Effect of fluctuation of oxygenation on the development of severe retinopathy of prematurity in extremely preterm infants

Continuous oxygen saturation and risk of retinopathy of prematurity in a Japanese cohort

BACKGROUND/AIMS

We assessed the associations between retinopathy of prematurity (ROP) and continuous measurements of oxygen saturation (SpO2), and developed a risk prediction model for severe ROP using birth data and SpO2 data.

METHODS

This retrospective study included infants who were born before 30 weeks of gestation between August 2009 and January 2019 and who were screened for ROP at a single hospital in Japan. We extracted data on birth weight (BW), birth length, gestational age (GA) and minute-by-minute SpO2 during the first 20 days from the medical records. We defined four SpO2 variables using sequential measurements. Multivariate logistic regression was used to develop a model that combined birth data and SpO2 data to predict treatment-requiring ROP (TR-ROP). The model's performance was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

Among 350 infants, 83 (23.7%) required ROP treatment. The SpO2 variables in infants with TR-ROP differed significantly from those with non-TR-ROP. The average SpO2 and high SpO2 showed strong associations with GA (r=0.73 and r=0.70, respectively). The model incorporating birth data and the four SpO2 variables demonstrated good discriminative ability (AUC=0.83), but it did not outperform the model incorporating BW and GA (AUC=0.82).

CONCLUSION

Data obtained by continuous SpO2 monitoring demonstrated valuable associations with severe ROP, as well as with GA. Differences in the distribution of average SpO2 and high SpO2 between infants with TR-ROP and non-TR-ROP could be used to establish efficient cut-off values for risk determination.

Oxygen saturation histogram classification system to evaluate response to doxapram treatment in preterm infants

BACKGROUND

An oxygen saturation (SpO₂) histogram classification system has been shown to enable quantification of SpO₂ instability into five types, based on histogram distribution and time spent at SpO₂ ≤ 80%. We aimed to investigate this classification system as a tool to describe response to doxapram treatment in infants with severe apnea of prematurity.

METHODS

This retrospective study included 61 very-low-birth-weight infants who received doxapram. SpO₂ histograms were generated over the 24-h before and after doxapram start. Therapy response was defined as a decrease of ≥1 histogram types after therapy start.

RESULTS

The median (IQR) histogram type decreased from 4 (3-4) before to 3 (2-3) after therapy start (p < 0.001). The median (IQR) FiO₂ remained constant before (27% [24-35%]) and after (26% [22-35%]) therapy. Thirty-six infants (59%) responded to therapy within 24 h. In 34/36 (94%) of the responders, invasive mechanical ventilation (IMV) was not required during the first 72 h of therapy, compared to 15/25 (60%) of non-responders (p = 0.002). Positive and negative predictive values of the 24-h response for no IMV requirement within 72 h were 0.46 and 0.94, respectively.

CONCLUSIONS

Classification of SpO₂ histograms provides an objective bedside measure to assess response to doxapram therapy and can serve as a tool to detect changes in oxygenation status around respiratory interventions.

IMPACT

The SpO₂ histogram classification system provides a tool for quantifying response to doxapram therapy. The classification system allowed estimation of the probability of invasive mechanical ventilation requirement, already within a few hours of treatment. The SpO₂ histogram classification system allows an objective bedside assessment of the oxygenation status of the preterm infant, making it possible to assess the changes in oxygenation status in response to respiratory interventions.

Automated oxygen control for very preterm infants and neurodevelopmental outcome at 2 years-a retrospective cohort study

Faster resolution of hypoxaemic or hyperoxaemic events in preterm infants may reduce long-term neurodevelopmental impairment. Automatic titration of inspiratory oxygen increases time within the oxygen saturation target range and may provide a more prompt response to hypoxic and hyperoxic events. We assessed routinely performed follow-up at 2 years of age after the implementation of automated oxygen control (AOC) as standard care and compared this with a historical cohort. Neurodevelopmental outcomes at 2 years of age were compared for infants born at 24-29 weeks gestational age before (2012-2015) and after (2015-2018) the implementation of AOC as standard of care. The primary outcome was a composite outcome of either mortality or severe neurodevelopmental impairment (NDI), and other outcomes assessed were mild-moderate NDI, Bayley-III composite scores, cerebral palsy GMFCS, and CBCL problem behaviour scores. A total of 289 infants were included in the pre-AOC epoch and 292 in the post-AOC epoch. Baseline characteristics were not significantly different. Fifty-one infants were lost to follow-up (pre-AOC 6.9% (20/289), post-implementation 10.6% (31/292). The composite outcome of mortality or severe NDI was observed in 17.9% pre-AOC (41/229) vs. 24.0% (47/196) post-AOC (p = 0.12). No significant differences were found for the secondary outcomes such as mild-moderate NDI, Bayley-III composite scores, cerebral palsy GMFCS, and problem behaviour scores, with the exception of parent-reported readmissions until the moment of follow-up which was less frequent post-AOC than pre-AOC.

CONCLUSION

In this cohort study, the implementation of automated oxygen control in our NICU as standard of care for preterm infants led to no statistically significant difference in neurodevelopmental outcome at 2 years of age.

WHAT IS KNOWN

• Neurodevelopmental outcome is linked to hypoxemia, hyperoxaemia and choice of SpO2 target range. • Automated titration of inspired oxygen may provide a faster resolution of hypoxaemic and hyperoxaemic events.

WHAT IS NEW

• This cohort study did not find a significant difference in neurodevelopmental outcome at two years of age after implementing automated oxygen control as standard of care.

Clinical outcomes of preterm infants while using automated controllers during standard care: comparison of cohorts with different automated titration strategies

OBJECTIVE

To compare short-term clinical outcome after using two different automated oxygen controllers (OxyGenie and CLiO₂).

DESIGN

Propensity score-matched retrospective observational study.

SETTING

Tertiary-level neonatal unit in the Netherlands.

PATIENTS

Preterm infants (OxyGenie n=121, CLiO₂ n=121) born between 24+0-29+6 weeks of gestation. Median (IQR) gestational age in the OxyGenie cohort was 28+3 (26+3.5-29+0) vs 27+5 (26+5-28+3) in the CLiO₂ cohort, respectively 42% and 46% of infants were male and mean (SD) birth weight was 1034 (266) g vs 1022 (242) g.

INTERVENTIONS

Inspired oxygen was titrated by OxyGenie (SLE6000) or CLiO₂ (AVEA) during respiratory support.

MAIN OUTCOME MEASURES

Mortality, retinopathy of prematurity (ROP), bronchopulmonary dysplasia and necrotising enterocolitis.

RESULTS

Fewer infants in the OxyGenie group received laser coagulation for ROP (1 infant vs 10; risk ratio 0.1 (95% CI 0.0 to 0.7); p=0.008), and infants stayed shorter in the neonatal intensive care unit (NICU) (28 (95% CI 15 to 42) vs 40 (95% CI 25 to 61) days; median difference 13.5 days (95% CI 8.5 to 19.5); p<0.001). Infants in the OxyGenie group had fewer days on continuous positive airway pressure (8.4 (95% CI 4.8 to 19.8) days vs 16.7 (95% CI 6.3 to 31.1); p<0.001) and a significantly shorter days on invasive ventilation (0 (95% CI 0 to 4.2) days vs 2.1 (95% CI 0 to 8.4); p=0.012). There were no statistically significant differences in all other morbidities.

CONCLUSIONS

In this propensity score-matched retrospective study, the OxyGenie epoch was associated with less morbidity when compared with the CLiO₂ epoch. There were significantly fewer infants that received treatment for ROP, received less intensive respiratory support and, although there were more supplemental oxygen days, the duration of stay in the NICU was shorter. A larger study will have to replicate these findings.

Aggressive Retinopathy of Prematurity in a Larger and Less Preterm Infant: A Review of Possible Risk Factors

Aggressive retinopathy of prematurity (A-ROP), formerly known as aggressive posterior retinopathy of prematurity (APROP), occurs generally in extremely premature infants less than 28 weeks gestational age with extreme low birth weight of ≤1000g. We report a case of A-ROP occurring in a larger and less preterm infant. The possible risk factors that lead to the occurrence of A-ROP in this infant will be discussed. An infant born vaginally at 30 weeks gestational age weighing 1550g was diagnosed with A-ROP. Retinopathy of prematurity (ROP) screening was performed due to the presence of risk factors: prematurity, low birth weight, received supplemental oxygen, intraventricular hemorrhage and history of maternal chorioamnionitis. Following a single injection of intravitreal ranibizumab, significant regression of A-ROP was observed. A-ROP was unexpected in this infant and was believed to have developed as a result of receipt of supplemental oxygen, maternal chorioamnionitis, and Ureaplasma infection.