Incidence of severe retinopathy of prematurity before and after a modest reduction in target oxygen saturation levels

Unmet Need for ROP Screening in Peripheral Rural Areas

Aim

To study the incidence and risk factors associated with retinopathy of prematurity (ROP) at a tertiary care centre in Western India.

Methods

A retrospective review of records of both referred and babies born in our hospital who were screened for ROP within the last 21 months at a tertiary care centre was done. The newborns were screened as per National Neonatology Forum of India guidelines. ROP was classified according to the International Classification for Retinopathy of Prematurity criteria.

Results

A total of 167 neonates were screened with an incidence of ROP of 26.9%. The mean gestational age (GA) and mean birth weight (BW) were 31.89 ± 2.824 weeks and 1538.11 ± 530.84 gm. The mean BW of neonates having any ROP was significantly lower (1296.98gm, p < 0.001), and the mean GA was also significantly lower in ROP babies (30.67 weeks, p < 0.001). O2 supplementation, RDS, IVH, and NEC were the systemic risk factors that significantly correlated with ROP p-value <0.001. On analysis of the correlation of stage of ROP with BW and GA, a significant correlation of −0.307 (p < 0.001) and −0.283 (p < 0.001) was found.

Conclusion

The incidence of ROP in this study is similar to that reported in the literature from other regions. Other than LBW and GA, oxygen supplementation, RDS, IVH, and NEC were significant risk factors associated with ROP.

Comparative cohorts of retinopathy of prematurity outcomes of differing oxygen saturation: real-world outcomes

Objective

An ongoing third epidemic of retinopathy of prematurity (ROP) is contributed largely by developing nations. We describe a cohort of infants in a single neonatal unit where two limits of oxygen saturation were administered, to show real-world outcomes from trend in neonatology for higher oxygen to improve survival.

Methods and analysis

This retrospective, comparative study of prospectively collected data in an ROP screening programme included infants indicated by gestational age ≤32 weeks, birth weight <1501 g, ventilation for 7 days or requiring oxygen >1 month, who underwent dilated fundoscopic examination from age 4 weeks, every 2 weeks until full retinal vascularisation. Infants with ROP were examined weekly and treated where indicated. Data were divided into two epochs. Epoch 1 oxygen saturation targets were [88–92%], epoch 2 targets [90–95% (99%)] with allowance of increase to 20% for several hours after procedures. Outcome measures included development of ROP, treatment, mortality, sepsis and intraventricular haemorrhage.

Results

A total of 651 infants underwent examination between 2003 and 2016. The incidence of ROP in epoch 1 was 29.1% and epoch 2 was 29.3% (p=0.24). ROP progression doubled in epoch 2 (5 vs 11%, p=0.006), proportion of cases treated halved (14% vs 6%, p=0.0005), sepsis was halved (78.5% vs 41.2%, p<0.0001) and intraventricular haemorrhage doubled (20.2% vs 43.8%, p=0.0001) in epoch 2. Mortality was 4% and 0% in epochs 1 and 2, respectively.

Conclusion

Incidence of ROP did not differ, although ROP cases that worsened doubled with higher oxygen targets. ROP cases requiring treatment decreased, as did sepsis and mortality. Intraventricular haemorrhage cases doubled.

Survival rate dependent variations in retinopathy of prematurity treatment rates in very low birth weight infants

As increased oxidative stress causes increased mortality and morbidities like bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) in very low birth weight infants (VLBWIs), the conundrum of improved survival but increased ROP observed with the high oxygen saturation target range of 91–95% is difficult to explain. To determine the survival rate-dependent variation in ROP treatment rate, 6292 surviving eligible VLBWIs registered in the Korean Neonatal Network were arbitrarily grouped according to the survival rate of infants at 23–24 weeks’ gestation as group I (> 70%, n = 1626), group II (40–70%, n = 2984) and group III (< 40%, n = 1682). Despite significantly higher survival and lower BPD rates in group I than in groups II and III, the ROP treatment rate was higher in group I than in groups II and III. However, the adjusted odds ratios for ROP treatment were not significantly different between the study groups, and the ROP treatment rate in the infants at 23–24 weeks’ gestation was 21-fold higher than the infants at ≥ 27 weeks’ gestation. The controversial association between improved survival and reduced BPD reflecting quality improvement of neonatal intensive care but increased ROP treatment rate might be primarily attributed to the improved survival of the most immature infants.

Using intermittent pulse oximetry to guide neonatal oxygen therapy in a low-resource context

OBJECTIVE

To evaluate the effectiveness of intermittent pulse oximetry in guiding oxygen therapy in neonates in a low-resource setting.

DESIGN AND SETTING

Prospective validation study at three hospitals in southwest Nigeria. We performed concealed continuous pulse oximetry on participants to evaluate intermittent SpO₂ monitoring.

PATIENTS

We recruited all preterm or low birthweight neonates, and all term neonates who required oxygen therapy, who were admitted to the neonatal ward(s) of the study hospitals during the study period.

MAIN OUTCOME MEASURES

Proportion of time preterm/low birthweight neonates on oxygen spent within, above and below the target SpO₂ range of 90%-95%; and the proportion of time term neonates and neonates not on oxygen spent within and below the target range of 90%-100%.

RESULTS

Preterm/low birthweight neonates receiving oxygen therapy (group A) spent 15.7% (95% CI 13.3 to 18.9) of time in the target SpO₂ range of 90%-95%. They spent 75.0% (63.6-81.1) of time above 95%, and 2.7% (1.7-5.6) of time below 85%. Term neonates and all neonates not receiving oxygen (group B) spent 97.3% (95% CI 96.4 to 98.6) of time within the target range of 90%-100%, and 0.9% (0.3-1.4) of time below 85%. Guidelines recommended SpO₂ monitoring 3 times per day for all patients, however neonates in groups A and B were monitored an average of 4.7 and 5.3 times per day, respectively.

CONCLUSIONS

To better maintain SpO₂ within the target range, preterm/low birthweight neonates on oxygen should have their SpO₂ monitored more frequently than the current 4.7 times per day. In all other neonates, however, monitoring SpO₂ 5.3 times per day appears suitable.

Retinal microglia - A key player in healthy and diseased retina

Microglia, the resident immune cells of the brain and retina, are constantly engaged in the surveillance of their surrounding neural tissue. During embryonic development they infiltrate the retinal tissues and participate in the phagocytosis of redundant neurons. The contribution of microglia in maintaining the purposeful and functional histo-architecture of the adult retina is indispensable. Within the retinal microenvironment, robust microglial activation is elicited by subtle changes caused by extrinsic and intrinsic factors. When there is a disturbance in the cell-cell communication between microglia and other retinal cells, for example in retinal injury, the activated microglia can manifest actions that can be detrimental. This is evidenced by activated microglia secreting inflammatory mediators that can further aggravate the retinal injury. Microglial activation as a harbinger of a variety of retinal diseases is well documented by many studies. In addition, a change in the microglial phenotype which may be associated with aging, may predispose the retina to age-related diseases. In light of the above, the focus of this review is to highlight the role played by microglia in the healthy and diseased retina, based on findings of our own work and from that of others.

Interventions To Prevent Retinopathy of Prematurity: A Meta-analysis

CONTEXT

The effectiveness of many interventions aimed at reducing the risk of retinopathy has not been well established.

OBJECTIVE

To estimate the effectiveness of nutritional interventions, oxygen saturation targeting, blood transfusion management, and infection prevention on the incidence of retinopathy of prematurity (ROP).

DATA SOURCES

A comprehensive search of several databases was conducted, including Medline, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus through March 2014.

STUDY SELECTION

We included studies that evaluated nutritional interventions, management of supplemental oxygen, blood transfusions, or infection reduction and reported the incidence of ROP and mortality in neonates born at <32 weeks.

DATA EXTRACTION

We extracted patient characteristics, interventions, and risk of bias indicators. Outcomes of interest were any stage ROP, severe ROP or ROP requiring treatment, and mortality.

RESULTS

We identified 67 studies enrolling 21 819 infants. Lower oxygen saturation targets reduced the risk of developing any stage ROP (relative risk [RR] 0.86, 95% confidence interval [CI], 0.77-0.97) and severe ROP or ROP requiring intervention (RR 0.58, 95% CI, 0.45-0.74) but increased mortality (RR 1.15, 95% CI, 1.04-1.29). Aggressive parenteral nutrition reduced the risk of any stage ROP but not severe ROP. Supplementation of vitamin A, E, or inositol and breast milk feeding were beneficial but only in observational studies. Use of transfusion guidelines, erythropoietin, and antifungal agents were not beneficial.

LIMITATIONS

Results of observational studies were not replicated in randomized trials. Interventions were heterogeneous across studies.

CONCLUSIONS

At the present time, there are no safe interventions supported with high quality evidence to prevent severe ROP.

Trends in retinopathy of prematurity over a 5-year period in a racially diverse population

BACKGROUND AND OBJECTIVE

Retinopathy of prematurity presents differently in developing versus developed countries, which may be due to environmental as well as racial differences.

PATIENTS AND METHODS

Retrospective chart review of infants screened for ROP at a single neonatal intensive care unit. Risk factors were reviewed. Main outcome measures were rates of plus disease or treatment-requiring ROP by race.

RESULTS

The study included 497 infants screened for ROP in an urban neonatal intensive care unit. Gestational age, birth weight, and bronchopulmonary dysplasia were independent risk factors for both plus disease and treatment-requiring ROP with type 3 multivariate analysis. Self-identified white race was also a risk factor for plus disease and treatment-requiring ROP. Race was significantly associated with maternal age, multiple births, and blood transfusions.

CONCLUSION

In the study population, white race was an independent risk factor for plus disease and ROP treatment.

A randomised controlled trial of an automated oxygen delivery algorithm for preterm neonates receiving supplemental oxygen without mechanical ventilation

Aim

Providing consistent levels of oxygen saturation (SpO₂) for infants in neonatal intensive care units is not easy. This study explored how effectively the Auto-Mixer® algorithm automatically adjusted fraction of inspired oxygen (FiO₂) levels to maintain SpO₂ within an intended range in extremely low birth weight infants receiving supplemental oxygen without mechanical ventilation.

Methods

Twenty extremely low birth weight infants were randomly assigned to the Auto-Mixer® group or the manual intervention group and studied for 12 h. The SpO₂ target was 85–93%, and the outcomes were the percentage of time SpO₂ was within target, SpO₂ variability, SpO₂ >95%, oxygen received and manual interventions.

Results

The percentage of time within intended SpO₂ was 58 ± 4% in the Auto-Mixer® group and 33.7 ± 4.7% in the manual group, SpO₂ >95% was 26.5% vs 54.8%, average SpO₂ and FiO₂ were 89.8% vs 92.2% and 37% vs 44.1%, and manual interventions were 0 vs 80 (p < 0.05). Brief periods of SpO₂ < 85% occurred more frequently in the Auto-Mixer® group.

Conclusion

The Auto-Mixer® effectively increased the percentage of time that SpO₂ was within the intended target range and decreased the time with high SpO₂ in spontaneously breathing extremely low birth weight infants receiving supplemental oxygen.

The pathophysiology of retinopathy of prematurity: an update of previous and recent knowledge

Retinopathy of prematurity (ROP) is a disease that can cause blindness in very low birthweight infants. The incidence of ROP is closely correlated with the weight and the gestational age at birth. Despite current therapies, ROP continues to be a highly debilitating disease. Our advancing knowledge of the pathogenesis of ROP has encouraged investigations into new antivasculogenic therapies. The purpose of this article is to review the findings on the pathophysiological mechanisms that contribute to the transition between the first and second phases of ROP and to investigate new potential therapies. Oxygen has been well characterized for the key role that it plays in retinal neoangiogenesis. Low or high levels of pO2 regulate the normal or abnormal production of hypoxia-inducible factor 1 and vascular endothelial growth factors (VEGF), which are the predominant regulators of retinal angiogenesis. Although low oxygen saturation appears to reduce the risk of severe ROP when carefully controlled within the first few weeks of life, the optimal level of saturation still remains uncertain. IGF-1 and Epo are fundamentally required during both phases of ROP, as alterations in their protein levels can modulate disease progression. Therefore, rhIGF-1 and rhEpo were tested for their abilities to prevent the loss of vasculature during the first phase of ROP, whereas anti-VEGF drugs were tested during the second phase. At present, previous hypotheses concerning ROP should be amended with new pathogenetic theories. Studies on the role of genetic components, nitric oxide, adenosine, apelin and β-adrenergic receptor have revealed new possibilities for the treatment of ROP. The genetic hypothesis that single-nucleotide polymorphisms within the β-ARs play an active role in the pathogenesis of ROP suggests the concept of disease prevention using β-blockers. In conclusion, all factors that can mediate the progression from the avascular to the proliferative phase might have significant implications for the further understanding and treatment of ROP.

Effects of oxygen on the development and severity of retinopathy of prematurity

In 1942, when retinopathy of prematurity (ROP) first manifested as retrolental fibroplasia, the technology to monitor or regulate oxygen did not exist, and a fundus examination of preterm infants was not routinely performed. Supplemental, uncontrolled oxygen at birth has since been found to cause retrolental fibroplasia. At the same time, technological advances have made it possible to regulate oxygen and detect early forms of ROP. Nevertheless, despite our better understanding of ROP and ongoing investigations of supplemental therapeutic oxygen, including recent clinical trials (Surfactant, Positive Airway Pressure, Pulse Oximetry Randomized Trial [SUPPORT] and Benefits of Oxygen Saturation Targeting [BOOST]), the best oxygen profiles to reduce ROP risk while optimizing preterm infant health and development remain unknown. This article reviews major studies on oxygen use in preterm infants and the effects on the development of ROP.

The toxigen initiative: targeting oxygen saturation to avoid sequelae in very preterm infants

Supplemental oxygen plays a critical role in the care of infants born at the lower limits of viability, but not without the risk of morbidity resulting from high levels or prolonged exposure.

PURPOSE

The purpose of this quality improvement project was to reduce exposure to hyperoxia as evidenced by SpO2 values within the established target range (88%-92%) among very preterm infants (VPIs) in a level 3 neonatal intensive care unit (NICU). Reducing exposure to hyperoxia in this population of exquisitely vulnerable infants has been associated with reduced morbidity, including retinopathy of prematurity, chronic lung disease, and brain injury.

SUBJECTS

Two populations of interest were identified: VPIs receiving supplemental oxygen and NICU clinicians.

DESIGN

Interventions were employed to (1) improve knowledge regarding hyperoxia and associated outcome sequelae in an interdisciplinary sample of clinicians (pretest posttest design) and (2) reinforce content of the educational intervention by triggering caregiver behaviors to reduce time the VPIs is above target SpO2 range while receiving supplemental oxygen (cohort design).

METHODS

: Retrospective chart review, baseline clinician knowledge assessment, education, posteducation assessment, collaborative rounds with regular feedback citing time VPIs spent above target oxygen saturation levels (SpO2), and evaluation of impact on time infants spent above target SpO2 range aligned with the project purpose.

OUTCOME MEASURES

Pre- and postintervention dependent variables included clinician knowledge of hyperoxia and related evidence as measured by a 24-item multiple-choice Knowledge Assessment Tool before and after attending an educational presentation. Time VPIs were exposed to hyperoxia was evaluated using SpO2 readings and calculating the percentage of time readings were above target range before and after the introduction of educational and behavioral interventions.

PRINCIPAL RESULTS

Outcome 1 was to increase knowledge about hyperoxia among clinician caregivers. Paired-samples t test showed a significant difference between preintervention and postintervention Knowledge Assessment Tool scores (P = .000). Outcome 2 measured reduction in time spent with SpO2 readings above target range. An independent-samples t test was used to compare outcomes in preintervention and postintervention VPI cohorts. Mean time spent with SpO2 greater than target range increased in the postintervention cohort, reaching statistical significance with P = .047.

CONCLUSIONS

Knowledge acquisition on the subject of hyperoxia in VPIs was achieved. Decreasing the percent time VPIs were exposed to hyperoxia was not attained. The postintervention VPI cohort spent more time above the target saturation range despite greater knowledge among clinicians.

Effect of the oxygen saturation target on clinical characteristics of early- versus late-onset retinopathy of prematurity

PURPOSE

To investigate the relationship between postmenstrual age of onset of retinopathy of prematurity (ROP) and the need for treatment, while examining the effects of two different neonatal oxygen saturation protocols on this relationship.

METHODS

A retrospective chart review was conducted for eligible inborn infants born before and after the institution of a new oxygen protocol adjusting target oxygen saturation from 90%-99% to 85%-93%. Early versus late-onset ROP was defined as first presence of any stage disease on examination at <36 versus ≥ 36 weeks' postmenstrual age, respectively.

RESULTS

The median birth weight/postmentrual age of infants was 840 g per 26.1 weeks (early-onset ROP) versus 952.5 g per 28 weeks (late-onset ROP; P < 0.01 vs P < 0.01). ROP developed in 119 of 369 (32.2%) of high oxygen target infants, and 100 of 373 (26.8%) infants in the low-target group (P = 0.11). Cumulatively, 35 of 144 (24.3%) of early-onset and 8 of 69 (11.6%) of late-onset patients required treatment (P = 0.03). Maximal severity of disease after treatment, including retinal detachment frequency, was similar in early- and late-onset patients, independent of the oxygen protocol (P = 1.00).

CONCLUSIONS

The clinical behavior of type 1 ROP is similar in early-and late-onset disease, regardless of oxygen saturation targets. Type 1 ROP disease occurred in 11.6% of patients with late-onset ROP.

The association between stage 3 or higher retinopathy of prematurity and other disorders of prematurity

OBJECTIVE

To evaluate the association between stage III or higher retinopathy of prematurity (ROP) and other prematurity disorders and parameters.

DESIGN

Retrospective, case-control study.

PARTICIPANTS

The subjects of the study were 55 consecutive premature neonates with stage III or higher ROP and 110 consecutive premature neonates without ROP.

METHODS

We compared consecutive premature neonates regarding the presence of ROP and other disorders as well as demographic and laboratory parameters.

RESULTS

Gestational age (p < 0.001); birth weight (p < 0.001); male sex (p = 0.031); bilirubin levels (p < 0.001); breast feeding (p < 0.001); clinical and laboratory sepsis (p < 0.001); number of sepsis events (p < 0.001); ventilation need (p < 0.001); number of ventilation days (p < 0.001); theophylline and surfactant use (p < 0.001); blood transfusions (p < 0.001); number of blood transfusions (p < 0.001); intraventricular hemorrhage and bronchopulmonary dysplasia (p = 0.001); and other factors differed in the two groups. The logistic regression model showed a correlation between low gestational age (OD 0.474, CI 0.359-0.626); male sex (OD 2.991, CI 1.077-8.305); blood transfusion (OD 14.159, CI 1.570-127.7); and sepsis (OD 12.376, CI 2.532-60.503).

CONCLUSIONS

Certain disorders and parameters, such as sepsis and blood transfusions, may be predict the appearance of stage III or higher ROP. Close monitoring of neonates with these findings is imperative. Early detection and treatment of sepsis and reduction of blood transfusions may decrease the incidence of ROP that requires treatment.

Hyperoxia in very preterm infants: a systematic review of the literature

Supplemental oxygen plays a critical role in the management of infants born at the lower limit of viability, but not without the risk of complications resulting from high levels or prolonged exposure. Longitudinal studies of very premature infants, born at less than 28 weeks' gestation, establish a clear relationship between pulse oximetry saturation readings above 92%, or hyperoxia, and development of severe retinopathy of prematurity, chronic lung disease, and brain injury. Hyperoxia is neither natural nor random. It is an unintended consequence of intervention. A comprehensive review of the literature reveals a strong association between exposure to hyperoxia and subsequent expression of comorbidities. Owing to this knowledge, eradication of hyperoxia, and consequent reduction of sequelae, is a significant public health concern that deserves attention by the neonatal community. Although prospective, collaborative meta-analyses will soon provide needed additional data to inform practice, existing compelling evidence supports urgent practice change to reduce exposure to hyperoxia in very preterm infants.

Infection, oxygen, and immaturity: interacting risk factors for retinopathy of prematurity

BACKGROUND

Interactions among known risk factors for retinopathy of prematurity (ROP) remain to be clarified.

OBJECTIVES

The aim of this study was to identify risk factors associated with ROP and to explore the interrelationships between prominent risk factors for ROP.

METHODS

From an institutional cohort of 1,646 very preterm newborns with gestational age <30 weeks or birth weight <1,501 g, we selected infants with a gestational age <30 weeks who met the criteria for ROP screening (n = 622) for a nested case-control analysis.

RESULTS

Of the 622 eligible newborns, 293 (47%) were diagnosed with ROP. From multivariable analyses, gestational age <26 weeks (OR 2.9, CI 1.7-4.9), oxygen exposure at 28 days (OR 1.7, CI 1.0-2.7), and neonatal sepsis (OR 2.1, CI 1.4-3.2) emerged as prominent risk factors for ROP. Oxygen- associated ROP risk was more prominent among infants of 23-25 weeks' gestational age, while infection-associated ROP risk was higher among infants born at 28-29 weeks. The OR for the joint effect of all 3 risk factors (23.5) was higher than would have been expected under the additive (8.6) and the multiplicative (16.5) patterns of interaction.

CONCLUSIONS

Our study suggests that neonatal sepsis, oxygen exposure, and low gestational age are not only independently associated with a significantly increased risk of ROP, but also interact beyond additive and even multiplicative patterns.

Studies on the pathogenesis of avascular retina and neovascularization into the vitreous in peripheral severe retinopathy of prematurity (an american ophthalmological society thesis)

PURPOSE

To study vascular endothelial growth factor (VEGF) regulation in the development of intravitreous neovascularization and peripheral avascular retina in peripheral severe retinopathy of prematurity (ROP).

METHODS

The rat 50/10 model of ROP mimics zone II, stage 3 severe ROP and recreates fluctuations in transcutaneous oxygen levels in preterm infants. On postnatal (p) day ages p0, p8, p11-p14, and p18, retinas from the model or room-air (RA) age-matched pups were analyzed for mRNA of VEGF splice variants and receptors using real-time polymerase chain reaction or VEGF protein using enzyme-linked immunosorbent assay.

RESULTS

On p14, when retinas were only 70% vascularized in the model but fully vascularized in RA, VEGF₁₆₄ expression was threefold greater in the model compared to RA. On p18, intravitreous neovascularization was associated with a 5-fold increase in VEGF₁₆₄ mRNA in the model compared to RA. By analysis of variance, VEGF₁₆₄ and VEGFR2 mRNAs were up-regulated in association with increasing developmental age (P<.0001 for both comparisons) or exposure to the model compared to RA (P<.0001 and P=.0247, respectively), whereas increasing developmental age was associated only with up-regulated VEGF₁₂₀ (P=.0006), VEGF₁₈₈ (P=.0256), and VEGFR1 (P<.0001) mRNAs. VEGF protein increased significantly in the model and on p14 and p18 compared to RA (P<.0001).

CONCLUSIONS

The model mimics contemporary severe ROP in the United States unlike other models of oxygen-induced retinopathy. Compared to RA retinas, VEGF significantly increased in association with avascular retina and intravitreous neovascularization. A hypothesis is proposed that VEGF up-regulation plays a role in the development of both important features.

Effect of decreasing target oxygen saturation on retinopathy of prematurity

INTRODUCTION

The authors of previous studies suggest that the oxygenation status of premature infants contributes to the development of retinopathy of prematurity (ROP). In this study we compared the incidence and severity of ROP before and after institution of a new neonatal intensive care unit oxygen protocol.

METHODS

A retrospective chart review was performed of all eligible inborn patients screened for ROP during the 2 years immediately before (Group 1) to and the 2 years after (Group 2) the initiation of a new oxygen protocol. In the new protocol, target oxygen saturation was adjusted from 90%-99% to 85%-93%. Treatment criteria adhered to Early Treatment for Retinopathy of Prematurity guidelines for the study's duration.

RESULTS

There were 387 infants in Group 1 and 386 infants in Group 2 (descriptive statistics adjusted for correlation due to multiple births). Mean birth weights (BWs) and gestational ages were 1,194 g and 29.2 weeks (ranges, 525-2,085 g; 23 2/7-39 6/7 weeks) for Group 1 and 1,139 g and 28.9 weeks (ranges, 520-2,500 g; 22 6/7-35 3/7 weeks) for Group 2 (p = 0.02/0.10). ROP developed in 32.7% of infants in Group 1 and 27.8% in Group 2 (p = 0.17). The incidence of ROP requiring treatment was 19.9% in Group 1 and 20.5% in Group 2 (p = 0.91). Subanalysis of infants with BW ≤ 1,000g (Group 1, n = 119; Group 2, n = 141) revealed ROP incidence of 75.1% versus 57.1%, respectively (p < 0.01); treatable disease occurred in 37.5% and 21.9% of affected infants (p = 0.19).

CONCLUSIONS

Lowering target oxygen saturation for inborn premature infants was associated with decreased incidence of ROP only in infants with BW ≤ 1,000 g. Severity of disease, including need for treatment, was similar in both groups.

Stanford University network for diagnosis of retinopathy of prematurity (SUNDROP): 36-month experience with telemedicine screening

BACKGROUND AND OBJECTIVE

to report the 36-month experience of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.

PATIENTS AND METHODS

retrospective analysis of the SUNDROP archival data between December 1, 2005, and November 30, 2008, to evaluate this diagnostic technology for retinopathy of prematurity (ROP) screening. A total of 230 consecutively enrolled infants meeting ROP examination criteria were screened with the Ret-Cam II (Clarity Medical Systems, Pleasanton, CA) and evaluated by the SUNDROP reading center at Stanford University. Outcomes included referral-warranted ROP, treatment-warranted ROP, and anatomic outcomes.

RESULTS

in the initial 36-month period, the SUNDROP telemedicine initiative did not miss any treatment-warranted ROP. A total of 230 infants (460 eyes) were imaged, resulting in 1,059 examinations and 10,921 unique images. Ten infants were identified with referral-warranted ROP: nine underwent laser photocoagulation and one regressed spontaneously. The sensitivity was 100% with a specificity of 99.5%. No patient progressed to retinal detachment or other adverse outcomes.

CONCLUSION

the SUNDROP telemedicine screening initiative for ROP has demonstrated high reliability for identification of treatment-warranted disease. All cases of treatment-warranted disease were captured. There were no adverse outcomes.

High or low oxygen saturation and severe retinopathy of prematurity: a meta-analysis

CONTEXT

Low oxygen saturation appears to decrease the risk of severe retinopathy of prematurity (ROP) in preterm newborns when administered during the first few weeks after birth. High oxygen saturation seems to reduce the risk at later postmenstrual ages (PMAs). However, previous clinical studies are not conclusive individually.

OBJECTIVE

To perform a systematic review and meta-analysis to report the association between severe ROP incidence of premature infants with high or low target oxygen saturation measured by pulse oximetry.

METHODS

Studies were identified through PubMed and Embase literature searches through May 2009 by using the terms "retinopathy of prematurity and oxygen" or "retinopathy of prematurity and oxygen therapy." We selected 10 publications addressing the association between severe ROP and target oxygen saturation measured by pulse oximetry. Using a random-effects model we calculated the summary-effect estimate. We visually inspected funnel plots to examine possible publication bias.

RESULTS

Low oxygen saturation (70%-96%) in the first several postnatal weeks was associated with a reduced risk of severe ROP (risk ratio [RR]: 0.48 [95% confidence interval (CI): 0.31-0.75]). High oxygen saturation (94%-99%) at > or = 32 weeks' PMA was associated with a decreased risk for progression to severe ROP (RR: 0.54 [95% CI: 0.35-0.82]).

CONCLUSIONS

Among preterm infants with a gestational age of < or = 32 weeks, early low and late high oxygen saturation were associated with a reduced risk for severe ROP. We feel that a large randomized clinical trial with long-term developmental follow-up is warranted to confirm this meta-analytic result.

Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): 24-month experience with telemedicine screening

PURPOSE

To report the 24-month experience of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.

METHODS

Retrospective analysis of the SUNDROP archival data gathered between 1 December 2005 and 30 November 2007 to evaluate this diagnostic technology for ROP screening. One hundred and sixty consecutively enrolled infants meeting ROP examination criteria were screened with the RetCam II and evaluated by the SUNDROP reading centre at Stanford University. Nurses obtained five or six images in each eye. All patients also received a dilated examination within 1 week of discharge. Outcomes included treatment-warranted retinopathy of prematurity (TW-ROP) and anatomical outcomes.

RESULTS

In the initial 24-month period, the SUNDROP telemedicine initiative has not missed any TW-ROP. A total of 160 infants (320 eyes) were imaged, resulting in 669 exams and 7556 images. Seven infants were identified with TW-ROP; six underwent laser photocoagulation and one regressed spontaneously. The sensitivity was 100%, with specificity of 99.4%. No patient progressed to retinal detachment or other adverse outcomes.

CONCLUSION

The SUNDROP telemedicine screening initiative for ROP has been proven to have a high degree of sensitivity and specificity for the identification of treatment-warranted disease. All cases of treatment-warranted disease were captured. There were no adverse outcomes.

The effects of oxygen stresses on the development of features of severe retinopathy of prematurity: knowledge from the 50/10 OIR model

The objective of this study is to determine growth factor expression and activation of signaling pathways associated with intravitreous neovascularization and peripheral avascular retina using a model of retinopathy of prematurity (ROP) relevant to today with oxygen monitoring in neonatal units. Studies using 50/10 oxygen-induced retinopathy (OIR) and 50/10 OIR+SO models were reviewed. Repeated fluctuations in oxygen increased retinal vascular endothelial growth factor (VEGF) even while peripheral avascular retina persisted and prior to the development of intravitreous neovascularization. Repeated fluctuations in oxygen increased VEGF(164) expression but not VEGF(120). Neutralizing VEGF bioactivity significantly reduced intravitreous neovascularization and arteriolar tortuosity without interfering with ongoing retinal vascularization. Repeated oxygen fluctuations led to retinal hypoxia and increased reactive oxygen species (ROS). Inhibiting ROS with NADPH oxidase inhibitor, apocynin, reduced avascular retina by interfering with apoptosis. Supplemental oxygen reduced retinal VEGF concentration and exacerbated NADPH oxidase activation to contribute to intravitreous neovascularization through activation of the JAK/STAT pathway. Oxygen stresses relevant to those experienced by preterm infants today trigger signaling of different pathways to cause avascular retina and intravitreous neovascularization. Increased signaling of VEGF appears important to the development of both avascular retina and intravitreous neovascularization.

Retinopathy of prematurity in extremely premature infants

INTRODUCTION

The incidence and severity of retinopathy of prematurity (ROP) in extremely premature infants have not been reported since publication of the Early Treatment of ROP study results. The survival rate of these infants continues to increase. We sought to determine the characteristics of ROP in a group of surviving infants <25 weeks estimated gestational age (EGA) at birth compared to a group 25 to 27 weeks EGA at birth.

METHODS

Retrospective review of infants born prior to 27 weeks EGA between January 2003 and July 2007 at a level-3 nursery at a regional academic medical center.

RESULTS

A total of 231 medical records were reviewed and found to have analyzable data. Of 79 infants <25 weeks EGA, 69 (87%) developed ROP, compared to 95 of 152 (62%) infants 25 to 27 weeks EGA. Type 1 ROP developed in 23% of infants in the <25 weeks EGA group, compared to 9% of infants in the 25 to 27 weeks EGA group. There was no difference in mean postmenstrual age when type 1 ROP was diagnosed. Lower birth weight predicted increased risk of type 1 ROP in the 25 to 27 weeks EGA group, but not in the <25 weeks EGA group.

CONCLUSIONS

Extremely premature infants are more likely to develop ROP and type 1 ROP, but the incidence may be lower than previously reported. Birth weight may not influence the incidence of type 1 ROP in this group of infants. Type 1 ROP does not develop at an earlier postmenstrual age in the extremely premature infant.

[Risk factors and prevention of retinopathy of prematurity]

The history of retinopathy of prematurity (ROP) gives a prime example of how dangerous the uncontrolled introduction of a new medical treatment--particularly in the field of neonatology--may be. The most important risk factors for the development of ROP are the immaturity of premature infants as well as uncontrolled and/or inadequate treatment with oxygen. In comparison to the fetus, the premature infant is exposed to a nonphysiologically high oxygen concentration. This hyperoxia leads to formation of aggressive oxygen radicals on the one hand and, on the other hand, to temporarily reduced production of growth factors such as vascular endothelial growth factor and erythropoietin, which both play an important role in the pathogenesis of ROP. The most important measure to prevent ROP is restrictive and carefully monitored oxygen treatment. Medical treatment to prevent ROP includes injection of D-penicillamine and retinol, but the available data are still limited, particularly with regard to the long-term effects of this treatment. A higher oxygenation in prethreshold ROP does not lead to recovery of ocular findings, but it increases the incidence of pulmonary complications. A reduction of light intensity in neonatal intensive care units proved not to be efficient for preventing ROP. To avoid blindness, standardized screening of the risk group is needed.

The role of supplemental oxygen and JAK/STAT signaling in intravitreous neovascularization in a ROP rat model

PURPOSE

To investigate whether oxygen stresses experienced in retinopathy of prematurity (ROP) trigger signaling through reactive oxygen species (ROS) and whether the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway lead to intravitreous neovascularization (IVNV) in an oxygen-induced retinopathy (OIR) rat model.

METHODS

Newborn rat pups exposed to repeated fluctuations in oxygen and rescued in supplemental oxygen (28% O(2), 50/10 OIR+SO) were treated with apocynin, an NADPH oxidase and ROS inhibitor (10 mg/kg/d), AG490, a JAK2 inhibitor (5 mg/kg/d), or phosphate-buffered saline. Intraperitoneal injections were given from postnatal day (P)12 to P17 (apocynin), or from P3 to P17 (AG490). Outcomes were intravitreous neovascularization and avascular/total retinal areas, vascular endothelial growth factor, phosphorylated JAK2, and phosphorylated STAT3.

RESULTS

Apocynin significantly reduced phosphorylated STAT3 in 50/10 OIR+SO (P = 0.04), in association with previously reported inhibition of the IVNV area. Inhibition of JAK with AG490 significantly reduced phosphorylated JAK2 (P < 0.001), phosphorylated STAT3 (P = 0.002), and IVNV area (P = 0.033) in the 50/10 OIR+SO model compared with control.

CONCLUSIONS

Activation of NADPH oxidase from supplemental oxygen works through activated STAT3 to lead to IVNV. In addition, inhibition of the JAK/STAT pathway reduces IVNV. Further studies are needed to determine the effects and relationships of oxygen stresses on JAK/STAT and NAPDH oxidase signaling.

Restricted versus liberal oxygen exposure for preventing morbidity and mortality in preterm or low birth weight infants

BACKGROUND

While the use of supplemental oxygen has a long history in neonatal care, resulting in both significant health care benefits and harms, uncertainty remains as to the most appropriate range to target blood oxygen levels in preterm and low birth weight infants. Potential benefits of higher oxygen targeting may include more stable sleep patterns and improved long-term growth and development. However, there may be significant deleterious pulmonary effects and health service use implications resulting from such a policy.

OBJECTIVES

To determine whether targeting ambient oxygen concentration to achieve a lower vs. higher blood oxygen range, or administering restricted vs. liberal supplemental oxygen, effects mortality, retinopathy of prematurity, lung function, growth or development in preterm or low birth weight infants.

SEARCH STRATEGY

The standard search strategy of the Neonatal Review Group was used. An additional literature search was conducted of the MEDLINE and CINAHL databases in order to locate any trials in addition to those provided by the Cochrane Controlled Trials Register (CENTRAL/CCTR). Search updated to week two July 2008.

SELECTION CRITERIA

All trials in preterm or low birth weight infants utilising random or quasi-random patient allocation in which ambient oxygen concentrations were targeted to achieve a lower vs. higher blood oxygen range, or restricted vs. liberal oxygen was administered were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

The methodological quality of the eligible trials was assessed independently by each review author for the degree of selection, performance, attrition and detection bias. Data were extracted and reviewed independently by the each author. Data analysis was conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

In the meta-analysis of the five trials included in this review, the restriction of oxygen significantly reduced the incidence and severity of retinopathy of prematurity without unduly increasing death rates The one prospective, multicenter, double-blind, randomized trial investigating lower vs. higher blood oxygen levels from 32 weeks postmenstrual age showed no significant differences in the rates of ROP, mortality or growth and development between the two groups. However, this study did show increased rates of chronic lung disease and home oxygen use.

AUTHORS' CONCLUSIONS

The results of this systematic review confirm that (the now historical) policy of unrestricted, unmonitored oxygen therapy has potential harms without clear benefits. However, the question of what is the optimal target range for maintaining blood oxygen levels in preterm/LBW infants was not answered by the data available for inclusion in this review.

Clinical practices in neonatal oxygenation: where have we failed? What can we do?

INTRODUCTION

Oxygen is among the most frequently used therapies in neonates worldwide. Nevertheless, many times it is used unnecessarily. Neonatal practices have changed over the last several years; treatments originally believed to be beneficial have been discarded.

STUDY DESIGN

Oxygen utilized 'just in case' or 'prophylactically' can lead to great damage previously ignored and/or unseen by healthcare providers. It is imperative to improve education on neonatal oxygenation and saturation monitoring. It is also important not to depend on old assumptions, which were not based on evidences. The potential for unseen damage at the cellular and tissue levels cannot be ignored. Therapies that prove to be outdated or even dangerous must be eliminated while further research and confirmation of the best practices are determined. Freedom to choose can come at a price.