[Retinopathy of prematurity and oxygen therapy: a changing relationship]

Risk factors of bronchopulmonary dysplasia depending on the severity of the disease in very preterm infants

OBJECTIVE

Bronchopulmonary dysplasia (BPD) remains a common pathology in very preterm infants. The risk of complications increases with the severity of the disease.The study aimed to determine the factors affecting the formation of moderate/severe BPD in the modern population of very preterm infants.

METHODS

Data from 201 very low birth weight infants < 32 weeks of gestation were used in a retrospective cohort study. Infants were retrospectively divided into two groups based on the type of respiratory support at 36 weeks of postmenstrual age (PMA) - mild BPD (133 infants) and moderate/severe BPD (68 infants). The influence of major perinatal risk factors, neonatal morbidity, and medical interventions on the development of moderate/severe BPD was assessed.

RESULTS

The groups were different in the incidence of intrauterine growth restriction (5% vs. 15%; p = 0.02), maternal hypertension (5% vs. 18%; p = 0.004), cesarean section (29% vs. 43%; p = 0.04), severe intraventricular hemorrhage (9% vs. 19%; p = 0.04), and retinopathy of prematurity (5% vs. 18%; p = 0.002), as well as in need for chest compressions during resuscitation at birth (2% vs. 9%; p = 0.01) for mild and moderate/severe BPD, respectively. Infants in the moderate/severe BPD group had lower Apgar scores at 1 and 5 min, required longer mechanical ventilation (220 (10-1904) hours vs. 72 (1-614) hours; p < 0.0001), CPAP duration (456 (16-1320) hours vs. 278 (10-1200) hours; p = 0.0002), oxygen supply (50 (3-146) days vs. 29 (2-68) days; p < 0.0001), as well as antibacterial therapy (61 (16-177) days vs. 52 (9-121) days; p = 0.0001) and hospital stay (109 (59-321) days vs. 85 (45-205) days; p < 0.0001). Infants with more severe BPD were also significantly more likely to die after reaching the PMA of 36 weeks (12% vs. 1%; p = 0.0003).According to the multivariable logistic regression analysis, the moderate/severe BPD was reliably and independently determined by maternal hypertension (aOR 4.53, 95% CI 1.48-13.91) and genitourinary infections (aOR 4.41, 95% CI 1.41-13.78), as well as the duration of CPAP (aOR 1.002, 95% CI 1.001-1.004) and mechanical ventilation (aOR 1.006, 95% CI 1.004-1.009).

CONCLUSIONS

Duration of respiratory support is the main risk factor that determines the development of moderate/severe BPD in the modern population of very preterm infants. Maternal hypertension and genitourinary infections may influence the severity of lung injury.

Hyperbaric oxygen therapy as an adjunt treatment for glioma and brain metastasis: a literature review

The incidence and mortality rates of malignant tumors are increasing annually, with gliomas and brain metastases linked to a poor prognosis. Hyperbaric oxygen therapy is a promising treatment modality for both gliomas and brain metastases. It can alleviate tumor hypoxia and enhance radiosensitivity. When combined with other treatments for gliomas, this therapy has the potential to enhance survival rates. This review addresses the progress in research on the use of hyperbaric oxygen therapy combined with radiotherapy. For brain metastases, the combination of hyperbaric oxygen therapy and stereotactic radiosurgery is both feasible and advantagenous. This combination not only offers protection against radiation-induced brain injury but also supports the recovery of neurological and motor functions. The incidence of adverse reactions to hyperbaric oxygen therapy is relatively low, and it is safe and manageable. Future efforts should be made to investigate the mechanisms by which hyperbaric oxygen therapy combined with radiotherapy treats gliomas and brain metastases, optimize protection of the combined treatment against brain injury, minimizing adverse reactions, conducting multidisciplinary research and clinical trials, and training healthcare providers to facilitate broader clinical application.

Evaluating the Utility of Initial Examinations in Retinopathy of Prematurity: Proposal of FIRST-ROP Algorithm for a Medium-Risk Cohort

PURPOSE

To assess the utility of the first or second examinations for retinopathy of prematurity (ROP) in a medium-risk cohort of infants and to propose an optimization to the current ROP screening guidelines.

DESIGN

Retrospective consecutive study.

PARTICIPANTS

Infants screened for ROP between January 2017 and August 2023 at 3 different tertiary-level care neonatal intensive care units.

METHODS

Analysis of patients who did not meet criteria for microprematurity or nanoprematurity (those born at ≥ 27 weeks and weighing ≥ 800 g).

MAIN OUTCOME MEASURES

The primary outcomes included the rates of ROP and treatment-warranted ROP (TW-ROP), the presence of TW-ROP at the first or second inpatient examinations, the number of inpatient examinations performed before the first ROP diagnosis, and the overall number of inpatient examinations performed.

RESULTS

A total of 2004 neonates were screened for ROP, among whom 1125 (56.1%) met the inclusion criteria. Of those, 237 neonates (21.1%) had ROP. Eleven infants (1.0%) required treatment for active disease. The median postmenstrual age (PMA) at first ROP diagnosis was 35.3 weeks (interquartile range [IQR], 33.7-37 weeks; range, 30.3-46.7 weeks). The median PMA at stage 3 diagnosis was 39.3 weeks (IQR, 38.3-41.2 weeks; range, 35.1-44.4 weeks). The median PMA at first treatment was 39.6 weeks (IQR, 35.8-43.3 weeks; range, 35.3-49.6 weeks). The median number of inpatient examinations was 2.0 (IQR, 1-4 examinations) for traditional screening, 1.0 examination (IQR, 1-3 examinations) after eliminating the first ROP inpatient examination, and 1.0 examination (IQR, 1-2 examinations) after eliminating the first and second ROP examinations (P < 0.001). No patients met type 1 ROP treatment criteria at either the first or second inpatient examination (100% sensitivity for TW-ROP). In this cohort, starting examinations at 34 weeks' PMA could save 30.6% of inpatient examinations.

CONCLUSIONS

In infants not meeting criteria for microprematurity or nanoprematurity, no type 1 ROP was diagnosed at either of the first 2 inpatient examinations. We propose an amendment algorithm (FIRST-ROP) in which ROP examinations start at 34 weeks' PMA for neonates born at ≥27 weeks gestational age and ≥800 grams.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Monitoring SpO2: The Basics of Retinopathy of Prematurity (Back to Basics) and Targeting Oxygen Saturation

Oxygen (O2) is a drug frequently used in newborn care. Adverse effects of hypoxia are well known but the damaging effects of excess oxygen administration and oxidative stress have only been studied in the last 2 decades. Many negative effects have been described, including retinopathy of prematurity . Noninvasive pulse oximetry (SpO2) is useful to detect hypoxemia but requires careful evaluation and understanding of the frequently changing relationship between O2 and hemoglobin to prevent hyperoxemia. Intention to treat SpO2 ranges should be individualized for every newborn receiving supplemental O2, according to gestational age, post-natal age, and clinical condition.

A General Overview on the Hyperbaric Oxygen Therapy: Applications, Mechanisms and Translational Opportunities

Hyperbaric oxygen therapy (HBOT) consists of using of pure oxygen at increased pressure (in general, 2-3 atmospheres) leading to augmented oxygen levels in the blood (Hyperoxemia) and tissue (Hyperoxia). The increased pressure and oxygen bioavailability might be related to a plethora of applications, particularly in hypoxic regions, also exerting antimicrobial, immunomodulatory and angiogenic properties, among others. In this review, we will discuss in detail the physiological relevance of oxygen and the therapeutical basis of HBOT, collecting current indications and underlying mechanisms. Furthermore, potential areas of research will also be examined, including inflammatory and systemic maladies, COVID-19 and cancer. Finally, the adverse effects and contraindications associated with this therapy and future directions of research will be considered. Overall, we encourage further research in this field to extend the possible uses of this procedure. The inclusion of HBOT in future clinical research could be an additional support in the clinical management of multiple pathologies.

How to prevent ROP in preterm infants in Indonesia?

BACKGROUND AND AIMS

Retinopathy of prematurity (ROP) is a severe disease in preterm infants. It is seen more frequently in Low-Middle Income Countries (LMIC) like Indonesia compared to High-Income Countries (HIC). Risk factors for ROP development are -extreme- preterm birth, use of oxygen, neonatal infections, respiratory problems, inadequate nutrition, and blood and exchange transfusions. In this paper, we give an overview of steps that can be taken in LMIC to prevent ROP and provide guidelines for screening and treating ROP.

METHODS

Based on the literature search and data obtained by us in Indonesia's studies, we propose guidelines for the prevention, screening, and treatment of ROP in preterm infants in LMIC.

RESULTS

Prevention of ROP starts before birth with preventing preterm labor, transferring a mother who might deliver <32 weeks to a perinatal center and giving corticosteroids to mothers that might deliver <34 weeks. Newborn resuscitation must be done using room air or, in the case of very preterm infants (<29-32 weeks) by using 30% oxygen. Respiratory problems must be prevented by starting continuous positive airway pressure (CPAP) in all preterm infants <32 weeks and in case of respiratory problems in more mature infants. If needed, the surfactant should be given in a minimally invasive manner, as ROP's lower incidence was found using this technique. The use of oxygen must be strictly regulated with a saturation monitor of 91-95%. Infections must be prevented as much as possible. Both oral and parenteral nutrition should be started in all preterm infants on day one of life with preferably mothers' milk. Blood transfusions can be prevented by reducing the amount of blood needed for laboratory analysis.

DISCUSSION

Preterm babies should be born in facilities able to care for them optimally. The use of oxygen must be strictly regulated. ROP screening is mandatory in infants born <34 weeks, and infants who received supplemental oxygen for a prolonged period. In case of progression of ROP, immediate mandatory treatment is required.

CONCLUSION

Concerted action is needed to reduce the incidence of ROP in LMIC. "STOP - R1O2P3" is an acronym that can help implement standard practices in all neonatal intensive care units in LMIC to prevent development and progression.

Improving Uptake of Key Perinatal Interventions Using Statewide Quality Collaboratives

Regional and statewide quality improvement collaboratives have been instrumental in implementing evidence-based practices and facilitating quality improvement initiatives within neonatology. Statewide collaboratives emerged from larger collaborative organizations, like the Vermont Oxford Network, and play an increasing role in collecting and interpreting data, setting priorities for improvement, disseminating evidence-based clinical practice guidelines, and creating regional networks for synergistic learning. In this review, we highlight examples of successful statewide collaborative initiatives, as well as challenges that exist in initiating and sustaining collaborative efforts.

Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified

Significance: Hyperbaric oxygen therapy (HBOT) is an important advanced therapy in the treatment of problem wounds, including diabetic foot ulcers and late effect radiation injury. HBOT remains among the safest therapies used today. Nonetheless, there are side effects associated with HBOT. It is important for providers to be able to identify, understand, and quantify these side effects for prevention, management, and informed consent. Recent Advances: The past two decades have seen significant advancements in our understanding of the underlying mechanisms of HBOT. This has led to a better understanding of the underlying reason for clinical benefit. It has also led to a better understanding of its side effects. Moreover, more recent literature allows for better quantification of these side effects. This review will highlight these side effects. Critical Issues: Wound healing in the case of problem nonhealing wounds requires the use of various advanced treatment modalities, including HBOT. HBOT has been shown to significantly improve healing rates in certain problem wounds, including advanced diabetic foot ulcers and late effect radiation injury. It is provided in a variety of clinical settings by providers with varying levels of expertise. It is important for those providing this therapy to understand the potential side effects. Future Directions: Research in HBOT has led to significant advancements in the area of wound healing. At the same time, there remains a variety of treatment protocols used at different institutions. It is important to quantify risk and benefit at different treatment pressures and times to better standardize treatment and improve patient care.

Differentially expressed miRNAs in oxygen‑induced retinopathy newborn mouse models

The present study aimed to identify microRNAs (miRNAs) involved in regulating retinal neovascularization and retinopathy of prematurity (ROP). A total of 80 healthy C57BL/6 neonatal mice were randomly divided into the oxygen-induced retinopathy (OIR) group (n=40), in which 7-day-old mice were maintained in 75% oxygen conditions for 5 days, or the control group (n=40). Following collection of retinal tissue, retinal angiography and hematoxylin and eosin (H&E) staining were performed. Total RNA was also extracted from retinal tissue, and miRNA microarrays and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were performed to identify differentially expressed miRNAs in the two groups. Retinal angiography and H&E staining revealed damage to retinas in the OIR group. Compared with the control group, 67 miRNAs were differentially expressed in the OIR group, of which 34 were upregulated and 33 were downregulated. Of these differentially expressed miRNAs, 32 exhibited a fold change ≥2, of which 21 were upregulated and 11 were downregulated. The results of RT-qPCR for miR-130a-3p and miR-5107-5p were in accordance with those of the miRNA microarray. The newly identified miRNAs may be important in the development of ROP, and may provide a basis for future research into the mechanisms of ROP.

Time outside targeted oxygen saturation range and retinopathy of prematurity

OBJECTIVE

To better understand the impact of hypoxia and hyperoxia on neonatal morbidity and mortality, we examined the number of hypoxia and hyperoxia events as well as percentage of time spent outside oxygen saturation targets in relationship to threshold retinopathy of prematurity (tROP) and mortality in preterm infants.

STUDY DESIGN

Saturation data in 2-second sampling from pulse oximeters was prospectively collected in a single NICU. Average SaO2, low and high saturation events, duration of events, and percentage of time infants spent outside of oxygen saturation range were collected and analyzed continuously during the hospitalization.

RESULTS

102 infants <1500g or <32 weeks gestation were enrolled. There were 125, 112, and 43 hypoxia events/day and 106, 80, and 34 hyperoxia events/day for tROP (N=8), non-survivor (N=16) and non-tROP patients (N=78), respectively. Infants were outside saturation targets for 2:35, 1:38, and 1:03 (hypoxia) and 2:02, 1:25, and 0:38 hours/day (hyperoxia) for tROP, non-survivor and non-tROP, respectively. Time spent outside saturation range (hypoxia, hyperoxia and total time) for the hospital course was higher in tROP (P≤0.006) and non-survivor (P≤0.005) compared with non-tROP patients. The three groups defined themselves in the first 10 days after birth, with regard to duration of hypoxia (P=0.0003), hyperoxia (P=0.0004) and total time outside the targeted saturation range (P=0.0006).

CONCLUSIONS

Information such as the duration and number of hypoxia and hyperoxia events, as well as total time outside the targeted saturation range, could be factored into assessing clinical interventions and research studies in the prevention, treatment and evaluation of neonatal outcomes.

The role of hemoglobin variant replacement in retinopathy of prematurity

OBJECTIVE

To conduct tests of relationships between different factors that could influence the course of retinopathy of prematurity (ROP) and ROP, particularly the role of hemoglobin variant replacement in adult blood transfusions.

METHODS

A retrospective, observational study of 83 infants born between 23 and 34 wks gestation was conducted.

RESULTS

The infants without ROP, with 1 and 2 stage of ROP and with ≥ 3 stage of ROP received Q 28 (12-134); 51 (14-149); 156 (38-244) ml/kg of transfused blood, respectively, and the factor Qt was 1,545 (560-10,045); 3,093 (614-13,419); 11,907 (1,288-20,638) (ml/kg)·day, respectively. For the same groups MCV(35) (mean cell volume at the arbitrary time of the 35(th) wk post-conception) was 92.3 (82.9-110.5); 91.0 (79.3-101.4); 87.1 (80.2-94.8) fl, respectively, and factor P(MCV)/t was 99.5 (89.2-108.8); 96.3 (84.6-106.3); 90.7 (85.3-96.5) fl, respectively. There is high influence on the stage of ROP of the amount of transfused blood and MCV, both with or without the time factor. The statistical differences between P(MCV)/t were more significant than the differences between MCV(35), for different stages of ROP.

CONCLUSIONS

The influence of the time factor on the statistical differences of MCV but not on the amount of transfused adult blood suggests that HbF - HbA replacement may play a role in ROP development.

Reduced oxygen protocol decreases the incidence of threshold retinopathy of prematurity in infants of <33 weeks gestation

BACKGROUND

The relationship between oxygen and retinopathy of prematurity (ROP) has been studied frequently, and a pulse oximeter has the potential to facilitate the control of oxygen fluctuation in neonates. The objective of the present study was to compare the incidence of threshold ROP (stage 3 requiring laser treatment and stage 4) in infants of <33 weeks gestation after implementing a new clinical O(2) management practice.

METHODS

A retrospective study of data from the Kyoto First Red Cross Hospital neonatal intensive care unit (NICU) from 1 July 2004 to 31 October 2007 (closed 1 December 2006-30 March 2007 for reconstruction). A reduced oxygen protocol was implemented to maintain oxygen saturation (SpO(2)) values using a pulse oximeter between 88% and 92%. The incidence of threshold ROP in the earlier period (1 July 2004-31 December 2005) and the later period (1 January 2006-31 October 2007) were compared.

RESULTS

The incidence of threshold ROP significantly decreased from 32.2% to 16.7%, after changing to the reduced oxygen protocol (P < 0.05).

CONCLUSION

A significant decrease in the rate of threshold ROP in infants of <33 weeks gestation was observed after implementation of the new clinical O(2) management practice.

Pulse oxygen saturation levels and arterial oxygen tension values in newborns receiving oxygen therapy in the neonatal intensive care unit: is 85% to 93% an acceptable range?

OBJECTIVE

Our aim was to define the relationship of PaO(2) and pulse oxygen saturation values during routine clinical practice and to evaluate whether pulse oxygen saturation values between 85% and 93% were associated with PaO(2) levels of <40 mmHg.

METHODS

Prospective comparison of PaO(2) and pulse oxygen saturation values in 7 NICUs at sea level in 2 countries was performed. The PaO(2) measurements were obtained from indwelling arterial catheters; simultaneous pulse oxygen saturation values were recorded if the pulse oxygen saturation values changed <1% before, during, and after the arterial gas sample was obtained.

RESULTS

We evaluated 976 paired PaO(2)/pulse oxygen saturation values in 122 neonates. Of the 976 samples, 176 (18%) from infants breathing room air had a mean pulse oxygen saturation of 93.9 +/- 4.3% and a median of 95.5%. The analysis of 800 samples from infants breathing supplemental oxygen revealed that, when pulse oxygen saturation values were 85% to 93%, the mean PaO(2) was 56 +/- 14.7 mmHg and the median 54 mmHg. At this pulse oxygen saturation level, 86.8% of the samples had PaO(2) values of 40 to 80 mmHg, 8.6% had values of <40 mmHg, and 4.6% had values of >80 mmHg. When the pulse oxygen saturation values were >93%, the mean PaO(2) was 107.3 +/- 59.3 mmHg and the median 91 mmHg. At this pulse oxygen saturation level, 39.5% of the samples had PaO(2) values of 40 to 80 mmHg and 59.5% had values of >80 mmHg.

CONCLUSIONS

High PaO(2) occurs very rarely in neonates breathing supplemental oxygen when their pulse oxygen saturation values are 85% to 93%. This pulse oxygen saturation range also is infrequently associated with low PaO(2) values. Pulse oxygen saturation values of >93% are frequently associated with PaO(2) values of >80 mmHg, which may be of risk for some newborns receiving supplemental oxygen.

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.

Elevated erythropoietin mRNA and protein concentrations in the developing human eye

Erythropoietin (Epo) is an erythropoietic, neurotropic, and angiogenic factor, and may be involved in retinal development. Studies in adult diabetic retinopathy patients reveal significantly elevated vitreal Epo concentrations. It is unknown whether Epo plays a similar role in retinopathy of prematurity. We sought to determine whether Epo is present in the normally developing human eye. Fetal serum and vitreous samples were obtained from 12 to 24 wk gestation. RNA was extracted from isolated retina for Epo mRNA and hypoxia inducible factor-1alpha (HIF) mRNA determination by real-time polymerase chain reaction. Fetal serum was isolated from the umbilical cord. Serum and vitreous samples were analyzed for Epo protein by enzyme-linked immunosorbent serologic assay. In fetal retina, Epo mRNA increased with increasing gestational age, while HIF mRNA remained constant. Epo protein increased with increasing gestation in both vitreous and serum. At each gestational group measured (12-14, 15-17, 18-20, and 21-24 wk), Epo concentrations were significantly greater in vitreous than in serum (p < 0.05). Epo mRNA and protein concentrations increase with increasing gestational age and are greater in the vitreous than serum. We speculate that changes in Epo production following preterm delivery might affect retinal vascular development.

Treatment-by-gender effect when aiming to avoid hyperoxia in preterm infants in the NICU

OBJECTIVE

To examine gender-specific differences in response to the O(2) saturation (SpO(2)) targets aimed at avoiding hyperoxia in very low birth weight infants (VLBW).

METHODS

Analysis of a prospectively collected database of all infants </=1250 g in two perinatal centres. A change was instituted in January 2003 with the objective of avoiding hyperoxia with target SpO(2) at 85-93% (period II). Prior to this, SpO(2) high alarms were set at 100% and low alarms at 92% (period I; from January 2000 to December 2002).

RESULTS

Of the 497 infants that met enrolment criteria, 297 (60%) were born during period I and 140 (47%) of them were male. During period II, 200 infants were born and 101 (50%) were male. Analysis by gender showed that the rate of retinopathy of prematurity, bronchopulmonary dysplasia and length of stay is significantly better for female infants than males on period II compared to period I. Neither gender experienced increased short-term neurological morbidity in response to lower SpO(2) targets.

CONCLUSIONS

There is a significant gender-specific difference favouring females in the beneficial effects produced by avoiding high SpO(2) and hyperoxia, with no difference in the distribution of any potential short-term detrimental effects.

Oxygen as a neonatal health hazard: call for détente in clinical practice

Education in oxygenation and in how oxygen is given to newborns needs to increase. Treatment with oxygen should no longer be considered proverbial and customary, regardless of our 'past experience' or consensus recommendations in clinical guidelines, since oxygen may lead to acute or chronic health effects.

CONCLUSION

Inappropriate oxygen use is a neonatal health hazard associated with aging, DNA damage and cancer, retinopathy of prematurity, injury to the developing brain, infection and others. Neonatal exposure to pure O2, even if brief, or to pulse oximetry >95% when breathing supplemental O2 must be avoided as much as possible.

La retinopatía del prematuro en el siglo XXI en un país en desarrollo: una urgencia que debe ser resuelta

INTRODUCTION

Retinopathy of prematurity (ROP) is the first cause of childhood blindness in Argentina and is reaching epidemic proportions. To gain greater insight into the issues involved in this epidemic, we analyzed the characteristics of the infants referred for treatment of very severe ROP to the Dr. Juan P. Garrahan Pediatric Hospital, located in the city of Buenos Aires.

METHODS

We performed a retrospective study of patients referred for ROP from 01/01/96 to 12/31/03. Very severe ROP was defined as threshold disease or worse in both eyes, plus disease in zones 1 or 2, or Rush disease. Unusual patients were defined as those with very severe ROP with a gestational age (GA) of > 31 weeks or birth weight (BW) > 1500 g. Patients were divided into two groups according to the distance between the referring center and our hospital: group A consisted of those from nearby areas (<or= 70 km) and group B comprised those from areas > 70 km from the hospital.

RESULTS

During the study period, the number of cases progressively increased while the proportion of "unusual" patients slightly decreased. The total number of infants referred was 809 and 14 % were unusual patients; 55 % had very severe ROP, 89 % were treated, and 7 % were referred too late and lost the opportunity for treatment. Group B comprised 61 % of the infants referred. Very severe ROP was present in 53 % of patients in group A and in 56 % of those in group B. The mean GA was 29.5 +/- 3.1 weeks in group A and 30.8 +/- 2.6 in group B (p < 0.001); 90.5 % of the patients in group A and 64 % of those in group B required mechanical ventilation (p < 0.001). No predictors for very severe ROP were found in multifactorial analysis.

CONCLUSIONS

We report a childhood epidemic of blindness in which the prevalence of very severe ROP increased during the study period and the disease occurred in large, fairly mature newborns. The differences found in relation to the referring center and the lack of correlation between very severe ROP and prematurity or the use of mechanical ventilation suggests substantial disparity in healthcare, which should be taken into account when planning prevention strategies.

Retinopatía del prematuro y estrés oxidativo

INTRODUCTION

There is some evidence that retinopathy of prematurity is due to excessive oxidative stress on the developing retina caused by high free radical production or reduced ability to eliminate these radicals.

OBJECTIVE

To determine the relationship between high levels of oxidative stress and retinopathy of prematurity.

MATERIAL AND METHODS

A prospective cohort study was designed. Fifty premature infants of less than 33 weeks' gestational age were included. Serum lipoperoxide levels were determined as a measure of oxidative stress. Samples were taken once a week for 1 month, starting from the first week of life. The results of all four samples were compared between infants who developed any degree of retinopathy of prematurity and those without it. Ophthalmological examinations were performed after the fourth week of life.

RESULTS

The incidence of retinopathy of prematurity was 22 % (11/50). The mean values of all the samples showed a significant difference between infants who developed retinopathy of prematurity (5.44 +/- 1.30 nmol/ml) and those who did not (2.94 +/- 0.89 nmol/ml, p = 0.0001). The relative risk of developing retinopathy of prematurity with high serum lipoperoxide levels was 5.15, 5.63, 4.15 and 12.70 for each of the weekly samples.

CONCLUSIONS

There is an association between high serum lipoperoxide levels, as a measure of oxidative stress, and the incidence of retinopathy of prematurity.