Pulmonary surfactant therapy

Marangoni-driven spreading of a droplet on a miscible thin liquid layer

HYPOTHESIS

The coalescence of droplets with liquid-gas interfaces of different surface tensions is common in nature and industrial applications, where the Marangoni-driven film spreading is an essential process. Unlike immiscible fluids governed by triple contact line dynamics, the mixing between two miscible fluids strongly couples with the film spreading process, which are expected to manifest distinct power-law relations for the temporal increase in the film radius.

EXPERIMENTS

We experimentally investigate the Marangoni-driven film spreading phenomenon for a droplet with lower surface tension dropping onto a miscible, thin liquid layer. The temporal growth of the film radius was detected by using a novel deep convolutional neural network, the U2-net method. Scaling analysis was performed to interpret the spreading dynamics of the film.

FINDINGS

We find that the film radius exhibits a three-stage power-law relation over time, with the exponent varying from 1/2 to 1/8, and back to 1/2. The diffusion-affected Marangoni stresses in these three stages were derived, and two estimations of viscous stress were considered. Through estimating and balancing the viscous stress with the Marangoni stress, the three-stage power-law relation was derived and validated.

Decrease in lipid metabolic indexes in infants with neonatal respiratory distress syndrome

Incomplete pulmonary function and insufficient production of pulmonary surfactant in premature infants may affect alveolar relaxation, inducing neonatal respiratory distress syndrome (NRDS). The present study was a retrospective comparison of lipid metabolism indexes and clinic information between NRDS and non-NRDS infants. Data on general information, pregnancy, clinical symptoms, family history as well as plasma biochemical and lipid metabolic indexes were retrospectively collected and statistically analyzed from 79 patients with NRDS and 44 non-NRDS infants. Infants in the NRDS group showed lower body weight (2,055 vs. 3,225 g) and gestation age (33.39 vs. 38.53 weeks) than those in the non-NRDS group (P<0.05). Baseline information was corrected by the inverse probability of treatment weighting (IPTW) analysis. The weighted adjusted median age was the same in both groups and there was no significant difference between two groups in birth weight. The IPTW analysis revealed that the levels of plasma triglyceride (TG), total cholesterol, low-density lipoprotein, free triiodothyronine, free thyroxine, glucose, calcium (Ca2+) and phosphorus in the NRDS infants were significantly lower compared with those in the non-NRDS infants. Additionally, NRDS infants had significantly higher incidence rates of pneumonia, sepsis, brain injury infection, preterm birth, patent foramen ovale, patent ductus arteriosus and premature rupture of membranes compared with the non-NRDS infants (P<0.05). Multivariate logistic analysis showed that TG and Ca2+ were risk factors associated with NRDS (P<0.05). Infants with NRDS have significantly lower levels of plasma lipid indexes. The results of the present study provide data to guide the clinical management of NRDS.

Pulmonary Surfactant: A Mighty Thin Film

Pulmonary surfactant is a critical component of lung function in healthy individuals. It functions in part by lowering surface tension in the alveoli, thereby allowing for breathing with minimal effort. The prevailing thinking is that low surface tension is attained by a compression-driven squeeze-out of unsaturated phospholipids during exhalation, forming a film enriched in saturated phospholipids that achieves surface tensions close to zero. A thorough review of past and recent literature suggests that the compression-driven squeeze-out mechanism may be erroneous. Here, we posit that a surfactant film enriched in saturated lipids is formed shortly after birth by an adsorption-driven sorting process and that its composition does not change during normal breathing. We provide biophysical evidence for the rapid formation of an enriched film at high surfactant concentrations, facilitated by adsorption structures containing hydrophobic surfactant proteins. We examine biophysical evidence for and against the compression-driven squeeze-out mechanism and propose a new model for surfactant function. The proposed model is tested against existing physiological and pathophysiological evidence in neonatal and adult lungs, leading to ideas for biophysical research, that should be addressed to establish the physiological relevance of this new perspective on the function of the mighty thin film that surfactant provides.

Neonatal surfactant therapy beyond respiratory distress syndrome

Whilst exogenous surfactant therapy is central to the management of newborn infants with respiratory distress syndrome, its use in other neonatal lung diseases remains inconsistent and controversial. Here we discuss the evidence and experience in relation to surfactant therapy in newborns with other lung conditions in which surfactant may be deficient or dysfunctional, including meconium aspiration syndrome, pneumonia, congenital diaphragmatic hernia and pulmonary haemorrhage. We find that, for all of these diseases, administration of exogenous surfactant as bolus therapy is frequently associated with transient improvement in oxygenation, likely related to temporary mitigation of surfactant inhibition in the airspaces. However, for none of them is there a lasting clinical benefit of surfactant therapy. By virtue of interrupting disease pathogenesis, lavage therapy with dilute surfactant in MAS offers the greatest possibility of a more pronounced therapeutic effect, but this has yet to be definitively proven. Lavage therapy also involves a greater degree of procedural risk.

Surfactant therapy guided by tests for lung maturity in preterm infants at risk of respiratory distress syndrome

BACKGROUND

Administration of various exogenous surfactant preparations has been shown to decrease lung injury and pneumothorax and improve survival in very preterm infants with respiratory distress syndrome (RDS). There is no consensus on the threshold for surfactant administration, to allow timely intervention and avoid over-treatment, also considering the invasiveness of the procedure and its cost. Rapid tests for lung maturity, which include the click test, lamellar body counts and stable microbubble test, might guide the identification of those infants needing surfactant administration.

OBJECTIVES

To assess the effects of surfactant treatment guided by rapid tests for surfactant deficiency in preterm infants at risk for or having RDS. Comparison 1: In preterm infants at risk for RDS, does surfactant treatment guided by rapid tests for surfactant deficiency compared to prophylactic surfactant administration to all high-risk infants minimize the need for surfactant treatment and prevent bronchopulmonary dysplasia and mortality? Comparison 2: In preterm infants who require early respiratory support, does surfactant treatment guided by rapid tests for surfactant deficiency compared to surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria minimize the need for surfactant treatment and prevent bronchopulmonary dysplasia and mortality?

SEARCH METHODS

We searched in October 2022 CENTRAL, PubMed, Embase and three additional trial registries. We also screened the reference lists of included studies and related systematic reviews for studies not identified by the database searches.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs evaluating rapid tests after birth for surfactant deficiency in infants at high risk of RDS or requiring respiratory support. We specified two comparisons: 1)surfactant treatment guided by rapid tests for surfactant deficiency versus prophylactic surfactant administration to all high-risk infants in extremely preterm (less than 28 weeks' gestation) and very preterm (28 to 32 weeks' gestation); 2)surfactant treatment guided by rapid tests for surfactant deficiency versus surfactant therapy provided to preterm infants (less than 37 weeks' gestation) with RDS diagnosed on clinical and radiologic criteria.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We used the fixed-effect model with risk ratio (RR) and risk difference (RD), with their 95% confidence intervals (CIs) for dichotomous data. Our primary outcomes were: neonatal mortality, mortality prior to hospital discharge, bronchopulmonary dysplasia and the composite outcome bronchopulmonary dysplasia or mortality. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included three RCTs enrolling 562 newborn infants in this review. No studies compared surfactant treatment guided by rapid tests for surfactant deficiency versus prophylactic surfactant administration to all high-risk infants. Comparing surfactant therapy guided by rapid tests for surfactant deficiency versus surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria. No studies reported neonatal mortality. Compared with surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria, the evidence is very uncertain about the effect of surfactant treatment guided by rapid tests for surfactant deficiency on mortality prior to hospital discharge: RR 1.25, 95% CI 0.65 to 2.41, RD 0.01, 95% CI -0.03 to 0.05, 562 participants, 3 studies; I² for RR and RD = 75% and 43%, respectively; very low-certainty evidence. Surfactant treatment guided by rapid tests for surfactant deficiency may result in little to no difference in bronchopulmonary dysplasia: RR 0.90, 95% CI 0.61 to 1.32, RD -0.02, 95% CI -0.08 to 0.04, 562 participants, 3 studies; I² for RR and RD = 0%; low-certainty evidence. No studies reported the composite outcome bronchopulmonary dysplasia or mortality. Surfactant treatment guided by rapid tests for surfactant deficiency may result in little to no difference in surfactant utilization (RR 0.97, 95% CI 0.85 to 1.11, RD -0.02, 95% CI -0.10 to 0.06, 562 participants, 3 studies, I² for RR and RD = 63% and 65%, respectively, low-certainty evidence), and any pneumothorax (RR 0.53, 95% CI 0.15 to 1.92, RD -0.01, 95% CI -0.04 to 0.01, 506 participants, 2 studies, I² for RR and RD = 0%, low-certainty evidence) compared with surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria. No studies reported moderate to severe neurodevelopmental impairment. We identified two large ongoing RCTs.

AUTHORS' CONCLUSIONS

No studies compared surfactant treatment guided by rapid tests for surfactant deficiency to prophylactic surfactant administration to all high-risk infants. Low to very low-certainty evidence from three studies is available on surfactant therapy guided by rapid tests for surfactant deficiency versus surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria. No studies reported neonatal mortality, the composite outcome 'bronchopulmonary dysplasia or mortality', or neurodevelopmental outcomes. Compared with surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria, the evidence is very uncertain about the effect of surfactant treatment guided by rapid tests for surfactant deficiency on mortality prior to hospital discharge. Surfactant treatment guided by rapid tests for surfactant deficiency may result in little to no difference in bronchopulmonary dysplasia, surfactant utilization and any pneumothorax. The findings of the two large ongoing trials identified in this review are likely to have an important impact on establishing the effects of surfactant treatment guided by rapid tests for surfactant deficiency in preterm infants.

Patent ductus arteriosus (PDA) and response to late surfactant treatment in premature infants

OBJECTIVE

To determine the clinical/echocardiography (ECHO) phenotype of patients with hypoxic respiratory failure (HRF) and response to late surfactant, according to patent ductus arteriosus (PDA) status.

STUDY DESIGN

This retrospective study included infants ≤26+6 weeks gestation who received ≥1 surfactant dose after 6 postnatal days and where PDA status was available by ECHO. Response to surfactant was appraised based on change in respiratory severity score over 48 h. The relationship between PDA status and response to surfactant was evaluated via univariate analysis.

RESULT

We studied late surfactant (n = 71 doses) administration in 35 preterm infants born at a mean weight and GA at birth were 595 g (508, 696) and 23.3 (22.7, 25) weeks, respectively of whom 16 (46%) had a diagnosis of PDA. Positive response to late surfactant treatment was independently associated with absence of PDA [OR 26 (2, 334), p = 0.01] whereas presence of PDA was independently associated with negative response [OR 12 (1.1, 126), p = 0.04].

CONCLUSIONS

In neonates ≤26+6 weeks gestation, with HRF, response to surfactant after postnatal day 6 is influenced by PDA status. Future trials should consider PDA status which may enhance diagnostic precision and refine patient selection for late surfactant treatment.

Exploring pulmonary distribution of intratracheally instilled liquid foams in excised porcine lungs

The applicability of inhalation therapy to some severe pulmonary conditions is often compromised by limited delivery rates (i.e. total dose) and low deposition efficiencies in the respiratory tract, most notably in the deep pulmonary acinar airways. To circumvent such limitations, alternative therapeutic techniques have relied for instance on intratracheal liquid instillations for the delivery of high-dose therapies. Yet, a longstanding mechanistic challenge with such latter methods lies in delivering solutions homogeneously across the whole lungs, despite an inherent tendency of non-uniform spreading driven mainly by gravitational effects. Here, we hypothesize that the pulmonary distribution of instilled liquid solutions can be meaningfully improved by foaming the solution prior to its instillation, owing to the increased volume and the reduced gravitational bias of foams. As a proof-of-concept, we show in excised adult porcine lungs that liquid foams can lead to significant improvement in homogenous pulmonary distributions compared with traditional liquid instillations. Our ex-vivo results suggest that liquid foams can potentially offer an attractive novel pulmonary delivery modality with applications for high-dose regimens of respiratory therapeutics.

Periventricular- intraventricular hemorrhage in the premature infant- A historical perspective

The objective of this chapter is to trace the evolution of intraventricular hemorrhage in the premature infant highlighting the importance of the germinal matrix, a critical role for cerebral blood flow changes in the genesis of hemorrhage, clinical factors that increase the bleeding risk, and potential preventative strategies. In 1976, neuropathological studies demonstrated capillary rupture within the germinal matrix as the precursor of hemorrhage. In 1980, introduction of cranial ultrasound facilitated diagnosis of intraventricular hemorrhage. In 1979, loss of cerebral autoregulation in sick newborn infants was demonstrated. In the 1980's, studies demonstrated the importance of intravascular factors in provoking hemorrhage. In 1983, the association of cerebral blood flow velocity fluctuations and subsequent hemorrhage was demonstrated. In 1994, antenatal steroids use to accelerate lung development was recommended. This was associated with an unanticipated reduction in hemorrhage. In the mid 1990's early indomethacin administration was associated with a reduction of severe hemorrhage.

Pathogenesis of pneumonia and acute lung injury

Pneumonia and its sequelae, acute lung injury, present unique challenges for pulmonary and critical care healthcare professionals, and these challenges have recently garnered global attention due to the ongoing Sars-CoV-2 pandemic. One limitation to translational investigation of acute lung injury, including its most severe manifestation (acute respiratory distress syndrome, ARDS) has been heterogeneity resulting from the clinical and physiologic diagnosis that represents a wide variety of etiologies. Recent efforts have improved our understanding and approach to heterogeneity by defining sub-phenotypes of ARDS although significant gaps in knowledge remain. Improving our mechanistic understanding of acute lung injury and its most common cause, infectious pneumonia, can advance our approach to precision targeted clinical interventions. Here, we review the pathogenesis of pneumonia and acute lung injury, including how respiratory infections and lung injury disrupt lung homoeostasis, and provide an overview of respiratory microbial pathogenesis, the lung microbiome, and interventions that have been demonstrated to improve outcomes-or not-in human clinical trials.

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.

Lung cell membrane-coated nanoparticles capable of enhanced internalization and translocation in pulmonary epithelial cells

Cell membrane-coated nanoparticles (CMCNP), which involve coating a core nanoparticle (NP) with cell membranes, have been gaining attention due to their ability to mimic the properties of the cells, allowing for enhanced delivery and efficacy of therapeutics. Two CMCNP systems comprised of an acetalated dextran-based NP core loaded with curcumin (CUR) coated with cell membranes derived from pulmonary epithelial cells were developed. The NP were approximately 200 nm and their surface charges varied based on their coating, where CMCNP systems exhibited negative surface charge like natural cell membranes. The NP were smooth, spherical, and homogeneous with distinct coatings on their cores. Minimal in vitro toxicity was observed for the NP and controlled release of CUR was observed. The CMCNP internalized into and translocated across an in vitro pulmonary epithelial monolayer significantly more than the control NP. Blocking endocytosis pathways reduced the transcytosis of NP, indicating a relationship between endocytosis and transcytosis. These newly developed CMCNP have the potential to be used in pulmonary drug delivery applications to potentially enhance NP internalization and transport into and across the pulmonary epithelium.

Quantifying neonatal patient effort using non-invasive model-based methods

Patient-specific spontaneous breathing effort (SB) is common in invasively mechanically ventilated (MV) adult patients, and especially common in preterm neonates who are not typically sedated. However, there is no proven, ethically feasible and non-invasive method to quantify SB effort in neonates, creating the potential for model-based measures. Lung mechanics and SB effort are segregated using a basis function model to identify passive lung mechanics, and an additional time-varying elastance model to identify patient-specific SB effort and asynchrony as negative and positive added elastances, respectively. Data from ten preterm neonates on standard MV care in the neonatal intensive care unit (NICU) are used to assess this model-based approach, using area under the curve (AUC) for positive (asynchrony) and negative (SB effort) time-varying elastance. Median [interquartile-range (IQR)] of passive pulmonary lung elastance was 3.82 [2.09-5.80] cmH₂O/ml. Median [IQR] AUC quantified SB effort was -0.32 [-0.43--0.12]cmH₂O/ml. AUC quantified asynchrony was 0.00 [0.00-0.01]cmH₂O/ml, and affected 28% of the 25,287 total breaths. This proof of concept model-based approach provides a non-invasive, computationally straightforward, and thus clinically feasible means to quantify patient-specific spontaneous breathing effort and asynchrony.

Early nasal continuous positive airway pressure failure prediction in preterm infants less than 32 weeks gestational age suffering from respiratory distress syndrome

BACKGROUND

Early continuous positive airway pressure (CPAP) and surfactant replacement are effective treatments for neonatal respiratory distress syndrome (RDS). CPAP is the first line in preterm infants needing respiratory support, with surfactant replacement in case of CPAP failure (CPAP-F).

OBJECTIVES

To analyze incidence and factors associated with CPAP-F in preterm infants with RDS.

DESIGN, SETTING AND PATIENTS

Single-center retrospective database analysis (2004-2017) of inborn infants, gestational age (GA) 24 + 0/7-31 + 6/7 weeks, not intubated on admission to the neonatal intensive care unit, managed with CPAP. CPAP-F was defined as intubation and surfactant administration in the first 72 h of life; CPAP success (CPAP-S) was CPAP alone without need for additional RDS treatments. Demographic, respiratory, and clinical data associated with CPAP-F were studied using logistic regression analysis.

RESULTS

A total of 562 infants met the inclusion criteria: 252 (44.8%) were CPAP-F and 310 (55.2%) were CPAP-S. The CPAP-F, compared to CPAP-S group, had lower GA and birth weight, and were less likely to receive antenatal steroids or to be vaginal births. Logistic regression showed that the fraction of inspired oxygen (FiO₂ ) ≥ 0.23 between 180 and 240 min of life (FiO₂ 180-240 min) was the strongest factor associated with CPAP-F (odds ratio: 16.01 [95% confidence interval: 10.34-24.81]).

CONCLUSION

FiO₂ 180-240 min was highly predictive of CPAP-F in preterm infants. With this model for surfactant administration/CPAP-F, 11.2% of infants would have unnecessarily received treatment, but importantly, 27.7% would have been treated much earlier, with a potential reduction in air leaks and duration of mechanical ventilation.

Efficacy of continuous positive airway pressure in neonates with respiratory distress syndrome: A protocol for systematic review and meta-analysis

BACKGROUND

Respiratory distress syndrome (RDS) is a condition caused by a deficiency in pulmonary surfactant. Many interventions, including pulmonary surfactant, non-invasive respiratory support, and other supportive treatments have been used to prevent RDS. However, recent studies have focused on the continuous positive airway pressure as a significant potential agent for preventing RDS. However, its safety and effectiveness are yet to be assessed. To this end, the current study aims to perform to explore the safety and effectiveness of continuous positive airways in treating neonates with RDS.

METHODS

We will conduct comprehensive literature searches on MEDLINE, Cochrane Library, EMBASE, Chinese National Knowledge Infrastructure, and Chinese BioMedical Literature from their inception to April 2021. The search aims to identify all the randomized controlled studies on continuous positive airway pressure in treating neonates with RDS. In addition, we aim to search the gray literature to establish any available potential studies. We will use 2 independent authors to determine study eligibility, extract data using the structured pro-forma table, analyze data, and utilize suitable tools in assessing the risk of bias in the selected studies. Accordingly, we will conduct all statistical analyses using RevMan 5.3 software.

RESULTS

The current study aims to provide high-quality synthesis of existing evidence concerning the continuous positive airway pressure to treat neonates suffering from RDS.

CONCLUSION

Our findings seek to provide evidence to establish whether continuous positive airway pressure can ascertain safety and effectiveness for neonates with RDS.

ETHICS AND DISSEMINATION

The study will require ethical approval.

OSF REGISTRATION NUMBER

May 20, 2021.osf.io/7nj8s. (https://osf.io/7nj8s/).

Surfactant Adsorption to Different Fluid Interfaces

Surfactant adsorption to fluid interfaces is ubiquitous in biological systems, industrial applications, and scientific fields. Herein, we unravel the impact of the hydrophobic phase (air and oil) and the role of oil polarity on the adsorption of surfactants to fluid interfaces. We investigated the adsorption of anionic (sodium dodecyl sulfate), cationic (dodecyltrimethylammonium bromide), and non-ionic (polyoxyethylene-(23)-monododecyl ether) surfactants at different interfaces, including air and oils, with a wide range of polarities. The surfactant-induced interfacial tension decrease, called the interfacial pressure, correlates linearly with the initial interfacial tension of the clean oil-water interface and describes the experimental results of over 30 studies from the literature. The higher interfacial competition of surfactant and polar oil molecules caused the number of adsorbed molecules at the interface to drop. Further, we found that the critical micelle concentration of surfactants in water correlates to the solubility of the oil molecules in water. Hence, the nature of the oil affects the adsorption behavior and equilibrium state of the surfactant at fluid interfaces. These results broaden our understanding and enable better predictability of the interactions of surfactants with hydrophobic phases, which is essential for emulsion, foam, and capsule formation, pharmaceutical commodities, cosmetics, and many food products.

Surfactant therapy via thin catheter in preterm infants with or at risk of respiratory distress syndrome

BACKGROUND

Non-invasive respiratory support is increasingly used for the management of respiratory dysfunction in preterm infants. This approach runs the risk of under-treating those with respiratory distress syndrome (RDS), for whom surfactant administration is of paramount importance. Several techniques of minimally invasive surfactant therapy have been described. This review focuses on surfactant administration to spontaneously breathing infants via a thin catheter briefly inserted into the trachea.

OBJECTIVES

Primary objectives In non-intubated preterm infants with established RDS or at risk of developing RDS to compare surfactant administration via thin catheter with: 1. intubation and surfactant administration through an endotracheal tube (ETT); or 2. continuation of non-invasive respiratory support without surfactant administration or intubation. Secondary objective 1. To compare different methods of surfactant administration via thin catheter Planned subgroup analyses included gestational age, timing of intervention, and use of sedating pre-medication during the intervention.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL), in the Cochrane Library; Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Daily and Versions(R); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL), on 30 September 2020. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-randomised trials.

SELECTION CRITERIA

We included randomised trials comparing surfactant administration via thin catheter (S-TC) with (1) surfactant administration through an ETT (S-ETT), or (2) continuation of non-invasive respiratory support without surfactant administration or intubation. We also included trials comparing different methods/strategies of surfactant administration via thin catheter. We included preterm infants (at < 37 weeks' gestation) with or at risk of RDS.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed study quality and risk of bias and extracted data. Authors of all studies were contacted regarding study design and/or missing or unpublished data. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included 16 studies (18 publications; 2164 neonates) in this review. These studies compared surfactant administration via thin catheter with surfactant administration through an ETT with early extubation (Intubate, Surfactant, Extubate technique - InSurE) (12 studies) or with delayed extubation (2 studies), or with continuation of continuous positive airway pressure (CPAP) and rescue surfactant administration at pre-specified criteria (1 study), or compared different strategies of surfactant administration via thin catheter (1 study). Two trials reported neurosensory outcomes of of surviving participants at two years of age. Eight studies were of moderate certainty with low risk of bias, and eight studies were of lower certainty with unclear risk of bias. S-TC versus S-ETT in preterm infants with or at risk of RDS Meta-analyses of 14 studies in which S-TC was compared with S-ETT as a control demonstrated a significant decrease in risk of the composite outcome of death or bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age (risk ratio (RR) 0.59, 95% confidence interval (CI) 0.48 to 0.73; risk difference (RD) -0.11, 95% CI -0.15 to -0.07; number needed to treat for an additional beneficial outcome (NNTB) 9, 95% CI 7 to 16; 10 studies; 1324 infants; moderate-certainty evidence); the need for intubation within 72 hours (RR 0.63, 95% CI 0.54 to 0.74; RD -0.14, 95% CI -0.18 to -0.09; NNTB 8, 95% CI; 6 to 12; 12 studies, 1422 infants; moderate-certainty evidence); severe intraventricular haemorrhage (RR 0.63, 95% CI 0.42 to 0.96; RD -0.04, 95% CI -0.08 to -0.00; NNTB 22, 95% CI 12 to 193; 5 studies, 857 infants; low-certainty evidence); death during first hospitalisation (RR 0.63, 95% CI 0.47 to 0.84; RD -0.02, 95% CI -0.10 to 0.06; NNTB 20, 95% CI 12 to 58; 11 studies, 1424 infants; low-certainty evidence); and BPD among survivors (RR 0.57, 95% CI 0.45 to 0.74; RD -0.08, 95% CI -0.11 to -0.04; NNTB 13, 95% CI 9 to 24; 11 studies, 1567 infants; moderate-certainty evidence). There was no significant difference in risk of air leak requiring drainage (RR 0.58, 95% CI 0.33 to 1.02; RD -0.03, 95% CI -0.05 to 0.00; 6 studies, 1036 infants; low-certainty evidence). None of the studies reported on the outcome of death or survival with neurosensory disability. Only one trial compared surfactant delivery via thin catheter with continuation of CPAP, and one trial compared different strategies of surfactant delivery via thin catheter, precluding meta-analysis.

AUTHORS' CONCLUSIONS

Administration of surfactant via thin catheter compared with administration via an ETT is associated with reduced risk of death or BPD, less intubation in the first 72 hours, and reduced incidence of major complications and in-hospital mortality. This procedure had a similar rate of adverse effects as surfactant administration through an ETT. Data suggest that treatment with surfactant via thin catheter may be preferable to surfactant therapy by ETT. Further well-designed studies of adequate size and power, as well as ongoing studies, will help confirm and refine these findings, clarify whether surfactant therapy via thin tracheal catheter provides benefits over continuation of non-invasive respiratory support without surfactant, address uncertainties within important subgroups, and clarify the role of sedation.

IntraVoxel Incoherent Motion (IVIM) MRI of fetal lung and kidney: Can the perfusion fraction be a marker of normal pulmonary and renal maturation?

PURPOSE

To investigate the use of IntraVoxel Incoherent Motion (IVIM) MRI in the study of microstructural tissue changes occurring in fetal lung and kidney during gestation.

METHODS

34 normal pregnancies were enrolled. Patients were divided into two groups based on gestational age (GA): group A (21-29 weeks) and group B (30-39 weeks). MR examinations were performed at 1.5T, with a standard fetal MR protocol including a Diffusion-Weighted Echo-Planar Imaging sequence with 10 different b-values (0, 10, 30, 50, 75, 100, 200, 400, 700, 1000s/mm²). For each fetus, two bilateral ROIs were manually placed in lung and renal parenchyma. Mean values of perfusion fraction f, pseudo-diffusion coefficient D* and diffusion coefficient D were obtained. The correlation between IVIM parameters and GA was investigated.

RESULTS

In renal ROIs a positive correlation between f_kidney and GA (p < 0.005) was found; similarly f_lung showed a statistically significant correlation with GA (p < 0.001). F mean values were significantly higher in group B compared to group A in both renal (p = 0.0002) and lung (p = 0.018) ROIs. No correlation was found in D and D* as a function of GA.

CONCLUSIONS

The IVIM perfusion fraction f may be considered as a potential marker of pulmonary and renal maturation in relation to hemodynamic changes described in intrauterine life. Our results highlight that IVIM model is useful as an additional prenatal diagnostic tool to study lung and renal development.

Trends in survival, neonatal morbidity and neurodevelopmental outcome of very preterm infants in Tainan, Southern Taiwan, 1995-2016

BACKGROUND

Using regression modeling analysis to investigate the breakpoints of the trends in survival-without-major-neonatal-morbidities (MNM) or -without-neurodevelopmental- impairment (NDI) by year and gestational age (GA) in preterm infants.

METHODS

We enrolled 2237 preterm infants (GA < 32 weeks) in Tainan, Taiwan. The trends in survival-without-MNM or -without-NDI by year (1995-2016) and GA (23-31 weeks), and the epochs and GA ranges with distinct changes were examined. Adjusted rate ratios (aRR) (95% confidence interval [CI]) were calculated using the rates in infants born at 23 weeks in 1995 as the reference.

RESULTS

For yearly trend, there were three epochs (1995-2000, 2001-2006, 2007-2016) with distinct changes in the rates of survival-without-MNM (aRR [95% CI] 1.07 [1.02-1.12], 1.04 [1.02-1.07], 1.02 [1.01-1.04]) and -without-NDI (1.03 [1.02-1.07], 1.02 [1.01-1.04], 1.01 [0.98-1.04]). For GA trend, the three GA ranges with different increases in the rates of survival-without-MNM were 23⁺⁰-26⁺⁶ (1.60 [1.31-1.94]), 27⁺⁰-28⁺⁶ (1.24 [1.14-1.34]) and 29⁺⁰-31⁺⁶ weeks (1.17 [1.02-1.34]), while those in the rates of survival-without-NDI were 23⁺⁰-25⁺⁶ (1.14 [1.03-1.25]), 26⁺⁰-28⁺⁶ (1.06 [1.02-1.12]) and 29⁺⁰-31⁺⁶ weeks (1.04 [1.02-1.07]). The trends in survival-without-MNM and -without-NDI increased over years in infants with GA 25-31 but not < 25 weeks.

CONCLUSION

The yearly trends in survival-without-MNM and -without-NDI had steady increases from 1995 to 2016 with distinct changes in three epochs, and the GA trends also increased with different rates per week in three GA ranges. Infants with GA < 25 weeks did not improve on the rates of survival-without-MNM or -without-NDI per year from 1995 to 2016.

Predicting the outcomes of preterm neonates beyond the neonatal intensive care unit: What are we missing?

Preterm infants are a population at high risk for mortality and adverse health outcomes. With recent improvements in survival to childhood, increasing attention is being paid to risk of long-term morbidity, specifically during childhood and young-adulthood. Although numerous tools for predicting the functional outcomes of preterm neonates have been developed in the past three decades, no studies have provided a comprehensive overview of these tools, along with their strengths and weaknesses. The purpose of this article is to provide an in-depth, narrative review of the current risk models available for predicting the functional outcomes of preterm neonates. A total of 32 studies describing 43 separate models were considered. We found that most studies used similar physiologic variables and standard regression techniques to develop models that primarily predict the risk of poor neurodevelopmental outcomes. With a recently expanded knowledge regarding the many factors that affect neurodevelopment and other important outcomes, as well as a better understanding of the limitations of traditional analytic methods, we argue that there is great room for improvement in creating risk prediction tools for preterm neonates. We also consider the ethical implications of utilizing these tools for clinical decision-making. IMPACT: Based on a literature review of risk prediction models for preterm neonates predicting functional outcomes, future models should aim for more consistent outcomes definitions, standardized assessment schedules and measurement tools, and consideration of risk beyond physiologic antecedents. Our review provides a comprehensive analysis and critique of risk prediction models developed for preterm neonates, specifically predicting functional outcomes instead of mortality, to reveal areas of improvement for future studies aiming to develop risk prediction tools for this population. To our knowledge, this is the first literature review and narrative analysis of risk prediction models for preterm neonates regarding their functional outcomes.

The COVID-19 pandemic: a target for surfactant therapy?

INTRODUCTION

The dramatic impact of COVID-19 on humans worldwide has initiated an extraordinary search for effective treatment approaches. One of these is the administration of exogenous surfactant, which is being tested in ongoing clinical trials.

AREAS COVERED

Exogenous surfactant is a life-saving treatment for premature infants with neonatal respiratory distress syndrome. This treatment has also been tested for acute respiratory distress syndrome (ARDS) with limited success possibly due to the complexity of that syndrome. The 60-year history of successes and failures associated with surfactant therapy distinguishes it from many other treatments currently being tested for COVID-19 and provides the opportunity to discuss the factors that may influence the success of this therapy.

EXPERT OPINION

Clinical data provide a strong rationale for using exogenous surfactant in COVID-19 patients. Success of this therapy may be influenced by the mechanical ventilation strategy, the timing of treatment, the doses delivered, the method of delivery and the preparations utilized. In addition, future development of enhanced preparations may improve this treatment approach. Overall, results from ongoing trials may not only provide data to indicate if this therapy is effective for COVID-19 patients, but also lead to further scientific understanding and improved treatment strategies.

Bronchopulmonary dysplasia requiring tracheostomy: A review of management and outcomes

Bronchopulmonary Dysplasia (BPD) is a pulmonary disease affecting newborns, commonly those with prematurity or low birth weight. Its pathogenesis involves underdevelopment of lung tissue with subsequent limitations in ventilation and oxygenation, resulting in impaired postnatal alveolarization. Despite advances in care with improved survival, BPD remains a prevalent comorbidity of prematurity. In severe cases, management may involve mechanical ventilation via tracheostomy. BPD's demand for multidisciplinary care compounds the challenges in management of this condition. Here, we review existing literature: the history of disease, criteria for diagnosis, pathogenesis, and modes of treatment with a focus on the severe subtype: that which is associated with pulmonary hypertension (PAH) for which tracheostomy is often required to facilitate long-term mechanical ventilation. We review the current recommendations for tracheostomy and decannulation.

Survival rate of very low birth weight infants over a quarter century (1994-2019): A single-institution experience

BACKGROUND

Newborn infants with birth weight less than 1500 grams defining very low birth weight (VLBW) constitute 1.2-1.5% of total live births and 15-20% of all admissions to neonatal units. Advances in antenatal care, care at delivery, and neonatal practice over the past few decades, have substantially improved outcomes in VLBW infants, and reduced neonatal mortality.

METHODS

A retrospective single tertiary care center cohort study of VLBW infants with gestational age between 23-33 weeks admitted to the neonatal intensive care unit (NICU) in King Abdulaziz Medical City, Jeddah (KAMC-J) between January 1, 1994, and December 31, 2019 (26 years). The trends of survival of VLBW infants and major changes in clinical practice of premature care over a period of 26 years were evaluated.

RESULTS

Over a period of 26 years, 1,247 VLBW infants were admitted to the NICU that represents 1.43% (1.25-1.83%) of total live births. 50.80% (n = 634) were male, whereas the 49.2% (n = 613) were female. Among them, 1013 (81.2%) were discharged home alive. There was a significant and progressive improvement in the survival rate of VLBW infants over a 26-year period from 66.83% in period 1 (1994 -1998) to 90.0 % in period 5 (2014 -2019), which represents a 34.67% total improvement rate. The improvement in survival rates was observed in all gestational ages between 23-33 weeks, particularly in infants weighing ≤750 grams and ≤1000 grams, and with gestational age between 23-27 weeks. Infants with a gestational age of ≤26 weeks and birth weight ≤750 grams delivered by cesarean section had a higher survival rate. Moreover, female infants with a gestational age of ≤26 weeks and birth weight ≤750 grams had a higher survival rate compared to males but not statistically significant.

CONCLUSIONS

The survival rate of VLBW infants had improved significantly over the past 26 years (1994 -2019). This is attributed mainly to the improved survival of ELBW infants (<1000 grams) and gestational age of ≤26 weeks.

Genetic Polymorphisms of LPCAT1, CHPT1 and PCYT1B and Risk of Neonatal Respiratory Distress Syndrome among a Chinese Han Population

BACKGROUND

The study of genetic polymorphisms of surfactant-lipids related genes can help to understand individual variability in the susceptibility to development of pulmonary pathologies. The purpose of this study was to evaluate the association of polymorphisms of surfactant-lipids related genes (LPCAT1, CHPT1 and PCYT1B) with the risk/severity of respiratory distress syndrome (RDS) in preterm neonates among the Chinese Han population in Southern China.

METHODS

Four hundred and forty-six preterm neonates were enrolled in a case-control study. Six polymorphisms of 3 genes were analyzed by PCR amplification of genomic DNA and genotyping was performed using an improved multiplex ligation detection reaction (iMLDR) technique based on LDR.

RESULTS

The GG genotype and G allele of LPCAT1-rs9728 were found less frequently in the RDS group than in the controls (11.5% vs. 22.0% and 38.3% vs. 48.2%, respectively) (p < 0.05).

CONCLUSION

This report is the first study to evaluate a direct genetic association between polymorphisms of LPCAT1 and RDS development in Chinese Han preterm infants. Our study raises the possibility that a genetic variation of LPCAT1 could be implicated in the pathophysiology of RDS in preterm neonates. GG genotype and G allele of rs9728 are protective factors for the development of RDS in preterm infants.

Using Experimental Models to Identify Pathogenic Pathways and Putative Disease Management Targets in Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common and serious complication of preterm birth. Limited pharmacological and other medical interventions are currently available for the management of severely affected, very preterm infants. BPD can be modelled in preclinical studies using experimental animals, and experimental animal models have been extremely valuable in the development of hallmark clinical management strategies for BPD, including pulmonary surfactant replacement and single-course antenatal corticosteroids. A gradual move away from large animal models of BPD in favor of term-born rodents has facilitated the identification of a multitude of new mechanisms of normal and stunted lung development, but this has also potentially limited the utility of experimental animal models for the identification of pathogenic pathways and putative disease management targets in BPD. Indeed, more recent pharmacological interventions for the management of BPD that have been validated in randomized controlled trials have relied very little on preclinical data generated in experimental animal models. While rodent-based models of BPD have tremendous advantages in terms of the availability of genetic tools, they also have considerable drawbacks, including limited utility for studying breathing mechanics, gas exchange, and pulmonary hemodynamics; and they have a less relevant clinical context where lung prematurity and a background of infection are now rarely present in the pathophysiology under study. There is a pressing need to refine existing models to better recapitulate pathological processes at play in affected infants, in order to better evaluate new candidate pharmacological and other interventions for the management of BPD.

Mechanically ventilated premature babies have sex differences in specific elastance: A pilot study

OBJECTIVES

A pilot study to compare pulmonary mechanics in a neonatal intensive care unit (NICU) cohort, specifically, comparing lung elastance between male and female infants in the NICU.

HYPOTHESIS

Anecdotally, male infants are harder to ventilate than females. We hypothesize that males have higher model-based elastance (converse: lower specific compliance) compared to females, reflecting underlying stiffer lungs.

STUDY DESIGN

A clinically validated, single-compartment model is used to identify specific elastance (inverse of specific compliance) and resistance for each breath. Specific elastance accounts for weight differences when comparing male and female infants. Relative percent breath-to-breath variability (%ΔE) in specific elastance is also compared. Level of asynchrony was also determined.

PATIENT-SUBJECT SELECTION

Ten invasively mechanically ventilated patients from Christchurch Women's Hospital.

METHODOLOGY

Airway pressure and flow data from 10 invasive mechanical ventilation (MV) infants from Christchurch Women's Hospital Neonatal Intensive Care Unit, New Zealand was prospectively recorded under standard MV care. Model-based specific elastance and resistance are identified for each breath, as well as relative percent breath-to-breath variability (%ΔE) in specific elastance.

RESULTS

Male infants overall had higher specific elastance compared to females infants (P ≤ .01), with median (interquartile range) for males of 1.91 (1.33-2.48) cmH₂ O·kg/mL compared to 1.31 (0.86-2.02) cmH₂ O·kg/mL in females. Male infants had lower variability with %ΔE of -0.03 (-7.56 to 8.01)% vs female infants of -0.59 (12.56-12.86)%. Males had 14.75% asynchronous breaths whereas females had 17.54%.

CONCLUSION

Overall, males had higher specific elastance and correspondingly lower breath-to-breath variability. These results indicate male and female infants may require different MV settings, mode, and monitoring.

Health Economics and Outcomes of Surfactant Treatments for Respiratory Distress Syndrome Among Preterm Infants in US Level III/IV Neonatal Intensive Care Units

OBJECTIVE

To compare length of stay (LOS), costs, mechanical ventilation (MV), and mortality in preterm infants treated in the Neonatal Intensive Care Unit (NICU) with beractant (BE), calfactant (CA), and poractant alfa (PA) for Respiratory Distress Syndrome (RDS).

METHODS

This study evaluated preterm infants born between 2010 and 2013 with RDS diagnosis, gestational age of 25 to 36 weeks, birthweight of ≥500 g, and age of ≤2 days on first surfactant administration. Multivariable regression was used to evaluate all NICU outcomes.

RESULTS

Of 13,240 infants meeting the study criteria, 4136 (31.2%) received BE, 2502 (18.9%) received CA, and 6602 (49.9%) received PA. Adjusted analyses estimated similar mean LOS (BE 26.7 days, CA 27.8 days, and PA 26.2 days) and hospital costs (BE: $50,929; CA: $50,785; and PA: $50,212). Compared to PA, BE and CA were associated with greater odds of MV use on day 3 (OR = 1.56 and 1.60, respectively) and day 7 (OR = 1.39 and 1.28, respectively; all p < 0.05). Adjusted NICU mortality was significantly higher only with CA vs PA (OR = 1.51; p = 0.015).

CONCLUSION

Adjusted NICU LOS and costs were similar among BE, CA, and PA. Infants receiving PA were less likely to be on MV at 3 and 7 days, and PA treatment was associated with lower odds of NICU mortality when compared to CA.

Impact of surfactant administration through a thin catheter in the delivery room: A quality control chart analysis coupled with a propensity score matched cohort study in preterm infants

INTRODUCTION

Most infants born before 30 weeks gestational age (GA) develop respiratory distress syndrome soon after birth. Methods of surfactant administration that avoid ventilation have been recently introduced. The aim of this study was to evaluate the impact of implementing a new procedure of less invasive surfactant administration (LISA) and determine whether it is associated with an improvement in respiratory outcome.

METHODS

This single center cohort quality improvement study analyzed preterm infants born before 30 weeks GA between May 2010 and April 2016. Changes in health care practices and respiratory outcomes following the implementation of a LISA, i.e. the administration of surfactant through a thin catheter, were analyzed using quality control charts. Then, the effect of LISA on respiratory outcome was assessed by propensity score matching and logistic regression weighted by the inverse of the propensity score.

RESULTS

During the study period, 379 infants were included. Of those that were not intubated at ten minutes of life, 129 received surfactant and were ventilated for one hour or more (InVent), 127 received LISA, five received surfactant with tracheal mechanical ventilation for less than one hour (InSurE), and 55 were only treated with nasal continuous positive pressure during the first hour of neonatal care (nCPAP). Quality-chart analysis revealed rapid implementation of the method with a concomitant decrease in required ventilation. LISA was associated with fewer tracheal ventilation days and a lower incidence of supplemental oxygen on day 28. When controlling for the propensity to be exposed or not to LISA, this procedure was not associated with a lower risk of death or bronchopulmonary dysplasia (BPD) at 36 weeks postmenstrual age.

CONCLUSION

In this study, the successful implementation of the new method was associated with lower rates of mechanical ventilation, but without a significant reduction of grade I/II/III BPD or death.

Surfactant therapy guided by tests for lung maturity in preterm infants at risk of respiratory distress syndrome

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects of surfactant treatment guided by rapid tests for surfactant deficiency in preterm infants at risk for or having RDS.

Comparison 1: In preterm infants at risk for RDS, does surfactant treatment guided by rapid tests for surfactant deficiency compared to prophylactic surfactant administration to all high‐risk infants minimize the need for surfactant treatment and prevent bronchopulmonary dysplasia and mortality?

Comparison 2: In preterm infants who require early respiratory support, does surfactant treatment guided by rapid tests for surfactant deficiency compared to surfactant therapy provided to infants with RDS diagnosed on clinical and radiologic criteria minimize the need for surfactant treatment and prevent bronchopulmonary dysplasia and mortality?

Planned subgroup analysis: gestational age, disease severity, timing of testing and treatment, surfactant preparation, exposure to antenatal steroids.

A Proposed Role of Surfactant in Platelet Function and Treatment of Pulmonary Hemorrhage in Preterm and Term Infants

BACKGROUND

We evaluated the effect of surfactant on platelet function as a potential contributing mechanism to the pathogenesis of pulmonary hemorrhage (PHEM) in term and preterm infants.

METHODS

Cord blood samples were collected from neonates following delivery. Complete blood count and platelet function were measured using a cone and platelet analyzer (CPA). Increasing surfactant concentrations were added to platelets in vitro, and the adhesion molecule P-selectin and the monoclonal antibody PAC-1 were evaluated following platelet activation by flow cytometry.

RESULTS

Forty-one infants (11 preterm and 30 term) were studied. CPA revealed a significant decrease in the average size of the aggregates and in platelet adhesion when surfactant was added. In term infants, the addition of surfactant to native platelets yielded an increased binding capacity of PAC-1 but did not affect P-selectin expression. In preterm infants, platelet activation with adenosine diphosphate in the presence of a high surfactant concentration (0.5 mg/mL) resulted in increased PAC-1 binding and no change in P-selectin expression.

CONCLUSIONS

The platelets of preterm infants are less active (hyporesponsive) than those of term infants, both in their native state as well as after stimulation with various agonists. Surfactant may play an important role in treating PHEM in preterm infants.

Heterozygous Mutations in OAS1 Cause Infantile-Onset Pulmonary Alveolar Proteinosis with Hypogammaglobulinemia

Pulmonary alveolar proteinosis (PAP) is characterized by accumulation of a surfactant-like substance in alveolar spaces and hypoxemic respiratory failure. Genetic PAP (GPAP) is caused by mutations in genes encoding surfactant proteins or genes encoding a surfactant phospholipid transporter in alveolar type II epithelial cells. GPAP is also caused by mutations in genes whose products are implicated in surfactant catabolism in alveolar macrophages (AMs). We performed whole-exome sequence analysis in a family affected by infantile-onset PAP with hypogammaglobulinemia without causative mutations in genes associated with PAP: SFTPB, SFTPC, ABCA3, CSF2RA, CSF2RB, and GATA2. We identified a heterozygous missense variation in OAS1, encoding 2,′5′-oligoadenylate synthetase 1 (OAS1) in three affected siblings, but not in unaffected family members. Deep sequence analysis with next-generation sequencing indicated 3.81% mosaicism of this variant in DNA from their mother’s peripheral blood leukocytes, suggesting that PAP observed in this family could be inherited as an autosomal-dominant trait from the mother. We identified two additional de novo heterozygous missense variations of OAS1 in two unrelated simplex individuals also manifesting infantile-onset PAP with hypogammaglobulinemia. PAP in the two simplex individuals resolved after hematopoietic stem cell transplantation, indicating that OAS1 dysfunction is associated with impaired surfactant catabolism due to the defects in AMs.

Surfactant protein C dampens inflammation by decreasing JAK/STAT activation during lung repair

Surfactant protein C (SPC), a key component of pulmonary surfactant, also plays a role in regulating inflammation. SPC deficiency in patients and mouse models is associated with increased inflammation and delayed repair, but the key drivers of SPC-regulated inflammation in response to injury are largely unknown. This study focuses on a new mechanism of SPC as an anti-inflammatory molecule using SPC-TK/SPC-KO (surfactant protein C-thymidine kinase/surfactant protein C knockout) mice, which represent a novel sterile injury model that mimics clinical acute respiratory distress syndrome (ARDS). SPC-TK mice express the inducible suicide gene thymidine kinase from by the SPC promoter, which targets alveolar type 2 (AT2) cells for depletion in response to ganciclovir (GCV). We compared GCV-induced injury and repair in SPC-TK mice that have normal endogenous SPC expression with SPC-TK/SPC-KO mice lacking SPC expression. In contrast to SPC-TK mice, SPC-TK/SPC-KO mice treated with GCV exhibited more severe inflammation, resulting in over 90% mortality; there was only 8% mortality of SPC-TK animals. SPC-TK/SPC-KO mice had highly elevated inflammatory cytokines and granulocyte infiltration in the bronchoalveolar lavage (BAL) fluid. Consistent with a proinflammatory phenotype, immunofluorescence revealed increased phosphorylated signal transduction and activation of transcription 3 (pSTAT3), suggesting enhanced Janus kinase (JAK)/STAT activation in inflammatory and AT2 cells of SPC-TK/SPC-KO mice. The level of suppressor of cytokine signaling 3, an anti-inflammatory mediator that decreases pSTAT3 signaling, was significantly decreased in the BAL fluid of SPC-TK/SPC-KO mice. Hyperactivation of pSTAT3 and inflammation were rescued by AZD1480, a JAK1/2 inhibitor. Our findings showing a novel role for SPC in regulating inflammation via JAK/STAT may have clinical applications.

A genome-wide association study identifies only two ancestry specific variants associated with spontaneous preterm birth

Preterm birth (PTB), or the delivery prior to 37 weeks of gestation, is a significant cause of infant morbidity and mortality. Although twin studies estimate that maternal genetic contributions account for approximately 30% of the incidence of PTB, and other studies reported fetal gene polymorphism association, to date no consistent associations have been identified. In this study, we performed the largest reported genome-wide association study analysis on 1,349 cases of PTB and 12,595 ancestry-matched controls from the focusing on genomic fetal signals. We tested over 2 million single nucleotide polymorphisms (SNPs) for associations with PTB across five subpopulations: African (AFR), the Americas (AMR), European, South Asian, and East Asian. We identified only two intergenic loci associated with PTB at a genome-wide level of significance: rs17591250 (P = 4.55E-09) on chromosome 1 in the AFR population and rs1979081 (P = 3.72E-08) on chromosome 8 in the AMR group. We have queried several existing replication cohorts and found no support of these associations. We conclude that the fetal genetic contribution to PTB is unlikely due to single common genetic variant, but could be explained by interactions of multiple common variants, or of rare variants affected by environmental influences, all not detectable using a GWAS alone.

Hydrodynamic Signatures of Stationary Marangoni-Driven Surfactant Transport

We experimentally study steady Marangoni-driven surfactant transport on the interface of a deep water layer. Using hydrodynamic measurements, and without using any knowledge of the surfactant physicochemical properties, we show that sodium dodecyl sulphate and Tergitol 15-S-9 introduced in low concentrations result in a flow driven by adsorbed surfactant. At higher surfactant concentration, the flow is dominated by the dissolved surfactant. Using camphoric acid, whose properties are a priori unknown, we demonstrate this method's efficacy by showing its spreading is adsorption dominated.

Absence of lung fibrosis after a single pulmonary delivery of lipid nanocapsules in rats

Lipid nanocapsules (LNCs) are potential drug carriers for pulmonary delivery since they can be nebulized without any structural or functional changes, and the aerosols produced are highly compatible with pulmonary drug delivery in human beings. The alveolar surface tension, in vitro cytotoxicity, biodistribution and pulmonary toxicity in rats of a single endotracheal spray of LNCs or paclitaxel-loaded LNCs were studied. In vitro cytotoxicity of LNCs after a spray remained unchanged. Biodistribution study showed a homogeneous repartition in the lungs in rats with an improvement in lung retention of the radiolabeled tracer loaded in LNCs compared to the absence of LNCs with a lung half-time of 8.8±0.7 hours. Bronchoalveolar fluid analysis revealed transient 7-day alveolar inflammation, reaching a maximum between days 2 and 4, characterized by a peak of granulocytes at day 1 followed by a peak of lymphocytes at day 3. Alveolar protein levels were increased at days 3 and 7. Acute inflammation was increased with paclitaxel-loaded LNCs in comparison with blank LNCs but dropped out at day 7. No histological pulmonary lesion was observed at day 60. LNCs lowered surface tension to a greater degree than Curosurf^® in a physicochemical model of the pulmonary alveolus. A single pulmonary delivery of LNCs induces a short-term alveolar inflammation with no residual lesions in rats at day 60. These data permit to start the study of LNCs in surfactant replacement therapy.

Early Assessment and Correlations of Nanoclay's Toxicity to Their Physical and Chemical Properties

Nanoclays' functionalization with organic modifiers increases their individual barrier properties, thermal stability, and mechanical properties and allows for ease of implementation in food packaging materials or medical devices. Previous reports have shown that, while organic modifiers integration between the layered mineral silicates leads to nanoclays with different degrees of hydrophobicity that become easily miscible in polymers, they could also pose possible effects at inhalation or ingestion routes of exposure. Through a systematic analysis of three organically modified and one pristine nanoclay, we aimed to relate for the first time the physical and chemical characteristics, determined via microscopical and spectroscopical techniques, with the potential of these nanoclays to induce deleterious effects in in vitro cellular systems, i.e. in immortalized and primary human lung epithelial cell lines. To derive information on how functionalization could lead to toxicological profiles throughout nanoclays' life cycle, both as-received and thermally degraded nanoclays were evaluated. Our analysis showed that the organic modifiers chemical composition influenced both the physical and chemical characteristics of the nanoclays as well as their toxicity. Overall, when cells were exposed to nanoclays with organic modifiers containing bioreactive groups, they displayed lower cellular numbers as well more elongated cellular morphologies relative to the pristine nanoclay and the nanoclay containing a modifier with long carbon chains. Additionally, thermal degradation caused loss of the organic modifiers as well as changes in size and shape of the nanoclays, which led to changes in toxicity upon exposure to our model cellular systems. Our study provides insight into the synergistic effects of chemical composition, size, and shape of the nanoclays and their toxicological profiles in conditions that mimic exposure in manufacturing and disposal environments, respectively, and can help aid in safe-by-design manufacturing of nanoclays with user-controlled functionalization and lower toxicity levels when food packaging applications are considered.

Investigating increased admissions to neonatal intensive care in England between 1995 and 2006: data linkage study using Hospital Episode Statistics

BACKGROUND

A 44 % increase was observed in admissions to neonatal intensive care of babies born ≤26 weeks completed gestational age in England between 1995 and 2006. Hospital Episode Statistics (HES) may provide supplementary information to investigate this. The methods and results of a probabilistic data linkage exercise are reported.

METHODS

Two data sets were linked for each year (1995 and 2006) using 3 different algorithms (Fellegi and Sunter, Contiero and estimation-maximisation).

RESULTS

In 1995, linkage was performed between 668 EPICure and 486,705 HES records; 1,820 linked pairs were identified of which 422 (63.17 %) were confirmed. In 2006, from 2,750 EPICure and 631,401 HES records, 8,913 linked pairs were identified with 1,662 (60.40 %) confirmed as true. Reported births in HES at <26 weeks gestation increased 37.0 % from 867 to 1188.

CONCLUSIONS

Results support the EPICure findings that there was an increase in the birth rate for extremely premature babies between 1995 and 2006. There were insufficient data available for detailed investigation. Routine data sources may not be suitable for investigations at the margins of viability.

Soluble surfactant spreading: How the amphiphilicity sets the Marangoni hydrodynamics

Amphiphiles are molecules combining hydrophilic and hydrophobic parts. The way they arrange in bulk and at interfaces is related to the balance between these two parts, and can be quantified by introducing the critical micellar concentration (cmc). Amphiphiles (also named "surfactants") are also at the origin of dynamical effects: local gradients of interfacial concentrations create the so-called Marangoni flows. Here we study the coupling between the molecule amphiphilicity and these Marangoni flows. We investigate in detail a spreading configuration, where a local excess of surfactants is locally sustained, and follow how these surfactants spread at the interface and diffuse in bulk. We have measured the features of this flow (maximal distance and maximal speed), for different types of surfactant, and as a function of all experimentally available parameters, as well as for two different configurations. In parallel, we propose a detailed hydrodynamical model. For all the measured quantities, we have found a good agreement between the data and the model, evidencing that we have captured the key mechanisms under these spreading experiments. In particular, the cmc turns out to be-as for the static picture of a surfactant-a key element even under dynamical conditions, allowing us to connect the molecule amphiphilicity to its ability to create Marangoni flows.

The effect of maternal hypertension on mortality in infants 22, 29weeks gestation

OBJECTIVE

To evaluate the effect of maternal hypertension on mortality risk prior to discharge, in infants 22+0 to 29+6weeks gestational age.

STUDY DESIGN

We evaluated 88,275 North American infants whose births were recorded in Vermont Oxford Network centers between 2008 and 2011 Infants born between 22+0 and 29+6weeks gestational age were evaluated in 2-week gestational age cohorts and followed until death or discharge. Logistic regression was used to adjust for birth weight, antenatal steroid exposure, infant sex, maternal race, inborn/outborn, prenatal care and birth year.

RESULTS

21,896 infants were born to hypertensive mothers; 13% died prior to Neonatal Intensive Care Unit discharge compared to 20% of the 66,379 infants born to mothers without hypertension. After adjustment, infants had significantly lower mortality compared to preterm infants not born to hypertensive mothers, at all gestational ages examined (22/23: odds ratio (OR)=0.65 (95% Confidence Interval (CI): 0.55, 0.77; 24/25); OR=0.77 (95% CI: 0.71, 0.84); 26/27: OR=0.66 (95% CI: 0.59, 0.74); 28/29: OR=0.58 (95% CI: 0.51, 0.67). Additionally, births associated with maternal hypertension increase dramatically by gestational age, resulting in a larger proportion of births associated with maternal hypertension at later gestational ages.

CONCLUSIONS

Preterm birth due to any cause carries significant risk of mortality, especially at the earliest of viable gestational ages. Maternal hypertension independently influences mortality, with lower odds of mortality seen in infants born to hypertensive mothers, after adjustment, and should be taken into consideration as an element in counseling parents.

In Vitro Evaluation of a Device for Intra-Pulmonary Aerosol Generation and Delivery

For infants born with respiratory distress syndrome (RDS), liquid bolus delivery of surfactant administered through an endotracheal tube is common practice. While this method is generally effective, complications such as transient hypoxia, hypercapnia, and altered cerebral blood flow may occur. Aerosolized surfactant therapy has been explored as an alternative. Unfortunately, past efforts have led to disappointing results as aerosols were generated outside the lungs with significant pharyngeal deposition and minimal intrapulmonary instillation. A novel aerosol generator (Microjet™) is evaluated herein for intrapulmonary aerosol generation within an endotracheal tube and tested with Curosurf and Infasurf surfactants. Compared with other aerosol delivery devices, this process utilizes low air flow (range 0.01-0.2 L/min) that is ideal for limiting potential barotrauma to the premature newborn lung. The mass mean diameter (MMD) of the particles for both tested surfactants was less than 4 μm, which is ideal for both uniform and distal lung delivery. As an indicator of phospholipid function, surfactant surface tension was measured before and after aerosol formation; with no significant difference. Moreover, this device has an outside diameter of <1mm, which permits insertion into an endotracheal tube (of even 2.0 mm). In the premature infant where intravenous access is either technically challenging or difficult, aerosol drug delivery may provide an alternative route in patient resuscitation, stabilization and care. Other potential applications of this type of device include the delivery of nutrients, antibiotics, and analgesics via the pulmonary route.

Surfactant therapy for bronchiolitis in critically ill infants

BACKGROUND

Bronchiolitis is one of the most frequent causes of respiratory failure in infants; some infants will require intensive care and mechanical ventilation. There is lack of evidence regarding effective treatment for bronchiolitis other than supportive care. Abnormalities of surfactant quantity or quality (or both) have been observed in severe cases of bronchiolitis. Exogenous surfactant administration appears to favourably change the haemodynamics of the lungs and may be a potentially promising therapy for severe bronchiolitis. This is an update of a review published in Issue 9, 2012. We did not identify any new studies for inclusion, and our conclusions remain unchanged.

OBJECTIVES

To evaluate the efficacy of exogenous surfactant administration (i.e. intratracheal administration of surfactant of any type (whether animal-derived or synthetic), at any dose and at any time after start of ventilation) compared to placebo, no intervention or standard care in reducing mortality and the duration of ventilation in infants and children with bronchiolitis requiring mechanical ventilation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Studies (CENTRAL; 2015, Issue 5) which contains the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (1948 to June week 3, 2015); EMBASE (1974 to June 2015); CINAHL (1982 to June 2015); LILACS (1985 to June 2015); and Web of Science (1985 to June 2015).

SELECTION CRITERIA

We considered prospective, randomised controlled trials (RCTs) and quasi-RCTs evaluating the effect of exogenous surfactant in infants and children with bronchiolitis requiring mechanical ventilation.

DATA COLLECTION AND ANALYSIS

Two review authors selected studies independently. We extracted the data using a predefined proforma, independently analysed the data, and performed meta-analyses.

MAIN RESULTS

We included three small RCTs enrolling 79 participants. Two trials did not use a placebo in the control arms and the third trial used air placebo. Two included studies reported no mortality. We judged all three of the included studies to be at low risk or unclear risk across all risk of bias categories; we did not judge any of the studies to be at high risk of bias in any category. Our pooled analysis of the three trials revealed that duration of mechanical ventilation was not significantly different between the groups (mean difference (MD) -63.04, 95% confidence interval (CI) -130.43 to 4.35 hours) but duration of intensive care unit (ICU) stay was less in the surfactant group compared to the control group: MD -3.31, 95% CI -6.38 to -0.25 days. After excluding one trial which produced significant heterogeneity, the duration of mechanical ventilation and duration of ICU stay were significantly lower in the surfactant group compared to the control group: MD -28.99, 95% CI -40.10 to -17.87 hours; and MD -1.81, 95% CI -2.42 to -1.19 days, respectively. Use of surfactant had favourable effects on oxygenation and CO2 elimination. No adverse effects and no complications were observed in any of the three included studies. The level of evidence for duration of mechanical ventilation, duration of intensive care unit stay, oxygenation parameters, and carbon dioxide parameters was of moderate quality.

AUTHORS' CONCLUSIONS

Use of surfactant had favourable effects on duration of mechanical ventilation, duration of ICU stay, oxygenation, and CO2 elimination. However, the studies are few and small (n = 79) so available evidence is insufficient to establish the effectiveness of surfactant therapy for bronchiolitis in critically ill infants who require mechanical ventilation. There is a need for larger trials with adequate power and a cost-effectiveness analysis to evaluate the effectiveness of exogenous surfactant therapy for infants with bronchiolitis who require intensive care management.

Animal derived surfactant extract versus protein free synthetic surfactant for the prevention and treatment of respiratory distress syndrome

BACKGROUND

A wide variety of surfactant preparations have been developed and tested including synthetic surfactants and surfactants derived from animal sources. Although clinical trials have demonstrated that both synthetic surfactant and animal derived surfactant preparations are effective, comparison in animal models has suggested that there may be greater efficacy of animal derived surfactant products, perhaps due to the protein content of animal derived surfactant.

OBJECTIVES

To compare the effect of animal derived surfactant to protein free synthetic surfactant preparations in preterm infants at risk for or having respiratory distress syndrome (RDS).

SEARCH METHODS

Searches were updated of the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2014), PubMed, CINAHL and EMBASE (1975 through November 2014). All languages were included.

SELECTION CRITERIA

Randomized controlled trials comparing administration of protein free synthetic surfactants to administration of animal derived surfactant extracts in preterm infants at risk for or having respiratory distress syndrome were considered for this review.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Fifteen trials met the inclusion criteria. The meta-analysis showed that the use of animal derived surfactant rather than protein free synthetic surfactant resulted in a significant reduction in the risk of pneumothorax [typical relative risk (RR) 0.65, 95% CI 0.55 to 0.77; typical risk difference (RD) -0.04, 95% CI -0.06 to -0.02; number needed to treat to benefit (NNTB) 25; 11 studies, 5356 infants] and a marginal reduction in the risk of mortality (typical RR 0.89, 95% CI 0.79 to 0.99; typical RD -0.02, 95% CI -0.04 to -0.00; NNTB 50; 13 studies, 5413 infants).Animal derived surfactant was associated with an increase in the risk of necrotizing enterocolitis [typical RR 1.38, 95% CI 1.08 to 1.76; typical RD 0.02, 95% CI 0.01 to 0.04; number needed to treat to harm (NNTH) 50; 8 studies, 3462 infants] and a marginal increase in the risk of any intraventricular hemorrhage (typical RR 1.07, 95% CI 0.99 to 1.15; typical RD 0.02, 95% CI 0.00 to 0.05; 10 studies, 5045 infants) but no increase in Grade 3 to 4 intraventricular hemorrhage (typical RR 1.08, 95% CI 0.91 to 1.27; typical RD 0.01, 95% CI -0.01 to 0.03; 9 studies, 4241 infants).The meta-analyses supported a marginal decrease in the risk of bronchopulmonary dysplasia or mortality associated with the use of animal derived surfactant preparations (typical RR 0.95, 95% CI 0.91 to 1.00; typical RD -0.03, 95% CI -0.06 to 0.00; 6 studies, 3811 infants). No other relevant differences in outcomes were noted.

AUTHORS' CONCLUSIONS

Both animal derived surfactant extracts and protein free synthetic surfactant extracts are effective in the treatment and prevention of respiratory distress syndrome. Comparative trials demonstrate greater early improvement in the requirement for ventilator support, fewer pneumothoraces, and fewer deaths associated with animal derived surfactant extract treatment. Animal derived surfactant may be associated with an increase in necrotizing enterocolitis and intraventricular hemorrhage, though the more serious hemorrhages (Grade 3 and 4) are not increased. Despite these concerns, animal derived surfactant extracts would seem to be the more desirable choice when compared to currently available protein free synthetic surfactants.

Animal Models, Learning Lessons to Prevent and Treat Neonatal Chronic Lung Disease

Bronchopulmonary dysplasia (BPD) is a unique injury syndrome caused by prolonged injury and repair imposed on an immature and developing lung. The decreased septation and decreased microvascular development phenotype of BPD can be reproduced in newborn rodents with increased chronic oxygen exposure and in premature primates and sheep with oxygen and/or mechanical ventilation. The inflammation caused by oxidants, inflammatory agonists, and/or stretch injury from mechanical ventilation seems to promote the anatomic abnormalities. Multiple interventions targeted to specific inflammatory cells or pathways or targeted to decreasing ventilation-mediated injury can substantially prevent the anatomic changes associated with BPD in term rodents and in preterm sheep or primate models. Most of the anti-inflammatory therapies with benefit in animal models have not been tested clinically. None of the interventions that have been tested clinically are as effective as anticipated from the animal models. These inconsistencies in responses likely are explained by the antenatal differences in lung exposures of the developing animals relative to very preterm humans. The animals generally have normal lungs while the lungs of preterm infants are exposed variably to intrauterine inflammation, growth abnormalities, antenatal corticosteroids, and poorly understood effects from the causes of preterm delivery. The animal models have been essential for the definition of the mediators that can cause a BPD phenotype. These models will be necessary to develop and test future-targeted interventions to prevent and treat BPD.

Neonatal exposure to mild hyperoxia causes persistent increases in oxidative stress and immune cells in the lungs of mice without altering lung structure

Preterm infants often require supplemental oxygen due to lung immaturity, but hyperoxia can contribute to an increased risk of respiratory illness later in life. Our aim was to compare the effects of mild and moderate levels of neonatal hyperoxia on markers of pulmonary oxidative stress and inflammation and on lung architecture; both immediate and persistent effects were assessed. Neonatal mice (C57BL6/J) were raised in either room air (21% O2), mild (40% O2), or moderate (65% O2) hyperoxia from birth until postnatal day 7 (P7d). The mice were killed at either P7d (immediate effects) or lived in air until adulthood (P56d, persistent effects). We enumerated macrophages in lung tissue at P7d and immune cells in bronchoalveolar lavage fluid (BALF) at P56d. At P7d and P56d, we assessed pulmonary oxidative stress [heme oxygenase-1 (HO-1) and nitrotyrosine staining] and lung architecture. The data were interrogated for sex differences. At P7d, HO-1 gene expression was greater in the 65% O2 group than in the 21% O2 group. At P56d, the area of nitrotyrosine staining and number of immune cells were greater in the 40% O2 and 65% O2 groups relative to the 21% O2 group. Exposure to 65% O2, but not 40% O2, led to larger alveoli and lower tissue fraction in the short term and to persistently fewer bronchiolar-alveolar attachments. Exposure to 40% O2 or 65% O2 causes persistent increases in pulmonary oxidative stress and immune cells, suggesting chronic inflammation within the adult lung. Unlike 65% O2, 40% O2 does not affect lung architecture.

Animal derived surfactant extract versus protein free synthetic surfactant for the prevention and treatment of respiratory distress syndrome

BACKGROUND

A wide variety of surfactant preparations have been developed and tested including synthetic surfactants and surfactants derived from animal sources. Although clinical trials have demonstrated that both synthetic surfactant and animal derived surfactant preparations are effective, comparison in animal models has suggested that there may be greater efficacy of animal derived surfactant products, perhaps due to the protein content of animal derived surfactant.

OBJECTIVES

To compare the effect of animal derived surfactant to protein free synthetic surfactant preparations in preterm infants at risk for or having respiratory distress syndrome (RDS).

SEARCH METHODS

Searches were updated of the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2014), PubMed, CINAHL and EMBASE (1975 through November 2014). All languages were included.

SELECTION CRITERIA

Randomized controlled trials comparing administration of protein free synthetic surfactants to administration of animal derived surfactant extracts in preterm infants at risk for or having respiratory distress syndrome were considered for this review.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were conducted according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Fifteen trials met the inclusion criteria. The meta-analysis showed that the use of animal derived surfactant rather than protein free synthetic surfactant resulted in a significant reduction in the risk of pneumothorax [typical relative risk (RR) 0.65, 95% CI 0.55 to 0.77; typical risk difference (RD) -0.04, 95% CI -0.06 to -0.02; number needed to treat to benefit (NNTB) 25; 11 studies, 5356 infants] and a marginal reduction in the risk of mortality (typical RR 0.89, 95% CI 0.79 to 0.99; typical RD -0.02, 95% CI -0.04 to -0.00; NNTB 50; 13 studies, 5413 infants).Animal derived surfactant was associated with an increase in the risk of necrotizing enterocolitis [typical RR 1.38, 95% CI 1.08 to 1.76; typical RD 0.02, 95% CI 0.01 to 0.04; number needed to treat to harm (NNTH) 50; 8 studies, 3462 infants] and a marginal increase in the risk of any intraventricular hemorrhage (typical RR 1.07, 95% CI 0.99 to 1.15; typical RD 0.02, 95% CI 0.00 to 0.05; 10 studies, 5045 infants) but no increase in Grade 3 to 4 intraventricular hemorrhage (typical RR 1.08, 95% CI 0.91 to 1.27; typical RD 0.01, 95% CI -0.01 to 0.03; 9 studies, 4241 infants).The meta-analyses supported a marginal decrease in the risk of bronchopulmonary dysplasia or mortality associated with the use of animal derived surfactant preparations (typical RR 0.95, 95% CI 0.91 to 1.00; typical RD -0.03, 95% CI -0.06 to 0.00; 6 studies, 3811 infants). No other relevant differences in outcomes were noted.

AUTHORS' CONCLUSIONS

Both animal derived surfactant extracts and protein free synthetic surfactant extracts are effective in the treatment and prevention of respiratory distress syndrome. Comparative trials demonstrate greater early improvement in the requirement for ventilator support, fewer pneumothoraces, and fewer deaths associated with animal derived surfactant extract treatment. Animal derived surfactant may be associated with an increase in necrotizing enterocolitis and intraventricular hemorrhage, though the more serious hemorrhages (Grade 3 and 4) are not increased. Despite these concerns, animal derived surfactant extracts would seem to be the more desirable choice when compared to currently available protein free synthetic surfactants.

Factors influencing independent oral feeding in preterm infants

OBJECTIVE

Determine the mean post-menstrual age when preterm infants attain independent oral feeding skills and whether gestational age, common neonatal morbidities, gender, race, delivery route, or birth year affects this reflex.

METHODS

A retrospective chart review of 2700 preterm infants, born before 37 weeks gestational age admitted to a level III NICU between January 1978 and July 2013, to determine the post-menstrual age when independent oral feedings occur.

RESULTS

Mean post-menstrual age at achievement of independent oral feeding was 36 + 4/7 weeks ± 14 days. Gestational age under 29 weeks correlated with delayed post-menstrual age at achievement of independent oral feeding at 37 + 3/7 weeks versus 36 + 1/7 weeks for gestational age 29-33 weeks and 36 + 3/7 weeks for late preterm infants (p < 0.0001). Preterm infants with certain morbidities experienced a delay in independent oral feeding: necrotizing enterocolitis at 38 + 6/7 weeks (p < 0.0001), bronchopulmonary dysplasia at 38 + 1/7 weeks (p < 0.0001), severe intraventricular hemorrhage at 37 + 6/7 weeks (p < 0.001). Preterm infants born before the year 2000 achieved independent oral feeding two days later than preterm infants born since the year 2000 (p < 0.0001). Preterm infants delivered vaginally achieved independent oral feeding three days sooner than infants delivered via c-section (p < 0.0001). Female infants orally fed one day sooner than male preterm infants (p = 0.0008).

CONCLUSIONS

Preterm infants achieve independent oral feeding at 36 + 4/7 weeks. Factors negatively influencing when the preterm infant will achieve independent oral feeding include gestational age under 29 weeks and major morbidities, whereas vaginal delivery and ongoing advances in neonatal care may accelerate the transition to independent oral feeding.

Laparoscopic versus open repair of recto-bladderneck and recto-prostatic anorectal malformations: a systematic review and meta-analysis

OBJECTIVE

The laparoscopically-assisted anorectal pull-through (LAARP) for recto-bladderneck and recto-prostatic anorectal malformations (RB/RP-ARMs) is believed to improve patient outcomes. We performed a systematic review of the effect of LAARP on postoperative mucosal prolapse and defecation dysfunction.

METHODS

A comprehensive search of MEDLINE, EMBASE, CENTRAL, and grey literature was performed (2000-2014). Full-text screening, data abstraction and quality appraisal were conducted in duplicate. Included studies reported a primary diagnosis of RB/RP-ARM and compared LAARP versus open repair (OPEN).

RESULTS

From 3681 retrieved articles, 7 studies enrolling 187 patients were analyzed. One was a randomized control trial, 6 were retrospective observational studies, and all were single-centre. The majority were of poor-moderate quality (MINORS scores: mean 16.42 (SD 2.225) out of 24). Mucosal prolapse was not significantly different after LAARP versus OPEN (p = 0.18). Defecation outcomes were inconsistently reported but were no different between LAARP and OPEN for either children >3 years old (p = 0.84), or all ages combined (p = 0.11).

CONCLUSION

We found no significant difference in rates of mucosal prolapse or defecation scores for LAARP compared to OPEN for children with RB/RP-ARMs. However, studies are small and of poor-moderate quality and results are heterogeneous. Comprehensive, standardized, reliable reporting is necessary to guide practice and inform postoperative guidelines.

LEVEL OF EVIDENCE

1c.