Blood gases and retinopathy of prematurity: the ELGAN Study

Efficacy comparison of 21 interventions to prevent retinopathy of prematurity: a Bayesian network meta-analysis of randomized controlled trials

BACKGROUND

The objective of this study was to evaluate the comparative efficacy of current interventions for the prevention of retinopathy of prematurity (ROP) in premature infants.

METHODS

A network meta-analysis (NMA) was performed. We searched PubMed, Web of Science, Scopus, Embase, and the Cochrane Library for relevant studies from their inception to May 5, 2022. Publications were eligible for our study if they were randomized controlled trials (RCTs) involving preterm infants at <37 weeks of gestational age and reported the incidence of any-stage ROP treated with the interventions of interest. The overall effect was pooled using the random effects model.

RESULTS

We identified 106 RCTs (involving 23894 participants). This NMA showed that vitamin A supplementation markedly reduced the incidence of ROP, in comparison with placebo (odds ratio [OR] = 0.59, 95% credible interval [95% CrI] 0.33, 0.85), fish oil-based lipid emulsion (OR = 0.57, 95% CrI 0.24, 0.90), early erythropoietin (OR = 0.51, 95% CrI 0.34, 0.98), probiotics (OR = 0.48, 95% CrI 0.32, 0.97), and human milk (OR = 0.50, 95% CrI 0.21, 0.78). Vitamin A supplementation has the highest probability of being the best option for reducing the ROP risk compared with the other 20 interventions based on its surface under the cumulative ranking curve (SUCRA) value (SUCRA = 92.50%, 95% CrI 0.71, 1.00).

CONCLUSIONS

Our findings suggest that among 21 interventions, vitamin A supplementation might be the best method of preventing ROP. This NMA offers an important resource for further efforts to develop preventive strategies for ROP.

Antimicrobial peptides modulate lung injury by altering the intestinal microbiota

BACKGROUND

Mammalian mucosal barriers secrete antimicrobial peptides (AMPs) as critical, host-derived regulators of the microbiota. However, mechanisms that support microbiota homeostasis in response to inflammatory stimuli, such as supraphysiologic oxygen, remain unclear.

RESULTS

We show that supraphysiologic oxygen exposure to neonatal mice, or direct exposure of intestinal organoids to supraphysiologic oxygen, suppresses the intestinal expression of AMPs and alters intestinal microbiota composition. Oral supplementation of the prototypical AMP lysozyme to hyperoxia-exposed neonatal mice reduced hyperoxia-induced alterations in their microbiota and was associated with decreased lung injury.

CONCLUSIONS

Our results identify a gut-lung axis driven by intestinal AMP expression and mediated by the intestinal microbiota that is linked to lung injury in newborns. Together, these data support that intestinal AMPs modulate lung injury and repair. Video Abstract.

Retinopathy of prematurity: from oxygen management to molecular manipulation

INTRODUCTION

Retinopathy of prematurity (ROP) is a vasoproliferative disorder of the premature retina with the potential to progress to extraretinal neovascularisation. This review serves as an introduction to retinopathy of prematurity (ROP), outlining key parts of ROP pathophysiology, diagnosis and treatment. ROP is traditionally diagnosed by indirect ophthalmoscopy and classified using anatomical zones, stages of disease, and the presence or absence of "plus disease" (dilation and tortuosity of the major retinal arterioles and venules). ROP has a bi-phasic pathophysiology: initial hyperoxia causes reduced retinal vascularisation, followed by pathological vaso-proliferation resulting from subsequent hypoxia and driven by vascular endothelial growth factor (VEGF).

ADVANCEMENTS IN MANAGEMENT

This review summarises previous trials to establish optimum oxygen exposure levels in newborns and more recently the development of anti-VEGF agents locally delivered to block pathological neovascularisation, which is technically easier to administer and less destructive than laser treatment.

FUTURE DIRECTIONS

There remains an ongoing concern regarding the potential unwanted systemic effects of intravitreally administered anti-VEGF on the overall development of the premature baby. Ongoing dosing studies may lessen these fears by identifying the minimally effective dose required to block extraretinal neovascularisation.

Modifiable Risk Factors and Preventative Strategies for Severe Retinopathy of Prematurity

Severe ROP is characterized by the development of retinal fibrovascular proliferation that may progress to retinal detachment. The purpose of this report is to review five of the most common and well-studied perinatal and neonatal modifiable risk factors for the development of severe ROP. Hyperoxemia, hypoxia, and associated prolonged respiratory support are linked to the development of severe ROP. While there is a well-established association between clinical maternal chorioamnionitis and severe ROP, there is greater variability between histologic chorioamnionitis and severe ROP. Neonatal sepsis, including both bacterial and fungal subtypes, are independent predictors of severe ROP in preterm infants. Although there is limited evidence related to platelet transfusions, the risk of severe ROP increases with the number and volume of red blood cell transfusions. Poor postnatal weight gain within the first six weeks of life is also strongly tied to the development of severe ROP. We also discuss preventative strategies that may reduce the risk of severe ROP. Limited evidence-based studies exist regarding the protective effects of caffeine, human milk, and vitamins A and E.

Antimicrobial peptides modulate lung injury by altering the intestinal microbiota

Mammalian mucosal barriers secrete antimicrobial peptides (AMPs) as critical host-derived regulators of the microbiota. However, mechanisms that support homeostasis of the microbiota in response to inflammatory stimuli such as supraphysiologic oxygen remain unclear. Here, we show that neonatal mice breathing supraphysiologic oxygen or direct exposure of intestinal organoids to supraphysiologic oxygen suppress the intestinal expression of AMPs and alters the composition of the intestinal microbiota. Oral supplementation of the prototypical AMP lysozyme to hyperoxia exposed neonatal mice reduced hyperoxia-induced alterations in their microbiota and was associated with decreased lung injury. Our results identify a gut-lung axis driven by intestinal AMP expression and mediated by the intestinal microbiota that is linked to lung injury. Together, these data support that intestinal AMPs modulate lung injury and repair.

In Brief

Using a combination of murine models and organoids, Abdelgawad and Nicola et al. find that suppression of antimicrobial peptide release by the neonatal intestine in response to supra-physiological oxygen influences the progression of lung injury likely via modulation of the ileal microbiota.

Highlights

Supraphysiologic oxygen exposure alters intestinal antimicrobial peptides (AMPs).Intestinal AMP expression has an inverse relationship with the severity of lung injury.AMP-driven alterations in the intestinal microbiota form a gut-lung axis that modulates lung injury.AMPs may mediate a gut-lung axis that modulates lung injury.

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.

Effects of Early Treatment of Retinopathy of Prematurity at a Tertiary Care Hospital in Saudi Arabia: A Retrospective Study

PURPOSE

To estimate the prevalence of retinopathy of prematurity (ROP) among high-risk neonates and to illuminate the benefits of early treatment in type 2 ROP (zone II, stage 3 without plus) and ROP milder than type 1 with pre-plus disease (zone III, stage 3).

METHODS

This retrospective cross-sectional study was conducted among 307 high-risk neonates (614 eyes) with a gestational age of 32 weeks or younger at birth and a birth weight of 1,500 g or less, from 2011 to 2016. Treatment was initiated for neonates with low-risk type 2 ROP and ROP milder than type 1 with pre-plus disease, whenever retinopathy was evident for 3 clock hours with or without vitreous hemorrhage. Post-treatment progression was recorded.

RESULTS

The prevalence of ROP in the current study was 33.71%. Two hundred seven eyes had ROP; 47.34% had mild retinopathy that did not require treatment, and 52.66% received laser treatment, including the early treated group. Of the 207 eyes with ROP, 46.86% had low-risk type 2 ROP disease and ROP milder than type 1 with pre-plus disease, and underwent photocoagulation therapy. After treatment, 15.38% and 10.71% eyes were stable, 84.62% and 88.10% eyes had regressed retinopathy, and 0% and 1.19% progressed in both groups, respectively.

CONCLUSIONS

Early treatment of type 2 ROP and ROP milder than type 1 with pre-plus disease in certain cases significantly decreased the rate of progression to more advanced stages and resulted in good clinical outcomes. [J Pediatr Ophthalmol Strabismus. 2021;58(4):240-245.].

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.

Early Life Supraphysiological Levels of Oxygen Exposure Permanently Impairs Hippocampal Mitochondrial Function

Preterm infants requiring prolonged oxygen therapy often develop cognitive dysfunction in later life. Previously, we reported that 14-week-old young adult mice exposed to hyperoxia as newborns had spatial and learning deficits and hippocampal shrinkage. We hypothesized that the underlying mechanism was the induction of hippocampal mitochondrial dysfunction by neonatal hyperoxia. C57BL/6J mouse pups were exposed to 85% oxygen or room air from P2-P14. Hippocampal proteomic analysis was performed in young adult mice (14 weeks). Mitochondrial bioenergetics were measured in neonatal (P14) and young adult mice. We found that hyperoxia exposure reduced mitochondrial ATP-linked oxygen consumption and increased state 4 respiration linked proton leak in both neonatal and young adult mice while complex I function was decreased at P14 but increased in young adult mice. Proteomic analysis revealed that hyperoxia exposure decreased complex I NDUFB8 and NDUFB11 and complex IV 7B subunits, but increased complex III subunit 9 in young adult mice. In conclusion, neonatal hyperoxia permanently impairs hippocampal mitochondrial function and alters complex I function. These hippocampal mitochondrial changes may account for cognitive deficits seen in children and adolescents born preterm and may potentially be a contributing mechanism in other oxidative stress associated brain disorders.

Carbon dioxide and retinopathy of prematurity in extremely low birth weight infants

Objective: To evaluate the relationship between partial pressure of carbon dioxide (PCO₂) during the first 3 days of life and retinopathy of prematurity (ROP) in extremely low birthweight (ELBW) infants.Patients and methods: A retrospective evaluation of data on ELBW infants were collected over a period of 4 years. Data during the first 72 hours of life was divided into six, 12-hour epochs. The average highest and overall means of PCO₂, PO₂, FiO_2, and glucose were calculated for each epoch. Logistic regression analysis was used to determine the association between PCO₂ and ROP after controlling for covariables.Results: A total of 78 neonates were included: birth weight (BW) (703 ± 157 g) and gestational age (25 ± 1.4 weeks). A total of 45 out of 78 had ROP: stage 1 (N = 8), stage 2 (N = 26), stage 3 (N = 14), and plus (N = 4). The overall mean PCO₂ correlated with ROP in the first 72 hours of life (R = 0.31, p = .0069). This correlation was significant in epochs 2 (p = .049), 4 (p = .008) and 6 (p = .038). The average of the highest PCO₂ also correlated with ROP in the first 72 hours of life (R = 0.38, p = .0007). This correlation was significant in epochs 2 (p = .0115), 4 (p = .0011), 5 (p = .028) and 6 (p = .037). The correlation between the stage of ROP and PCO₂ was significant after controlling for PO₂ and glucose concentrations. Other variables that correlated with ROP were the overall means of FiO₂ (R = 0.23, p = .04), PO₂ (R = 0.39, p = .0005) and glucose (R = 0.39, p = .0004) as well as the average highest concentrations of FiO₂ (R = 0.26, p = .025), PO₂ (R = 0.38, p = .0008) and glucose (R = 0.34, p = .007).Conclusion: After controlling for confounding variables, ROP correlated with the overall means and average highest PCO₂. ROP also correlated with FiO₂, PO₂ and glucose concentrations. Further studies are needed to define the safe PCO₂ range and the effect of PCO₂ on the normal development of the retina.

A Causally Naïve and Rigid Population Model of Disease Occurrence Given Two Non-Independent Risk Factors

We describe a computational population model with two risk factors and one outcome variable in which the prevalence (%) of all three variables, the association between each risk factor and the disease, as well as the association between the two risk factors is the input. We briefly describe three examples: retinopathy of prematurity, diabetes in Panama, and smoking and obesity as risk factors for diabetes. We describe and discuss the simulation results in these three scenarios including how the published information is used as input and how changes in risk factor prevalence changes outcome prevalence.

Chorioamnionitis as a risk factor for retinopathy of prematurity: An updated systematic review and meta-analysis

The role of chorioamnionitis (CA) in the development of retinopathy of prematurity (ROP) is difficult to establish, because CA-exposed and CA-unexposed infants frequently present different baseline characteristics. We performed an updated systematic review and meta-analysis of studies reporting on the association between CA and ROP. We searched PubMed and EMBASE for relevant articles. Studies were included if they examined preterm or very low birth weight (VLBW, <1500g) infants and reported primary data that could be used to measure the association between exposure to CA and the presence of ROP. Of 748 potentially relevant studies, 50 studies met the inclusion criteria (38,986 infants, 9,258 CA cases). Meta-analysis showed a significant positive association between CA and any stage ROP (odds ratio [OR] 1.39, 95% confidence interval [CI] 1.11 to 1.74). CA was also associated with severe (stage ≥3) ROP (OR 1.63, 95% CI 1.41 to 1.89). Exposure to funisitis was associated with a higher risk of ROP than exposure to CA in the absence of funisitis. Additional meta-analyses showed that infants exposed to CA had lower gestational age (GA) and lower birth weight (BW). Meta-regression showed that lower GA and BW in the CA-exposed group was significantly associated with a higher risk of ROP. Meta-analyses of studies with data adjusted for confounders could not find a significant association between CA and ROP. In conclusion, our study confirms that CA is a risk factor for developing ROP. However, part of the effects of CA on the pathogenesis of ROP may be mediated by the role of CA as an etiological factor for very preterm birth.

Supraphysiological Levels of Oxygen Exposure During the Neonatal Period Impairs Signaling Pathways Required for Learning and Memory

Preterm infants often require prolonged oxygen supplementation and are at high risk of neurodevelopmental impairment. We recently reported that adult mice exposed to neonatal hyperoxia (postnatal day [P] 2 to 14) had spatial navigation memory deficits associated with hippocampal shrinkage. The mechanisms by which early oxidative stress impair neurodevelopment are not known. Our objective was to identify early hyperoxia-induced alterations in hippocampal receptors and signaling pathways necessary for memory formation. We evaluated C57BL/6 mouse pups at P14, exposed to either 85% oxygen or air from P2 to 14. We performed targeted analysis of hippocampal ligand-gated ion channels and proteins necessary for memory formation, and global bioinformatic analysis of differentially expressed hippocampal genes and proteins. Hyperoxia decreased hippocampal mGLU7, TrkB, AKT, ERK2, mTORC1, RPS6, and EIF4E and increased α3, α5, and ɤ2 subunits of GABA_A receptor and PTEN proteins, although changes in gene expression were not always concordant. Bioinformatic analysis indicated dysfunction in mitochondria and global protein synthesis and translational processes. In conclusion, supraphysiological oxygen exposure reduced proteins necessary for hippocampus-dependent memory formation and may adversely impact hippocampal mitochondrial function and global protein synthesis. These early hippocampal changes may account for memory deficits seen in preterm survivors following prolonged oxygen supplementation.

End-tidal carbon dioxide measurement in preterm infants with low birth weight

Objective

There are conflicting data regarding the use of end-tidal carbon dioxide (PetCO₂) measurement in preterm infants. The aim of this study was to evaluate the effects of different dead space to tidal volume ratios (V_D/V_T) on the correlation between PetCO₂ and arterial carbon dioxide pressure (PaCO₂) in ventilated preterm infants with respiratory distress syndrome (RDS).

Methods

We enrolled ventilated preterm infants (with assist control mode or synchronous intermittent mandatory mode) with RDS who were treated with surfactant in this prospective study. Simultaneous PetCO₂ and PaCO₂ data pairs were obtained from ventilated neonates monitored using mainstream capnography. Data obtained before and after surfactant treatment were also analyzed.

Results

One-hundred and one PetCO₂ and PaCO₂ pairs from 34 neonates were analyzed. There was a moderate correlation between PetCO₂ and PaCO₂ values (r = 0.603, P < 0.01). The correlation was higher in the post-surfactant treatment group (r = 0.786, P < 0.01) than the pre-surfactant treatment group (r = 0.235). The values of PaCO₂ and PetCO₂ obtained based on the treatment stage of surfactant therapy were 42.4 ± 8.6 mmHg and 32.6 ± 7.2 mmHg, respectively, in pre-surfactant treatment group, and 37.8 ± 10.3 mmHg and 33.7 ± 9.3 mmHg, respectively, in the post-surfactant treatment group. Furthermore, we found a significant decrease in V_D/V_T in the post-surfactant treatment group when compared to the pre-surfactant treatment group (P = 0.003).

Conclusions

V_D/V_T decreased significantly after surfactant therapy and the correlation between PetCO₂ and PaCO₂ was higher after surfactant therapy in preterm infants with RDS.

Probiotic supplementation in preterm infants does not affect the risk of retinopathy of prematurity: a meta-analysis of randomized controlled trials

Retinopathy of prematurity (ROP) is a vascular disorder of the developing retina in preterm infants and is a leading cause of childhood blindness. Perinatal infection plays a pathogenic role in ROP. Probiotic supplementation reduces the risk of late onset sepsis (LOS) in preterm infants but it remains to be determined whether this reduction translates into a reduction of other complications. We conducted a systematic review and meta-analysis to evaluate the possible role of probiotics in altering the risk of ROP. Eleven randomized controlled trials (4250 infants; probiotics: 2121) were included in the meta-analysis that showed a significantly decreased rate of LOS with a risk ratio (RR) of 0.807 and a 95% confidence interval (CI) of 0.705 to 0.924 (P = 0.010; fixed effects model) but could not demonstrate a significant effect of probiotics on any stage ROP (RR 1.053, 95% CI 0.903 to 1.228, P = 0.508, 4 studies), or severe ROP (RR 0.841, 95% CI 0.666 to 1.063, P = 0.148, 9 studies). Meta-regression did not show any significant association between the RR for LOS and the RR for severe ROP. In conclusion, our results suggest that infection prevention by probiotics does not affect the risk of developing ROP in preterm infants.

Reduced internalization of TNF-ɑ/TNFR1 down-regulates caspase dependent phagocytosis induced cell death (PICD) in neonatal monocytes

Phagocytosis-induced cell death (PICD) is diminished in cord blood monocytes (CBMO) as compared to cells from adults (PBMO) due to differences in the CD95-pathway. This may support a prolonged pro-inflammatory response with sequels of sustained inflammation as seen in neonatal sepsis. Here we hypothesized that TNF-α mediated induction of apoptosis is impaired in CBMO due to differences in the TNFR1-dependent internalization. Monocytes were infected with Escherichia coli-GFP (E. coli-GFP). Monocyte phenotype, phagocytic activity, induction of apoptosis, and TNF-α/TNF-receptor (TNFR) -expression were analysed. In the course of infection TNF-α-secretion of CBMO was reduced to 40% as compared to PBMO (p<0.05). Neutralization of TNF-α by an αTNF-α antibody reduced apoptotic PICD in PBMO four-fold (p < 0.05 vs. infection with E. coli). PICD in CBMO was reduced 5-fold compared to PBMO and showed less responsiveness to αTNF-α antibody. CBMO expressed less pro-apoptotic TNFR1, which, after administration of TNF-α or infection with E. coli was internalized to a lesser extent. With similar phagocytic capacity, reduced TNFR1 internalization in CBMO was accompanied by lower activation of caspase-8 (p < 0.05 vs. PBMO). Stronger caspase-8 activation in PBMO caused more activation of effector caspase-3 and apoptosis (all p < 0.05 vs. PBMO). Our results demonstrate that TNFR1 internalization is critical in mediating PICD in monocytes after infection with E.coli and is reduced in CBMO.

Advances in understanding and management of retinopathy of prematurity

The understanding, diagnosis, and treatment of retinopathy of prematurity have changed in the 70 years since the original description of retrolental fibroplasia associated with high oxygenation. It is now recognized that retinopathy of prematurity differs in appearance worldwide and as ever smaller and younger premature infants survive. New methods are being evaluated to image the retina, diagnose severe retinopathy of prematurity, and determine windows of time for treatment to save eyes and improve visual and neural outcomes. New treatments to promote physiologic retinal vascular development, vascular repair, and inhibit vasoproliferation by regulating proteins involved in vascular endothelial growth factor, insulin-like growth factor, or erythropoietin signaling. Reducing excessive oxidative/nitrosative stress and understanding progenitor cells and neurovascular and glial vascular interactions are being studied.

Newborn blood gas derangements of children born extremely preterm and neurocognitive dysfunctions at age 10 years

Among 740 children born extremely preterm, we evaluated the relationship between the highest and lowest quartiles of the distributions of PaO₂ and PaCO₂, as well as the lowest quartile of pH on one day, and separately on two days, and the risk of neurocognitive, language, and behavioral dysfunctions at age 10 years. Children who had hypoxemia, hyperoxemia, hypocapnia, hypercapnia, and acidemia, sometimes on only one day, and sometimes on two or more days, were more likely than others to have a high illness severity score (within the first 12 postnatal hours), and 10 years later to have multiple dysfunctions. The tendency of blood gas derangements to be associated with high illness severity scores and with multiple dysfunctions 10 years later is compatible with the possibility that blood gas derangements are indicators of physiologic instability/vulnerability/immaturity rather than contributors to brain damage.

Retinopathy of Prematurity: Therapeutic Strategies Based on Pathophysiology

Retinopathy of prematurity (ROP) continues to be a major preventable cause of blindness and visual handicaps globally. With improved perinatal care, improved survival of moderately preterm infants, and limited resources for oxygen delivery and monitoring, more mature preterm infants are developing severe ROP in developing countries. The pathophysiology of ROP is characterized by two phases. Phase I ROP is due to vaso-obliteration beginning immediately after birth secondary to a marked decrease in vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1). Phase II begins around 33 weeks' postmenstrual age (PMA). During this phase, VEGF levels increase, especially if there is retinal hypoxia with increasing retinal metabolism and demand for oxygen leading to abnormal vasoproliferation. Since the original description of ROP in 1942 by Terry et al. [Am J Ophthalmol 1942;25:203-204], four epidemics of ROP have been observed. Prevention or early treatment of ROP involves careful titration of oxygen saturation by pulse oximeter (SpO2). Optimal SpO2 target remains elusive. Most of the large trials have focused on either a low SpO2 (85-89%) or a high SpO2 (91-95%) from the first day of birth to 36 weeks' PMA. Although the incidence of severe ROP and bronchopulmonary dysplasia decreased significantly, predischarge mortality was higher in these studies. Use of graded SpO2 during the 2 different phases of ROP (early, low SpO2 during phase I vs. late, high SpO2 during phase II) may be the best approach to prevent this disabling condition. Further trials should focus on this strategy. Other biological agents that are currently being studied include IGF-1 with IGF-binding protein-3 (rhIGF-1 + rhIGFBP-3) and propranolol. For advanced stages of ROP, laser ablation of avascular retina, early treatment of ROP (ETROP) protocol, intravitreal injection of anti-VEGF antibodies (e.g. bevacizumab) and vitrectomy are used to protect central vision and prevent retinal detachment. Long-term complications such as refractory errors, recurrence of ROP and risk of retinal detachment require continued follow-up with an ophthalmologist through adolescence and beyond. Optimal nutrition including adequate intake of omega-3 polyunsaturated fatty acids and decreasing infection/inflammation to promote normal vascularization are important strategies. Screening guidelines for ROP based on local incidence of ROP in different regions of the world are very important. Oxygen therapy is clearly a modifiable risk factor to decrease ROP that needs further study. Understanding the two phases of ROP will help to identify appropriate therapeutic strategies and improve visual outcomes in many preterm infants globally.

Genomics in the neonatal nursery: Focus on ROP

Retinopathy of prematurity (ROP) is a complex disease that is influenced by both genetic and environmental factors. Several small studies have found genetic variants in EPAS1, VEGF, SOD, and members of the WNT family in association with ROP. Design in genetic studies is challenging because of changing recommendations for the management of prematurity and ROP, the fact ROP is rare, and that availability of resources for managing premature infants can vary throughout the world. In addition, there is a shortage of ophthalmologists with the ability to diagnose and characterize severe ROP. Careful determination of the degree of prematurity is important when evaluating genetic studies. Controlling for significant epidemiologic factors and multiple comparisons is also important to consider when evaluating genetic studies. One large candidate gene study controlled for degree of prematurity, significant epidemiologic factors, and multiple comparisons and found variants within the intron of BDNF associated with severe ROP. Future studies using unbiased techniques to assess genetic risk are important as are in-depth study of BDNF through deep sequencing and associated mechanistic studies using appropriate experimental models.

Blood flow assessed by color Doppler imaging in retinopathy of prematurity

OBJECTIVE

To quantify central retinal arterial and venous blood flow using ultrasound color Doppler imaging.

STUDY DESIGN

In this prospective observational study, eyes of eight preterm infants with retinopathy of prematurity stage 2 and of eight preterm infants without retinopathy (gestational age <30 weeks, birth weight <1500 g) were evaluated by color Doppler imaging.

RESULT

Ocular blood flow velocities measured at 28±1 days of life did not differ significantly in the eyes of preterm infants who subsequently did and did not develop retinopathy. Development of retinopathy was associated with highly significant (P<0.0001 each) increases in central retinal vein maximum velocities (from 1.99±0.36 to 3.72±0.61 cm s(-1)), central retinal artery systolic flow velocities (from 6.44±1.52 to 9.87±1.99 cm s(-1)) and flow velocity integrals (from 1.27±0.30 to 2.17±0.50 cm) at 64±13 days of life. In infants without retinopathy, no significant changes were observed except for an increase in central retinal vein maximum velocities (from 1.96±0.22 to 2.62±0.44 cm s(-1), P=0.003).

CONCLUSION

Retinopathy of prematurity appears to be accompanied by increased retinal blood flow.

A rate-based transcutaneous CO2 sensor for noninvasive respiration monitoring

The pain and risk of infection associated with invasive blood sampling for blood gas measurements necessitate the search for reliable noninvasive techniques. In this work we developed a novel rate-based noninvasive method for a safe and fast assessment of respiratory status. A small sampler was built to collect the gases diffusing out of the skin. It was connected to a CO2 sensor through gas-impermeable tubing. During a measurement, the CO2 initially present in the sampler was first removed by purging it with nitrogen. The gases in the system were then recirculated between the sampler and the CO2 sensor, and the CO2 diffusion rate into the sampler was measured. Because the measurement is based on the initial transcutaneous diffusion rate, reaching mass transfer equilibrium and heating the skin is no longer required, thus, making it much faster and safer than traditional method. A series of designed experiments were performed to analyze the effect of the measurement parameters such as sampler size, measurement location, subject positions, and movement. After the factor analysis tests, the prototype was sent to a level IV NICU for clinical trial. The results show that the measured initial rate of increase in CO2 partial pressure is linearly correlated with the corresponding arterial blood gas measurements. The new approach can be used as a trending tool, making frequent blood sampling unnecessary for respiratory status monitoring.

Antecedents and correlates of visual field deficits in children born extremely preterm

AIM

We sought to identify the antecedents and correlates of visual field deficits (VFDs) at age 2 years among infants born before the 28th week of gestation.

METHODS

The visual fields of 1023 infants were assessed by confrontation at age 2 years. We compared the ante-and postnatal characteristics and exposures of the 65 infants with a VFD to their peers who did not have a VFD. We used time-oriented logistic regression risk models to assess the associations of potential antecedents and correlates with a VFD.

RESULTS

In the final regression model, VFD was associated with maternal consumption of aspirin during the current pregnancy, recurring/persistent acidemia during the first 3 postnatal days, cerebral ventriculomegaly seen on neonatal ultrasound, prethreshold retinopathy of prematurity (ROP), and supplemental oxygen and ventilator dependence at 36 weeks post-menstrual age. Birth before the 27th week was also associated with increased risk, but its significance was diminished by the addition of postnatal variables.

CONCLUSION

In this sample of extremely preterm born infants, antenatal as well as early and late postnatal characteristics and exposures are associated with an increased risk of having a VFD. Our study adds to our knowledge about the complex etiology of visual deficits of prematurity, and supports a multifactorial cause of these deficits.

Prethreshold retinopathy in premature infants with intrauterine growth restriction

AIM

To determine, among very preterm newborns, whether those who are growth-restricted are at increased risk of retinopathy of prematurity (ROP), and to explore whether the mixed findings of prior studies are the consequence of sampling based upon birthweight instead of gestational age.

METHODS

Using data from the ELGAN Study, we created logistic regression models of prethreshold ROP risk to adjust for confounders and calculate odds ratios and 99% confidence intervals. We created scatter plots to display the gestational age/birthweight relationship in infants enrolled in studies with different selection criteria.

RESULTS

Low gestational age [23-24 weeks, OR 11.6 (2.9, 47); 25-26 weeks, 8.1 (2.1, 32)] and severe growth restriction [birthweight Z-score <-2, OR 9.1 (1.1, 76)] were associated with increased risk of prethreshold ROP. We documented in scatter plots that a sample defined by birthweight has an excess of gestationally older, severely growth-restricted newborns.

CONCLUSION

In this sample, low gestational age and severe growth restriction were associated with increased risk of prethreshold ROP.

Vascular endothelial growth factor antagonist therapy for retinopathy of prematurity

In this article, the growing problem of retinopathy of prematurity (ROP) worldwide, treatments for severe ROP including standard-of-care laser treatment, and the need for new treatments are discussed. Also discussed are the reasons to consider inhibiting the vascular endothelial growth factor (VEGF) signaling pathway in severe ROP and the concerns about broad VEGF inhibition. Finally, the potential role of VEGF in ROP based on studies in animal models of oxygen-induced retinopathy, the effects of anti-VEGF based on basic research data, and the clinical relevance of these data are covered.

Impaired visual fixation at the age of 2 years in children born before the twenty-eighth week of gestation. Antecedents and correlates in the multicenter ELGAN study

BACKGROUND

Very little is known about the prevalence, antecedents, and correlates of impaired visual fixation in former very preterm newborns.

METHODS

In the multicenter ELGAN study sample of 1057 infants born before the twenty-eighth week of gestation who had a developmental assessment at 2 years corrected age, we identified 73 who were unable to follow an object across the midline. We compared them to the 984 infants who could follow an object across the midline.

RESULTS

In this sample of very preterm newborns, those who had impaired visual fixation were much more likely than those without impaired visual fixation to have been born after the shortest of gestations (odds ratio, 3.2; 99% confidence interval, 1.4-7.5) and exposed to maternal aspirin (odds ratio, 5.2; 99% confidence interval, 2.2-12). They were also more likely than their peers to have had prethreshold retinopathy of prematurity (odds ratio, 4.1; 99% confidence interval, 1.8-9.0). At age 2 years, the children with impaired fixation were more likely than others to be unable to walk (even with assistance) (odds ratio, 7.5; 99% confidence interval, 2.2-26) and have a Mental Development Index more than three standard deviations below the mean of a normative sample (odds ratio, 3.6; 99% confidence interval, 1.4-8.2).

CONCLUSION

Risk factors for brain and retinal damages, such as very low gestational age, appear to be risk factors for impaired visual fixation. This inference is further supported by the co-occurrence at age 2 years of impaired visual fixation, inability to walk, and a very low Mental Development Index.

Retinopathy of prematurity and brain damage in the very preterm newborn

PURPOSE

To explain why very preterm newborns who develop retinopathy of prematurity (ROP) appear to be at increased risk of abnormalities of both brain structure and function.

METHODS

A total of 1,085 children born at <28 weeks' gestation had clinically indicated retinal examinations and had a developmental assessment at 2 years corrected age. Relationships between ROP categories and brain abnormalities were explored using logistic regression models with adjustment for potential confounders.

RESULTS

The 173 children who had severe ROP, defined as prethreshold ROP (n = 146) or worse (n = 27) were somewhat more likely than their peers without ROP to have brain ultrasound lesions or cerebral palsy. They were approximately twice as likely to have very low Bayley Scales scores. After adjusting for risk factors common to both ROP and brain disorders, infants who developed severe ROP were at increased risk of low Bayley Scales only. Among children with prethreshold ROP, exposure to anesthesia was not associated with low Bayley Scales.

CONCLUSIONS

Some but not all of the association of ROP with brain disorders can be explained by common risk factors. Most of the increased risks of very low Bayley Scales associated with ROP are probably not a consequence of exposure to anesthetic agents.

Risk factors and rate of progression for zone I versus zone II type 1 retinopathy of prematurity

PURPOSE

To compare the risk factors and rate of progression of zone I versus zone II type 1 retinopathy of prematurity (ROP).

METHODS

The medical records of consecutive preterm infants with bilateral type 1 ROP in zone I and age-matched control infants with type 1 ROP in zone II were retrospectively analyzed. Fundus findings at each screening examination and systemic parameters were compared between groups. Univariate and conditional multivariate regression analyses were employed to identify variables significantly associated with zone I ROP.

RESULTS

A total of 30 cases and 30 controls were included. The mean gestational age of included infants was 24.6 weeks in both groups, and the mean birth weights were 685 g in the zone I group and 667 g in the zone II group. The postmenstrual age (PMA) at the time of initial ROP detection did not differ between groups, but the PMA at the time of type 1 ROP detection was significantly earlier in the zone I group (mean, 34.9 vs 37.6 weeks). Conditional multiple logistic regression revealed that mechanical ventilation for 30 days or more was significantly associated with the type 1 ROP in zone I compared with zone II (OR, 3.5; 95% CI, 1.2-10.0).

CONCLUSIONS

Zone I ROP exhibited rapid progression, necessitating close monitoring and prompt treatment. Compromised pulmonary function with associated mechanical ventilation in early life may restrict retinal vascular growth and increase the likelihood of zone I type 1 ROP.

Targeting Müller cell-derived VEGF164 to reduce intravitreal neovascularization in the rat model of retinopathy of prematurity

PURPOSE

To determine whether knockdown of Müller cell-derived VEGFA-splice variant, VEGF164, which is upregulated in the rat retinopathy of prematurity (ROP) model, safely inhibits intravitreal neovascularization (IVNV).

METHODS

Short hairpin RNAs for VEGF164 (VEGF164.shRNAs) or luciferase.shRNA control were cloned into lentivectors with CD44 promoters that specifically target Müller cells. Knockdown efficiency, off-target effects, and specificity were tested in HEK reporter cell lines that expressed green fluorescent protein (GFP)-tagged VEGF164 or VEGF120 with flow cytometry or in rat Müller cells (rMC-1) by real-time PCR. In the rat oxygen-induced retinopathy (OIR) ROP model, pups received 1 μL subretinal lentivector-driven luciferase.shRNA, VEGFA.shRNA, or VEGF164.shRNA at postnatal day 8 (P8). Analyses at P18 and P25 included: IVNV and avascular retina (AVA); retinal and serum VEGF (ELISA); density of phosphorylated VEGFR2 (p-VEGFR2) in lectin-labeled retinal endothelial cells (ECs; immunohistochemistry); TUNEL staining and thickness of inner nuclear (INL) and outer nuclear layers (ONL) in retinal cryosections; and pup weight gain.

RESULTS

In HEK reporter and in rMC-1 cells and in comparison to lucifferase.shRNA, VEGFA.shRNA reduced both VEGF120 and VEGF164, but VEGF164.shRNA only reduced VEGF164 and not VEGF120. Compared with luciferase.shRNA, VEGFA.shRNA and VEGF164.shRNA reduced retinal VEGF and IVNV without affecting AVA at P18 and P25. At P25, VEGF164.shRNA more effectively maintained IVNV inhibition than VEGFA.shRNA. VEGFA.shRNA and VEGF164.shRNA reduced pVEGFR2 in retinal ECs at P18, but VEGFA.shRNA increased it at P25. VEGFA.shRNA increased TUNEL+ cells at P18 and decreased ONL thickness at P18 and P25. VEGFA.shRNA and VEGF164.shRNA did not affect pup weight gain and serum VEGF.

CONCLUSIONS

Short hairpin RNA to Müller cell VEGF164 maintained long-term inhibition of IVNV and limited cell death compared with shRNA to VEGFA.

Current concepts of oxygen management in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a potentially blinding disorder in premature infants. The underlying pathophysiology is incompletely understood, limiting the prevention and treatment of this devastating condition. Current therapies are directed toward management of aberrant neovascularization thought to result from retinal ischemia in the developing preterm retina. The molecular mediators important for development of retinal ischemia and subsequent neovascular pathology are not fully understood. However, oxygen has been shown to be a key mediator of disease and the oxygen environment for preterm infants has been extensively studied. Despite this, the optimal oxygen environment for preterm infants remains unclear and recent works seeking to clarify this relationship demonstrate somewhat disparate findings. These data further substantiate that ROP is a complex disease with multifactorial etiology including genetic and environmental factors. Therefore, while environmental factors such as oxygen are important to our understanding of the disease process and care of preterm infants, identification of the molecular mediators downstream of oxygen which are necessary for development of ROP pathology will be critical to improve prevention, diagnosis and treatment strategies.

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.

Increased morbidity and mortality in very preterm/VLBW infants with congenital heart disease

PURPOSE

To study the association between congenital heart diseases (CHD) and in-hospital mortality and morbidity of very preterm/very low birth weight (VLBW) infants.

METHODS

The area-based prospective cohort study ACTION included all infants with gestational age (GA) 22-31 weeks or birth weight <1,500 g admitted to neonatal care between July 2003 and June 2005 in six Italian regions (n = 3,684). CHD were coded according to ICD9-CM. Cluster multivariable logistic regression analyses were used to assess the relationship between CHD and mortality and selected morbidities [neonatal infection, ultrasound brain abnormalities, retinopathy of prematurity (ROP), and bronchopulmonary dysplasia (BPD)] adjusting for potential confounders.

RESULTS

Seventy-one patients had CHD [19.3 ‰, 95 % confidence interval (CI) 15.1-24.2 ‰]. The most common lesions were isolated atrial and ventricular septal defects (31.1 and 26.8 %, respectively), pulmonary valvar stenosis (12.7 %), and tetralogy of Fallot (5.6 %). Compared with other infants, CHD patients showed significantly higher GA and frequency of small for gestational age (SGA, i.e., birth weight ≤3rd centile). After adjustment for GA, sex, SGA, presence of extracardiac malformations or chromosomal anomalies, and region of birth, CHD patients had a significantly higher likelihood of infection, BPD, ROP, and, after 27 weeks gestation only, hospital mortality. The increased risk of ROP appeared to be partly due to infection.

CONCLUSIONS

In very preterm/VLBW infants CHD are more prevalent than in the general liveborn population, and confer an increased risk of death and serious morbidities independently of other risk factors. These results may be useful to better tailor prognostic assessment and diagnostic and therapeutic interventions for these children.

Sidestream microstream end tidal carbon dioxide measurements and blood gas correlations in neonatal intensive care unit

OBJECTIVE

The study was designed to assess the use of newer sidestream microstream end tidal carbon dioxide (ETCO(2) ) device in predicting blood carbon dioxide (PCO(2) ) measurements in very low birth weight (VLBW = birth weight <1,500 g) and non-VLBW NICU neonates.

STUDY DESIGN

Sidestream microstream ETCO(2) detectors were allowed time to calibrate and reach steady state prior to blood gas measurements. Blood CO(2) (PCO(2) ) and simultaneous ETCO(2) were recorded. Ratio of dead space to tidal volume (VD/VT) was calculated using modified Bohr's equation. Correlation coefficient, estimates of difference, standard deviation, and 95% limits of agreement between ETCO(2) and PCO(2) concentrations were calculated.

RESULTS

Two hundred eighty-six paired samples were collected from 48 ventilated NICU patients. Average PCO(2) and ETCO(2) were 58.4 and 50.6 with a correlation of 0.76. Subgroup analysis showed a correlation of 0.73 in 204 paired blood from 34 VLBW infants and 0.82 in 82 paired samples from non-VLBW infants. Estimates of difference ± standard deviation between PCO(2) and ETCO(2) concentrations in these three groups, respectively (ALL, VLBW, and non-VLBW) were 7.84 ± 9.96, 8.2 ± 10.16, and 6.95 ± 9.45. The correlation coefficient significantly improved in the VLBW group to 0.86 with dead space to tidal volume ratio (VD/VT) <30% (0.86 vs. 0.42; P < 0.001).

CONCLUSION

ETCO(2) measurements using sidestream microstream technology in VLBW demonstrated that the correlation of ETCO(2) and PCO(2) was moderate, but the agreement was less than adequate (bias > 5 mmHg in all groups). The results improved with lower VD/VT, suggesting that sidestream capnography is more reliable in conditions of less severe lung disease.

The use of the WINROP screening algorithm for the prediction of retinopathy of prematurity in a Chinese population

BACKGROUND

Retinopathy of prematurity (ROP) is a gestational age (GA)-related illness that can lead to blindness in premature infants. Timely screening of premature infants could improve visual prognosis.

OBJECTIVE

To evaluate the WINROP algorithm as a method of predicting severe ROP in a Chinese population.

METHODS

590 infants with a GA <32 weeks were entered into an online surveillance system (www.winrop.com) that included ROP evaluations and weekly weight measurements from birth to a corrected GA of 40 weeks. If the rate of weight gain decreased to a certain degree, the algorithm signaled an alarm that the infant was at risk for developing sight-threatening ROP. Each infant was categorized as having no, mild, or severe ROP.

RESULTS

Among the 590 infants with a GA <32 weeks, an alarm was triggered in 85 infants (14.4%), 50 of which developed severe ROP and were identified in this alarm group. Twenty-seven infants triggered the alarm signal in the first week after birth and 7 infants triggered the alarm at birth. Seven of the infants developed proliferative ROP and the median GA at birth for these infants was 31 weeks.

CONCLUSIONS

The WINROP system had a sensitivity of 87.5% in a Chinese population for the early identification of infants that developed severe ROP. Postnatal weight gain may help predict ROP in lower birth weight infants.

The relationship between patterns of intermittent hypoxia and retinopathy of prematurity in preterm infants

BACKGROUND

We have previously shown an increased incidence of intermittent hypoxemia (IH) events in preterm infants with severe retinopathy of prematurity (ROP). Animal models suggest that patterns of IH events may play a role in ROP severity as well. We hypothesize that specific IH event patterns are associated with ROP in preterm infants.

METHODS

Variability in IH event duration, severity, and the time interval between IH events (≤80%, ≥10 s, and ≤3 min) along with the frequency spectrum of the oxygen saturation (SpO2) waveform were assessed.

RESULTS

Severe ROP was associated with (i) an increased mean and SD of the duration of IH event (P < 0.005), (ii) more variability (histogram entropy) of the time interval between IH events (P < 0.005), (iii) a higher IH nadir (P < 0.05), (iv) a time interval between IH events of 1-20 min (P < 0.05), and (v) increased spectral power in the range of 0.002-0.008 Hz (P < 0.05), corresponding to SpO2 waveform oscillations of 2-8 min in duration. Spectral differences were detected as early as 14 d of life.

CONCLUSION

Severe ROP was associated with more variable, longer, and less severe IH events. Identification of specific spectral components in the SpO2 waveform may assist in early identification of infants at risk for severe ROP.

Placenta microbiology and histology and the risk for severe retinopathy of prematurity

PURPOSE

To test the hypothesis that the presence of bacteria and/or histologic inflammation in the placenta of infants born preterm is associated with an increased risk for severe retinopathy of prematurity (ROP).

METHODS

This was a prospective cohort study. Exploratory and multivariable data analyses were used, including logistic regression models with interaction terms. Main outcomes were four definitions of severe ROP: stage 3 or higher, any ROP in zone I, prethreshold/threshold, and plus disease.

RESULTS

Individually, placenta bacteria and histologic inflammation were not associated with severe ROP in univariable analyses among 1064 infants with gestational age <28 weeks or among 715 infants with gestational age <27 weeks (we excluded infants with a gestational age of 27 weeks because of the very small number of ROP cases). However, the co-occurrence of bacteria and inflammation was associated with an increased risk for ROP in zone I (odds ratio, 3.1; 95% confidence interval, 1.02-9.5). Among 339 infants with any placental bacteria, the co-occurrence of (1) inflammation and a gestational age of 23 to 24 weeks and (2) inflammation and hyperoxia were associated with prominent increases in risk for all definitions of severe ROP.

CONCLUSIONS

While antenatal exposure to infection or inflammation alone does not appear to convey risk information for severe ROP, their co-occurrence does. This finding supports the hypothesis that a fetal inflammatory response to antenatal infection might be part of the etiology of severe ROP.

Blood protein concentrations in the first two postnatal weeks associated with early postnatal blood gas derangements among infants born before the 28th week of gestation. The ELGAN Study

AIM

To explore the relationships between blood gas derangements and blood concentrations of inflammation-related proteins shortly after preterm birth.

DESIGN

Observational cohort.

SETTING

Fourteen neonatal intensive care units.

SUBJECTS

Seven hundred and forty five infants born before the 28th week of gestation who were classified by their blood gas derangements during the first three postnatal days and by the concentrations of 25 proteins in their blood on days 1, 7, and 14. We classified these newborns by whether or not they had a highest or lowest PaO2, PCO2, and lowest pH in the most extreme quartile, and by whether or not they had a protein concentration in the highest quartile.

RESULTS

Blood gas derangements on two days were much more likely to be accompanied or followed by sustained or recurrent systemic inflammation than a derangement on only one day. This was most evident for acidemia, and slightly less so for hypercapnia.

CONCLUSIONS

Our finding that protein concentration patterns indicative of systemic inflammation are associated with several blood gas derangements raises the possibility that organ damage attributed to these derangements might be accompanied by or involve an inflammatory response.