Neonatal Oxygen Therapy: Titration and Retinopathy of Prematurity

Preterm infants in Australia are surviving at earlier gestational ages than ever before, thanks to coordinated neonatal intensive care networks that stretch from Sydney to Perth. With survival gains have come new responsibilities for clinicians managing supplemental oxygen, since both deficiency and excess carry measurable risks. Among the most scrutinised adverse outcomes is retinopathy of prematurity, a vasoproliferative disorder of the developing retina that remains a leading cause of childhood vision impairment in high-income nations. The challenge for bedside teams is to titrate oxygen delivery precisely enough to support neurodevelopment while avoiding the hyperoxic swings that drive retinal neovascularisation.

Australian practice is informed by local data registries and by international consensus statements, and the country contributes actively to the evidence base. Clinicians in tertiary perinatal centres across Melbourne, Brisbane, Adelaide and the Gold Coast routinely balance the competing demands of cerebral and pulmonary oxygen delivery against the long-term integrity of the immature retina. The pages that follow summarise the physiology, the saturation targets supported by current trials, and the practical weaning strategies used in Australian neonatal intensive care units, or NICUs, with attention to retinopathy surveillance and family-centred communication.

The physiological tightrope of oxygen in preterm infants

Oxygen is both substrate and potential toxin in the preterm newborn. The fetal retina develops in a relatively hypoxic environment, with partial pressures of oxygen in the mid-teens, and the transition to extrauterine life requires careful support of oxidative metabolism in the brain and myocardium. When supplemental oxygen is delivered without precise monitoring, the partial pressure in arterial blood can rise rapidly above the physiological range for the postmenstrual age, generating reactive oxygen species that disrupt the carefully sequenced vascular development of the retina.

The immaturity of antioxidant systems compounds the problem. Enzymes such as superoxide dismutase and catalase are expressed at low levels in infants born before 30 weeks of gestation, leaving the retina poorly equipped to neutralise oxidative stress. Simultaneously, the ductus arteriosus and the cerebral vasculature respond to fluctuations in arterial oxygen content, meaning that a saturation intended to protect the brain may inadvertently destabilise the retinal microcirculation. Understanding this biology is the foundation for the targeted saturation ranges that guide modern practice, and ongoing education through initiatives such as the FAOPS 2020 portal helps disseminate updated physiology to multidisciplinary teams.

Hyperoxia is not the only concern. Intermittent hypoxaemia, common in the first weeks after birth, has itself been associated with worse neurodevelopmental outcomes, and the goal of modern titration is to avoid both extremes. Continuous monitoring with pulse oximetry, ideally with signal extraction technology that resists motion artefact, allows nurses to respond to trends rather than isolated values, and reduces the cognitive load of manual adjustment during busy shift handovers.

Saturation targets and the evidence base

A series of large randomised trials has shaped contemporary oxygen targeting. The SUPPORT, BOOST-II and COT trials examined the effect of targeting lower versus higher arterial oxygen saturations in extremely preterm infants. The pooled interpretation, reflected in guidance from the Australian and New Zealand Neonatal Network, suggests that a target range of 90 to 95 percent balances the risks of mortality, necrotising enterocolitis and severe retinopathy.

The table summarises the trade-offs most often discussed in Australian NICU morbidity and mortality reviews. SpO₂ alarms are typically set with a lower limit around 89 percent and an upper limit near 95 percent in infants older than 28 weeks corrected age, with a brief acceptance of lower saturations in the first hours after birth while the ductus closes. Fractional inspired oxygen is titrated in increments of 1 to 2 percent, and recent pulse oximetry technology allows more reliable readings in dark-skinned infants, an important consideration for Australia's diverse population.

A common source of confusion is the difference between SpO₂ targets and PaO₂ targets. SpO₂ is a surrogate for arterial oxygen saturation, and clinicians must remember that the relationship between SpO₂ and PaO₂ is sigmoidal, not linear. A saturation of 90 percent corresponds to a PaO₂ of approximately 60 mmHg on the steep portion of the curve, while a saturation of 95 percent corresponds to a PaO₂ closer to 80 mmHg. This steep relationship explains why small changes in FiO₂ can produce large swings in PaO₂, and why careful titration matters.

Pathophysiology of retinopathy of prematurity

Retinopathy of prematurity unfolds in two overlapping phases. In phase one, hyperoxia and the loss of maternal insulin-like growth factor 1 signalling arrest the growth of retinal vessels, leaving an avascular peripheral retina. In phase two, the metabolically active avascular retina releases vascular endothelial growth factor, which drives neovascularisation that can lead to retinal detachment if untreated. The disorder is graded by the international classification system, with treatment reserved for type 1 prethreshold disease or worse.

Several risk factors modify the likelihood and severity of disease. These include low birth weight, early gestational age, prolonged mechanical ventilation, sepsis, and exposure to high ambient light, though the last of these is now considered less important than once thought. Genetic susceptibility is increasingly recognised, and Aboriginal and Torres Strait Islander infants have been shown in registry analyses to experience higher rates of severe ROP, a finding that has prompted targeted screening enhancements in Western Australia and the Northern Territory. International consensus guidelines are regularly updated, and practitioners can access curated summaries through portals such as the APSR digital news service, which covers perinatal and respiratory research across the Asian Pacific region.

Treatment has evolved considerably. Cryotherapy, once the standard, has been largely replaced by laser photocoagulation and, more recently, by intravitreal anti-VEGF agents such as bevacizumab and ranibizumab. Anti-VEGF therapy offers the advantage of preserving more peripheral retina, but long-term systemic safety data are still being collected, and infants require extended follow-up because late recurrence is possible. Australian guidelines currently recommend anti-VEGF for zone I disease and laser for zone II disease, with treatment decisions individualised by the treating ophthalmologist.

Oxygen weaning in Australian neonatal units

Australian NICUs operate under shared guidelines while adapting protocols to local case mix. In Royal Brisbane and Women's Hospital, for example, oxygen weaning follows a stepwise reduction in FiO₂ once saturations remain stable in the target band for six hours, with a documented ceiling of 30 percent before considering a step down to nasal high flow or low-flow nasal cannulae. Similar protocols in Melbourne's Royal Women's Hospital and Sydney's Royal Prince Alfred Hospital emphasise saturation trend monitoring rather than absolute values, recognising that brief desaturations are common during handling, feeding and eye examinations.

Screening for retinopathy begins at 30 to 31 weeks postmenstrual age or at four weeks chronological age, whichever is later. Ophthalmological examination is performed by paediatric ophthalmologists or by trained neonatal nurse practitioners using digital retinal imaging. For infants in rural Queensland or Western Australia, telemedicine platforms transmit images to tertiary centres, allowing earlier detection without the logistical burden of transferring fragile newborns over long distances. The cost of screening is covered under Medicare for eligible infants, and related clinical guidance, such as the FAOPS briefing on neonatal jaundice observation, illustrates the same careful titration philosophy that underpins oxygen management.

Weaning does not end at discharge. Many preterm infants continue to require supplemental oxygen at home, and Australian programs such as the Royal Children's Hospital Melbourne home oxygen service provide ongoing support, including home visits, oximetry downloads, and regular multidisciplinary review. The transition from hospital to home is coordinated with the infant's general practitioner, the local paediatrician, and the regional ophthalmology service, ensuring continuity of care for both respiratory and visual development.

Practical recommendations for the clinical team

The following recommendations reflect current consensus within the Australian and New Zealand Neonatal Network and align with international guidelines from bodies such as the American Academy of Pediatrics and the European Consensus Guidelines on ROP management.

• Target SpO₂ at 90 to 95 percent from the second day of life in infants born before 28 weeks of gestation, avoiding sustained saturations above 96 percent.
• Use dual-alarm pulse oximetry with short averaging times to reduce the delay between true desaturation and audible alarm.
• Wean FiO₂ in small increments of 1 to 2 percent when saturations remain stable in the target band for several hours, and avoid abrupt changes during clustered care.
• Schedule the first ophthalmic examination no later than 31 weeks postmenstrual age, and ensure digital imaging is available in regional centres through telehealth links.
• Counsel families using culturally appropriate resources, including Aboriginal health liaison officers where relevant, and provide written follow-up plans in the preferred language of the family.

Parents of preterm infants often experience anxiety about oxygen dependence and the possibility of vision loss, and structured communication can substantially reduce that burden. Australian neonatal units increasingly employ family-integrated care models in which parents participate in rounds, learn saturation monitoring, and contribute to weaning decisions under nursing supervision. For families returning to communities far from the tertiary centre, outreach nursing teams coordinate ongoing oximetry supplies and review growth, development and ophthalmic findings at scheduled intervals. National advocacy groups, including the Miracle Babies Foundation headquartered in Sydney, provide peer support and assist with travel costs for rural families who must attend repeated screening appointments.

Clinicians and researchers are invited to register for forthcoming FAOPS educational events and to access the archived scientific resources of the 2020 congress, where the challenges of oxygen titration and retinopathy prevention remain a central theme of the perinatal curriculum. The archived platform offers a rich repository of plenary lectures, poster abstracts and clinical guidelines that continue to inform bedside practice across the region, and participation in subsequent congresses will help shape the next generation of oxygen titration protocols.