At what oxygen saturation level in room air does a premature infant require supplemental oxygen and what is the initial oxygen flow rate?

Oxygen Supplementation Threshold and Initial Flow Rate for Premature Infants

Supplemental oxygen should be initiated when a premature infant's oxygen saturation persistently falls below 90% in room air, starting with low-flow oxygen (typically 0.1-0.25 L/min for infants) titrated to maintain SpO2 ≥90-95%. 1, 2

Critical SpO2 Thresholds

Intervention Threshold

• SpO2 <90% is the primary indication for supplemental oxygen in premature infants, representing a clinical threshold requiring intervention 1, 2
• Before initiating oxygen, verify the accuracy of the pulse oximetry reading by repositioning the probe and repeating the measurement, and suction the infant's nose and oral airway if necessary 1
• Multiple determinations should be made in various states including rest, sleep, feeding, and high activity 1

Target Range During Oxygen Therapy

• Target SpO2 of 90-95% is generally appropriate for premature infants requiring supplemental oxygen, balancing the risks of hypoxia against oxygen toxicity 3, 4, 5
• The 91-95% range may be safer than lower targets (85-89%), though lower targets reduce severe retinopathy of prematurity (ROP) risk but increase mortality 4
• Once past the age of oxygen-induced retinopathy risk, target saturations of ≥95% are recommended to prevent pulmonary hypertension and provide a buffer against desaturation 1

Initial Oxygen Flow Rate

Starting Flow for Premature Infants

• Begin with low-flow oxygen at 0.1-0.25 L/min via nasal cannula for small premature infants 1
• Most clinicians provide low-flow 100% oxygen to reach a predetermined oxygen saturation reading, which is easily adjusted to match specific levels of activity 1
• Flow rates should be titrated based on continuous pulse oximetry monitoring rather than fixed FiO2 calculations 1

Delivery Method

• Nasal cannula is the most widely used device for oxygen delivery in premature infants, as it is convenient, safe, and well tolerated 1
• Many nurseries utilize a system to blend oxygen with room air to provide a relatively precise FiO2, as small changes in flow rates may produce unpredictable changes in FiO2 1
• Humidification of oxygen is advocated by most centers, though studies of efficacy are lacking 1

Special Considerations for Premature Infants

Age-Dependent Targets

• During the period of ROP risk (typically first weeks to months), oxygen saturation targets are more controversial and must balance neurodevelopmental outcomes against ROP progression 1
• Infants with unresolved ROP and chronic lung disease require careful oxygen control, as poor control may lead to worsening ROP 1
• Higher saturation targets (95-99%) do not appear to increase ROP progression in infants with pre-threshold ROP, and may even decrease risk in some cases 1

Monitoring Requirements

• Continuous pulse oximetry monitoring is essential when supplemental oxygen is administered, with the probe placed on the right upper extremity (preductal location) 1, 2
• Premature infants on supplemental oxygen spend only 31% of time in target SpO2 range (88-92%), with frequent episodes of severe hyperoxia (SpO2 ≥98%) and hypoxia (SpO2 <80%) 6
• Arterial blood gas, end-tidal CO2, or bicarbonate determination can be helpful in infants with suspected carbon dioxide retention 1

Common Pitfalls and How to Avoid Them

Accuracy Limitations

• Pulse oximetry overestimates arterial oxygen saturation (SaO2) by approximately 3%, and when SpO2 readings are within target range, 21% of actual SaO2 values may be below target 7
• In 57% of patients, PaO2 levels <6 kPa (45 mmHg) can occur while SpO2 readings are >90%, indicating significant hypoxemia despite apparently adequate saturations 7
• Poorly placed probes and motion artifact lead to inaccurate measurements and false readings 1

Balancing Risks

• Both hypoxemia and hyperoxia are harmful to premature infants—desaturation below 80-85% must be avoided to prevent cerebral palsy, while SpO2 >95% increases risk of ROP and bronchopulmonary dysplasia 5
• Infants treated with supplemental oxygen show a threefold increased risk of hypoxemia compared to infants breathing room air, requiring vigilant monitoring 7
• The infant's clinical work of breathing should be assessed and considered as a factor in decisions about oxygen supplementation 1

Adjustment Frequency

• FiO2 adjustments are typically made 25 times per day in premature infants on CPAP, reflecting the dynamic nature of oxygen requirements 6
• Oxygen saturation targeting is challenging in preterm infants, with a high proportion of time spent outside target range and frequent prolonged hypoxic and hyperoxic episodes 6