Effect of blood transfusion on lipid peroxidation in preterm infants

Blood products transfusion and retinopathy of prematurity: A cohort study

AIM

The aim of the study was to assess the influence of blood product transfusions on the development and severity of retinopathy of prematurity (ROP).

METHODS

A retrospective cohort study was conducted of very low birth weight (VLBW) newborns with less than 32 weeks gestational age (GA) admitted to the neonatal unit of a tertiary care hospital during the period from 1 January 2008 to 31 December 2021. Data on the degree of ROP and the transfusions received were obtained and analysed. Both univariate and multivariate analyses were performed, by logistic regression.

RESULTS

A total of 565 VLBW newborns were recruited, of whom 263 received a red blood cell transfusion prior to 36 weeks corrected GA. The newborns with ROP received significantly more red blood cell transfusions than those not presenting this condition. After adjusting for oxygen therapy and GA, the risk of ROP was found to be 2.77 times higher (95% CI 1.31-5.88) after receiving three or more transfusions, with a 3.95 times higher risk (95% CI 1.40-11.1) of developing severe ROP. Having received the first red blood cell transfusion before 32 weeks corrected GA is associated with an increased risk of ROP (OR 2.18; 95% CI: 1.09-4.36).

CONCLUSION

In VLBW neonates, the number of red blood cell transfusions and their administration before 32 weeks corrected GA are important risk factors for ROP.

A Retrospective Analysis of Retinopathy of Prematurity (ROP) in a Tertiary Newborn Intensive Care Unit: Incidence and Risk Factors of ROP

Background Retinopathy of prematurity (ROP) is the most frequent problem which causes blindness in preterm babies. In our study we evaluate the frequency of retinopathy, the risk factors, and their effects on disease development in premature newborns admitted to our neonatal intensive care unit (NICU).

Methods A total of 139 premature infants with gestational ages less than 34 weeks followed in our NICU between January 1, 2008 and January 1, 2011. The infants were divided into two groups as group 1 (no ROP/mild ROP) and as group 2 (severe ROP).

Results The demographics of 139 patients were as follows: 79 (56.83%) were female and 60 (43.17%) were male. Overall, 104 (74.8%) patients were found to have no or mild ROP and 35 (25.2%) had severe ROP. Among the patients in the severe ROP group, 25 of them had plus disease. With logistic regression analysis, lower gestational age (odds ratio [OR]: 4.1, confidence interval [CI]: 1.9–9.2), the central catheter usage (OR: 13.4, CI: 1.2–146.6), hypotension (OR: 7.5, CI: 1.1–49.6), perinatal asphyxia (OR: 261.3, CI: 8.8–7725.4), apnea (OR: 18.1, CI: 1.6–202.6), and high FiO2 (OR: 1.2 CI: 1.0–1.5) were found to be related to severe ROP.

Conclusion Among the preterms with very low body weight included in our study, we found that the frequency of severe ROP requiring treatment was low. The most important factors related to severe ROP were found to be low gestational age and birth weight. Being aware of the risk factors related to severe ROP in addition to screening every preterm infant carrying these risk factors is extremely important for the early diagnosis and treatment to prevent blindness due to severe retinopathy.

Risk factors for the development and progression of retinopathy of prematurity in preterm infants in Indonesia

BACKGROUND

Risk factors other than supplemental oxygen might play a role in the development of retinopathy of prematurity (ROP). In Indonesia ROP occurs in infants up to 34 weeks and 2000 g. Risk factors for the development of ROP in Indonesian NICUs have not been evaluated. Our aim was to identify other risk factors than the use of oxygen in the development and progression of ROP in preterm infants in Indonesia.

METHODOLOGY

Data on 98 preterm infants with ROP and 77 controls were collected from four NICUs and two eye centers in Jakarta, Indonesia, between 2009 and 2014. We used multivariate logistic regression analysis to determine the relationship between infants and environmental variables and the development and progression of ROP. We obtained variables for ROP severity by using Cox regression analysis.

RESULTS

Factors associated with the development of ROP were birthweight (BWt), intrauterine growth retardation (IUGR), exchange transfusion, duration of oxygen supplementation, minimum saturation monitor setting, and socioeconomic factors. Regarding the progression, gestational age (GA), out-born, duration of supplemental oxygen, minimum saturation monitor setting, and socioeconomic factors were identified as risk factors.

CONCLUSION

The use and control of supplemental oxygen are the main risk factors for the development and progression of ROP in preterms in Indonesia. Additionally, we confirm that GA, BWt, and IUGR are risk factors. Moreover, we found exchange transfusion to be a risk factor, and we found a lower rate of ROP in infants from a lower socioeconomic background. These risk factors apply to infants with a GA up to 34 weeks and a BWt up to 2000 g.

Increased Oxidative Stress in Acute Myeloid Leukemia Patients after Red Blood Cell Transfusion, but Not Platelet Transfusion, Results Mainly from the Oxidative/Nitrative Protein Damage: An Exploratory Study

Chronic oxidative stress (OS) can be an important factor of acute myeloid leukemia (AML) progression; however, there are no data on the extent/consequence of OS after transfusion of packed red blood cells (pRBCs) and platelet concentrates (PCs), which are commonly used in the treatment of leukemia-associated anemia and thrombocytopenia. We aimed to investigate the effects of pRBC/PC transfusion on the OS markers, i.e., thiol and carbonyl (CO) groups, 3-nitrotyrosine (3-NT), thiobarbituric acid reactive substances (TBARS), advanced glycation end products (AGE), total antioxidant capacity (TAC), SOD, GST, and LDH, in the blood plasma of AML patients, before and 24 h post-transfusion. In this exploratory study, 52 patients were examined, of which 27 were transfused with pRBCs and 25 with PCs. Age-matched healthy subjects were also enrolled as controls. Our results showed the oxidation of thiols, increased 3-NT, AGE levels, and decreased TAC in AML groups versus controls. After pRBC transfusion, CO groups, AGE, and 3-NT significantly increased (by approximately 30, 23, and 35%; p < 0.05, p < 0.05, and p < 0.01, respectively) while thiols reduced (by 18%; p < 0.05). The PC transfusion resulted in the raise of TBARS and AGE (by 45%; p < 0.01 and 31%; p < 0.001), respectively). Other variables showed no significant post-transfusion changes. In conclusion, transfusion of both pRBCs and PCs was associated with an increased OS; however, transfusing the former may have more severe consequences, since it is associated with the irreversible oxidative/nitrative modifications of plasma proteins.

The effects of storage conditions on long-chain polyunsaturated fatty acids, lipid mediators, and antioxidants in donor human milk - A review

Donor human milk (DHM) is the recommended alternative, if maternal milk is unavailable. However, current human milk banking practices may negatively affect the nutritional quality of DHM. This review summarises the effects of these practices on polyunsaturated fatty acids, lipid mediators and antioxidants of human milk. Overall, there is considerable variation in the reported effects, and further research is needed, particularly with lipid mediators and antioxidants. However, to preserve nutritional quality, DHM should be protected from light exposure and storage at 4 °C minimised, to prevent decreases in vitamin C and endocannabinoids and increases in free fatty acids and lipid peroxidation products. Storage at -20 °C prior to pasteurisation should also be minimised, to prevent free fatty increases and total fat and endocannabinoid decreases. Storage ≤-70 °C is preferable wherever possible, although post-pasteurisation storage at -20 °C for three months appears safe for free fatty acids, lipid peroxidation products, and total fat content.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Incidence, risk factors and severity of retinopathy of prematurity in Turkey (TR-ROP study): a prospective, multicentre study in 69 neonatal intensive care units

Background

To evaluate the prevalence, risk factors and treatment of retinopathy of prematurity (ROP) in Turkey and to establish screening criteria for this condition.

Methods

A prospective cohort study (TR-ROP) was performed between 1 April 2016 and 30 April 2017 in 69 neonatal intensive care units (NICUs). Infants with a birth weight (BW)≤1500 g or gestational age (GA)≤32 weeks and those with a BW>1500 g or GA>32 weeks with an unstable clinical course were included in the study. Predictors for the development of ROP were determined by logistic regression analyses.

Results

The TR-ROP study included 6115 infants: 4964 (81%) with a GA≤32 weeks and 1151 (19%) with a GA>32 weeks. Overall, 27% had any stage of ROP and 6.7% had severe ROP. A lower BW, smaller GA, total days on oxygen, late-onset sepsis, frequency of red blood cell transfusions and relative weight gain were identified as independent risk factors for severe ROP in infants with a BW≤1500 g. Of all infants, 414 needed treatment and 395 (95.4%) of the treated infants had a BW≤1500 g. Sixty-six (16%) of the treated infants did not fulfil the Early Treatment for Retinopathy of Prematurity requirements for treatment.

Conclusions

Screening of infants with a GA≤34 weeks or a BW<1700 g appears to be appropriate in Turkey. Monitoring standards of neonatal care and conducting quality improvement projects across the country are recommended to improve neonatal outcomes in Turkish NICUs.

Trial registration number

NCT02814929, Results.

Chronic Intermittent Hypoxia Causes Lipid Peroxidation and Altered Phase 1 Drug Metabolizing Enzymes in the Neonatal Rat Liver

Critically ill preterm neonates requiring oxygen therapy often experience frequent apneas with intermittent hypoxia (IH). IH-induced oxidative stress causes lipid peroxidation, which targets the liver and contributes to toxic drug reactions. We tested the hypothesis that incremental IH episodes induce oxidative damage in the neonatal liver and alter the expression of genes that regulate drug metabolism. Newborn rats were exposed to increasing IH episodes (12% O₂) during hyperoxia (50% O₂), or placed in room air (RA) until postnatal day 21 (P21) for recovery from IH (IHR). RA littermates served as controls, and pups exposed to 50% O₂ served as hyperoxia controls. Hepatic histopathology, biomarkers of oxidative stress and oxidative DNA damage, antioxidants, and expression of genes that regulate drug metabolism were assessed. Oxidative stress and DNA damage, evidenced by 8-isoprostaglandin F_2α (8-isoPGF_2α) and 8-hydroxy-2'-deoxyguanosine (8-OH-dG), respectively, increased as a function of IH episodes, and was associated with decreased superoxide dismutase (SOD) and increased catalase activities. Pathological changes including cellular swelling, steatosis, necrosis, and focal sinusoid congestion were seen in IH, but not in IHR. Similarly, IH was associated with upregulation of several genes involved in DNA repair, which were downregulated during IHR. Of the genes involved in drug metabolism, aldehyde dehydrogenases (involved in lipid peroxidation) and cytochrome P450 (CYP) genes of the 2C family (involved in oxidative stress) were robustly upregulated both in IH and in IHR. Hepatic oxidative stress and lipid peroxidation occurring in response to chronic IH have implications for preterm infants, and may explain, in part, the pharmacokinetic variations and drug toxicities in this vulnerable population.

The impact of acute lung injury, ECMO and transfusion on oxidative stress and plasma selenium levels in an ovine model

The purpose of this study was to determine the effects of smoke induced acute lung injury (S-ALI), extracorporeal membrane oxygenation (ECMO) and transfusion on oxidative stress and plasma selenium levels. Forty ewes were divided into (i) healthy control (n=4), (ii) S-ALI control (n=7), (iii) ECMO control (n=7), (iv) S-ALI+ECMO (n=8) and (v) S-ALI+ECMO+packed red blood cell (PRBC) transfusion (n=14). Plasma thiobarbituric acid reactive substances (TBARS), selenium and glutathione peroxidase (GPx) activity were analysed at baseline, after smoke injury (or sham) and 0.25, 1, 2, 6, 7, 12 and 24h after initiation of ECMO. Peak TBARS levels were similar across all groups. Plasma selenium decreased by 54% in S-ALI sheep (1.36±0.20 to 0.63±0.27μmol/L, p<0.0001), and 72% in sheep with S-ALI+ECMO at 24h (1.36±0.20 to 0.38±0.19, p<0.0001). PRBC transfusion had no effect on TBARS, selenium levels or glutathione peroxidase activity in plasma. While ECMO independently increased TBARS in healthy sheep to levels which were similar to the S-ALI control, the addition of ECMO after S-ALI caused a negligible increase in TBARS. This suggests that the initial lung injury was the predominant feature in the TBARS response. In contrast, the addition of ECMO in S-ALI sheep exacerbated reductions in plasma selenium beyond that of S-ALI or ECMO alone. Clinical studies are needed to confirm the extent and duration of selenium loss associated with ECMO.

Intravenous lipids for preterm infants: a review

Extremely low birth weight infants (ELBW) are born at a time when the fetus is undergoing rapid intrauterine brain and body growth. Continuation of this growth in the first several weeks postnatally during the time these infants are on ventilator support and receiving critical care is often a challenge. These infants are usually highly stressed and at risk for catabolism. Parenteral nutrition is needed in these infants because most cannot meet the majority of their nutritional needs using the enteral route. Despite adoption of a more aggressive approach with amino acid infusions, there still appears to be a reluctance to use early intravenous lipids. This is based on several dogmas that suggest that lipid infusions may be associated with the development or exacerbation of lung disease, displace bilirubin from albumin, exacerbate sepsis, and cause CNS injury and thrombocytopena. Several recent reviews have focused on intravenous nutrition for premature neonate, but very little exists that provides a comprehensive review of intravenous lipid for very low birth and other critically ill neonates. Here, we would like to provide a brief basic overview, of lipid biochemistry and metabolism of lipids, especially as they pertain to the preterm infant, discuss the origin of some of the current clinical practices, and provide a review of the literature, that can be used as a basis for revising clinical care, and provide some clarity in this controversial area, where clinical care is often based more on tradition and dogma than science.

[Effects of various anesthesia maintenance on serum levels of selenium, copper, zinc, iron and antioxidant capacity]

BACKGROUND AND OBJECTIVES

In this study, we aimed to investigate the effects of sevoflurane, desflurane and propofol maintenances on serum levels of selenium, copper, zinc, iron, malondialdehyde, and glutathion peroxidase measurements, and antioxidant capacity.

METHODS

60 patients scheduled for unilateral lower extremity surgery which would be performed with tourniquet under general anesthesia were divided into three groups. Blood samples were collected to determine the baseline serum levels of selenium, copper, zinc, iron, malondialdehyde and glutathion peroxidase. Anesthesia was induced using 2-2.5mgkg(-1) propofol, 1mgkg(-1) lidocaine and 0.6mgkg(-1) rocuronium. In the maintenance of anesthesia, under carrier gas of 50:50% O2:N2O 4Lmin(-1), 1 MAC sevoflorane was administered to Group S and 1 MAC desflurane to Group D; and under carrier gas of 50:50% O2:air 4Lmin(-1) 6mgkgh(-1) propofol and 1μgkgh(-1) fentanyl infusion were administered to Group P. At postoperative blood specimens were collected again.

RESULTS

It was observed that only in Group S and P, levels of MDA decreased at postoperative 48th hour; levels of glutathion peroxidase increased in comparison to the baseline values. Selenium levels decreased in Group S and Group P, zinc levels decreased in Group P, and iron levels decreased in all three groups, and copper levels did not change in any groups in the postoperative period.

CONCLUSION

According to the markers of malondialdehyde and glutathion peroxidase, it was concluded that maintenance of general anesthesia using propofol and sevoflurane activated the antioxidant system against oxidative stress and using desflurane had no effects on oxidative stress and antioxidant system.

Effect of blood transfusions on the outcome of very low body weight preterm infants under two different transfusion criteria

BACKGROUND

Multiple packed red blood cell (PRBC) transfusions in very low birth weight (VLBW) prematurity have been suggested to be a risk factor for the development of retinopathy of prematurity (ROP) or for chronic lung disease (CLD). The purpose of this study was to examine the effect of PRBC transfusions on the outcome of VLBW prematurity.

METHODS

In total, between July 2005 and June 2006, 36 VLBW preterm babies were admitted to our neonatal intensive care unit and were randomly allocated to the "restrictive" (n= 19) or "liberal" (n= 17) criteria for PRBC transfusion. Complete blood count (CBC) was examined at admission and 30 days later. Reticulocyte counts, serum iron and ferritin were examined and compared with the clinical outcomes.

RESULTS

Infants in the liberal group received a larger PRBC transfusion volume compared with the restrictive group over 30 days (41.7+/-20.1 vs. 27.2+/-15.9mL, p=0.029). There were no significant differences in the proportion of patients with respiratory distress syndrome, patent ductus arteriosus, severe intraventricular hemorrhage, ROP or CLD between the two groups. The laboratory data, except reticulocyte count, showed no significant difference on day 30. Further analysis of premature babies with and without CLD showed that total transfused blood volume greater than 30mL over 30 days was a risk factor for developing CLD in VLBW infants.

CONCLUSION

Both criteria of PRBC transfusion had similar clinical outcomes, although liberal transfusion resulted in a greater amount of blood transfused and a low reticulocyte count at 30 days of age. We suggest restrictive criteria for minimizing the overall amount of transfusion to less than 30 mL may be a better way of preventing CLD in VLBW infants.

Iron homeostasis in the neonate

The regulation of the availability of micronutrients is particularly critical during periods of rapid growth and differentiation such as the fetal and neonatal stages. Both iron deficiency and excess during the early weeks of life can have severe effects on neurodevelopment that may persist into adulthood and may not be corrected by restoration of normal iron levels. This article provides a succinct overview of our current understanding of the extent to which newborns, particularly premature newborns, are able (or not able) to regulate their iron status according to physiologic need. Postnatal development of factors important to iron homeostasis such as intestinal transport, extracellular transport, cellular uptake and storage, intracellular regulation, and systemic control are examined. Also reviewed are how factors peculiar to the sick and premature neonate can further adversely influence iron homeostasis and exacerbate iron-induced oxidative stress, predispose the infant to bacterial infections, and, thus, compromise his or her clinical situation further. The article concludes with a discussion of the areas of relative ignorance that require urgent investigation to rectify our lack of understanding of iron homeostasis in what is a critical stage of development.

Iron overload following red blood cell transfusion and its impact on disease severity

Transfusion of red blood cells can be a life-saving therapy both for patients with chronic anemias and for those who are critically ill with acute blood loss. However, transfusion has been associated with significant morbidity. Chronic transfusion results in accumulation of excess iron that surpasses the binding capacity of the major iron transport protein, transferrin. The resulting non-transferrin bound iron (NTBI) can catalyze the production of highly reactive oxygen species (ROS) leading to significant and wide spread injury to the liver, heart, and endocrine organs as well as increases in infection. Acute transfusion of red blood cells in critically ill patients likewise has significant effects including increased mortality, prolonged hospital stays, and elevated risk of nosocomial infection. These effects appear to be more profound with increasing age of stored blood. The progressive release of free iron associated with storage time suggests that morbidity following acute transfusion, like that seen in chronic transfusion, may be due in part to elevated levels of NTBI. It is clear that transfusion is necessary in many instances; however, its risks and benefits must be carefully balanced before proceeding to avoid unnecessary iron toxicity.

Oxygen free radicals: effects in the newborn period

Free radical production occurs continuously in all cells as a by-product of cell metabolism. In tandem, the human body has developed endogenous antioxidant systems as well as taken advantage of dietary exogenous antioxidants to process and detoxify free radicals appropriately. However, certain conditions may increase free radical production beyond the body's endogenous and exogenous antioxidant systems. The neonatal period is a vulnerable time for free radical damage and injury, particularly for preterm infants whose antioxidant defense systems have not fully matured. Endogenous and passively acquired exogenous antioxidant defense systems do not accelerate in maturation until late in the third trimester. To explore the complexities of these concepts, this article includes a description, an evolutionary perspective of oxygen, and a basic background on free radical chemistry in biology. In addition, this chemistry is applied to the etiology of many of the most common diseases seen in the neonatal period. Finally, the current research addressing clinical strategies in this area is critically appraised. Implications for practice and directions for further research are presented with an emphasis on strategies that support the prudent use of oxygen therapies.

Lower erythrocyte glutathione peroxidase activity in bronchopulmonary dysplasia in the first week of neonatal life

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a major pulmonary complication in premature infants and is considered a free radical disorder. Erythrocyte catalase (CAT) and cellular glutathione peroxidase (c-GPx) are antioxidant enzymes that detoxify peroxides generated from dismutation of superoxide anion. The study goal was to measure enzyme activity for preterm infants during the first week of life.

METHODS

Blood samples were collected from umbilical arterial lines or the radial artery of 44 preterm infants (gestational age range: 25-30 weeks) on days 0, 2, and 5 after delivery. Erythrocyte CAT and c-GPx activities were evaluated, while clinical data were obtained and the correlations of enzyme activity and BPD status were examined.

RESULTS

There was no correlation between enzyme activity and gestational age or birth weight. Packed red cell transfusion did not affect enzyme activity and there was no difference in CAT activity between the patient groups. C-GPx activity from preterm infants with BPD was significantly lower than those of preterm infants without BPD on day 5.

CONCLUSIONS

Erythrocyte c-GPx may play an important role in the development of BPD. Lower c-GPx activity in early post-natal life might be a risk factor of BPD.

Does Insulin-Like Growth Factor 1 Contribute in Red Blood Cell Transfusions to the Pathogenesis of Retinopathy of Prematurity during Retinal Neovascularization?

BACKGROUND

Red blood cell (RBC) transfusions are associated with the development of retinopathy of prematurity (ROP). During the period of retinal neovascularization a rise of insulin-like growth factor 1 (IGF-1) may trigger rapid growth of new blood vessels.

OBJECTIVES

To study endocrine factors in RBC transfusions that might be of importance for ROP.

METHODS

IGF-1, IGF-2 and their binding proteins 1-3 (IGFBP-1-3) were determined by radioimmunoassays in 7 very-low-birthweight (VLBW) infants with ROP >or= stage 2 receiving a RBC transfusion, in 10 controls (VLBW infants with ROP <or= stage 1, no transfusion), in supernatants of 7 RBCs and of 5 washed RBCs (WRBC).

RESULTS

IGF-1 (mean +/- SD) in infants with ROP was 20.0 +/- 4.2 microg/l, in controls 35.9 +/- 15.2 microg/l (Mann-Whitney U test, p = 0.030). IGF-1 in RBC was 12.88 +/- 5.03 microg/l and in WRBC 0.45 +/- 0.74 microg/l (average of the three-course washing procedure). IGF-2 in infants with ROP was 485.67 +/- 158.73 microg/l, in controls 389.9 +/- 102.8 microg/l (not significant), in RBC 109.50 +/- 117.89 microg/l, in WRBC 61.07 +/- 30.0 microg/l. Except for IGFBP-3 other IGFBPs were barely or not detectable in RBC or WRBC.

CONCLUSIONS

Considering lower IGF-1 concentrations in preterm infants than in adults (factor 20), the IGF-1 in RBC transfusions is equivalent to a single dose of 1 microg/kg IGF-1 (5-10% of the adult dose with proved metabolic responses). Endocrinological relationships between the donor's load and the acceptor's individual features are a new aspect of potential side effects of RBC transfusions. Further research is necessary to clarify the share of the described IGF administration on the development of ROP.

Is there a causal relationship between the receipt of blood transfusions and the development of chronic lung disease of prematurity?

The number and total volume of blood transfusions received by premature babies is, after gestational age and birth weight a good predictor of the likelihood of developing chronic lung disease of prematurity (CLD) and retinopathy of prematurity (ROP). Oxidative damage, inflammation and pulmonary infections are also strongly associated with the development of CLD. It is currently not clear whether there is a causal relationship between the receipt of blood transfusions and oxidative damage, infection, inflammation and CLD in these babies. Strong arguments may be made both for and against a causal relationship. The babies who receive blood transfusions are usually smaller than those who do not, and are ventilated, often with high oxygen levels, for a longer period of time. The longer the baby is on a ventilator the more likely it is to develop pulmonary infection and inflammation. All these factors will promote free radical production and oxidative damage irrespective of the receipt of blood transfusion. This would argue against a causal relationship. On the other hand, an argument may be presented which is based on iron promoted free radical generation, infection and fibrosis consequent to the breakdown of haeme released from transfused erythrocytes. Haeme is broken down by haeme oxygenase (HO) to iron, CO and bilirubin. Under normal circumstances the products of HO activity are beneficial to the organism, but when HO activity is excessive, the products are potentially damaging. Free iron, (in the Fe2+ form) if not sequestered with protein or urate, will generate highly toxic free radicals via the Fenton and Heber-Wiess reactions, predispose the tissue to infection and promote fibrosis. The iron chelating ability of the premature baby appears to be limited so that it would be difficult to deal with any increase in free iron production. Free iron will in turn induce HO activity leading to a potentially serious positive feedback process. The lung is particularly sensitive to iron induced HO activity. In addition, HO activity may be enhanced by other events occurring in the premature lung such as the production of proinflammatory cytokines and the reduced level of glutathione. Thus, the possibility of a causal relationship clearly exists and needs to be examined. This can be attempted by measuring the products of HO activity in relation to the receipt of blood transfusions.

Erythrocyte Cu/Zn Superoxide Dismutase Activity in Preterm Infants with and without Bronchopulmonary Dysplasia

BACKGROUND

Erythrocyte Cu/Zn superoxide dismutase is believed to play a major role as a first-line antioxidant defense. Studies have reported varying results from measures of superoxide dismutase activity in cord blood samples from neonates.

OBJECTIVE

The study goal was to assess enzyme activity for preterm infants representing a range of gestational ages during the 1st week of life. Clinical data were obtained and correlations with superoxide dismutase activity were examined.

METHODS

We collected blood samples from umbilical arterial lines or the radial artery of 44 preterm infants (gestational age range 25-30 weeks) on days 1, 3, and 6 after delivery and evaluated erythrocyte Cu/Zn superoxide dismutase activity.

RESULTS

There was no correlation between enzyme activity and gestational age or birth weight. Superoxide dismutase activity gradually increased in preterm infants with bronchopulmonary dysplasia on days 3 and 6, with levels significantly higher than those of preterm infants without bronchopulmonary dysplasia on day 6. We found that packed red cell transfusion did not affect erythrocyte superoxide dismutase activity in either group. However, higher cumulative oxygen administration was noted in preterm infants with bronchopulmonary dysplasia.

CONCLUSION

Higher cumulative oxygen administration may be one factor that upregulates the activity of erythrocyte superoxide dismutase.

Blood transfusion and pulmonary lipid peroxidation in ventilated premature babies

Urinary malondialdehyde (MDA; a biochemical marker of lipid peroxidation) is increased following the receipt of blood transfusions in premature babies. This indicates an increased level of oxidative damage somewhere in the body. The aim of this study was to determine whether the lung may be a site of increased oxidative damage following blood transfusions. This was achieved by examining the relationship between blood transfusion and levels of MDA in bronchoalveolar lavage (BAL) fluid from ventilated premature babies. The study was a retrospective analysis of data obtained from a group of 42 ventilated premature babies of less than 32 weeks' gestation. Twenty-seven babies received blood transfusions, and 9 received at least one transfusion during the first week of life when daily BAL samples were being taken. Pulmonary epithelial lining fluid (ELF) was sampled by BAL daily during the first week of life and weekly thereafter. MDA was measured by an established high performance liquid chromatography (HPLC) technique. There was a significant positive correlation between volume of blood transfusions received and peak and mean ELF MDA levels (r=0.810, peak; r=0.740, mean; n=21). During the first week of life, when daily samples were being taken, the mean ELF MDA level after blood transfusion (1.829 microM; SE, 0.529) was significantly greater than before transfusion (0.928 microM; SE, 0.297) (n=9). In babies who received 2 transfusions within the first week (n=5), the MDA level was elevated further following the second transfusion (2.825 microM; SE, 0.346). The results of this study indicate that pulmonary oxidative damage increases after the receipt of blood transfusions. Babies receiving blood transfusions show a greater incidence of pulmonary oxidative stress and poor clinical outcome. This may simply reflect that the sickest babies are those most in need of blood transfusion, and that there is no causal relationship. However, the possibility of a causal relationship between blood transfusions and oxidative damage exists and should be investigated.

Non-protein-bound iron and free radical damage in fetuses with rhesus haemolytic disease: influence of intrauterine transfusions

OBJECTIVE

To determine iron-induced free radical damage in fetal rhesus haemolytic disease (RHD) before and after repeated intrauterine red blood cell transfusions and its relation to hydrops fetalis.

DESIGN

Prospective, observational study.

SETTING

Department of Obstetrics, Leiden University Medical Centre, the Netherlands.

POPULATION

Fifty anaemic fetuses, including 13 hydropic ones, 9 preterm and 12 term neonates and 8 female non-pregnant adults.

METHODS

Venous blood plasma samples were collected from 50 fetuses suffering from RHD preliminary to the first, and if appropriate, subsequent intrauterine red blood cell transfusions for determination of iron status including non-protein-bound iron (NPBI) and iron-binding primary antioxidant proteins, total plasma anti-oxidant capacity and its contributing secondary antioxidants (e.g. vitamin C, uric acid, sulphydryl groups and peroxidation products). Results were compared with values of healthy preterm and term neonates directly at birth and adult controls. Within the fetal haemolytic group, 13 hydropic fetuses were analysed as a separate group.

MAIN OUTCOME MEASURES

Non-protein-bound iron, antioxidants, total antioxidant capacity and peroxidation products. Sub analysis of the outcome measures of the hydropic fetuses.

RESULTS

RHD fetuses had at initial cordocentesis a significantly higher NPBI level and a significantly lower total plasma antioxidant capacity than control babies and adults. Their vitamin C tended to be more oxidised but lipid peroxidation had not increased, when compared with preterm babies. The repeated intrauterine red blood cell transfusions had a positive effect on the total antioxidant capacity of plasma and did not increase the concentration of NPBI. The hydropic fetuses, who had higher NPBI concentrations and lower plasma protein concentrations and total antioxidant capacity, did not show more peroxidation products in plasma than the non-hydropic fetuses. Fetuses without reversal of hydrops despite intrauterine transfusions showed decreasing levels of proteins with subsequent transfusions but peroxidation products remained constant.

CONCLUSION

Repeated intrauterine red blood cell transfusions do not lead to free radical damage in the fetus in utero. Iron-induced free radical activity does not appear to play a causative role in the proceeding of hydrops fetalis in RHD.

Role of redox in fetal development and neonatal diseases

In the cell, reducing and oxidizing molecules modulate the redox state. In embryonic and fetal growth, increased oxidative stress may be detrimental, but an oxidized state can also be beneficial. This is because redox may also affect key transcription factors that can alter gene expression during development. In addition, redox may impact on placentation and amniotic membrane integrity during pregnancy. Lastly, diseases of prematurity, such as necrotizing enterocolitis, retinopathy of prematurity, and chronic lung disease, may be modulated by redox in the premature. Because antioxidant therapies have not necessarily modified the outcome of these diseases, some debate exists as to this. Nonetheless, sufficient evidence suggests a role for redox throughout embryonic, fetal, and postnatal development. This evidence will be explored here.