Technique for intrapartum administration of surfactant without requirement for an endotracheal tube

Avoidance of mechanical ventilation by surfactant treatment of spontaneously breathing preterm infants (AMV): an open-label, randomised, controlled trial

BACKGROUND

Surfactant is usually given to mechanically ventilated preterm infants via an endotracheal tube to treat respiratory distress syndrome. We tested a new method of surfactant application to spontaneously breathing preterm infants to avoid mechanical ventilation.

METHOD

In a parallel-group, randomised controlled trial, 220 preterm infants with a gestational age between 26 and 28 weeks and a birthweight less than 1·5 kg were enrolled in 12 German neonatal intensive care units. Infants were independently randomised in a 1:1 ratio with variable block sizes, to standard treatment or intervention, and randomisation was stratified according to centre and multiple birth status. Masking was not possible. Infants were stabilised with continuous positive airway pressure and received rescue intubation if necessary. In the intervention group, infants received surfactant treatment during spontaneous breathing via a thin catheter inserted into the trachea by laryngoscopy if they needed a fraction of inspired oxygen more than 0·30. The primary endpoint was need for any mechanical ventilation, or being not ventilated but having a partial pressure of carbon dioxide more than 65 mm Hg (8·6 kPa) or a fraction of inspired oxygen more than 0·60, or both, for more than 2 h between 25 h and 72 h of age. Analysis was by intention to treat. This study is registered, number ISRCTN05025922.

FINDINGS

108 infants were assigned to the intervention group and 112 infants to the standard treatment group. All infants were analysed. On day 2 or 3 after birth, 30 (28%) infants in the intervention group were mechanically ventilated versus 51 (46%) in the standard treatment group (number needed to treat 6, 95% CI 3-20, absolute risk reduction 0·18, 95% CI 0·30-0·05, p=0·008). 36 (33%) infants in the intervention group were mechanically ventilated during their stay in the hospital compared with 82 (73%) in the standard treatment group (number needed to treat: 3, 95% CI 2-4, p<0·0001). The intervention group had significantly fewer median days on mechanical ventilation, (0 days. IQR 0-3 vs 2 days, 0-5) and a lower need for oxygen therapy at 28 days (30 infants [30%] vs 49 infants [45%], p=0·032) compared with the standard treatment group. We recorded no differences between groups for mortality (seven deaths in the intervention group vs five in the standard treatment group) and serious adverse events (21 vs 28).

INTERPRETATION

The application of surfactant via a thin catheter to spontaneously breathing preterm infants receiving continuous positive airway pressure reduces the need for mechanical ventilation.

FUNDING

German Ministry of Research and Technology, University of Lübeck, and Chiesi Pharmaceuticals.

Laryngeal mask airway surfactant administration for prevention of morbidity and mortality in preterm infants with or at risk of respiratory distress syndrome

BACKGROUND

Laryngeal mask airway (LMA) administration is one way of delivering surfactant to the infant lung, with the potential benefit of avoiding endotracheal intubation and ventilation, ventilator induced lung injury and bronchopulmonary dysplasia (BPD).

OBJECTIVES

To determine the effect of LMA surfactant administration either as prophylaxis or treatment compared to placebo, no treatment, or intratracheal surfactant administration on morbidity and mortality in preterm infants with, or at risk of, respiratory distress syndrome (RDS).

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library, October 2010), MEDLINE and PREMEDLINE (1950 to October 2010), EMBASE (1980 to October 2010) and CINAHL (1982 to October 2010). We also searched proceedings of scientific meetings, clinical trial registries, Google Scholar and reference lists of identified studies, as well as contacting expert informants and surfactant manufacturers.

SELECTION CRITERIA

Randomised, cluster-randomised or quasi-randomised controlled trials of laryngeal mask surfactant administration compared to placebo, no treatment, or other routes of administration (nebulised, pharyngeal instillation of surfactant before the first breath, thin endotracheal catheter surfactant administration or intratracheal surfactant instillation) on morbidity and mortality in preterm infants at risk of RDS. We considered published, unpublished and ongoing trials.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility and quality, and extracted data.

MAIN RESULTS

We found no studies of prophylactic or early LMA surfactant administration. A single small study of late rescue LMA surfactant was identified as eligible for inclusion. The study enrolled 26 preterm infants born ≥ 1200 g with RDS on continuous positive airway pressure (nCPAP). LMA surfactant administration compared to no treatment resulted in a reduction in mean FiO(2) required to maintain oxygen saturation between 88% and 92% for 12 hours after the intervention. No significant difference was reported in subsequent mechanical ventilation and endotracheal surfactant, pneumothorax, days on intermittent positive airway pressure (IPPV), and days on IPPV or oxygen.

AUTHORS' CONCLUSIONS

There is evidence from a single small trial that LMA surfactant administration in preterm infants ≥ 1200 g with established RDS may have a short term effect in reducing oxygen requirements although the study is underpowered to detect important clinical effects. Adequately powered trials are required to determine the effect of LMA surfactant administration for prevention or treatment of RDS in preterm infants. LMA surfactant administration should be limited to clinical trials.

Pharyngeal instillation of surfactant before the first breath for prevention of morbidity and mortality in preterm infants at risk of respiratory distress syndrome

BACKGROUND

Intrapartum pharyngeal instillation of surfactant before the first breath may result in surfactant administration to the infant lung, with the potential benefit of avoiding endotracheal intubation and ventilation, ventilator induced lung injury and bronchopulmonary dysplasia.

OBJECTIVES

To determine the effect of pharyngeal instillation of surfactant before the first breath compared to placebo, no treatment or intratracheal surfactant administration followed by intermittent positive pressure ventilation (IPPV) on morbidity and mortality in preterm infants at risk of respiratory distress syndrome (RDS).

SEARCH STRATEGY

Searches were made of CENTRAL (The Cochrane Library, to September 2010), MEDLINE and PREMEDLINE (1950 to September 2010), EMBASE (1980 to 2010) and CINAHL (1982 to 2010). This strategy was supplemented by searches of proceedings of scientific meetings, Google Scholar and reference lists of identified studies, as well as contact with expert informants and surfactant manufacturers.

SELECTION CRITERIA

Published, unpublished and ongoing randomised controlled or quasi-randomised trials (using individual or cluster allocation) of pharyngeal instillation of surfactant before the first breath compared to placebo or no treatment, or intratracheal surfactant instillation followed by IPPV, on morbidity and mortality in preterm infants at risk of RDS.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility and quality.

MAIN RESULTS

No published, unpublished or ongoing trials that met the inclusion criteria for this review were found.

AUTHORS' CONCLUSIONS

There were no data from randomised controlled or quasi-randomised trials that evaluated the effect of intrapartum instillation of pharyngeal surfactant before the first breath. Evidence from animal and observational human studies suggest that pharyngeal instillation of surfactant before the first breath is potentially safe, feasible and may be effective. Well designed trials are needed.

Surfactant replacement therapy in developing countries

BACKGROUND

Since the first successful report of surfactant replacement therapy (SRT) in infants with respiratory distress syndrome (RDS), numerous randomized clinical trials have shown that SRT reduces mortality and morbidity in RDS. Surfactant is now a standard therapy for RDS. However, the use of SRT in the developing world has been extremely slow.

OBJECTIVE

The objective of this paper is to review the published information regarding the usage and barriers encountered in the use of SRT in developing countries.

METHODS

We reviewed the available literature and also gathered information from countries with a high burden of prematurity and high infant mortality rate regarding replacement therapy and the barriers to use of SRT.

RESULTS

We reviewed the available literature and found that developing countries bear a high burden of prematurity and RDS that contribute to high neonatal and infant mortality rates. Based on the effectiveness of SRT in RDS, surfactant preparations were included in the Essential Drug List of WHO in 2008. However, the use of SRT in developing countries is still limited because of (1) high cost, (2) lack of skilled personnel to administer SRT, and (3) lack of support systems after the SRT. The cost of SRT may exceed the per-capita GNP (300-500 USD) in some countries. Data from India and South Africa suggests that SRT is limited to rescue therapy in babies with potential for better survival, usually >28 weeks' gestation. Recent studies show that infants with RDS respond well to initial continuous positive airway pressure (CPAP) followed by SRT for those who do not respond.

CONCLUSIONS

In developing countries, CPAP may be used as the primary mode of management of RDS. SRT may be reserved for non-responders to CPAP. Alternate simpler methods of delivery of surfactant (aerosol technique) are also being explored. There is a need for further studies to develop and assess efficient and less expensive methods of application of CPAP and SRT in developing countries.

Global report on preterm birth and stillbirth (3 of 7): evidence for effectiveness of interventions

INTRODUCTION

Interventions directed toward mothers before and during pregnancy and childbirth may help reduce preterm births and stillbirths. Survival of preterm newborns may also be improved with interventions given during these times or soon after birth. This comprehensive review assesses existing interventions for low- and middle-income countries (LMICs).

METHODS

Approximately 2,000 intervention studies were systematically evaluated through December 31, 2008. They addressed preterm birth or low birth weight; stillbirth or perinatal mortality; and management of preterm newborns. Out of 82 identified interventions, 49 were relevant to LMICs and had reasonable amounts of evidence, and therefore selected for in-depth reviews. Each was classified and assessed by the quality of available evidence and its potential to treat or prevent preterm birth and stillbirth. Impacts on other maternal, fetal, newborn or child health outcomes were also considered. Assessments were based on an adaptation of the Grades of Recommendation Assessment, Development and Evaluation criteria.

RESULTS

Most interventions require additional research to improve the quality of evidence. Others had little evidence of benefit and should be discontinued. The following are supported by moderate- to high-quality evidence and strongly recommended for LMICs: Two interventions prevent preterm births--smoking cessation and progesterone. Eight interventions prevent stillbirths--balanced protein energy supplementation, screening and treatment of syphilis, intermittant presumptive treatment for malaria during pregnancy, insecticide-treated mosquito nets, birth preparedness, emergency obstetric care, cesarean section for breech presentation, and elective induction for post-term delivery. Eleven interventions improve survival of preterm newborns--prophylactic steroids in preterm labor, antibiotics for PROM, vitamin K supplementation at delivery, case management of neonatal sepsis and pneumonia, delayed cord clamping, room air (vs. 100% oxygen) for resuscitation, hospital-based kangaroo mother care, early breastfeeding, thermal care, and surfactant therapy and application of continued distending pressure to the lungs for respiratory distress syndrome

CONCLUSION

The research paradigm for discovery science and intervention development must be balanced to address prevention as well as improve morbidity and mortality in all settings. This review also reveals significant gaps in current knowledge of interventions spanning the continuum of maternal and fetal outcomes, and the critical need to generate further high-quality evidence for promising interventions.

Intra-amniotic surfactant for women at risk of preterm birth for preventing respiratory distress in newborns

BACKGROUND

Early surfactant reduces mortality and pulmonary complications in preterm infants with respiratory distress syndrome. However, current surfactant administration strategies require endotracheal intubation with or without continued mechanical ventilation. Bronchopulmonary dysplasia and chronic lung disease (CLD) are associated with mechanical ventilation and potentially life-long effects. Non-invasive methods of surfactant administration including intra-amniotic surfactant may avoid endotracheal intubation and mechanical ventilation, potentially preventing development of CLD.

OBJECTIVES

To determine if intra-amniotic instillation of surfactant for women at risk of preterm birth, compared to placebo or no treatment or post-delivery tracheal surfactant instillation, reduces morbidity or mortality, or both, in preterm infants. If intra-amniotic instillation is effective, in subgroup analysis to determine the effect of 1) gestational age; 2) type of surfactant; 3) dose; 4) timing; 5) indication; and 6) multiple pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (August 2009), MEDLINE (1950-August 2009), handsearched the Proceedings of Pediatric Academic Societies (American Pediatric Society, Society for Pediatric Research and European Society for Pediatric Research) from 1990-2009 in Pediatric Research Journal and Abstracts online and the Proceedings of Perinatal Society of Australia and New Zealand (PSANZ) (1996-2009). We also searched the Science Citation Index (Web of Science) (August 2009) and checked reference lists of identified studies. We contacted Abbott Laboratories, Inc for unpublished studies.

SELECTION CRITERIA

Published, unpublished and ongoing randomised controlled, cluster-randomised or quasi-randomised trials of intra-amniotic instillation of surfactant for women at risk of preterm birth, compared to placebo or no treatment or post-delivery tracheal surfactant instillation.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed study eligibility and quality.

MAIN RESULTS

We found no trials were found met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

We identified no randomised trials that evaluated the effect of intra-amniotic instillation of surfactant for women at risk of preterm birth. Evidence from animal and observational human studies suggest that intra-amniotic surfactant administration is potentially safe, feasible and effective. Well designed trials of intra-amniotic instillation of surfactant for women at risk of preterm birth are needed.

Non-invasive respiratory support of preterm neonates with respiratory distress: continuous positive airway pressure and nasal intermittent positive pressure ventilation

Non-invasive techniques of respiratory support were developed in order to reduce the adverse effects associated with ventilation via an endotracheal tube. Short bi-nasal prongs provide the most effective nasal interface for delivery of nasal continuous positive airway pressure (nCPAP). Devices used to generate CPAP include conventional ventilators, the 'bubbly bottle' system and the infant flow driver. NCPAP improves the rate of successful extubation. It is useful for preterm infants with respiratory distress syndrome, reducing time spent on an endotracheal tube and oxygen requirement at 28d. However, nCPAP is associated with an increased rate of pneumothorax. Nasal intermittent positive pressure ventilation (NIPPV) is useful for augmenting the effectiveness of nCPAP. It further improves rates of successful extubation and shows promise as an initial method of respiratory support. Further research is required to determine the optimal settings for both nCPAP and NIPPV.

Surfactant-replacement therapy for respiratory distress in the preterm and term neonate

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 indications, administration, formulations, and outcomes for surfactant-replacement therapy. The impact of antenatal steroids and continuous positive airway pressure on outcomes and surfactant use in preterm infants is reviewed. Because respiratory insufficiency may be a component of multiorgan dysfunction, preterm and term infants receiving surfactant-replacement therapy should be managed in facilities with technical and clinical expertise to administer surfactant and provide multisystem support.

Surfactants: past, present and future

In 1929 Kurt von Neergaard performed experiments suggesting the presence of pulmonary surfactant and its relevance to the newborn's first breath. Almost 25 years later, Richard Pattle, John Clements and Chris Macklin, each working on the effects of nerve gases on the lungs, contributed to the understanding of the physiology of pulmonary surfactant. About 5 years later Mary Ellen Avery and Jere Mead published convincing evidence that preterm neonates dying of hyaline membrane disease (respiratory distress syndrome, RDS) had a deficiency of pulmonary surfactant. The first trials of nebulized synthetic (protein-free) surfactant to prevent RDS were published soon after Patrick Bouvier Kennedy (son of President John F Kennedy) died of this disorder after treatment in Boston. These trials were unsuccessful; however, Goran Enhorning and Bengt Robertson in the early 1970s demonstrated that natural surfactants (containing proteins) were effective in an immature rabbit model of RDS. Soon after this Forrest Adams showed that a natural surfactant was also effective in an immature lamb model. Working with him was Tetsuro Fujiwara who 2 years later, after returning to Japan, published the seminal article reporting the responses of 10 preterm infants with RDS to a bolus of modified bovine surfactant. During the 1980s there were numerous randomized controlled trials of many different natural and synthetic surfactants, demonstrating reductions in pulmonary air leaks and neonatal mortality. Subsequently natural surfactants were shown to be superior to the protein-free synthetic products. Recently there have been a number of randomized trials comparing different natural surfactant preparations. Commercially available bovine surfactants may have similar efficacy but there is some evidence that a porcine surfactant used to treat RDS with an initial dose of 200 mg per kg is more effective than a bovine surfactant used in an initial dose of 100 mg per kg. Bovine and porcine surfactants have not been compared in trials of prophylaxis. Very recently a new synthetic surfactant with a surfactant protein mimic has been compared with other commercially available natural and synthetic surfactants in two trials. The new surfactant may be superior to one of the older protein-free synthetic surfactants but there is no evidence of its superiority over established natural products and it is currently not approved for clinical use. A number of other new synthetic surfactants have been tested in animal models or in treatment of adults with ARDS, but so far there have been no reports of treatment of neonatal RDS. Natural surfactants work best if given by a rapid bolus into the lungs but less invasive methods such as a laryngeal mask, pharyngeal deposition or rapid extubation to CPAP have showed promise. Unfortunately, delivery of surfactant by nebulization has so far been ineffective. Surfactant treatment has been tried in a number of other neonatal respiratory disorders but only infants with meconium aspiration seem to benefit although larger and more frequent doses are probably needed to demonstrate improved lung function. A surfactant protocol based upon early treatment and CPAP is suggested for very preterm infants. Earlier treatment may improve survival rates for these infants; however, there is a risk of increasing the prevalence of milder forms of chronic lung disease. Nevertheless, surfactant therapy has been a major contribution to care of the preterm newborn during the past 25 years.

What's new in surfactant? A clinical view on recent developments in neonatology and paediatrics

Surfactant therapy has significantly changed clinical practice in neonatology over the last 25 years. Recent trials in infants with respiratory distress syndrome (RDS) have not shown superiority of any natural surfactant over another. Advancements in the development of synthetic surfactants are promising, yet to date none has been shown to be superior to natural preparations. Ideally, surfactant would be administered without requiring mechanical ventilation. An increasing number of studies investigate the roles of alternative modes of administration and the use of nasal continuous positive airway pressure to minimise the need for mechanical ventilation. Whether children with other lung diseases benefit from surfactant therapy is less clear. Evidence suggests that infants with meconium aspiration syndrome and children with acute lung injury/acute respiratory distress syndrome may benefit, while no positive effect of surfactant is seen in infants with congenital diaphragmatic hernia. However, more research is needed to establish potential beneficial effects of surfactant administration in children with lung diseases other than RDS. Furthermore, genetic disorders of surfactant metabolism have recently been linked to respiratory diseases of formerly unknown origin. It is important to consider these disorders in the differential diagnosis of unexplained respiratory distress although no established treatment is yet available besides lung transplantation for the most severe cases.

CONCLUSION

Research around surfactant is evolving and recent developments include further evolution of synthetic surfactants, evaluation of surfactant as a therapeutic option in lung diseases other than RDS and the discovery of genetic disorders of surfactant metabolism. Ongoing research is essential to continue to improve therapeutic prospects for children with serious respiratory disease involving disturbances in surfactant.

Surfactant replacement therapy

Surfactant replacement therapy (SRT) has a proven role in the treatment of neonatal respiratory distress syndrome and severe meconium aspiration syndrome in infants, and may have a role in the treatment of pediatric patients with ARDS. Although newer delivery mechanisms and strategies are being studied, the classic surfactant administration paradigm consists of endotracheal intubation, surfactant instillation into the lung, and stabilization with mechanical ventilation followed by extubation when stable on low respiratory support. Currently, this surfactant administration procedure is bundled into Current Procedural Terminology (CPT) codes used when providing intensive care. A specific CPT code for surfactant administration is scheduled to be introduced in 2007. This article reviews clinical issues in SRT and the practice management considerations necessary to provide this care.

Aerosolized surfactants

PURPOSE OF REVIEW

To present existing data on the potential use of aerosolized surfactants for treatment of neonatal respiratory distress syndrome in the era of noninvasive ventilatory support.

RECENT FINDINGS

Current surfactant therapy requires endotracheal intubation and application of positive pressure ventilation. Instillation of the drug itself can be complicated by 'peridosing adverse events' including, but not limited to, desaturations, bradycardias, changes in blood pressure, drug reflux and even the need for reintubations. Increasing use of noninvasive ventilatory support for neonatal respiratory distress syndrome has motivated clinicians and researchers to look for alternate ways of introducing surfactants to patients. Aerosolized surfactants have been tested in animal models of respiratory distress syndrome. In addition, four small clinical studies have been performed to date. The effectiveness of this form of treatment requires further study, however, which will need to include optimizing the dose of aerosolized surfactant, choosing particle size, developing the best delivery system, and using a surfactant formulation that maintains its activity once aerosolized.

SUMMARY

Aerosolized surfactants for neonatal respiratory distress syndrome may prevent the need for endotracheal intubation. Appropriately designed randomized controlled studies are required to determine if this form of surfactant administration is as effective and safe as tracheal instillation.

Recent clinical trials of surfactant treatment for neonates

OBJECTIVE

To search for recent clinical trials of neonatal surfactant treatment and report their findings.

METHODS

Recent was defined as published between 2000 and 2005. An online search on PubMed was made on 30th December 2005 using the following terms: surfactant treatment, clinical trials and neonate, with limits of years 2000 to 2005 and age - newborn from birth to 1 month. Randomised clinical trials (RCTs) and systematic reviews of RCTs were prioritised and studies in children and animals were excluded from further analysis.

RESULTS

175 papers were found in this search. Only about half of these papers were directly related to some aspect of surfactant treatment and of these just over one-half were either RCTs or systematic reviews of RCTs. Of the 34 RCTs of surfactant treatment, 3 were excluded as they involved children or animals rather than neonates. Twenty-nine trials studied preterm babies with respiratory distress syndrome (RDS) and 2 were for meconium aspiration syndrome (MAS) in term infants. The median sample sizes of these studies were RDS (92, range 19-1,361) and MAS (42, range 22-61). Eighteen of the RDS trials compared two or more surfactant preparations, the most frequently studied being Curosurf and Survanta but altogether 11 different surfactants were compared. These new RCTs need to be analysed by meta-analyses in systematic reviews. Twelve systematic reviews were found and these demonstrated the superiority of prophylactic over selective use of surfactant in babies <30 weeks, natural over synthetic surfactant and the absence of an increase in long-term developmental sequelae. Surfactant for MAS may reduce the severity of respiratory illness and the need for extracorporeal membrane oxygenation. Of the non-randomised trials' novel delivery methods, failure to use evidence-based guidelines and the benefit of surfactant for babies <25 weeks were the most interesting.

CONCLUSIONS

Surfactant remains one of the most effective and safest interventions in neonatology. Prophylactic natural surfactant seems to be the most evidence-based treatment for babies <30 weeks. Of the newer synthetic surfactants, only Surfaxin has been compared with currently used surfactants and systematic reviews are needed to establish if it has a role in treatment of RDS. The improvement in outcome for babies <25 weeks has been due to a number of interventions: prenatal steroids, prenatal antibiotics and postnatal surfactant. Clinical trials of surfactant replacement in the neonate continue to be published with remarkable frequency.

Laryngeal Mask Airway Used as a Delivery Conduit for the Administration of Surfactant to Preterm Infants with Respiratory Distress Syndrome

BACKGROUND

The laryngeal mask airway (LMA(TM), Laryngeal Mask Co. Ltd, Jersey, UK) is a supraglottic device used to administer positive pressure ventilation (PPV) in adults, pediatric and neonatal patients.

OBJECTIVES

To avoid endotracheal intubation, we evaluated the feasibility and practicality of administering surfactant via the LMA(TM) in preterm infants with respiratory distress syndrome (RDS).

METHODS

Infants less than 72 h old with a gestational age of < or =35 weeks and a birth weight of >800 g, treated with nasal continuous positive airway pressure (CPAP, 5 cm H2O) for RDS were eligible for inclusion in the study if the arterial-to-alveolar oxygen tension ratio (a/APO2) was <0.20 over a period of >60 min.

RESULTS

Eight preterm infants, median gestational age 31 (range 28-35) weeks; birth weight 1,700 (880-2,520) g, treated with nasal CPAP for RDS were enrolled. Three hours after surfactant instillation, the mean a/APO2 was significantly increased (0.13 +/- 0.04 to 0.34 +/- 0.11; p < 0.01) without complications.

CONCLUSIONS

The LMA may be a useful and noninvasive conduit for the administration of surfactant therapy. A large randomized comparative clinical trial will be required to confirm the efficacy of this technique.

History of surfactant from 1980

The first successful trial of surfactant treatment for respiratory distress syndrome (RDS) was reported in 1980. Since then there have been numerous randomised trials demonstrating first, the efficacy of surfactant treatment in reducing pulmonary air leaks and increasing survival and second, assessing various other aspects of therapy. These studies show that multiple doses may be needed if surfactant is used to treat established RDS but early or prophylactic treatment is superior for infants with gestational ages less than 30 weeks. Natural surfactants (containing proteins) are more effective than synthetic products (protein free), the latter now being infrequently used. Natural surfactants vary and should not be considered to be equivalent in their effects. A porcine surfactant (poractant alfa) acts more rapidly than a bovine preparation (beractant) in infants with moderate to severe RDS. A meta-analysis of 5 comparative studies suggests that a dose of 200 mg/kg of poractant alfa is associated with lower mortality compared with 100 mg/kg of beractant. Chronic lung disease remains a problem but it is hoped that early treatment with surfactant combined with extubation to continuous positive airway pressure will reduce this complication of prematurity. The newer synthetic surfactants, containing analogues of surfactant protein B or C, have undergone some trials for treatment of RDS but comparative studies which have just been published do not show that they are superior to existing natural surfactants. However, as they are more resistant to inactivation they may have a role in treatment of adult or acute RDS. The last 25 years have seen a large increase in basic science research on surfactants with determination of the structure and function of the four surfactant proteins probably being the most important advances. Future studies will focus on widening the indications for surfactant treatment, developing non-invasive means of administration and assessing the role of the newer synthetic surfactants.