Effect of multiple INSURE procedures in extremely preterm infants

Hypoxia-Inducible Pathway Polymorphisms and Their Role in the Complications of Prematurity

Excessive oxidative stress resulting from hyperoxia or hypoxia is a recognized risk factor for diseases of prematurity. However, the role of the hypoxia-related pathway in the development of these diseases has not been well studied. Therefore, this study aimed to investigate the association between four functional single nucleotide polymorphisms (SNPs) in the hypoxia-related pathway, and the development of complications of prematurity in relation to perinatal hypoxia. A total of 334 newborns born before or on the 32nd week of gestation were included in the study. The SNPs studied were HIF1A rs11549465 and rs11549467, VEGFA rs2010963, and rs833061. The findings suggest that the HIF1A rs11549465T allele is an independent protective factor against necrotizing enterocolitis (NEC), but may increase the risk of diffuse white matter injury (DWMI) in newborns exposed to hypoxia at birth and long-term oxygen supplementation. In addition, the rs11549467A allele was found to be an independent protective factor against respiratory distress syndrome (RDS). No significant associations with VEGFA SNPs were observed. These findings indicate the potential involvement of the hypoxia-inducible pathway in the pathogenesis of complications of prematurity. Studies with larger sample sizes are needed to confirm these results and explore their clinical implications.

Polymorphisms of fibronectin-1 (rs3796123; rs1968510; rs10202709; rs6725958; and rs35343655) are not associated with bronchopulmonary dysplasia in preterm infants

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that mainly affects premature newborns. Many different factors, increasingly genetic, are involved in the pathogenesis of BPD. The aim of the study is to investigate the possible influence of fibronectin SNP on the occurrence of BPD. The study included 108 infants born between 24 and 32 weeks of gestation. BPD was diagnosed based on the National Institutes of Health Consensus definition. The 5 FN1 gene polymorphisms assessed in the study were the following: rs3796123; rs1968510; rs10202709; rs6725958; and rs35343655. BPD developed in 30 (27.8%) out of the 108 preterm infants. Incidence of BPD was higher in infants with lower APGAR scores and low birthweight. Investigation did not confirm any significant prevalence for BPD development in any genotypes and alleles of FN1. Further studies should be performed to confirm the role of genetic factors in etiology and pathogenesis of BPD.

Bi-level Nasal Positive Airway Pressure (BiPAP) versus Nasal Continuous Positive Airway Pressure (CPAP) for Preterm Infants with Birth Weight Less Than 1500 g and Respiratory Distress Syndrome Following INSURE Treatment: A Two-center Randomized Controlled Trial

The present study aimed to examine the effectiveness of bi-level positive airway pressure (BiPAP) versus continuous positive airway pressure (CPAP) in preterm infants with birth weight less than 1500 g and respiratory distress syndrome (RDS) following intubation-surfactant-extubation (INSURE) treatment. A two-center randomized control trial was performed. The primary outcome was the reintubation rate of infants within 72 h of age after INSURE. Secondary outcomes included bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP) and incidences of adverse events. Lung function at one year of corrected age was also compared between the two groups. There were 140 cases in the CPAP group and 144 in the BiPAP group. After INSURE, the reintubation rates of infants within 72 h of age were 15% and 11.1% in the CPAP group and the BiPAP group, respectively (P>0.05). Neonates in the BiPAP group was on positive airway pressure (PAP) therapy three days less than in the CPAP group (12.6 d and 15.3 d, respectively, P<0.05), and on oxygen six days less than in the CPAP group (20.6 d and 26.9 d, respectively, P<0.05). Other outcomes such as BPD, NEC, ROP and feeding intolerance were not significantly different between the two groups (P>0.05). There was no difference in lung function at one year of age between the two groups (P>0.05). In conclusion, after INSURE, the reintubation rate of infants within 72 h of age was comparable between the BiPAP group and the CPAP group. BiPAP was superior to CPAP in terms of shorter durations (days) on PAP support and oxygen supplementation. There were no differences in the incidences of BPD and ROP, and lung function at one year of age between the two ventilation methods.

Tracing exogenous surfactant in vivo in rabbits by the natural variation of 13C

BACKGROUND

Respiratory Distress Syndrome (RDS) is a prematurity-related breathing disorder caused by a quantitative deficiency of pulmonary surfactant. Surfactant replacement therapy is effective for RDS newborns, although treatment failure has been reported. The aim of this study is to trace exogenous surfactant by ¹³C variation and estimate the amount reaching the lungs at different doses of the drug.

METHODS

Forty-four surfactant-depleted rabbits were obtained by serial bronchoalveolar lavages (BALs), that were merged into a pool (BAL pool) for each animal. Rabbits were in nasal continuous positive airway pressure and treated with 0, 25, 50, 100 or 200 mg/kg of poractant alfa by InSurE. After 90 min, rabbits were depleted again and a new pool (BAL end experiment) was collected. Disaturated-phosphatidylcholine (DSPC) was measured by gas chromatography. DSPC-Palmitic acid (PA) ¹³C/¹²C was analyzed by isotope ratio mass spectrometry. One-way non-parametric ANOVA and post-hoc Dunn's multiple comparison were used to assess differences among experimental groups.

RESULTS

Based on DSPC-PA ¹³C/¹²C in BAL pool and BAL end experiment, the estimated amount of exogenous surfactant ranged from 61 to 87% in dose-dependent way (p < 0.0001) in animals treated with 25 up to 200 mg/kg. Surfactant administration stimulated endogenous surfactant secretion. The percentage of drug recovered from lungs did not depend on the administered dose and accounted for 31% [24-40] of dose.

CONCLUSIONS

We reported a risk-free method to trace exogenous surfactant in vivo. It could be a valuable tool for assessing, alongside the physiological response, the delivery efficiency of surfactant administration techniques.

Genetic Contributions to the Development of Complications in Preterm Newborns

Aim

We aimed to identify specific polymorphisms of genes encoding for vascular endothelial growth factor A (VEGFA), endothelial nitric oxide synthase (eNOS), renin-angiotensin system (angiotensinogen gene [AGT], angiotensinogen type 1 receptor [AGTR1], angiotensin-converting enzyme [ACE]), and heme oxygenase-1 (HMOX-1) in a cohort of preterm infants and correlate their presence with the development of respiratory distress syndrome (RDS) requiring mechanical ventilation (MV), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH) and retinopathy of prematurity (ROP).

Study Design

We carried out a retrospective study to evaluate the allele frequency and genotype distribution of polymorphisms of VEGFA, eNOS, AGT, AGTR1, ACE, and HMOX-1 in a population of preterm neonates (n=342) with a gestational age ≤28 weeks according to the presence or absence of RDS requiring MV, BPD, IVH, or ROP. Moreover, we evaluated through the haplotype reconstruction analysis whether combinations of the selected polymorphisms are related to the occurrence of RDS, BPD, IVH and ROP.

Results

In our population 157 infants developed RDS requiring MV, 71 BPD, 70 IVH, and 43 ROP. We found that TC+CC rs2070744 eNOS (41.7 vs. 25.4%, p=0.01) and GT+TT rs1799983 eNOS (51.8 vs. 35.2%, p=0.01) polymorphisms are independent risk factors for BPD. Haplotype reconstruction showed that haplotypes in VEGF and eNOS are significantly associated with different effects on RDS, BPD, IVH, and ROP in our population.

Conclusions

We found that TC+CC rs2070744 eNOS and GT+TT rs1799983 eNOS polymorphisms are independent predictors of an increased risk of developing BPD. Haplotypes of VEGFA and eNOS may be independent protective or risk markers for prematurity complications.

Is it feasible to identify preterm infants with respiratory distress syndrome for early extubation to continuous positive airway pressure post-surfactant treatment during retrieval?

AIM

Preterm infants with respiratory distress syndrome (RDS) requiring surfactant treatment are often retrieved mechanically ventilated to the receiving hospital. INSURE (INtubate, SURfactant, Extubate) technique is not routinely performed by Newborn and Pediatric Emergency Transport Services NSW (NETS) during retrieval. This study aims to evaluate the likelihood of using INSURE technique during retrieval. We attempted to study the clinical characteristics of preterm infants with RDS who were favourably extubated (FE) shortly after admission to the receiving hospital.

METHODS

Retrospective study of preterm infants, gestational age (GA) > 28 weeks with RDS requiring retrieval by NETS.

RESULTS

Two hundred twenty-three infants, median GA of 33 weeks (range 29-36), median birthweight 2200 g (1000-4080) were examined. A percentage of 49.7 received CPAP, and 50.3% required MV. Eighteen (16%) infants were FE (<6 h) at receiving hospital. FiO2 on stabilisation (FiO2 (st)) by NETS correlated with FiO2 on admission to receiving hospital (r = 0.863). A percentage of 81 of ventilated infants received premedications including morphine. No significant differences were noted for GA, stabilisation ventilator settings, surfactant dose (mean 155 mg/kg) and mode of transport between FE and non-FE groups. FiO2 (st) post-surfactant treatment was significantly lower in FE compared with non-FE group (mean 0.28 vs. 0.41 respectively). The area under the curve from receiver operating characteristic based on FiO2 (st) was 0.646 (P = 0.050), the sensitivity and specificity of FiO2 (st) cut-off points (between 0.25 and 0.30) was low.

CONCLUSION

FiO2 on stabilisation post-surfactant treatment has a weak predictive value and may not be adequate to be used as sole criteria to extubate to CPAP prior to transport. FiO2 at stabilisation should be included as an eligibility criteria for a randomised trial of INSURE during retrieval, but other clinical assessments are needed.

Early surfactant therapy with nasal continuous positive airway pressure or continued mechanical ventilation in very low birth weight neonates with respiratory distress syndrome

Background:

Various strategies have been suggested for the treatment of respiratory distress syndrome (RDS).

Objectives:

The aim of this study was to compare the efficacies of two common methods of RDS management among neonates with low birth weight.

Patients and Methods:

A cohort study was conducted on 98 neonates with definite diagnosis of RDS during 2008-2009. The neonates were divided into two groups by a blinded supervisor using simple randomization (odd and even numbers). Forty-five cases in the first group were treated with intubation, surfactant therapy, extubation (INSURE method) followed by nasal continuous positive airway pressure (N.CPAP) and 53 cases in the second group underwent intubation, surfactant therapy followed by mechanical ventilation (MV).

Results:

Five (11.1%) cases in the first group and 23 (43%) cases in the second group expired during the study. The rates of MV dependency among cases with INSURE failure and cases in the MV group were 37% and 83%, respectively (P < 0.001). Birth weight (BW) (P = 0.017), presence of retinopathy of prematurity (P = 0.022), C/S delivery (P = 0.029) and presence of lung bleeding (P = 0.010) could significantly predict mortality in the second group, although only BW (P = 0.029) had a significant impact on the mortality rate in the first group. Moreover, BW was significantly related to the success rate in the first group (P = 0.001).

Conclusions:

Our findings demonstrated that INSURE plus NCPAP was more effective than the routine method (permanent intubation after surfactant prescription). In addition, the lower rates of mortality, MV dependency, duration of hospitalization, and complications were observed in cases treated with the INSURE method compared to the routine one.

Exogenous surfactant therapy in 2013: what is next? Who, when and how should we treat newborn infants in the future?

Background

Surfactant therapy is one of the few treatments that have dramatically changed clinical practice in neonatology. In addition to respiratory distress syndrome (RDS), surfactant deficiency is observed in many other clinical situations in term and preterm infants, raising several questions regarding the use of surfactant therapy.

Objectives

This review focuses on several points of interest, including some controversial or confusing topics being faced by clinicians together with emerging or innovative concepts and techniques, according to the state of the art and the published literature as of 2013. Surfactant therapy has primarily focused on RDS in the preterm newborn. However, whether this treatment would be of benefit to a more heterogeneous population of infants with lung diseases other than RDS needs to be determined. Early trials have highlighted the benefits of prophylactic surfactant administration to newborns judged to be at risk of developing RDS. In preterm newborns that have undergone prenatal lung maturation with steroids and early treatment with continuous positive airway pressure (CPAP), the criteria for surfactant administration, including the optimal time and the severity of RDS, are still under discussion. Tracheal intubation is no longer systematically done for surfactant administration to newborns. Alternative modes of surfactant administration, including minimally-invasive and aerosolized delivery, could thus allow this treatment to be used in cases of RDS in unstable preterm newborns, in whom the tracheal intubation procedure still poses an ethical and medical challenge.

Conclusion

The optimization of the uses and methods of surfactant administration will be one of the most important challenges in neonatal intensive care in the years to come.

The role of surfactant in respiratory distress syndrome

The key feature of respiratory distress syndrome (RDS) is the insufficient production of surfactant in the lungs of preterm infants. As a result, researchers have looked into the possibility of surfactant replacement therapy as a means of preventing and treating RDS. We sought to identify the role of surfactant in the prevention and management of RDS, comparing the various types, doses, and modes of administration, and the recent development. A PubMed search was carried out up to March 2012 using phrases: surfactant, respiratory distress syndrome, protein-containing surfactant, protein-free surfactant, natural surfactant, animal-derived surfactant, synthetic surfactant, lucinactant, surfaxin, surfactant protein-B, surfactant protein-C.Natural, or animal-derived, surfactant is currently the surfactant of choice in comparison to protein-free synthetic surfactant. However, it is hoped that the development of protein-containing synthetic surfactant, such as lucinactant, will rival the efficacy of natural surfactants, but without the risks of their possible side effects. Administration techniques have also been developed with nasal continuous positive airway pressure (nCPAP) and selective surfactant administration now recommended; multiple surfactant doses have also reported better outcomes. An aerosolised form of surfactant is being trialled in the hope that surfactant can be administered in a non-invasive way. Overall, the advancement, concerning the structure of surfactant and its mode of administration, offers an encouraging future in the management of RDS.

Genetic polymorphisms of antioxidant enzymes as risk factors for oxidative stress-associated complications in preterm infants

We aimed to identify specific polymorphisms of genes encoding for superoxide dismutase (SOD) 1 (cytoplasmic Cu/ZnSOD), SOD2 (mitochondrial MnSOD), SOD3 (extracellular Cu/ZnSOD) and CAT in a cohort of preterm infants and correlate their presence to the development of respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH) and retinopathy of prematurity (ROP). We carried out a retrospective study to evaluate the allele frequency and the genotype distribution of polymorphisms of SODs and CAT in a population of preterm neonates (n = 152) with a gestational age ≤ 28 weeks according to the presence or absence of RDS, BPD, IVH and ROP. Moreover, we evaluated through the haplotype reconstruction analysis whether combinations of the selected polymorphisms are related to the occurrence of RDS, BPD, IVH and ROP. We found that rs8192287 SOD3 polymorphism is an independent protective factor for all grade IVH, while rs4880 and rs5746136 SOD2 polymorphisms are associated with a lower gestational age (rs4880, rs5746136) and birth weight (rs4880). Haplotypes reconstruction showed that SOD1 (GG) decreased the risk of RDS, IVH and ROP; SOD2 (GT) increased the risk of BPD and decreased the risk of RDS, IVH and ROP; SOD3 (TGC) decreased the risk of BPD and IVH; and 4) CAT (CTC) decreased the risk of RDS. The rs8192287 SOD3 polymorphism is per se an independent predictor of a decreased risk of developing IVH. Different SOD2 polymorphisms are associated per se with a lower gestational age and/or birth weight, and haplotypes of SOD1, SOD3 and CAT genes may be independent protecting or risk markers for prematurity complications.

Risk factors for intubation-surfactant-extubation (INSURE) failure and multiple INSURE strategy in preterm infants

The INSURE method, which consists of an intubation-surfactant-extubation sequence, is effective in reducing the need for mechanical ventilation (MV), the duration of respiratory support, and the need for surfactant replacement in preterm infants with respiratory distress syndrome. Although beneficial, the INSURE method fails to avoid MV in selected patients. We demonstrated that body weight <750 g, pO(2)/FiO(2) <218, and a/ApO(2) <0.44 at the first blood gas analysis are independent risk factors for INSURE failure in infants with gestational age <30 weeks. Moreover, we demonstrated that the INSURE treatment can be safely repeated with the aim to avoid MV, since the respiratory outcome did not differ between infants treated with single or multiple INSURE procedures.