Is routine vitamin E administration justified in very low-birthweight infants?

Concurrent Physiological and Pathological Angiogenesis in Retinopathy of Prematurity and Emerging Therapies

Retinopathy of prematurity (ROP) is an ocular vascular disease affecting premature infants, characterized by pathological retinal neovascularization (RNV), dilated and tortuous retinal blood vessels, and retinal or vitreous hemorrhages that may lead to retinal detachment, vision impairment and blindness. Compared with other neovascular diseases, ROP is unique because of ongoing and concurrent physiological and pathological angiogenesis in the developing retina. While the disease is currently treated by laser or cryotherapy, anti-vascular endothelial growth factor (VEGF) agents have been extensively investigated but are not approved in the U.S. because of safety concerns that they negatively interfere with physiological angiogenesis of the developing retina. An ideal therapeutic strategy would selectively inhibit pathological but not physiological angiogenesis. Our group recently described a novel strategy that selectively and safely alleviates pathological RNV in animal models of ROP by targeting secretogranin III (Scg3), a disease-restricted angiogenic factor. The preclinical profile of anti-Scg3 therapy presents a high potential for next-generation disease-targeted anti-angiogenic therapy for the ROP indication. This review focuses on retinal vessel development in neonates, the pathogenesis of ROP and its underlying molecular mechanisms, including different animal models, and provides a summary of current and emerging therapies.

The Thiol-Disulfide Homeostasis and Coenzyme Q10 in Conjunction with Vitamin E Effect on Retinopathy Prematurity

Purpose:

This study was performed to determine whether one drop of topical administration of Coqun® (Coenzyme Q10 and Vitamin E)-a potent antioxidant-twice a day has any effect on the thiol-disulphide homeostasis-a novel oxidative stress marker in the Retinopathy Of Prematurity (ROP) disease course.

Methods:

This was a prospective observational study comprising 28 infants with ROP at stage 2 and higher who followed up at the paediatric intensive care unit. Ferric reducing power of plasma (FRAP), albumin, ischemia-modified albumin (IMA) and thiol disulphide homeostasis levels were studied in the infants before and two weeks after Coqun® treatment.

Results:

The mean gestational age was 27 (24–32) weeks, the mean birth weight was 1,012±326 g and the mean duration of care in an incubator was 64±23 days. FRAP levels were 0.91±0.17 μmol/L, IMAs were 0.85±0.29, native thiols were 248±38.9 μmol/L and total thiols were 284±39.2 μmol/L, respectively, at the beginning of therapy.

FRAP levels 0.79±0.21(p= 0.006) μmol/L, IMAs 0.73±0.36(p = 0.096), native thiols 262±42.6(p = 0.164) μmol/L and total thiols 291±43.6(p = 0.344) μmol/L showed no difference after two weeks of therapy.

Conclusion:

Thiol disulphide homeostasis levels do not change with Coqun® therapy during ROP course.

Pharmacologic interventions for the prevention and treatment of retinopathy of prematurity

Retinopathy of prematurity (ROP), a significant morbidity in prematurely born infants, is the most common cause of visual impairment and blindness in children and persists till adulthood. Strict control of oxygen therapy and prevention of intermittent hypoxia are the keys in the prevention of ROP, but pharmacologic interventions have decreased risk of ROP. Various drug classes such as methylxanthines (caffeine), VEGF inhibitors, antioxidants, and others have decreased ROP occurrence. The timing of pharmacologic intervention remains unsettled, but early prevention rather than controlling disease progression may be preferred. These drugs act through different mechanisms, and synergistic approaches should be considered to maximize efficacy and safety.

Serum tocopherol levels in very preterm infants after a single dose of vitamin E at birth

OBJECTIVE

Our aim was to examine the impact of a single enteral dose of vitamin E on serum tocopherol levels. The study was undertaken to see whether a single dose of vitamin E soon after birth can rapidly increase the low α-tocopherol levels seen in very preterm infants. If so, this intervention could be tested as a means of reducing the risk of intracranial hemorrhage.

METHODS

Ninety-three infants <27 weeks' gestation and <1000 g were randomly assigned to receive a single dose of vitamin E or placebo by gastric tube within 4 hours of birth. The vitamin E group received 50 IU/kg of vitamin E as dl-α-tocopheryl acetate (Aquasol E). The placebo group received sterile water. Blood samples were taken for measurement of serum tocopherol levels by high-performance liquid chromatography before dosing and 24 hours and 7 days after dosing.

RESULTS

Eighty-eight infants received the study drug and were included in the analyses. The α-tocopherol levels were similar between the groups at baseline but higher in the vitamin E group at 24 hours (median 0.63 mg/dL vs. 0.42 mg/dL, P = .003) and 7 days (2.21 mg/dL vs 1.86 mg/dL, P = .04). There were no differences between groups in γ-tocopherol levels. At 24 hours, 30% of vitamin E infants and 62% of placebo infants had α-tocopherol levels <0.5 mg/dL.

CONCLUSIONS

A 50-IU/kg dose of vitamin E raised serum α-tocopherol levels, but to consistently achieve α-tocopherol levels >0.5 mg/dL, a higher dose or several doses of vitamin E may be needed.

Treatment of retinopathy of prematurity: a review of conventional and promising new therapeutic options

Retinopathy of prematurity (ROP), a retinal vascular disease of premature infants, continues to be a major cause of preventable childhood blindness all over the world. The incidence of ROP varies among countries, being influenced by the quality of the level of neonatal intensive care. Here, we discuss the potential treatments that are now available or will soon or probably be available for ROP. Although ablation of the avascular retina with laser photocoagulation remains the current gold standard and well established therapy for ROP, some new therapeutic options including angiostatic therapies are being explored based on our knowledge of the pathophysiology of the ROP and complications and efficacy of laser treatment. However, prevention of the development of severe ROP and screening for ROP seem to be the best strategy in avoiding visual impairment caused by ROP in premature infants. New therapeutic interventions including vascular endothelial growth factor antibody administration, gene therapy and supplemental therapies should be supported with evidence-based data for the treatment of ROP.

Vitamin E supplementation for prevention of morbidity and mortality in preterm infants

BACKGROUND

Treating very low birth weight (VLBW) infants with pharmacologic doses of vitamin E as an antioxidant agent has been proposed for preventing or limiting retinopathy of prematurity, intracranial hemorrhage, hemolytic anemia, and chronic lung disease. However, excessive doses of vitamin E may result in side effects.

OBJECTIVES

The aim of this systematic review was to assess the effects of vitamin E supplementation on morbidity and mortality in preterm infants.

SEARCH STRATEGY

We searched MEDLINE (October 2002), EMBASE (March 2002), the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library, 2003, Issue 1, and personal files for clinical trials assessing vitamin E in preterm infants.

SELECTION CRITERIA

We selected trials analyzing primary outcomes (mortality or combined long-term morbidity) or secondary outcomes (other morbidity) in infants with gestational age less than 37 weeks or birth weight less than 2500 grams. The intervention was allocation to routine supplementation with vitamin E in the treatment group versus placebo, no treatment or another type, dose or route of administration of vitamin E.

DATA COLLECTION AND ANALYSIS

We used standard methods of the Cochrane Collaboration and of the Cochrane Neonatal Review Group.

MAIN RESULTS

Twenty-six randomized clinical trials fulfilled entry criteria. No study assessed combined long-term morbidity. Routine vitamin E supplementation significantly reduced the risk of germinal/intraventricular hemorrhage (typical relative risk [RR] 0.85, 95% confidence interval [CI] 0.73, 0.99), increased the risk of sepsis (typical RR 1.52, CI 1.13, 2.04) and increased hemoglobin concentration by a small amount, but did not significantly affect mortality and other morbidity. In VLBW infants, vitamin E supplementation increased the risk of sepsis, and reduced the risk of severe retinopathy and blindness among those examined. Subgroup analyses in VLBW infants showed (1) an association between serum tocopherol levels greater than 3.5 mg/dl and increased risk of sepsis and reduced risk for severe retinopathy among those examined; and (2) an association between intravenous, high-dose administration of vitamin E and increased risk of sepsis.

REVIEWER'S CONCLUSIONS

Vitamin E supplementation in preterm infants reduced the risk of intracranial hemorrhage but increased the risk of sepsis. In very low birth weight infants it increased the risk of sepsis, and reduced the risk of severe retinopathy and blindness among those examined. Evidence does not support the routine use of vitamin E supplementation by intravenous route at high doses, or aiming at serum tocopherol levels greater than 3.5 mg/dl.

Retinopathy of prematurity: causation

The incidence of ROP is birth weight dependent and restricting therapeutic oxygen levels has dramatically reduced the incidence of ROP in infants of birth weight >1000 g. However, the incidence of ROP has remained high in very low birth weight (VLBW) infants and this appears to be related to these babies being more ill. Several risk factors have been identified in this group, however oxygen variability, rather than high levels, has been correlated with severity of disease in recent clinical and animal studies. Difficulties in defining 'normal' oxygen in this group has meant the optimal range of oxygen therapy has not yet been defined. Clinical studies are now underway using even lower oxygen therapy ranges. The impact this may have on ROP, neurological and respiratory outcomes will require further study.

Enteral feeding in the preterm infant

In planning enteral feeding in the preterm infant, decisions need to be made regarding the feeding schedule, choice of milk, and the route of administration. Feeds should be commenced within a week after birth beginning with subnutritional quantities. Preterm human milk from the infant's own mother is the milk of choice. When full enteral feeding is established, supplementation with human milk fortifier is recommended. Donor human milk and preterm formula are alternatives. Early establishment of enteral nutrition and maintenance of optimal nutrition during infancy are important as dietary manipulations in preterm infants have potential long-term influences on their health, growth and neurodevelopment.

Intraventricular hemorrhage: emphasis on prevention

Germinal matrix/intraventricular hemorrhage is a common type of cerebral injury in premature newborns. Based on the improved understanding of underlying pathogenetic mechanisms, numerous interventional strategies for prevention have been proposed. This article summarizes and evaluates the efficacy and safety of major interventions that are currently under consideration for the prevention of germinal matrix/intraventricular hemorrhage.

Vitamin E prophylaxis to reduce retinopathy of prematurity: a reappraisal of published trials

OBJECTIVE

We conducted a meta-analysis of the published randomized clinical trials of vitamin E prophylaxis designed to reduce retinopathy of prematurity (ROP) to determine whether increased serum concentrations of vitamin E reduced the incidence of severe, threshold (Stage 3+) ROP in the very low birth weight (VLBW) infant subset.

STUDY DESIGN

Among the six trials considered eligible for analyses, the incidence for all stages of ROP and for Stage 3+ ROP was computed for all randomly assigned infants (intention-to-treat analysis) and for those infants completing the trials. Odds ratios (ORs) and pooled estimates for event rate reductions (and the respective 95% confidence intervals [CIs]) were calculated for these outcome end points.

RESULTS

There were 704 VLBW infants in the vitamin E prophylaxis groups and 714 in control groups; 536 (76.1%) infants in the vitamin E and 551 (77.2%) in the control groups completed the trials. In all trials the mean serum vitamin E concentrations were within or above the physiologic range in the vitamin-treated groups and at or below the physiologic ranges in the control groups. The overall incidence of any stage ROP was similar between the groups: 39.8% in the vitamin E group and 43.5% in the control group. The overall incidence for Stage 3+ ROP was lower in the vitamin E-treated groups than in the control group (2.4% in vitamin E vs 5.3% in control). The pooled OR for developing Stage 3+ ROP with vitamin E prophylaxis was 0.44 (95% CI, 0.21, 0.81, p < 0.02). The reciprocal of the pooled estimate of mean risk reduction (2.8%, 95% CI: 0.55%, 5.1%) for Stage 3+ ROP revealed that on average, vitamin E prophylaxis given to 35 VLBW infants would prevent one case of threshold, Stage 3+ ROP.

CONCLUSIONS

Considering that there was a 52% reduction in the incidence of Stage 3+ ROP, we suggest that the role of vitamin E in reducing severe ROP be re-evaluated. We could not assess the adverse effect rates from vitamin E therapy in the trials analyzed; therefore, we recommend a well-controlled and focused trial in which the issues of benefit, adverse effects, and cost can be assessed with vitamin E prophylaxis in extremely low birth weight (< 1000 gm) infants.

Prevention of intraventricular hemorrhage in preterm infants

Prematurely born infants with intraventricular hemorrhage (IVH) suffer significant morbidity and mortality, particularly those infants with high grade hemorrhage. The more premature infants have a higher incidence, experiencing more severe IVH. Early onset IVH is also likely to be severe and to progress to a higher grade. The etiology of intraventricular hemorrhages is clearly multifactorial, with differing sets of risk factors for early onset and later occurring hemorrhage. Prevention requires multilayered strategies, both prenatal and postnatal. These strategies are discussed in detail, highlighting unresolved controversies. Certain recommendations for prevention can be made. These include efforts to prevent preterm delivery, transfer of high risk mothers to tertiary care centers and antenatal maternal steroid use. Postnatally, the importance of optimal resuscitation and neonatal care practices is stressed, particularly those which minimize cerebral blood flow fluctuation. Postnatal indomethacin use should be considered in most infants. Further investigation of other strategies is necessary, including multicenter randomized trials to further evaluate antenatal pharmacologic agents, as well as the relative efficacy of different modes of delivery. The different risk factors for early onset versus later onset IVH must be more clearly delineated. Most importantly, any strategy must include sustained neurodevelopmental followup.

Vitamin A and E status in very low birth weight infants: development of an improved parenteral delivery system

Plasma vitamin A and E levels were inadequate in very low birth weight infants receiving a continuous infusion of a parenteral multivitamin preparation, 1.5 ml/kg per day, in dextrose-amino acid solution. A new delivery system using 2 ml/kg per day, infused for 6 hours from the first day of life, avoided loss during infusion and significantly improved plasma vitamin A and E levels during the first 28 days of life in very low birth weight infants.

Vitamin E toxicity in neonatal piglets

Intravenous vitamin E was associated with the deaths of 38 infants in the US in 1984. Because the vitamin E preparation used contained both vitamin E and a high level of polysorbate detergent, the etiology of the syndrome remains unknown. In this study, we determined the tissue disposition of an intravenous preparation of vitamin E solubilized with polysorbate (E-Ferol) in neonatal piglets. One to two-day-old piglets were injected daily with 50 IU/kg/d of vitamin E for a period of 13 days. Other groups were injected intramuscularly, or with a slow, 7 h intravenous infusion with 50 IU/kg/d vitamin E for six days. Massive splenic accumulation of vitamin E (16,004 micrograms/g vs 73 micrograms/g in controls) occurred following rapid injection, with far lesser concentrations in the liver and lung. Levels of vitamin E in the kidney and heart were only slightly above control. Tissue changes correlated with dosage and duration of vitamin E administration and suggested massive accumulation of vitamin E in cells of the mononuclear phagocyte system. Following slow intravenous infusion the highest levels of vitamin E occurred in the liver rather than spleen. Intramuscular injections at similar doses produced slight, but insignificant changes in tissue levels of vitamin E. We speculate that rapid intravenous injection of vitamin E emulsions produces massive accumulation in phagocytic cells of the spleen and to a lesser extent liver and lung, possibly leading to increased susceptibility to sepsis and/or abnormal pulmonary function. Slow infusions of vitamin E produce major accumulations in the liver rather than spleen.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E therapy in retinopathy of prematurity

Vitamin E is a fat soluble antioxidant and as a result it is able to scavenge free radicals derived from oxygen. The premature infant and the retina are likely to be particularly vulnerable to the deleterious effects of these oxygen derived free radicals, and as a result prophylactic vitamin E has been suggested for the management of retinopathy of prematurity (ROP). However, despite numerous trials, prophylactic supplementation with vitamin E remains controversial. This paper will critically review the use of vitamin E in ROP and consider the risk/benefit relationship of such treatment in premature infants.