arterial blood oxygen tension. There appears to be a relationship between a higher than normal oxygen tension in the retinal arteries and retinopathy of prematurity (ROP). Susceptibility to ROP is increased in the preterm infant. An FiO2 of 0.4 or lower may be sufficient to raise the retinal artery oxygen tension to a dangerous level in many infants. Therefore, when an infant's clinical condition requires an oxygen enriched environment, frequent measurements of arterial blood gases and pH are mandatory.
- The normal PaO2 in utero is 30 mm Hg, while a normal infant breathing room air will have a PaO2 of 60-100 mm Hg.
- The PaO2 of a premature infant in oxygen enriched environment should not exceed 80 mm Hg and should be maintained between 50-70 mm Hg. An arterial oxygen tension of 40-50 mm Hg may be adequate, providing cardiac output and peripheral perfusion are normal. A term infant may require a PaO2 of 55-70 mm Hg to be adequately oxygenated.
- An infant requires the measurement of arterial blood gases and pH as frequently as demanded by the clinical status. When the condition is rapidly changing, measurements must be performed more frequently.
- When an infant is placed in an oxygen enriched environment, the FiO2 delivered to the infant must be measured by an oxygen analyzer at least once an hour.
- Mixtures of oxygen and air delivered to an infant by endotracheal tube, nasal CPAP, hood, or incubator should be warmed and humidified.
- An infant recovering from Respiratory Distress Syndrome should have the FiO2 lowered in steps of no more than 0.10 at intervals of not less than 15-20 minutes, or with the use of continuous pulse oximetry, the FiO2 can be decreased at a faster rate as long as the O2 saturation remains within acceptable limits. An infant with chronic lung disease, especially those requiring oxygen therapy for more than 5-6 days, may require lowering of the FiO2 in steps of 0.02 - 0.05.
- Exposure of the infant's eyes to bright light should be minimized.