Overview of surfactant replacement trials

Evaluation of a respiratory care protocol including less invasive surfactant administration in preterm infants

BACKGROUND

Respiratory care protocol including less invasive śsurfactant administration (LISA) in ≤29 weeks' gestational age (GA) infants introduced in October 2018.

METHODS

Retrospective study of infants admitted on continuous positive airway pressure (CPAP) October 2018 to December 2021. Maternal and neonatal variables were compared between infants managed on CPAP with and without LISA. Infants who received LISA and subsequently required mechanical ventilation (MV) within 72 h of life (HOL) [LISA failure (LF)] were compared with those who required no MV [LISA success (LS)].

RESULTS

249 infants were admitted on CPAP, 5 were intubated prior to LISA, 143 required LISA and 101 remained on CPAP without surfactant. Of those receiving LISA, 108 were LS and 35 were LF. Compared to LS, LF infants were of lower GA and birth weight, required higher fractional inspired oxygen (FiO2), and CPAP level at birth, admission, one HOL, and an hour after LISA. Moreover, LF infants had higher mortality and morbidity. Together GA ≤ 25 weeks' and FiO2 ≥ 0.3 an hour after LISA best predicted LF.

CONCLUSIONS

Over 80% of infants admitted on CPAP avoided MV within 72 HOL. Early predictors of LF provide targets for future interventions to decrease need for MV in preterm infants.

IMPACT

Less invasive surfactant administration (LISA) decreases the need for mechanical ventilation (MV) and improves outcomes. However, some infants require MV within 72 h of life (HOL) despite LISA (LISA failure). Over 80% of ≤29 weeks' gestational age (GA) infants can be successfully managed on CPAP with or without surfactant in the first 72 HOL. A combination of factors including ≤25 weeks' GA and fraction of inspired oxygen ≥0.3 an hour after LISA predict LISA failure. Evaluation of a noninvasive respiratory support strategy including LISA provides targets for intervention to decrease need for MV in preterm infants.

Non-invasive versus invasive respiratory support in preterm infants

Respiratory insufficiency is almost ubiquitous in infants born preterm, with its incidence increasing with lower gestational age. A wide range of respiratory support management strategies are available for these infants, separable into non-invasive and invasive forms of respiratory support. Here we review the history and evolution of respiratory care for the preterm infant and then examine evidence that has emerged to support a non-invasive approach to respiratory management where able. Continuous positive airway pressure (CPAP) is the non-invasive respiratory support mode currently with the most evidence for benefit. CPAP can be delivered safely and effectively and can commence in the delivery room. Particularly in early life, time spent on non-invasive respiratory support, avoiding intubation and mechanical ventilation, affords benefit for the preterm infant by virtue of a lessening of lung injury and hence a reduction in incidence of bronchopulmonary dysplasia. In recent years, enthusiasm for application of non-invasive support has been further bolstered by new techniques for administration of exogenous surfactant. Methods of less invasive surfactant delivery, in particular with a thin catheter, have allowed neonatologists to administer surfactant without resort to endotracheal intubation. The benefits of this approach appear to be sustained, even in those infants subsequently requiring mechanical ventilation. This cements the notion that any reduction in exposure to mechanical ventilation leads to alleviation of injury to the vulnerable preterm lung, with a long-lasting effect. Despite the clear advantages of non-invasive respiratory support, there will continue to be a role for intubation and mechanical ventilation in some preterm infants, particularly for those born <25 weeks' gestation. It is currently unclear what role early non-invasive support has in this special population, with more studies required.

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.

RDS-NExT workshop: consensus statements for the use of surfactant in preterm neonates with RDS

OBJECTIVE

To provide the best clinical practice guidance for surfactant use in preterm neonates with respiratory distress syndrome (RDS). The RDS-Neonatal Expert Taskforce (RDS-NExT) initiative was intended to add to existing evidence and clinical guidelines, where evidence is lacking, with input from an expert panel.

STUDY DESIGN

An expert panel of healthcare providers specializing in neonatal intensive care was convened and administered a survey questionnaire, followed by 3 virtual workshops. A modified Delphi method was used to obtain consensus around topics in surfactant use in neonatal RDS.

RESULT

Statements focused on establishing RDS diagnosis and indicators for surfactant administration, surfactant administration methods and techniques, and other considerations. After discussion and voting, consensus was achieved on 20 statements.

CONCLUSION

These consensus statements provide practical guidance for surfactant administration in preterm neonates with RDS, with a goal to contribute to improving the care of neonates and providing a stimulus for further investigation to bridge existing knowledge gaps.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

A pilot study of evaluation of semi-rigid and flexible catheters for less invasive surfactant administration in preterm infants with respiratory distress syndrome—a randomized controlled trial

Background

In respiratory distress syndrome, many neonatology centers worldwide perform minimal invasive surfactant application in premature infants, using small-diameter catheters for endotracheal intubation and surfactant administration.

Methods

In this single-center, open-label, randomized-controlled trial, preterm infants requiring surfactant administration after birth, using a standardized minimal invasive protocol, were randomized to two different modes of endotracheal catheterization: Flexible charrière-4 feeding tube inserted using Magill forceps (group 1) and semi-rigid catheter (group 2). Primary outcome was duration of laryngoscopy. Secondary outcomes were complication rate (intraventricular hemorrhage, soft-tissue damage in first week of life) and vital parameters during laryngoscopy. Between 2019 and 2020, 31 infants were included in the study. Prior to in-vivo testing, laryngoscopy durations were studied on a neonatal airway mannequin in students, nurses and doctors.

Results

Mean gestational age and birth weight were 27 + 6/7 weeks and 1009 g; and 28 + 0/7 weeks and 1127 g for group 1 and 2, respectively. Length of laryngoscopy was similar in both groups (61.1 s and 64.9 s) overall (p.77) and adjusted for weight (p.70) or gestational age (p.95). Laryngoscopy failed seven times in group 1 (43.8%) and four times (26.7%) in group 2 (p.46). Longer laryngoscopy was associated with lower oxygen saturation with lowest levels occurring after failed laryngoscopy attempts. Secondary outcomes were similar in both groups. In vitro data on 40 students, 40 nurses and 12 neonatologists showed significant faster laryngoscopy in students and nurses group 2 (p < .0001) unlike in neonatologists (p.13).

Conclusion

This study showed no difference in laryngoscopy duration in endotracheal catheterization when comparing semi-rigid and flexible catheters for minimal invasive surfactant application in preterm infants. In accordance with preliminary data and in contrast to published in-vitro trials, experienced neonatologists were able to perform endotracheal catheterization using both semi-rigid and flexible catheters at similar rates and ease, in vitro and in vivo.

Trial registration

ClinicalTrials.gov. NCT05024435 Registered 27 August 2021—Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03714-3.

Should less invasive surfactant administration (LISA) become routine practice in US neonatal units?

The harmful effects of mechanical ventilation (MV) on the preterm lung are well established. Avoiding MV at birth and stabilization on continuous positive airway pressure (CPAP) decreases the composite outcome of death or bronchopulmonary dysplasia. Although preterm infants are increasingly being admitted to the neonatal intensive care unit on CPAP, centers differ in the ability to manage infants primarily on CPAP. Over the last decade, less invasive surfactant administration (LISA), a method of administering surfactant with a thin catheter, has been devised and has been shown to decrease the need for MV and improve outcomes compared to surfactant administration via an endotracheal tube following intubation. While LISA has been widely adopted in Europe and other countries, its use is not widespread in the United States. This article provides a summary of the existing evidence on LISA, and practical guidance for US units choosing to implement a change of practice incorporating optimization of CPAP and LISA. IMPACT: The accumulated body of evidence for less invasive surfactant administration (LISA), a widespread practice in other countries, justifies its use as an alternative to intubation and surfactant administration in US neonatal units. This article summarizes the current evidence for LISA, identifies gaps in knowledge, and offers practical tips for the implementation of LISA as part of a comprehensive non-invasive respiratory support strategy. This article will help neonatal units in the US develop guidelines for LISA, provide optimal respiratory support for infants with respiratory distress syndrome, improve short- and long-term outcomes of preterm infants, and potentially decrease costs of NICU care.

Pulmonary surfactant: a unique biomaterial with life-saving therapeutic applications

Pulmonary surfactant is a complex lipoprotein mixture secreted into the alveolar lumen by type 2 pneumocytes, which is composed by tens of different lipids (approximately 90% of its entire mass) and surfactant proteins (approximately 10% of the mass). It is crucially involved in maintaining lung homeostasis by reducing the values of alveolar liquid surface tension close to zero at end-expiration, thereby avoiding the alveolar collapse, and assembling a chemical and physical barrier against inhaled pathogens. A deficient amount of surfactant or its functional inactivation is directly linked to a wide range of lung pathologies, including the neonatal respiratory distress syndrome. This paper reviews the main biophysical concepts of surfactant activity and its inactivation mechanisms, and describes the past, present and future roles of surfactant replacement therapy, focusing on the exogenous surfactant preparations marketed worldwide and new formulations under development. The closing section describes the pulmonary surfactant in the context of drug delivery. Thanks to its peculiar composition, biocompatibility, and alveolar spreading capability, the surfactant may work not only as a shuttle to the branched anatomy of the lung for other drugs but also as a modulator for their release, opening to innovative therapeutic avenues for the treatment of several respiratory diseases.

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 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.

Association of Adherence to Surfactant Best Practice Uses With Clinical Outcomes Among Neonates in Sweden

IMPORTANCE

While surfactant therapy for respiratory distress syndrome (RDS) in preterm infants has been evaluated in clinical trials, less is known about how surfactant is used outside such a framework.

OBJECTIVE

To evaluate registered use, off-label use, and omissions of surfactant treatment by gestational age (GA) and associations with outcomes, mainly among very preterm infants (GA <32 weeks).

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study used registry data for 97 377 infants born in Sweden between 2009 and 2018. Infants did not have malformations and were admitted for neonatal care. Data analysis was conducted from June 2019 to June 2020.

EXPOSURES

Timing and number of surfactant administrations, off-label use, and omission of use. Registered use was defined by drug label (1-3 administrations for RDS). Omissions were defined as surfactant not administered despite mechanical ventilation for RDS.

MAIN OUTCOME AND MEASURES

In-hospital survival, pneumothorax, intraventricular hemorrhage grade 3 to 4, duration of mechanical ventilation, use of postnatal systemic corticosteroids for lung disease, treatment with supplemental oxygen at 28 days' postnatal age and at 36 weeks' postmenstrual age. Odds ratios (ORs) were calculated and adjusted for any prenatal corticosteroid treatment, cesarean delivery, GA, infant sex, Apgar score at 10 minutes, and birth weight z score of less than -2.

RESULTS

In total, 7980 surfactant administrations were given to 5209 infants (2233 [42.9%] girls; 2976 [57.1%] boys): 629 (12.1%) born at full term, 691 (13.3%) at 32 to 36 weeks' GA, 1544 (29.6%) at 28 to 31 weeks' GA, and 2345 (45.0%) at less than 28 weeks' GA. Overall, 977 infants (18.8%) received off-label use. In 1364 of 3508 infants (38.9%) with GA of 22 to 31 weeks, the first administration of surfactant was given more than 2 hours after birth, and this was associated with higher odds of pneumothorax (adjusted OR [aOR], 2.59; 95% CI, 1.76-3.83), intraventricular hemorrhage grades 3 to 4 (aOR, 1.71; 95% CI, 1.23-2.39), receipt of postnatal corticosteroids (aOR, 1.57; 95% CI, 1.22-2.03), and longer duration of assisted ventilation (aOR, 1.34; 95% CI, 1.04-1.72) but also higher survival (aOR, 1.45; 95% CI, 1.10-1.91) than among infants treated within 2 hours of birth. In 146 infants (2.8%), the recommended maximum of 3 surfactant administrations was exceeded but without associated improvements in outcome. Omission of surfactant treatment occurred in 203 of 3551 infants (5.7%) who were receiving mechanical ventilation and was associated with lower survival (aOR, 0.49; 95% CI, 0.30-0.82). In full-term infants, 336 (53.4%) of those receiving surfactant had a diagnosis of meconium aspiration syndrome. Surfactant for meconium aspiration was not associated with improved neonatal outcomes.

CONCLUSIONS AND RELEVANCE

In this study, adherence to best practices and labels for surfactant use in newborn infants varied, with important clinical implications for neonatal outcomes.

A comparison of LISA versus InSurE: A single center experience

BACKGROUND

Less invasive surfactant replacement therapy (SRT) methods have been linked to better respiratory outcomes. The primary aim of this study was to determine if Less Invasive Surfactant Administration (LISA) altered the rate of bronchopulmonary dysplasia (BPD) in preterm infants. Secondary objectives were to determine if LISA compared to Intubation Surfactant Extubation (InSurE) resulted in different respiratory outcomes and hospital course.

METHODS

In this retrospective chart review, outcomes were compared in two preterm infant groups (25-32 weeks gestation). Infants in Group 1 received surfactant replacement therapy (SRT) via InSurE method, while infants in Group 2 received SRT via LISA method.

RESULTS

Regardless of SRT method utilized, there were no significant differences in rates of BPD between the two groups in infants born at 25-32 weeks gestation (30.6% vs 33.3%; P = 0.47).

CONCLUSIONS

Despite using LISA method rather than InSurE for SRT, premature infants continue to be at high risk for BPD. LISA shows promise as a safe, noninvasive SRT alternative to invasive methods like InSurE.

Outcomes associated with surfactant in more mature and larger premature infants with respiratory distress syndrome

OBJECTIVE

Examine the effect of off-label surfactant on mortality and morbidity in more mature and larger premature infants diagnosed with respiratory distress syndrome (RDS).

STUDY DESIGN

Cohort study of premature infants born at 30-36 weeks, birth weight > 2 kg, and a diagnosis of RDS. We compared the odds of mortality and morbidity between infants who were exposed vs unexposed to surfactant. We used a treatment effects model to balance covariates between groups.

RESULTS

Of 54,964 included infants, 25,278 (46%) were exposed to surfactant. The frequency of mortality and morbidities were higher in the exposed group in unadjusted analyses. Following adjustment with a doubly robust treatment effects model, we found no significant treatment effect of surfactant on mortality or morbidity.

CONCLUSION

Surfactant exposure is not associated with reduced or increased mortality or morbidity in more mature premature infants with RDS.

Predicting Lung Health Trajectories for Survivors of Preterm Birth

Rates of preterm birth (<37 weeks of gestation) are increasing worldwide. Improved perinatal care has markedly increased survival of very (<32 weeks gestation) and extremely (<28 weeks gestation) preterm infants, however, long term respiratory sequalae are common among survivors. Importantly, individual's lung function trajectories are determined early in life and tend to track over the life course. Preterm infants are impacted by antenatal, postnatal and early life perturbations to normal lung growth and development, potentially resulting in significant shifts from the "normal" lung function trajectory. This review summarizes what is currently known about the long-term lung function trajectories in survivors of preterm birth. Further, this review highlights how antenatal, perinatal and early life factors are likely to contribute to individual lung health trajectories across the life course.

Irremovable Blood Stain in Lung: Air-to-Interface Transport of Albumin and Its Mechanical Response to Biaxial Compression/Expansion

Serum proteins are believed to trigger a sudden failure of lung function, but to date the mechanism remains elusive. Most studies have focused on the transport of the proteins from the subphase to the lung surfactant interface, although the opposite direction of transport, i.e., from air-to-interface, could be equally important. Here, we report that physiological concentrations of serum droplets can rapidly form a film upon exposure to air, and the entire film can be transferred to the lung surfactant interface upon coalescence, displacing it. This film was mechanically stable and remains intact even for multiple biaxial compression/expansion cycles. Our findings provide a mechanism of lung surfactant replacement by serum proteins that is fundamentally different from the subphase-to-interface transport and demonstrate that it is nearly impossible to remove the film from the interface where the lung surfactant should be, thus impairing the lung in a permanent way.

Surfactant Administration in Preterm Infants: Drug Development Opportunities

OBJECTIVE

To evaluate how frequently surfactant is used off-label in preterm infants.

STUDY DESIGN

We conducted a retrospective cohort analysis of prospectively collected administrative data for 2005-2015 from 348 neonatal intensive care units in the US. We quantified off-label administration of poractant alfa, calfactant, or beractant in inborn infants born at <37 weeks of gestational age (GA). Off-label surfactant administration was defined according to the Food and Drug Administration (FDA) label.

RESULTS

Of a total of 110 822 preterm infants who received surfactant, 68 226 (62%) received the surfactant off-label. The majority of infants who received surfactant off-label had a higher birth weight than those who received surfactant on-label (40 716 [37%]), had an older GA than those who received surfactant on-label (35 191 [32%]), or were treated with intubation and surfactant administration followed by immediate extubation (INSURE) (32 310 [29%]). Poractant alfa was administered via INSURE more frequently than beractant or calfactant (16 688 [38%], 7137 [20%], and 8485 [27%], respectively). An increasing number of infants received surfactant via INSURE from 2005 to 2015 (from 1697 [19%] to 3368 [36%]).

CONCLUSIONS

The majority of surfactant given to preterm infants is administered off-label. The uptrend in administration via INSURE coincides with increased supporting evidence. The gap between FDA labeling and current clinic practice exemplifies an opportunity for label expansion, which may require additional prospective or retrospective safety and/or effectiveness data for infants of older GA and higher birth weight.

The Effect of Minimally Invasive Surfactant Therapy on Diaphragmatic Activity

BACKGROUND

Minimally invasive surfactant therapy (MIST) is increasingly used to treat preterm infants with respiratory distress syndrome (RDS). However, the effect of MIST on breathing effort is poorly studied.

OBJECTIVES

To describe the effect of MIST on neural breathing effort assessed with transcutaneous electromyography of the diaphragm (dEMG) in preterm infants with RDS.

METHODS

Preterm infants with a gestational age < 37 weeks treated with MIST for RDS were included. dEMG measurements were done from 15 min before to 1 h after MIST. The percentage change in dEMG activity after MIST and the clinical response were analyzed.

RESULTS

Twenty preterm infants (mean gestational age 29.3 [SD 2.1] weeks; mean birth weight 1,230 [SD 391] g) were included. Seventeen infants did complete the 1-h measurement. Eleven (65%) infants had a decrease in their peakdEMG activity (median change -11.8% [IQR -26.8 to 5.8, p = 0.08]) 1 h after MIST. TonicdEMG activity decreased in 12 (71%) infants, with a median reduction of 6.3% (IQR -29.2 to 9.0, p = 0.07). FiO2 showed a rapid decrease following MIST (before, 0.47 [IQR 0.38-0.84]; 1 h after, 0.25 [IQR 0.21-0.30], p < 0.001).

CONCLUSION

In addition to improved oxygenation, MIST results in a decrease in neural breathing effort measured by dEMG activity in the majority of preterm infants with RDS.

Update of minimally invasive surfactant therapy

To date, preterm infants with respiratory distress syndrome (RDS) after birth have been managed with a combination of endotracheal intubation, surfactant instillation, and mechanical ventilation. It is now recognized that noninvasive ventilation (NIV) such as nasal continuous positive airway pressure (CPAP) in preterm infants is a reasonable alternative to elective intubation after birth. Recently, a meta-analysis of large controlled trials comparing conventional methods and nasal CPAP suggested that CPAP decreased the risk of the combined outcome of bronchopulmonary dysplasia or death. Since then, the use of NIV as primary therapy for preterm infants has increased, but when and how to give exogenous surfactant remains unclear. Overcoming this problem, minimally invasive surfactant therapy (MIST) allows spontaneously breathing neonates to remain on CPAP in the first week after birth. MIST has included administration of exogenous surfactant by intrapharyngeal instillation, nebulization, a laryngeal mask, and a thin catheter. In recent clinical trials, surfactant delivery via a thin catheter was found to reduce the need for subsequent endotracheal intubation and mechanical ventilation, and improves short-term respiratory outcomes. There is also growing evidence for MIST as an alternative to the INSURE (intubation-surfactant-extubation) procedure in spontaneously breathing preterm infants with RDS. In conclusion, MIST is gentle, safe, feasible, and effective in preterm infants, and is widely used for surfactant administration with noninvasive respiratory support by neonatologists. However, further studies are needed to resolve uncertainties in the MIST method, including infant selection, optimal surfactant dosage and administration method, and need for sedation.

Efficacy of minimally invasive surfactant therapy in moderate and late preterm infants: A multicentre randomized control trial

BACKGROUND

Minimally invasive surfactant therapy (MIST) is a new strategy to avoid mechanical ventilation (MV) in respiratory distress syndrome. The primary aim of this study was to test MIST as a means of avoiding MV exposure and pneumothorax occurrence in moderate and late preterm infants (32 to 36 weeks' gestational age).

METHODS

This was a randomized controlled trial including three Canadian centres. Patients were randomized to standard management or to the intervention if they required nasal continuous positive airway pressure of 6 cm H2O and 35% FiO2 in the first 24 hours of life. Patients from the intervention group received MIST immediately after inclusion. The primary outcome was either need for MV or development of a pneumothorax requiring a chest tube. To ensure that clinicians were not biased toward delaying intubation in the intervention group, clinical failure criteria were also used as a primary outcome. The primary outcome was analyzed using bivariate and multivariate logistic regressions.

RESULTS

Among 45 randomized patients, 24 were assigned to MIST and 21 to standard management. Eight infants (33%) from the intervention group met the primary outcome criteria versus 19 (90%) in the control group (absolute risk reduction 0.57, 95% confidence interval 0.54 to 0.60). One patient in each group reached the primary outcome because of pneumothorax occurrence. The other patients were exposed to MV. None of the patients reached the clinical failure criteria.

CONCLUSION

MIST for respiratory distress syndrome management in moderate and late preterm infants was associated with a significant reduction of MV exposure and pneumothorax occurrence.

Intellectual outcomes of extremely preterm infants at school age

BACKGROUND

The survival rate of extremely preterm (EP) infants (<28 weeks of gestation) has improved dramatically, and there is great interest in the long-term prognosis. The aim of this study was to elucidate the influence of prenatal and postnatal care on long-term intellectual outcome in EP infants.

METHODS

Subjects were EP infants admitted to the neonatal intensive care unit from 1982 to 2005. The survival rate and neurodevelopmental outcomes at 6 years of age were analyzed for the periods 1982-1991 (period 1) and 1992-2005 (period 2). Logistic regression analysis was performed to examine risk factors for intellectual impairment.

RESULTS

Survival rate improved significantly from 84.5% (period 1) to 92.4% (period 2; P = 0.007). Follow-up data were obtained from 92 children in period 1 (69.7% of survivors) and from 245 in period 2 (72.3% of survivors). The incidence of intellectual impairment increased from 16.3% (period 1) to 31.0% (period 2). Significant factors associated with intellectual impairment were period 2 (OR, 3.53; P = 0.007), supplemental oxygen at 36 weeks' corrected age (OR, 2.22; P = 0.012), number of days in the hospital (OR, 1.01; P = 0.012), intraventricular hemorrhage (IVH; OR, 3.05; P = 0.024), and later tube-feeding commencement date (OR, 1.10; P = 0.032).

CONCLUSIONS

Despite an increase in survival rate, the rate of intellectual impairment increased in period 2. According to risk factor analysis, reducing the incidence of chronic lung disease and/or apnea, IVH, and nutritional deprivation is a key factor in improving the intellectual outcomes of EP infants.

Evolution of surfactant therapy for respiratory distress syndrome: past, present, and future

Respiratory distress syndrome (RDS) due to surfactant deficiency is the most common cause of respiratory failure in preterm infants. Tremendous progress has been made since the original description that surfactant deficiency is the major cause of RDS. Surfactant therapy has been extensively studied in preterm infants and has been shown to significantly decrease air leaks and neonatal and infant mortality. Synthetic and animal-derived surfactants from bovine as well as porcine origin have been evaluated in randomized controlled trials. Animal-derived surfactants generally result in faster weaning of respiratory support, shorter duration of invasive ventilation, and decreased mortality when compared to first- or second-generation of synthetic surfactants, but some of the second-generation synthetic surfactants are at least not inferior to the animal-derived surfactants. Using a higher initial dose of porcine derived surfactant may provide better outcomes when compared with using lower doses of bovine surfactants, likely, due to compositional difference and/or the dose. Third-generation synthetic surfactant containing peptide analogs of surfactant protein B and C are currently being studied. Less invasive intra-tracheal surfactant administration techniques in spontaneously breathing neonate receiving noninvasive ventilator support are also being evaluated. In the present era, prophylactic surfactant is not recommended as it may increase the risk of lung injury or death. In the future, surfactants may be used as vector to deliver steroids, or used in combination with molecules, such as, recombinant Club Cell Protein-10 (rhCC-10) to improve pulmonary outcomes. Also, noninvasive surfactant administration techniques, such as aerosolization or atomization of surfactant may play a greater role in the future.

hPSC-derived lung and intestinal organoids as models of human fetal tissue

In vitro human pluripotent stem cell (hPSC) derived tissues are excellent models to study certain aspects of normal human development. Current research in the field of hPSC derived tissues reveals these models to be inherently fetal-like on both a morphological and gene expression level. In this review we briefly discuss current methods for differentiating lung and intestinal tissue from hPSCs into individual 3-dimensional units called organoids. We discuss how these methods mirror what is known about in vivo signaling pathways of the developing embryo. Additionally, we will review how the inherent immaturity of these models lends them to be particularly valuable in the study of immature human tissues in the clinical setting of premature birth. Human lung organoids (HLOs) and human intestinal organoids (HIOs) not only model normal development, but can also be utilized to study several important diseases of prematurity such as respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), and necrotizing enterocolitis (NEC).

Structural Features Essential to the Antimicrobial Functions of Human SPLUNC1

SPLUNC1 is an abundantly secreted innate immune protein in the mammalian respiratory tract that exerts bacteriostatic and antibiofilm effects, binds to lipopolysaccharide (LPS), and acts as a fluid-spreading surfactant. Here, we unravel the structural elements essential for the surfactant and antimicrobial functions of human SPLUNC1 (short palate lung nasal epithelial clone 1). A unique α-helix (α4) that extends from the body of SPLUNC1 is required for the bacteriostatic, surfactant, and LPS binding activities of this protein. Indeed, we find that mutation of just four leucine residues within this helical motif to alanine is sufficient to significantly inhibit the fluid spreading abilities of SPLUNC1, as well as its bacteriostatic actions against Gram-negative pathogens Burkholderia cenocepacia and Pseudomonas aeruginosa. Conformational flexibility in the body of SPLUNC1 is also involved in the bacteriostatic, surfactant, and LPS binding functions of the protein as revealed by disulfide mutants introduced into SPLUNC1. In addition, SPLUNC1 exerts antibiofilm effects against Gram-negative bacteria, although α4 is not involved in this activity. Interestingly, though, the introduction of surface electrostatic mutations away from α4 based on the unique dolphin SPLUNC1 sequence, and confirmed by crystal structure, is shown to impart antibiofilm activity against Staphylococcus aureus, the first SPLUNC1-dependent effect against a Gram-positive bacterium reported to date. Together, these data pinpoint SPLUNC1 structural motifs required for the antimicrobial and surfactant actions of this protective human protein.

Comparison of efficacy and safety of two available natural surfactants in Iran, Curosurf and Survanta in treatment of neonatal respiratory distress syndrome: A randomized clinical trial

Introduction

The benefit of surfactant prescription for respiratory distress syndrome (RDS) has been approved. Curosurf and Survanta are two commonly used natural surfactants in Iran. Previous studies did not report priority for one of these two drugs. The present study aimed to compare the effectiveness and safety of Curosurf and Survanta in treatment of RDS.

Methods

In this randomized clinical trial, neonates were born with RDS diagnosis in two governmental and referral hospitals of Tehran (the capital of Iran) in 2014 were randomly selected. Neonates were randomly assigned into two groups receiving 100 mg/kg Curosurf or Survanta as soon as possible after randomization. Complications, mortality and needing the second dose were compared between the two groups.

Results

A total 112 patients with the mean gestational age of 32.59 ± 3.39 weeks were evaluated (56 patients in each group). There were no significant differences regarding birth weight, gestational age, delivery method, and parity between the two groups (P > 0.05). The complications were occurred in 18 neonates (32.1%) of Curosurf group and 20 neonates (35.7%) of Survanta group (RR = 0.922, 95% CI = 0.617–1.379). There were no significant differences regarding complications, mortality, and needing nasal CPAP and endotracheal tube between the two groups. In the neonates with gestational age of 29–32 weeks the IVH and NEC incidence were significantly more in Curosurf group compared to Survanta group (27.8% vs 0% and 22.3% vs 0%, P < 0.05).

Conclusion

There was no significant difference in complications or mortality between those two groups; however Curosurf was associated with less need of ET tube (in >32 birth weeks subgroup) and NCPAP (in 29–32 birth weeks subgroup) (p = 0.008). Further evaluations with longer follow-up duration are needed for comparing these two surfactants.

Comparison of Three Different Administration Positions for Intratracheal Beractant in Preterm Newborns with Respiratory Distress Syndrome

BACKGROUND

The aim of this study was to compare the efficacy and adverse effects of various intratracheal beractant administration positions in preterm newborns with respiratory distress syndrome.

METHODS

This study was performed on preterm newborns with respiratory distress syndrome. The inclusion criteria were being between 26 weeks and 32 weeks of gestational age, having a birth weight between 600 g and 1500 g, having received clinical and radiological confirmation for the diagnosis of respiratory distress syndrome (RDS) within 3 hours of life, having been born in one of the centers where the study was carried out, and having fractions of inspired oxygen (FiO2) ≥ 0.40 to maintain oxygen saturation by pulse oximeter at 88-96%. Beractant was administered in four positions to Group I newborns, in two positions to Group II, and in neutral position to Group III.

RESULTS

Groups I and II consisted of 42 preterm infants in each whereas Group III included 41 preterm infants. No significant differences were detected among the groups with regards to maternal and neonatal risk factors. Groups were also similar in terms of the following complications: patent ductus arteriosus (PDA), pneumothorax, intraventricular hemorrhage (IVH), chronic lung disease (CLD), retinopathy of prematurity (ROP), necrotising enterocolitis (NEC), death within the first 3 days of life, death within the first 28 days of life, and rehospitalization within 1 month after discharge. Neither any statistically significant differences among the parameters related with surfactant administration, nor any significant statistical differences among the FiO2 levels and the saturation levels before and after the first surfactant administration among the groups were determined.

CONCLUSION

In terms of efficacy and side effects, no important difference was observed between the recommended four position beractant application, the two position administration, and the neutral position.

Bovine Surfactant Replacement Therapy in Neonates of Less than 32 Weeks' Gestation: A Multicenter Controlled Trial of Prophylaxis versus Early Treatment in China--a Pilot Study

BACKGROUND

A domestic surfactant preparation has been used in China for a number of years. However, as for other surfactant preparations, there is debate among neonatologists regarding the optimal dose, mode of administration, and the best time of intervention.

OBJECTIVE

To evaluate whether prophylactic administration of surfactant is superior to early treatment in preterm infants < 32 weeks with a high risk of respiratory distress syndrome (RDS).

METHODS

We prospectively compared small premature infants (< 32 weeks) receiving 70 mg/kg bovine surfactant within 30 minutes after birth (prophylactic group, N = 116) with infants who received surfactant therapy for established RDS (early treatment group, N = 91). The primary outcome assessed was the incidence of RDS. The secondary outcomes assessed were severity of RDS, mortality, and bronchopulmonary dysplasia morbidity.

RESULTS

Compared with the early treatment group, the prophylactic group had a significantly better PaO2 (at 1 hour, 4 hours, and 12 hours postdose, respectively), better a/APO2 (at 1 hour, 4 hours, 12 hours, and 24 hours postdose, respectively), lower PaCO2 (at 1 hour postdose), and a significantly decreased need for mean airway pressure (MAP) and FiO2 on ventilation (p < 0.05). The prophylactic group had shorter durations for mechanical ventilation and supplemental oxygen compared with the early treatment group (p < 0.01 and p < 0.05, respectively). The incidence of RDS was comparable between the groups; however, the prophylactic group had a significantly lower incidence of severe RDS and significantly lower rate of repeated doses of surfactant than the early treatment group (p < 0.05). The incidences of bronchopulmonary dysplasia and patent ductus arteriosus were also lower in the prophylactic group than the early treatment group (p < 0.05). The two groups were comparable in mortality rate.

CONCLUSION

In preterm infants under 32 weeks' gestation, prophylactic use of a domestic surfactant preparation is better than early surfactant treatment in improving pulmonary status and in decreasing the incidence of severe RDS and duration on mechanical ventilation.

Effect of surfactant on regional lung function in an experimental model of respiratory distress syndrome in rabbit

We assessed the changes in regional lung function following instillation of surfactant in a model of respiratory distress syndrome (RDS) induced by whole lung lavage and mechanical ventilation in eight anaesthetized, paralyzed, and mechanically ventilated New Zealand White rabbits. Regional specific ventilation (sV̇) was measured by K-edge subtraction synchrotron computed tomography during xenon washin. Lung regions were classified as poorly aerated (PA), normally aerated (NA), or hyperinflated (HI) based on regional density. A functional category was defined within each class based on sV̇ distribution (High, Normal, and Low). Airway resistance (Raw), respiratory tissue damping (G), and elastance (H) were measured by forced oscillation technique at low frequencies before and after whole lung saline lavage-induced (100 ml/kg) RDS, and 5 and 45 min after intratracheal instillation of beractant (75 mg/kg). Surfactant instillation improved Raw, G, and H ( P < 0.05 each), and gas exchange and decreased atelectasis ( P < 0.001). It also significantly improved lung aeration and ventilation in atelectatic lung regions. However, in regions that had remained normally aerated after lavage, it decreased regional aeration and increased sV̇ ( P < 0.001) and sV̇ heterogeneity. Although surfactant treatment improved both central airway and tissue mechanics and improved regional lung function of initially poorly aerated and atelectatic lung, it deteriorated regional lung function when local aeration was normal prior to administration. Local mechanical and functional heterogeneity can potentially contribute to the worsening of RDS and gas exchange. These data underscore the need for reassessing the benefits of routine prophylactic vs. continuous positive airway pressure and early “rescue” surfactant therapy in very immature infants.

Bronchopulmonary dysplasia: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases

Bronchopulmonary dysplasia (BPD) is the most common complication of extreme preterm birth. Infants who develop BPD manifest aberrant or arrested pulmonary development and can experience lifelong alterations in cardiopulmonary function. Despite decades of promising research, primary prevention of BPD has proven elusive. This workshop report identifies current barriers to the conduct of primary prevention studies for BPD and causal pathways implicated in BPD pathogenesis. Throughout, we highlight promising areas for research to improve understanding of normal and aberrant lung development, distinguish BPD endotypes, and ascertain biomarkers for more targeted therapeutic approaches to prevention. We conclude with research recommendations and priorities to accelerate discovery and promote lung health in infants born preterm.

Incidence and treatment of retinopathy of prematurity in England between 1990 and 2011: database study

AIMS

To study the incidence and treatment of retinopathy of prematurity (ROP) in England, 1990-2011.

METHODS

English national Hospital Episode Statistics were analysed, for babies born in hospital and for inpatient admissions, to obtain annual rates of diagnosis of, and treatment for, babies with ROP. National data on low birthweight (LBW) babies, born <1500 g and therefore eligible for ROP screening, were used as denominators in calculating rates of ROP per 1000 babies at risk.

RESULTS

The recorded incidence of ROP increased tenfold, from 12.8 per 1000 LBW babies in 1990 to 125.5 per 1000 LBW babies in 2011. Tretment rates for ROP by cryotherapy or laser rose from 1.7 to 14.8 per 1000 LBW babies between 1990 and 2011. In 1990, 13.3% of babies with ROP were treated with cryotherapy, which fell to 0.1% in 2011. Rates for laser treatment rose from 1.8% of babies with ROP in 1999 to 11.7% in 2011.

CONCLUSIONS

Increased neonatal survival, improved awareness of ROP and dissemination of guidance on screening and treatment of ROP will all have contributed to the substantial rise in recorded incidence of ROP between 1990 and 2011. Retinal ablation is now almost always performed using laser treatment rather than cryotherapy.

Administration of surfactant using less invasive techniques as a part of a non-aggressive paradigm towards preterm infants

Traditional treatment of respiratory distress syndrome in preterm infants consisted of early intubation, mechanical ventilation and intra-tracheal administration of exogenous surfactant. Recently, non-invasive ventilation, which has shown some advantages in short- and long-term outcomes, has gained popularity for the initial management of respiratory insufficiency in preterm infants. However, non-invasive ventilation from the outset poses difficulties in relation to administration of exogenous surfactant. The customary INSURE technique requires tracheal intubation, surfactant administration, and rapid extubation, but the latter is not always possible. As a more elegant approach, several minimally invasive techniques of delivering surfactant have been developed for babies spontaneously breathing on CPAP. The most extensively studied have been those in which the trachea is briefly catheterized with a nasogastric tube or vascular catheter, and exogenous surfactant is administered. Although results seem promising they are not yet conclusive, and further studies will be needed to answer a number of outstanding questions.

The OPTIMIST-A trial: evaluation of minimally-invasive surfactant therapy in preterm infants 25-28 weeks gestation

Background

It is now recognized that preterm infants ≤28 weeks gestation can be effectively supported from the outset with nasal continuous positive airway pressure. However, this form of respiratory therapy may fail to adequately support those infants with significant surfactant deficiency, with the result that intubation and delayed surfactant therapy are then required. Infants following this path are known to have a higher risk of adverse outcomes, including death, bronchopulmonary dysplasia and other morbidities. In an effort to circumvent this problem, techniques of minimally-invasive surfactant therapy have been developed, in which exogenous surfactant is administered to a spontaneously breathing infant who can then remain on continuous positive airway pressure. A method of surfactant delivery using a semi-rigid surfactant instillation catheter briefly passed into the trachea (the “Hobart method”) has been shown to be feasible and potentially effective, and now requires evaluation in a randomised controlled trial.

Methods/design

This is a multicentre, randomised, masked, controlled trial in preterm infants 25–28 weeks gestation. Infants are eligible if managed on continuous positive airway pressure without prior intubation, and requiring FiO₂ ≥ 0.30 at an age ≤6 hours. Randomisation will be to receive exogenous surfactant (200 mg/kg poractant alfa) via the Hobart method, or sham treatment. Infants in both groups will thereafter remain on continuous positive airway pressure unless intubation criteria are reached (FiO₂ ≥ 0.45, unremitting apnoea or persistent acidosis). Primary outcome is the composite of death or physiological bronchopulmonary dysplasia, with secondary outcomes including incidence of death; major neonatal morbidities; durations of all modes of respiratory support and hospitalisation; safety of the Hobart method; and outcome at 2 years. A total of 606 infants will be enrolled. The trial will be conducted in >30 centres worldwide, and is expected to be completed by end-2017.

Discussion

Minimally-invasive surfactant therapy has the potential to ease the burden of respiratory morbidity in preterm infants. The trial will provide definitive evidence on the effectiveness of this approach in the care of preterm infants born at 25–28 weeks gestation.

Trial registration

Australia and New Zealand Clinical Trial Registry: ACTRN12611000916943; ClinicalTrials.gov: NCT02140580.

Lymphatic function is required prenatally for lung inflation at birth

Neonatal mice lacking lymphatic vessels due to loss of lymphangiogenic factor CCBE1 or VEGFR3 function fail to inflate their lungs, suggestive of respiratory failure in infants with congenital pulmonary lymphangiectasia.

Mammals must inflate their lungs and breathe within minutes of birth to survive. A key regulator of neonatal lung inflation is pulmonary surfactant, a lipoprotein complex which increases lung compliance by reducing alveolar surface tension (Morgan, 1971). Whether other developmental processes also alter lung mechanics in preparation for birth is unknown. We identify prenatal lymphatic function as an unexpected requirement for neonatal lung inflation and respiration. Mice lacking lymphatic vessels, due either to loss of the lymphangiogenic factor CCBE1 or VEGFR3 function, appear cyanotic and die shortly after birth due to failure of lung inflation. Failure of lung inflation is not due to reduced surfactant levels or altered development of the lung but is associated with an elevated wet/dry ratio consistent with edema. Embryonic studies reveal active lymphatic function in the late gestation lung, and significantly reduced total lung compliance in late gestation embryos that lack lymphatics. These findings reveal that lymphatic vascular function plays a previously unrecognized mechanical role in the developing lung that prepares it for inflation at birth. They explain respiratory failure in infants with congenital pulmonary lymphangiectasia, and suggest that inadequate late gestation lymphatic function may also contribute to respiratory failure in premature infants.

Fetal lung maturity testing: the end of an era

Respiratory distress syndrome is a major cause of neonatal morbidity and mortality that is most commonly caused by a deficiency in lung surfactant in premature infants. Therefore, laboratory tests were developed to measure the presence and/or concentration of lung surfactant in amniotic fluid in order to estimate maturity of the fetal lung. Although these tests were once widely employed, their utilization by physicians has decreased in recent years. Several studies have shown that demonstration of a mature fetal lung index by antenatal testing does not improve neonatal outcomes. Instead, decreased respiratory and nonrespiratory morbidities are most highly correlated with gestational age of the fetus. Therefore, fetal lung maturity testing may have passed the point of being clinically useful.

The use of surfactant in the neonatal period- the known aspects, those still under research and those which need to be investigated further

Respiratory distress syndrome is pulmoner insufficiency caused by the lack of surfactant and the main reason of morbidity and mortality in preterm infants. Mothers at high risk of preterm birth should be transferred to perinatal centers with experience for respiratory distress syndrome and ante-natal steroids should be given before 35 weeks' of gestational age. Surfactant treatment should be applied to babies with or at high risk for respiratory distress syndrome. Prophylaxis should be given to infants of <26 weeks of gestational age and to infants requiring entubation in the delivery room. Nasal continuous positive airway pressure should be considered in infants with complete steroid treatment and without entubation need. Early surfactant may be given if entubation is performed during follow-up. Natural forms of surfactant should be preferred when needed. If the infant is stable, early extubation and non-invasive respiratory support should be considered. In this review, the recent studies' current data about surfactant treatment will be discussed.

Lung ultrasound accuracy in respiratory distress syndrome and transient tachypnea of the newborn

BACKGROUND

Lung ultrasound (LUS) is a promising technique for the diagnosis of neonatal respiratory diseases. Preliminary data has shown a good sensitivity and specificity of LUS in the diagnosis of respiratory distress syndrome (RDS) and transient tachypnea of the newborn (TTN).

OBJECTIVE

The aim of this study was to calculate the sensitivity, specificity, and negative (NPV) and positive predictive value (PPV) of LUS for RDS and TTN, using an external reader blinded to the clinical condition.

DESIGN AND METHODS

Neonates with respiratory distress had a LUS within 1 h of admission. Images were uploaded and sent to the external reader, who made the ultrasound diagnosis according to the appearance of the images. The final clinical diagnosis was made according to all the available data, except LUS data. Sensitivity, specificity, PPV, and NPV were calculated considering the final clinical diagnosis as the gold standard.

RESULTS

Fifty-nine neonates were studied (mean gestational age: 33 ± 4 weeks, mean birth weight: 2,145 ± 757 g). Twenty-three infants had a final diagnosis of RDS and 30 of TTN. LUS showed a sensitivity of 95.6% and specificity of 94.4%, with a PPV of 91.6% and a NPV of 97.1% for RDS, and a sensitivity of 93.3% and specificity of 96.5% with a PPV of 96.5% and a NPV of 93.4% for TTN.

CONCLUSIONS

LUS showed high sensitivity and specificity in diagnosing RDS and TTN.

Surfactant replacement therapy for preterm and term neonates with respiratory distress

Respiratory failure secondary to surfactant deficiency is a major cause of morbidity and mortality in preterm infants. Surfactant therapy substantially reduces mortality and respiratory morbidity for this population. Secondary surfactant deficiency also contributes to acute respiratory morbidity in late-preterm and term neonates with meconium aspiration syndrome, pneumonia/sepsis, and perhaps pulmonary hemorrhage; surfactant replacement may be beneficial for these infants. This statement summarizes the evidence regarding indications, administration, formulations, and outcomes for surfactant-replacement therapy. The clinical strategy of intubation, surfactant administration, and extubation to continuous positive airway pressure and the effect of continuous positive airway pressure on outcomes and surfactant use in preterm infants are also reviewed.

[Premature infants bronchopulmonary dysplasia: past and present]

Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in premature infants. BPD was first described by Northway in 1967 as a chronic respiratory condition that developed in premature infants exposed to mechanical ventilation and high oxygen supplementation. DBP is currently defined by the need for supplemental oxygen at 28 days of life (mild BPD) and at the 36 weeks of post-menstrual age (moderate and severe BPD). With the advances of neonatal care, epidemiological characteristics and mechanisms of the disease as well as pathological characteristics and clinical course have profoundly changed within the last two decades, but still no effective curative treatment exists and BPD continue to occur among 10 to 20% of premature infants. Furthermore, BPD is a significant source of respiratory and neuro-cognitive morbidities. Thus, its treatment makes a considerable demand on health services. Regarding its pathophysiological mechanisms, it is now established that BPD is a complex disease combining genetic susceptibility and environmental injuries. The identification of genetic variants involved in BPD is a potential source of innovative development in terms of diagnosis and treatment. Indeed, no curative or effective prophylactic therapeutic exists and BPD treatment is currently symptomatic.

Short term outcomes after extreme preterm birth in England: comparison of two birth cohorts in 1995 and 2006 (the EPICure studies)

OBJECTIVE

To determine survival and neonatal morbidity for babies born between 22 and 26 weeks' gestation in England during 2006, and to evaluate changes in outcome since 1995 for babies born between 22 and 25 weeks' gestation.

DESIGN

Prospective national cohort studies.

SETTING

Maternity and neonatal units in England.

PARTICIPANTS

3133 births between 22 and 26 weeks' gestation in 2006; 666 admissions to neonatal units in 1995 and 1115 in 2006 of babies born between 22 and 25 weeks' gestation.

MAIN OUTCOME MEASURES

Survival to discharge from hospital, pregnancy and delivery outcomes, infant morbidity until discharge.

RESULTS

In 2006, survival of live born babies was 2% (n=3) for those born at 22 weeks' gestation, 19% (n=66) at 23 weeks, 40% (n=178) at 24 weeks, 66% (n=346) at 25 weeks, and 77% (n=448) at 26 weeks (P<0.001). At discharge from hospital, 68% (n=705) of survivors had bronchopulmonary dysplasia (receiving supplemental oxygen at 36 weeks postmenstrual age), 13% (n=135) had evidence of serious abnormality on cerebral ultrasonography, and 16% (n=166) had laser treatment for retinopathy of prematurity. For babies born between 22 and 25 weeks' gestation from March to December, the number of admissions for neonatal care increased by 44%, from 666 in 1995 to 959 in 2006. By 2006 adherence to evidence based practice associated with improved outcome had significantly increased. Survival increased from 40% to 53% (P<0.001) overall and at each week of gestation: by 9.5% (confidence interval -0.1% to 19%) at 23 weeks, 12% (4% to 20%) at 24 weeks, and 16% (9% to 23%) at 25 weeks. The proportions of babies surviving in 2006 with bronchopulmonary dysplasia, major cerebral scan abnormality, or weight and/or head circumference <-2 SD were similar to those in 1995, but the proportion treated for retinopathy of prematurity had increased from 13% to 22% (P=0.006). Predictors of mortality and morbidity were similar in both cohorts.

CONCLUSION

Survival of babies born between 22 and 25 weeks' gestation has increased since 1995 but the pattern of major neonatal morbidity and the proportion of survivors affected are unchanged. These observations reflect an important increase in the number of preterm survivors at risk of later health problems.

Pulmonary surfactant proteins and polymer combinations reduce surfactant inhibition by serum

Acute respiratory distress syndrome (ARDS) is an inflammatory condition that can be associated with capillary leak of serum into alveoli causing inactivation of surfactant. Resistance to inactivation is affected by types and concentrations of surfactant proteins, lipids, and polymers. Our aim was to investigate the effects of different combinations of these three components. A simple lipid mixture (DPPC/POPG) or a more complex lipid mixture (DPPC/POPC/POPG/cholesterol) was used. Native surfactant proteins SP-B and SP-C obtained from pig lung lavage were added either singly or combined at two concentrations. Also, non-ionic polymers polyethylene glycol and dextran and the anionic polymer hyaluronan were added either singly or in pairs with hyaluronan included. Non-ionic polymers work by different mechanisms than anionic polymers, thus the purpose of placing them together in the same surfactant mixture was to evaluate if the combination would show enhanced beneficial effects. The resulting surfactant mixtures were studied in the presence or absence of serum. A modified bubble surfactometer was used to evaluate surface activities. Mixtures that included both SP-B and SP-C plus hyaluronan and either dextran or polyethylene glycol were found to be the most resistant to inhibition by serum. These mixtures, as well as some with either SP-B or SP-C with combined polymers were as or more resistant to inactivation than native surfactant. These results suggest that improved formulations of lung surfactants are possible and may be useful in reducing some types of surfactant inactivation in treating lung injuries.

Surfactant use for premature infants with respiratory distress syndrome in three New York city hospitals: discordance of practice from a community clinician consensus standard

OBJECTIVE

To assess concordance with a locally developed standard of care for premature infants with respiratory distress syndrome (RDS) for whom the standard recommends surfactant treatment within 2 h of birth, and to examine the association between clinical, demographic, and hospital characteristics with discordance from the standard.

STUDY DESIGN

Retrospective cohort study of 773 infants weighing < or =1750 g born in any of the three New York City hospitals between 1999 and 2002.

RESULT

227 of the 773 infants (29%) met criteria for treatment according to the standard. Of these, 37% received surfactant by 2 h. By 4 h, 70% of infants who met the standard received surfactant. White infants were more likely to receive surfactant by 4 h (85%) than African American (61%) or Latino infants (67%). Multivariable logistic regression revealed significant odds ratios predicting discordance from the relaxed criteria (4 h) for African American race (4.10, 95% confidence interval: 1.30 to 13.00), 100 g of birth weight (odds ratio: 1.22, 95% confidence interval: 1.10 to 1.34), and hospital of birth.

CONCLUSION

Many infants with RDS failed to receive surfactant replacement therapy at 2 and 4 h after birth. African Americans and those born larger were less likely to receive surfactant. If these data can be generalized, there is a large opportunity to reduce infant morbidity from RDS and to reduce racial/ethnic disparities in birth outcomes by increasing the rate and speed with which surfactant is delivered to these infants.

Computed tomography assessment of exogenous surfactant-induced lung reaeration in patients with acute lung injury

Introduction

Previous randomized trials failed to demonstrate a decrease in mortality of patients with acute lung injury treated by exogenous surfactant. The aim of this prospective randomized study was to evaluate the effects of exogenous porcine-derived surfactant on pulmonary reaeration and lung tissue in patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS).

Methods

Twenty patients with ALI/ARDS were studied (10 treated by surfactant and 10 controls) in whom a spiral thoracic computed tomography scan was acquired before (baseline), 39 hours and 7 days after the first surfactant administration. In the surfactant group, 3 doses of porcine-derived lung surfactant (200 mg/kg/dose) were instilled in both lungs at 0, 12 and 36 hours. Each instillation was followed by recruitment maneuvers. Gas and tissue volumes were measured separately in poorly/nonaerated and normally aerated lung areas before and seven days after the first surfactant administration. Surfactant-induced lung reaeration was defined as an increase in gas volume in poorly/non-aerated lung areas between day seven and baseline compared to the control group.

Results

At day seven, surfactant induced a significant increase in volume of gas in poorly/non-aerated lung areas (320 ± 125 ml versus 135 ± 161 ml in controls, P = 0.01) and a significant increase in volume of tissue in normally aerated lung areas (189 ± 179 ml versus -15 ± 105 ml in controls, P < 0.01). PaO₂/FiO₂ ratio was not different between the surfactant treated group and control group after surfactant replacement.

Conclusions

Intratracheal surfactant replacement induces a significant and prolonged lung reaeration. It also induces a significant increase in lung tissue in normally aerated lung areas, whose mechanisms remain to be elucidated.

Trial registration

NCT00742482.

Immunomodulatory properties of exogenous surfactant in adult rat alveolar macrophages

BACKGROUND AND AIM

The study investigates the immune response of the lung alveolar macrophages in adult rats with intratracheal instillation of surfactant, isolated from porcine, rabbit and rat lung as well as the synthetic surfactant.

MATERIAL AND METHODS

Adult male rats were divided into five groups: Controls were instilled with buffer, similarly P-SF, R-SF, r-SF, and S-SF group of animals were instilled with porcine, rabbit, rat and synthetic surfactant, respectively.

RESULTS

After one month, IL-1beta secretions were found to be elevated in the supernatant of alveolar macrophages. Further, nitric oxide (NO) level was elevated with porcine and synthetic surfactant, while reactive oxygen species (ROS) generation was found to be inhibited significantly in all the treatment groups. Apoptoses were studied by using fluorescence dyes acridine orange/ethidium bromide, where percent of the apoptotic cells were found to be decreased in all the treated groups.

CONCLUSIONS

Exogenous surfactant elevates secretion of pro-inflammatory cytokine IL-1beta and also the NO as signaling molecule. The inhibitory effects of surfactants on ROS generation and on apoptosis may result from the interruption in the cell signaling pathway. In the treatment of respiratory distress syndrome, the anti-inflammatory response of surfactant may thus depend upon the specific preparation of the surfactant.

Overcoming rapid inactivation of lung surfactant: analogies between competitive adsorption and colloid stability

Lung surfactant (LS) is a mixture of lipids and proteins that line the alveolar air-liquid interface, lowering the interfacial tension to levels that make breathing possible. In acute respiratory distress syndrome (ARDS), inactivation of LS is believed to play an important role in the development and severity of the disease. This review examines the competitive adsorption of LS and surface-active contaminants, such as serum proteins, present in the alveolar fluids of ARDS patients, and how this competitive adsorption can cause normal amounts of otherwise normal LS to be ineffective in lowering the interfacial tension. LS and serum proteins compete for the air-water interface when both are present in solution either in the alveolar fluids or in a Langmuir trough. Equilibrium favors LS as it has the lower equilibrium surface pressure, but the smaller proteins are kinetically favored over multi-micron LS bilayer aggregates by faster diffusion. If albumin reaches the interface, it creates an energy barrier to subsequent LS adsorption that slows or prevents the adsorption of the necessary amounts of LS required to lower surface tension. This process can be understood in terms of classic colloid stability theory in which an energy barrier to diffusion stabilizes colloidal suspensions against aggregation. This analogy provides qualitative and quantitative predictions regarding the origin of surfactant inactivation. An important corollary is that any additive that promotes colloid coagulation, such as increased electrolyte concentration, multivalent ions, hydrophilic non-adsorbing polymers such as PEG, dextran, etc. added to LS, or polyelectrolytes such as chitosan, also promotes LS adsorption in the presence of serum proteins and helps reverse surfactant inactivation. The theory provides quantitative tools to determine the optimal concentration of these additives and suggests that multiple additives may have a synergistic effect. A variety of physical and chemical techniques including isotherms, fluorescence microscopy, electron microscopy and X-ray diffraction show that LS adsorption is enhanced by this mechanism without substantially altering the structure or properties of the LS monolayer.

Use of phosphatidylcholine for the correction of lower lid bulging due to prominent fat pads

BACKGROUND

Orbital fat tissue, while important in protecting the eye, can protrude during aging, making a patient look 'tired'. Surgical correction, although traditionally the treatment of choice, can lead to scarring. Phosphatidylcholine (PPT) has been shown to reduce the size of these fat pads after direct injection. The compound, licensed in Europe for intravenous treatment of fat embolism, has recently gained interest for reducing localized fat by subcutaneous injection. However, there is a dearth of clinical data relating to efficacy and side effects.

OBJECTIVE

An open-label study was conducted in 21 subjects with the goal of reducing the infraorbital fat pad size. The objective of this study was to evaluate the efficacy and safety of PPT after injection into infraorbital fat pads.

METHODS

Twenty-one subjects were injected with 0.4 ml of PPT every 6 weeks to reduce prominent infraorbital fat pads. Pre- and post-treatment digital photographs were taken to document efficacy. In addition, side effects were recorded on a follow-up questionnaire.

RESULTS

In all, 74% of the subjects showed significant improvement after two to three treatments. Five of the enrolled subjects (23%) were non-responsive after two or more procedures and their treatment was discontinued. None of the patients had adverse side effects other than mild burning, erythema and swelling at the injection site. Nearly every patient maintained the results with no evidence of tissue damage after 6 months.

CONCLUSION

PPT injection into infraorbital fat pads resulted in a satisfactory cosmetic effect in most treated subjects. Most subjects required more than one treatment. This simple, office-based treatment provides a non-surgical alternative to patients with prominent infraorbital fat pads. More clinical data are required to fully assess the long-term safety and efficacy of this procedure.

Inhaled nitric oxide in the neonate

Inhaled nitric oxide (iNO) has been used to treat both term and preterm infants with respiratory failure. Term infants with persistent pulmonary hypertension, either as a primary cause or secondary to other disease processes, respond to iNO with improvement in oxygenation indices and a decreased need for extracorporeal membrane oxygenation. Infants with congenital diaphragmatic hernia are the exception to this finding, with little clinical benefit observed with iNO treatment. Although respiratory disease in preterm infants has a component of increased pulmonary vascular resistance, little benefit of iNO administration has been observed in premature infants either early in their course or later as a treatment to prevent the evolution of chronic lung disease.