Early surfactant guided by lamellar body counts on gastric aspirate in very preterm infants

Gastric Aspirate Phosphatidylcholine Species in Preterm Neonates Receiving Aerosolized Surfactant

OBJECTIVE

To characterize phosphatidylcholine (PC) molecular species in serial gastric aspirates as biomarkers for lung maturity, delivery of aerosolized surfactant (AS), and need for intubation.

METHODS

In a phase II clinical trial of aerosolized surfactant in preterm neonates with respiratory distress syndrome receiving noninvasive ventilation, infants received a maximum of 2 doses of nebulized beractant. Gastric aspirates were collected before and after each dose and were analyzed for PCs using liquid chromatography mass spectrometry.

RESULTS

Of 149 infants enrolled, gastric aspirates were obtained before (n = 91) and after (n = 94) dose 1, and before (n = 56) and after (n = 57) dose 2 of nebulized beractant. The mean ± SD values of birthweight, gestational age, and age at collection of baseline gastric aspirate were 1.7 ± 0.6 kg, 31.7 ± 2.8 weeks, and 5.5 ± 1.7 hours, respectively. The most abundant PC in beractant and gastric aspirates was PC(16:0/16:0). Advancing gestational age and number of antenatal corticosteroid doses predicted increased gastric aspirate PC(16:0/16:0), whereas maternal diabetes predicted a decrease. Several PCs increased significantly (P < .05) after nebulized beractant, consistent with effective aerosol delivery. Infants who received intubation within 72 hours of birth were more likely to have lower PC(16:0/16:0) levels in baseline gastric aspirates compared with those who did not (P = .024).

CONCLUSIONS

PC molecular species in gastric aspirates of preterm neonates are potentially novel and precise biomarkers to assess lung maturity, aerosol delivery, and need for endotracheal intubation.

Surfactant status assessment and personalized therapy for surfactant deficiency or dysfunction

Surfactant is a pivotal neonatal drug used both for respiratory distress syndrome due to surfactant deficiency and for more complex surfactant dysfunctions (such as in case of neonatal acute respiratory distress syndrome). Despite its importance, indications for surfactant therapy are often based on oversimplified criteria. Lung biology and modern monitoring provide several diagnostic tools to assess the patient surfactant status and they can be used for a personalized surfactant therapy. This is desirable to improve the efficacy of surfactant treatment and reduce associated costs and side effects. In this review we will discuss these diagnostic tools from a pathophysiological and multi-disciplinary perspective, focusing on the quantitative or qualitative surfactant assays, lung mechanics or aeration measurements, and gas exchange metrics. Their biological and technical characteristics are described with practical information for clinicians. Finally, available evidence-based data are reviewed, and the diagnostic accuracy of the different tools is compared. Lung ultrasound seems the most suitable tool for assessing the surfactant status, while some other promising tests require further research and/or development.

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.

Clinical decision thresholds for surfactant administration in preterm infants: a systematic review and network meta-analysis

Background

The ideal threshold at which surfactant administration in preterm neonates with respiratory distress syndrome (RDS) is most beneficial is contentious. The aim of this systematic review was to determine the optimal clinical criteria to guide surfactant administration in preterm neonates with RDS.

Methods

The systematic review was registered in PROSPERO (CRD42022309433). Medline, Embase, CENTRAL and CINAHL were searched from inception till 16th May 2023. Only randomized controlled trials (RCTs) were included. A Bayesian random effects network meta-analysis (NMA) evaluating 33 interventions was performed. The primary outcome was requirement of invasive mechanical ventilation (IMV) within 7 days of life.

Findings

58 RCTs were included. In preterm neonates ≤30 weeks after adjusting for the confounding factor of modality of surfactant administration, an arterial alveolar oxygen tension ratio (aAO2) <0.36 (FiO2: 37-55%) was ranked the best threshold for decreasing the risk of IMV, very low certainty. Further, surfactant administration at an FiO2 40-45% possibly decreased mortality compared to rescue treatment when respiratory failure was diagnosed, certainty very low. The reasonable inference that could be drawn from these findings is that surfactant administration may be considered in preterm neonates of ≤30 weeks' with RDS requiring an FiO2 ≥ 40%. There was insufficient evidence for the comparison of FiO2 thresholds: 30% vs. 40%. The evidence was sparse for surfactant administration guided by lung ultrasound. For the sub-group >30 weeks, nebulized surfactant administration at an FiO2 < 30% possibly increased the risk of IMV compared to Intubate-Surfactant-Extubate at FiO2 < 30% and 40%, and less invasive surfactant administration at FiO2 40%, certainty very low.

Interpretation

Surfactant administration may be considered in preterm neonates of ≤30 weeks' with RDS if the FiO2 requirement is ≥40%. Future trials are required comparing lower FiO2 thresholds of 30% vs. 40% and that guided by lung ultrasound.

Funding

None.

Surfactant therapy in late preterm and term neonates with respiratory distress syndrome: a systematic review and meta-analysis

BACKGROUND

There are no evidence-based recommendations for surfactant use in late preterm (LPT) and term infants with respiratory distress syndrome (RDS).

OBJECTIVE

To investigate the safety and efficacy of surfactant in LPT and term infants with RDS.

METHODS

Systematic review, meta-analysis and evidence grading.

INTERVENTIONS

Surfactant therapy versus standard of care.

MAIN OUTCOME MEASURES

Mortality and requirement for invasive mechanical ventilation (IMV).

RESULTS

Of the 7970 titles and abstracts screened, 17 studies (16 observational studies and 1 randomised controlled trial (RCT)) were included. Of the LPT and term neonates with RDS, 46% (95% CI 40% to 51%) were treated with surfactant. We found moderate certainty of evidence (CoE) from observational studies evaluating infants supported with non-invasive respiratory support (NRS) or IMV that surfactant use may be associated with a decreased risk of mortality (OR 0.45, 95% CI 0.32 to 0.64). Very low CoE from observational trials in which surfactant was administered at FiO₂ >0.30-0.40 to infants on Continuous Positive Airway Pressure (CPAP) indicated that surfactant did not decrease the risk of IMV (OR 1.20, 95% CI 0.40 to 3.56). Very low to low CoE from the RCT and observational trials showed that surfactant use was associated with a significant decrease in risk of air leak, persistent pulmonary hypertension of the newborn (PPHN), duration of IMV, NRS and hospital stay.

CONCLUSIONS

Current evidence base on surfactant therapy in LPT and term infants with RDS indicates a potentially decreased risk of mortality, air leak, PPHN and duration of respiratory support. In view of the low to very low CoE and widely varying thresholds for deciding on surfactant replacement in the included studies, further trials are needed.

Oscillatory mechanics at birth for identifying infants requiring surfactant: a prospective, observational trial

BACKGROUND

Current criteria for surfactant administration assume that hypoxia is a direct marker of lung-volume de-recruitment. We first introduced an early, non-invasive assessment of lung mechanics by the Forced Oscillation Technique (FOT) and evaluated its role in predicting the need for surfactant therapy.

OBJECTIVES

To evaluate whether lung reactance (Xrs) assessment by FOT within 2 h of birth identifies infants who would need surfactant within 24 h; to eventually determine Xrs performance and a cut-off value for early detection of infants requiring surfactant.

METHODS

We conducted a prospective, observational, non-randomized study in our tertiary NICU in Milan. Eligible infants were born between 27+0 and 34+6 weeks' gestation, presenting respiratory distress after birth.

EXCLUSION CRITERIA

endotracheal intubation at birth, major malformations participation in other interventional trials, parental consent denied. We assessed Xrs during nasal CPAP at 5 cmH2O at 10 Hz within 2 h of life, recording flow and pressure tracing through a Fabian Ventilator for off-line analysis. Clinicians were blinded to FOT results.

RESULTS

We enrolled 61 infants, with a median [IQR] gestational age of 31.9 [30.3; 32.9] weeks and birth weight 1490 [1230; 1816] g; 2 infants were excluded from the analysis for set-up malfunctioning. 14/59 infants received surfactant within 24 h. Xrs predicted surfactant need with a cut-off - 33.4 cmH2O*s/L and AUC-ROC = 0.86 (0.76-0.96), with sensitivity 0.85 and specificity 0.83. An Xrs cut-off value of - 23.3 cmH2O*s/L identified infants needing surfactant or respiratory support > 28 days with AUC-ROC = 0.89 (0.81-0.97), sensitivity 0.86 and specificity 0.77. Interestingly, 12 infants with Xrs < - 23.3 cmH2O*s/L (i.e. de-recruited lungs) did not receive surfactant and subsequently required prolonged respiratory support.

CONCLUSION

Xrs assessed within 2 h of life predicts surfactant need and respiratory support duration in preterm infants. The possible role of Xrs in improving the individualization of respiratory management in preterm infants deserves further investigation.

Techniques to evaluate surfactant activity for a personalized therapy of RDS neonates

According to both European and American Guidelines, preterm neonates have to be treated by nasal continuous air pressure (CPAP) early in the delivery room. The administration of surfactant should be reserved only for babies with respiratory distress syndrome (RDS) with increased oxygen requirement, according to different thresholds of FiO₂. However, these oxygenation thresholds do not fully take into consideration the lung physiopathology and mechanics or the lung surfactant biology of RDS neonates. Since surfactant replacement therapy (SRT) seems to be more effective if it is initiated within the first 3 hours after birth, the use of a reliable bench-to-bedside biological test able to predict as soon as possible the necessity of SRT will help optimise individualised therapies and personalise the actual collective strategy used to treat RDS neonates. With this in mind, in the present review several quantitative and qualitative biological tests to assess the surfactant status in RDS neonates are introduced as potential candidates for the early prediction of SRT requirement, summarising the state-of-the-art in the evaluation of surfactant activity.

Bronchopulmonary dysplasia predicted at birth by artificial intelligence

Aim

To develop a fast bedside test for prediction and early targeted intervention of bronchopulmonary dysplasia (BPD) to improve the outcome.

Methods

In a multicentre study of preterm infants with gestational age 24‐31 weeks, clinical data present at birth were combined with spectral data of gastric aspirate samples taken at birth and analysed using artificial intelligence. The study was designed to develop an algorithm to predict development of BPD. The BPD definition used was the consensus definition of the US National Institutes of Health: Requirement of supplemental oxygen for at least 28 days with subsequent assessment at 36 weeks postmenstrual age.

Results

Twenty‐six (43%) of the 61 included infants developed BPD. Spectral data analysis of the gastric aspirates identified the most important wave numbers for classification and surfactant treatment, and birth weight and gestational age were the most important predictive clinical data. By combining these data, the resulting algorithm for early diagnosis of BPD had a sensitivity of 88% and a specificity of 91%.

Conclusion

A point‐of‐care test to predict subsequent development of BPD at birth has been developed using a new software algorithm allowing early targeted intervention of BPD which could improve the outcome.

Personalized Medicine for the Management of RDS in Preterm Neonates

Continuous positive airway pressure and surfactant represent the first- and second-line treatment for respiratory distress syndrome in preterm neonates, as European and American guidelines, since 2013 and 2014, respectively, started to recommend surfactant replacement only when continuous positive airway pressure fails. These recommendations, however, are not personalized to the individual physiopathology. Simple clinical algorithms may have improved the diffusion of neonatal care, but complex medical issues can hardly be addressed with simple solutions. The treatment of respiratory distress syndrome is a complex matter and can be only optimized with personalization. We performed a review of tools to individualize the management of respiratory distress syndrome based on physiopathology and actual patients' need, according to precision medicine principles. Advanced oxygenation metrics, lung ultrasound, electrical impedance tomography, and both quantitative and qualitative surfactant assays were examined. When these techniques were investigated with diagnostic accuracy studies, reliability measures have been meta-analysed. Amongst all these tools, quantitative lung ultrasound seems the more developed for the widespread use and has a higher diagnostic accuracy (meta-analytical AUC = 0.952 [95% CI: 0.951-0.953]). Surfactant adsorption (AUC = 0.840 [95% CI: 0.824-0.856]) and stable microbubble test (AUC = 0.800 [95% CI: 0.788-0.812]) also have good reliability, but need further industrial development. We advocate for a more accurate characterization and a personalized approach of respiratory distress syndrome. With the above-described currently available tools, it should be possible to personalize the treatment of respiratory distress syndrome according to physiopathol-ogy.

Predicting respiratory distress syndrome at birth using a fast test based on spectroscopy of gastric aspirates: 2. Clinical part

AIM

To evaluate the accuracy of our new rapid point-of-care (POC) test for lung maturity. The method as we describe in an accompanying article was developed with the purpose of improving the outcome from respiratory distress syndrome (RDS). The test enables the delivery of surfactant in infants with immature lungs already at birth and ensures that infants with mature lungs are not treated unnecessarily.

METHODS

Fresh gastric aspirate (GAS) was sampled at birth in a cohort of preterm infants with gestational ages ranging between 24 and 31 completed weeks for lung surfactant measurement as lecithin-sphingomyelin ratio (L/S). L/S was prospectively compared with RDS development. The clinical outcome was blinded for the investigators of L/S. The time for analysis was <15 minutes.

RESULTS

GAS was obtained from 72 infants. Forty-four (61%) developed RDS. The cut-off for L/S was 3.05; predicting RDS with a sensitivity of 91% and specificity of 79%.

CONCLUSION

The new improved spectroscopic L/S method of lung maturity on GAS has high sensitivity. The method is designed for use as a POC test at birth, and a spectroscopic prototype has been developed for bedside use. Clinical trials with this new lung maturity test are planned.

Club cell secretory protein (CC16) in gastric fluid at birth and subsequent lung disease in preterm infants

BACKGROUND

Club cell secretory protein (CC16) probably has a role in protecting the lung from inflammation.

AIM

To evaluate if low levels of CC16 in gastric fluid at birth, reflecting low levels of CC16 in the lung, would be associated with lung inflammation and respiratory morbidity.

METHODS

A study of 64 infants with mean gestational age 26.1 weeks. CC16 was analyzed in gastric fluid at birth. CC16, pro-inflammatory cytokines, and MMP-9 were analyzed in tracheal aspirate within 24 h from birth.

RESULTS

CC16 in gastric fluid increased with gestational age (P = 0.033). Lower concentrations of CC16 in gastric fluid at birth were associated with higher concentrations of IL-1β (P = 0.028), TNF-α (P = 0.034), and MMP-9 (P = 0.015) in tracheal aspirate. Infants who needed mechanical ventilation at 24 and 72 h of age had lower CC16 in gastric fluid than those not ventilated at these ages (P = 0.011 and P = 0.024, respectively). Lower CC16 in gastric fluid was associated with higher FiO₂ at 6 h (P = 0.009), higher PaCO₂ at 24 h (P = 0.03), more ventilator days (P = 0.012) and more days with supplemental oxygen (P = 0.03). Infants who had either died or were still treated with supplemental oxygen at 36 weeks postmenstrual age had lower CC16 in gastric fluid than infants with none of these outcomes (P = 0.049).

CONCLUSION

A low CC16 concentration in gastric fluid at birth was associated with increased inflammation in the trachea within the first 24 h of life and with more need for respiratory support in the neonatal period.

Hypothermia at neonatal intensive care unit admission was not associated with respiratory disease or death in very preterm infants

AIM

This study investigated the association between hypothermia and respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD) or death in very preterm infants admitted to a Danish neonatal intensive care unit (NICU).

METHODS

We studied 675 infants born at Aalborg University Hospital before 32 weeks and admitted to the NICU from April 1997 to December 2011. Hypothermia was defined as a core temperature of <36.5°C on admission. The primary outcome was severe RDS or death within the first three days of life, and the secondary outcome was BPD or death before 36 postmenstrual weeks. The multivariable logistic regression was adjusted for early-onset infection, gestational age, Apgar score, sex, treatment year and birth weight.

RESULTS

Infants with hypothermia had a twofold increase (OR) in the odds for RDS or death (2.03), but the adjusted OR was not statistically significant (1.36). They also demonstrated a twofold increase (OR) in the odds for BPD or death (2.28), but again the adjusted OR was not statistically significant (1.03).

CONCLUSION

After adjusting for confounders, we found that the association between hypothermia on admission to the NICU and RDS or death, or BPD or death was statistically insignificant.

Surfactant phospholipid composition of gastric aspirate samples differs between male and female very preterm infants

BackgroundAmong preterm infants, males have a greater incidence of respiratory distress and death than do females born at the same gestational age, likely due to sex-related differences in lung maturation. Our aim was to determine whether surfactant phospholipid composition differs between male and female preterm infants.MethodsGastric aspirate samples from male and female infants born between 25 and 30 weeks of gestation at The Royal Women's Hospital, Melbourne, Australia, were collected within 1 h after birth. Phospholipid composition was analyzed by electrospray ionization tandem mass spectrometry.ResultsPreterm males had higher proportions of total phosphatidylinositol (PI) and phosphatidylserine 36:2, lower proportions of total sphingomyelin (S) and S 33:1 and 35:1, and a greater phosphatidylcholine (PC)/S ratio than did females. The proportions of PC 30:0, PC 34:0, PC 34:2, PC 36:2, PC 36:3, and PC 38:2 differed between the sexes at different gestational weeks of birth; the proportion of PC 32:0 (dipalmitoylphosphatidylcholine) in males was lower than that in females at 25 weeks of gestation but higher at 27 weeks.ConclusionPhospholipid composition in pulmonary surfactant is different between male and female preterm infants of the same gestational age, which may contribute to the increased risk for respiratory morbidities in one sex.

Rapid test for lung maturity, based on spectroscopy of gastric aspirate, predicted respiratory distress syndrome with high sensitivity

AIM

Respiratory distress syndrome (RDS) is a major cause of mortality and morbidity in premature infants. By the time symptoms appear, it may already be too late to prevent a severe course, with bronchopulmonary dysplasia or mortality. We aimed to develop a rapid test of lung maturity for targeting surfactant supplementation.

METHODS

Concentrations of the most surface-active lung phospholipid dipalmitoylphosphatidylcholine and sphingomyelin in gastric aspirates from premature infants were measured by mass spectrometry and expressed as the lecithin/sphingomyelin ratio (L/S). The same aspirates were analysed with mid-infrared spectroscopy. Subsequently, L/S was measured in gastric aspirates and oropharyngeal secretions from another group of premature infants using spectroscopy and the results were compared with RDS development. The 10-minute analysis required 10 μL of aspirate.

RESULTS

An L/S algorithm was developed based on 89 aspirates. Subsequently, gastric aspirates were sampled in 136 infants of 24-31 weeks of gestation and 61 (45%) developed RDS. The cut-off value of L/S was 2.2, sensitivity was 92%, and specificity was 73%. In 59 cases, the oropharyngeal secretions had less valid L/S than gastric aspirate results.

CONCLUSION

Our rapid test for lung maturity, based on spectroscopy of gastric aspirate, predicted RDS with high sensitivity.

European Consensus Guidelines on the Management of Respiratory Distress Syndrome - 2016 Update

Advances in the management of respiratory distress syndrome (RDS) ensure that clinicians must continue to revise current practice. We report the third update of the European Guidelines for the Management of RDS by a European panel of expert neonatologists including input from an expert perinatal obstetrician based on available literature up to the beginning of 2016. Optimizing the outcome for babies with RDS includes consideration of when to use antenatal steroids, and good obstetric practice includes methods of predicting the risk of preterm delivery and also consideration of whether transfer to a perinatal centre is necessary and safe. Methods for optimal delivery room management have become more evidence based, and protocols for lung protection, including initiation of continuous positive airway pressure and titration of oxygen, should be implemented from soon after birth. Surfactant replacement therapy is a crucial part of the management of RDS, and newer protocols for surfactant administration are aimed at avoiding exposure to mechanical ventilation, and there is more evidence of differences among various surfactants in clinical use. Newer methods of maintaining babies on non-invasive respiratory support have been developed and offer potential for greater comfort and less chronic lung disease. As technology for delivering mechanical ventilation improves, the risk of causing lung injury should decrease although minimizing the time spent on mechanical ventilation using caffeine and if necessary postnatal steroids are also important considerations. Protocols for optimizing the general care of infants with RDS are also essential with good temperature control, careful fluid and nutritional management, maintenance of perfusion and judicious use of antibiotics all being important determinants of best outcome.

UGT1A1*28 Genotypes and Respiratory Disease in Very Preterm Infants: A Cohort Study

BACKGROUND

Respiratory disease in the very preterm infant is frequent and often severe. Bilirubin is both a potent neurotoxin and antioxidant, and may have a clinical impact on preterm respiratory disease. The Gilbert genotype, the UGT1A1*28 allele, is the major known genetic cause of variation in bilirubin.

OBJECTIVES

To study the association between respiratory disease in the very preterm infant and the UGT1A1*28 allele.

METHODS

This is a cohort study of 1,354 very preterm infants (gestational age <32 weeks) born in Jutland, Denmark in 1997-2011. Genotypes were obtained from the Danish Neonatal Screening Biobank, and clinical information was obtained from the databases of two tertiary neonatal intensive care units. Outcomes were the need for surfactant therapy, any need for and duration of supplementary oxygen and bronchopulmonary dysplasia (BPD).

RESULTS

Per UGT1A1*28 allele, odds were increased for any need of supplementary oxygen (odds ratio 1.26; 1.05-1.50) and for BPD (odds ratio 1.71; 1.23-2.39), the need of supplementary oxygen increased by 6.38 days (1.87-10.89), and chance per day of no longer needing supplementary oxygen was reduced (hazard rate 0.84; 0.76-0.93). No effect was observed for need of surfactant treatment (odds ratio 1.08; 0.91-1.28). Hardy-Weinberg equilibrium was unlikely for the cohort (p < 0.012). This could be explained by death prior to genotype sampling. In tests of robustness this failed to explain the primary results.

CONCLUSIONS

Compared to the common genotype, UGT1A1*28 genotypes were associated with an increased need of oxygen supplementation and risk of BPD in very preterm newborns.

A unique story in neonatal research: the development of a porcine surfactant

Surfactant deficiency was identified as the cause of respiratory distress syndrome (RDS) as long ago as 1959. Trials of surfactant replacement in the 1960s were unsuccessful because the preparations used contained only phospholipids and they were administered inefficiently by nebulization. In the 1970s Bengt Robertson and Göran Enhörning showed that natural surfactant, containing both phospholipids and proteins, could ameliorate the signs of RDS in immature rabbits. In the 1980s Bengt Robertson and Tore Curstedt developed a porcine surfactant, Curosurf (named after their surnames), which was effective in immature animals and was used in a pilot clinical trial beginning in 1983. Subsequent randomized clinical trials were planned a year later by Bengt Robertson, Tore Curstedt and Henry Halliday, and the first trial was begun in 1985. This showed that Curosurf reduced pulmonary air leaks and neonatal mortality in preterm infants with severe RDS. A second trial, coordinated by Christian Speer, demonstrated that multiple doses of Curosurf were more effective than a single dose. Subsequent trials conducted by the Collaborative European Multicenter Study Group, which included among others Guilio Bevilacqua, Janna Koppe, Ola Saugstad, Nils Svenningsen and Jean-Pierre Relier, showed that early treatment was more effective than later administration and that infants treated at birth had similar neurodevelopmental status to untreated controls at a corrected age of 2 years. Members of the Collaborative European Multicenter Study Group in Denmark and Sweden performed studies to demonstrate the benefits of a combination of surfactant treatment and early continuous positive airway pressure. Curosurf has also been compared with several synthetic and natural surfactants, and at a dose of 200 mg/kg Curosurf has been shown to be superior to either Survanta or Curosurf used at a dose of 100 mg/kg. Recently, new-generation synthetic surfactants containing both phospholipids and proteins have been developed. After preclinical testing, CHF5633 (developed by Tore Curstedt and Jan Johansson in collaboration with Chiesi Farmaceutici) has undergone a preliminary first study in humans under the guidance of Christian Speer. If effective, this new surfactant preparation could revolutionize the treatment of preterm infants worldwide as it could be made consistently and safely in almost unlimited quantities. This story of a porcine surfactant preparation has been truly remarkable, and many thousands of preterm babies worldwide are now alive and well because of it.