Multicentre randomised trial comparing high and low dose surfactant regimens for the treatment of respiratory distress syndrome (the Curosurf 4 trial)

Respiratory distress syndrome in preterm infants of less than 32 weeks: What difference does giving 100 or 200 mg/kg of exogenous surfactant make?

BACKGROUND

Surfactant dosing and effective delivery could affect continuous positive airways pressure (CPAP)-failure. Nevertheless, information on exogenous surfactant dosing with current administration methods is limited.

OBJECTIVE

To describe the effect of 100 or 200 mg/kg of surfactant as first-line treatment of respiratory distress syndrome in preterm infants of less than 32 weeks gestation.

STUDY DESIGN

A retrospective single-center cohort study comparing two epochs, before and after switching from 100 to 200 mg/kg surfactant therapy.

RESULTS

Six hundred and fifty-eight of the 1615 infants of less than 32 weeks were treated with surfactant: 282 received 100 mg/kg (S-100) and 376 received 200 mg/kg (S-200). There were no differences between S-100 and S-200 in perinatal data including prenatal corticosteroids, medication use, age at first surfactant administration and respiratory severity before surfactant. The S-200 vs. S-100 had fewer retreatments (17.0% vs. 47.2%, p < 0.001) and a shorter duration of oxygen therapy and mechanical ventilation (315 vs. 339 h, p = 0.018; 37 vs. 118 h, p = 0.000, respectively). There was no difference in postnatal corticosteroid use (S-200 10.0% vs. S-100 11.0%, p = 0.361). Bronchopulmonary dysplasia (BPD) was significantly lower in S-200 vs. S-100 when comparing either the 4 and 6-year periods before and after the dose switch (29.4% vs. 15.7%, p = 0.003, and 18.7% vs. 27.3%, p = 0.024, respectively) CONCLUSIONS: The switch from 100 to 200 mg/kg was associated with a marked reduction in the need for surfactant redosing, respiratory support, and BPD. This information could be important when designing a study in the modern era of less invasive administration as surfactant dosing and its effective delivery may affect the outcome.

Outcome of Very Premature Newborn Receiving an Early Second Dose of Surfactant for Persistent Respiratory Distress Syndrome

Background: Infants presenting respiratory distress syndrome (RDS) not responding to surfactant often receive a second instillation. Few studies evaluated the consequences of this second administration. This study aimed at determining the outcome of infants presenting persistent RDS and receiving an early second dose of surfactant. Methods: Infants below 32 weeks' gestation who received a second dose of 100mg/kg of surfactant within the first 72 h of life, were retrospectively involved in this 42 months' study. They were matched to two controls receiving a single dose of 200mg/Kg based upon gender and gestational age. Results: 52/156 infants receiving two doses (Group 2-doses) were significantly more often SGA [22 (42%) vs. 21 (20%) p = 0.04] and outborn [29 (56%) vs. 13 (12%) p = 0.001]. They had received antenatal corticos teroid therapy less often [26 (50%) vs. 89 (86%) p = 0.001] and presented more severe RDS based upon FiO2 level, oxygenation index and radiography. Group 2-doses survival was lower (65.4% vs. 79.6 % p < 0.1) but surviving infants did not have different morbidity than controls. Discussion: Premature newborn receiving a second dose of surfactant had adverse antenatal characteristics, presented more severe RDS and only partially responded to the first dose. Outcomes of surviving infants who received 2 doses of surfactant were comparable to others.

Effect of low-dose exogenous surfactant on infants with acute respiratory distress syndrome after cardiac surgery: a retrospective analysis

BACKGROUND

Acute respiratory distress syndrome (ARDS) in infants undergoing cardiac surgery is associated with significant mortality and prolonged ventilation; surfactant administration may be a useful therapy. The purpose of this study is to evaluate the effect of low-dose exogenous surfactant therapy on infants suffering ARDS after cardiac surgery.

METHODS

We conducted a case-control study of infants diagnosed with moderate-to-severe ARDS (PaO₂/FiO₂ < 150) after cardiac surgery. A case was defined as a patient that received surfactant and standard therapy, while a control was defined as a patient that underwent standard therapy. The primary endpoint was the improvement in oxygenation index (OI) after 24-h of surfactant treatment; and secondary endpoints were the ventilator time and PICU time.

RESULTS

Twenty-two infants treated with surfactant were matched with 22 controls. Early low-dose (20 mg/kg) surfactant treatment was associated with improved outcomes. After surfactant administration for 24-h, the surfactant group was much better compared with the control group at the 24-h in OI (difference in average change from baseline, - 6.7 [95% CI, - 9.3 to - 4.1]) (P < 0.01) and ventilation index (VI, mean difference, - 11.9 [95% CI, - 18.1 to - 5.7]) (P < 0.01). Ventilation time and PICU time were significantly shorter in the surfactant group compared with the control group (133.6 h ± 27.2 vs 218.4 h ± 28.7, P < 0.01; 10.7d ± 5.1 vs 17.5d ± 6.8, P < 0.01). Infants in the surfactant group under 3 months benefit more from OI and VI than the infants over 3 months in a preliminary exploratory analysis.

CONCLUSIONS

In infants with moderate-to-severe ARDS after cardiac surgery, early low-dose exogenous surfactant treatment could prominently improve oxygenation and reduce mechanical ventilation time and PICU time. Infants younger than 3 months may get more benefit of oxygenation than the older ones. Randomized controlled trials are needed to explore the effect of surfactant to ARDS of cardiac surgical infants.

The Use of Exogenous Lung Surfactant (Poractant Alfa) in Acute Respiratory Failure by Drowning

Drowning is an acute respiratory failure as a result from immersion or submersion of the airways in a liquid medium (predominantly water). Inhalation of water causes severe lung damage due to the destruction of pulmonary surfactant, resulting in decreased lung elasticity, alveolar collapse, alteration of ventilation-perfusion ratio, intrapulmonary blood shunting, hypoxia, acute lung injury, and Acute Respiratory Distress Syndrome (ARDS). Poractant alfa (Curosurf®), a natural surfactant effective in the treatment of newborn respiratory distress, has been used in various forms of ARDS, but in drowning syndromes, experience is still poor. We describe a series of nine clinical cases of drowning, six adults and three children, treated in our Intensive Care Unit (ICU) with endobronchial administration of poractant alfa. After 24 and 48 hours of administration in all cases, there was an improvement in arterial blood gas analysis (ABG) parameters and imaging. All patients were discharged without clinical consequences.

Review demonstrates that less invasive surfactant administration in preterm neonates leads to fewer complications

Surfactant treatment of neonatal respiratory distress syndrome (RDS) was introduced in Europe during the 1990s. Meta-analyses have indicated that using less invasive surfactant administration techniques on preterm neonates receiving continuous positive airway pressure (CPAP) results in improved survival rates without bronchopulmonary dysplasia. Surfactant should be administered early and ventilator settings adapted to changing oxygen requirements and lung mechanics. Side effects including initial bradycardia, oxygen desaturation, tube obstruction and isolated cases of pulmonary haemorrhage have been reported.

CONCLUSION

Less invasive surfactant therapy improves pulmonary outcomes in preterm neonates with RDS and should ideally be administered in combination with CPAP.

Comparison of the Pharmacoeconomics of Calfactant and Poractant Alfa in Surfactant Replacement Therapy

OBJECTIVE To compare the pharmacy costs of calfactant (Infasurf, ONY, Inc.) and poractant alfa (Curosurf, Chiesi USA, Inc., Cary, NC).

METHODS The University of South Alabama Children's and Women's Hospital switched from calfactant to poractant alfa in 2013 and back to calfactant in 2015. Retrospectively, we used deidentified data from pharmacy records that provided type of surfactant administered, gestational age, birth weight, and number of doses on each patient. We examined differences in the number of doses by gestational ages and the differences in costs by birth weight cohorts because cost per dose is based on weight.

RESULTS There were 762 patients who received calfactant and 432 patients who received poractant alfa. The average number of doses required per patient was 1.6 administrations for calfactant-treated patients and 1.7 administrations for poractant alfa-treated patients, p = 0.03. A higher percentage of calfactant patients needed only 1 dose (53%) than poractant alfa patients (47%). The distribution of the number of doses for calfactant-treated patients was significantly lower than for the poractant alfa-patients, p &lt; 0.001. Gestational age had no consistent effect on the number of doses required for either calfactant or poractant alfa. Per patient cost was higher for poractant alfa than for calfactant in all birth weight cohorts. Average per patient cost was $1160.62 for poractant alfa, 38% higher than the average per patient cost for calfactant ($838.34). Using poractant alfa for 22 months is estimated to have cost $202,732.75 more than it would have cost if the hospital had continued using calfactant.

CONCLUSION Our experience showed a strong pharmacoeconomic advantage for the use of calfactant compared to the use of poractant alfa because of similar average dosing and lower per patient drug costs.

Surfactant for Respiratory Distress Syndrome: New Ideas on a Familiar Drug with Innovative Applications

In the last 4 decades, advances in neonatology have led to a significant increase in the survival of preterm infants. One of the biggest advances was the introduction of surfactant replacement therapy for the treatment of respiratory distress syndrome. This is the main cause of respiratory insufficiency in preterm infants and is one of the major causes of perinatal morbidity and mortality. Surfactant replacement therapy is already a well-investigated and established therapy in neonatology. However, surfactant replacement therapy has progressed and been refined over recent decades, especially with the increasing care for preterm infants born before 26 weeks' gestational age and the recent clinical focus on avoiding mechanical ventilation. Clinical evidence is evolving on new types of surfactant, surfactant dosages, co-medication given before, with, or after surfactant replacement, and new technical advances regarding the mode of administration.

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.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

The role of surfactant and non-invasive mechanical ventilation in early management of respiratory distress syndrome in premature infants

BACKGROUND

Surfactant replacement therapy has been used for few decades for the treatment of respiratory distress syndrome (RDS) and has significantly improved morbidity and mortality in premature infants. Non-invasive respiratory support has recently emerged as a strategy in the early management of RDS. In this review, we discuss the different strategies of early management of RDS.

DATA SOURCES

A literature search of PubMed database was conducted to review the subject. The quality of evidence of key clinical studies was graded according to a modified grading system of the international GRADE group.

RESULTS

Continuous positive airway pressure (CPAP) with selective surfactant is a safe alternative to routine intubation, surfactant and mechanical ventilation in preterm infants with spontaneous breathing, and such an approach has been associated with decreased risk of death and bronchopulmonary dysplasia. There is a risk of pneumothorax when using a high pressure of CPAP (≥8 cm of H2O), a high partial pressure of carbon dioxide (PCO2 >75 mm of Hg), and a high fraction of inspired oxygen (FiO2 >0.6) as a threshold for intubation while on CPAP.

CONCLUSION

Not all preterm infants need surfactant treatment, and non-invasive respiratory support is a safe and effective approach.

Delivery and performance of surfactant replacement therapies to treat pulmonary disorders

Lung surfactant is crucial for optimal pulmonary function throughout life. An absence or deficiency of surfactant can affect the surfactant pool leading to respiratory distress. Even if the coupling between surfactant dysfunction and the underlying disease is not always well understood, using exogenous surfactants as replacement is usually a standard therapeutic option in respiratory distress. Exogenous surfactants have been extensively studied in animal models and clinical trials. The present article provides an update on the evolution of surfactant therapy, types of surfactant treatment, and development of newer-generation surfactants. The differences in the performance between various surfactants are highlighted and advanced research that has been conducted so far in developing the optimal delivery of surfactant is discussed.

Surfactant therapy: the current practice and the future trends

The efficacy of surfactant preparations used in the prevention and treatment of respiratory distress syndrome (RDS) is a well known fact; however, many controversies remain. The debate over which surfactant to be used, when and what is the best mode of delivery is still raging. Currently, animal-derived surfactants are preferred and clearly recommended by various practice guidelines, but new synthetic surfactants containing peptides that mimic the action of surfactant proteins are emerging and they seem to have a comparable efficacy profile to the natural surfactants. It is hoped that with further improvements, they will outperform their natural counterparts in terms of reliability and cost-effectiveness. Early surfactant administration was shown to further reduce the risk of RDS and its complications. However, as nasal continuous positive airway pressure (nCPAP) is becoming increasingly the preferred first-line therapy for RDS, the less invasive approaches of respiratory support along with early selective surfactant administration (e.g. INSURE) appears to provide a better option. Although neonatal RDS is still the main indication of surfactant therapy, other pathological processes received considerable attention and major research has been dedicated to explore the role of surfactant in their management, Meconium aspiration syndrome (MAS) and congenital pneumonia are two worthy examples. The most updated practice guidelines do recommend the use of endotracheal instillation as the preferred mode of surfactant delivery. However, aerosolization and other non-invasive methods are being investigated with some success; nonetheless, further improvements are very much in need.

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

BACKGROUND

We have developed a rapid method, based on lamellar body counts (LBC) on gastric aspirate, for identifying newborns who will develop respiratory distress syndrome with a need for surfactant supplementation.

OBJECTIVE

We set out to test whether it was possible to improve the outcome when used in a clinical trial.

METHODS

We randomly assigned 380 infants born at 24-29 weeks' gestation and supported with nasal continuous positive airway pressure (nCPAP) to receive surfactant guided either by LBC (intervention group) or increasing need for oxygen (control group). The primary outcome was mechanical ventilation or death within 5 days. Secondary outcomes included need for oxygen expressed by arterial to alveolar oxygen tension ratio (a/APO2) at the age of 6 h and need for oxygen at day 28.

RESULTS

The primary outcomes were equal (25%) in the two groups. The intervention group had higher a/APO2 than the control group at 6 h, median 0.64 versus 0.52 (p < 0.01), and the subgroup with gestational age 26-29 weeks needed fewer days of oxygen supplementation than the controls, median 2 vs. 9 days (p = 0.01), and fewer infants needed oxygen at day 28 (p = 0.04). Furthermore, there was a tendency in the intervention group towards a shorter duration of nCPAP. Too little or viscose aspirate in 23% of the cases was a limitation of the method.

CONCLUSION

Using LBC test as indicator of lung maturity and early surfactant therapy in very preterm newborns, it is possible to reduce the need for oxygen supplementation.

Inositol-trisphosphate reduces alveolar apoptosis and pulmonary edema in neonatal lung injury

D-myo-inositol-1,2,6-trisphosphate (IP3) is an isomer of the naturally occurring second messenger D-myo-inositol-1,4,5-trisphosphate, and exerts anti-inflammatory and antiedematous effects in the lung. Myo-inositol (Inos) is a component of IP3, and is thought to play an important role in the prevention of neonatal pulmonary diseases such as bronchopulmonary dysplasia and neonatal acute lung injury (nALI). Inflammatory lung diseases are characterized by augmented acid sphingomyelinase (aSMase) activity leading to ceramide production, a pathway that promotes increased vascular permeability, apoptosis, and surfactant alterations. A novel, clinically relevant triple-hit model of nALI was developed, consisting of repeated airway lavage, injurious ventilation, and lipopolysaccharide instillation into the airways, every 24 hours. Thirty-five piglets were randomized to one of four treatment protocols: control (no intervention), surfactant alone, surfactant + Inos, and surfactant + IP3. After 72 hours of mechanical ventilation, lungs were excised from the thorax for subsequent analyses. Clinically, oxygenation and ventilation improved, and extravascular lung water decreased significantly with the S + IP3 intervention. In pulmonary tissue, we observed decreased aSMase activity and ceramide concentrations, decreased caspase-8 concentrations, reduced alveolar epithelial apoptosis, the reduced expression of interleukin-6, transforming growth factor-β1, and amphiregulin (an epithelial growth factor), reduced migration of blood-borne cells and particularly of CD14(+)/18(+) cells (macrophages) into the airspaces, and lower surfactant surface tensions in S + IP3-treated but not in S + Inos-treated piglets. We conclude that the admixture of IP3 to surfactant, but not of Inos, improves gas exchange and edema in our nALI model by the suppression of the governing enzyme aSMase, and that this treatment deserves clinical evaluation.

Does surfactant type cause a differential proinflammatory response in preterm infants with respiratory distress syndrome?

INTRODUCTION

The objective of this study was to compare the pulmonary inflammatory response of premature infants with respiratory distress following instillation of one of two commonly available surfactant preparations.

METHODS

This was a prospective, randomized investigation of preterm infants who were less than 30 weeks of gestational age, weighed less than 1 kg at birth, and who qualified to receive surfactant. Infants with multiple congenital anomalies or whose mothers were taking anti-inflammatory medications were ineligible. Tracheal aspirates (TAs) were collected on days 1, 3, 5, and 7 and airway cytokines from TAs were assayed for interleukin (IL)-8 and IL-6.

RESULTS

Infants were evenly matched by gestation (26+/-2 days and 26+/-1 days [mean+/-SD], Surfactant A and B, respectively) and birth weight (730+/-141 g and 732+/-167 g). TA cytokine levels were not different between or within groups. Ventilator requirements and clinical outcomes were similar between the two groups.

CONCLUSION

The postnatal airway inflammatory response observed in preterm infants is not altered by the instillation of either surfactant preparation.

Chorioamnionitis alters the response to surfactant in preterm infants

OBJECTIVE

To study the association between antenatal exposure to chorioamnionitis and the neonatal response to surfactant.

STUDY DESIGN

Prospective observational cohort of 301 preterm infants of gestational age < or = 32.0 weeks, 146 of whom received surfactant according to standardized criteria. Fraction of inspired oxygen (FiO(2)) requirement (using analysis of variance) and time to extubation (using Kaplan-Meier and Cox regression analyses) were compared between groups based on the presence of histological chorioamnionitis (HC) with or without fetal involvement (HC-, n = 88; HC + F-, n = 25; HC + F+, n = 33) and between infants who developed bronchopulmonary dysplasia (BPD) or died (n = 57) and BPD-free survivors (n = 89). Multiple logistic regression was performed to investigate the association between HC and BPD.

RESULTS

Compared with HC- infants, HC + F+ infants had significantly greater FiO(2) requirement and prolonged time to extubation postsurfactant, not accounted for by differences in gestational age and birth weight. Infants with BPD/death had a strikingly similar pattern of increased FiO(2) requirement postsurfactant. Moreover, in infants who received surfactant, HC + F+ status was associated with increased risk for BPD (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.02-11.3; P = .047) and for BPD/death (OR = 2.72; 95% CI = 1.00-7.42; P = .049).

CONCLUSIONS

An impaired surfactant response was observed in preterm infants with severe chorioamnionitis and may be involved in the association between chorioamnionitis, mechanical ventilation, and the development of BPD.

Dosing of porcine surfactant: effect on kinetics and gas exchange in respiratory distress syndrome

OBJECTIVE

The goal was to study exogenous surfactant disaturated phosphatidylcholine (DSPC) kinetics in preterm infants with respiratory distress syndrome (RDS) who were treated with 100 or 200 mg/kg porcine surfactant.

METHODS

Sixty-one preterm infants with RDS undergoing mechanical ventilation received, within 24 hours after birth, 100 mg/kg (N = 40) or 200 mg/kg (N = 21) porcine surfactant mixed with [U-(13)C]dipalmitoylphosphatidylcholine. Clinical and respiratory parameters were recorded, and DSPC half-life and pool size and endogenous DSPC synthesis rate were calculated.

RESULTS

Clinical characteristics and short-term outcomes did not differ between groups. In the 100 mg/kg group, 28 infants (70%) received a second dose after 25 +/- 11 hours and 9 (22.5%) a third dose after 41 +/- 11 hours; in the 200 mg/kg group, 6 infants (28.6%) received a second dose after 33 +/- 8 hours and 1 a third dose. The DSPC half-life was longer in the 200 mg/kg group (first dose: 32 +/- 19 vs 15 +/- 15 hours [P = .002]; second dose: 43 +/- 32 vs 21 +/- 13 hours [P = .025]). DSPC synthesis rates and pool sizes before the first and second doses did not differ between the groups. The 200 mg/kg group exhibited a greater reduction in the oxygenation index than did the 100 mg/kg group after the first (P = .009) and second (P = .018) doses.

CONCLUSIONS

Porcine surfactant given to preterm infants with RDS at a dose of 200 mg/kg resulted in a longer DSPC half-life, fewer retreatments, and better oxygenation index values.

Nasal CPAP and surfactant for treatment of respiratory distress syndrome and prevention of bronchopulmonary dysplasia

The Scandinavian approach is an effective combined treatment for respiratory distress syndrome (RDS) and prevention of bronchopulmonary dysplasia (BPD). It is composed of many individual parts. Of significant importance is the early treatment with nasal continuous positive airway pressure (nCPAP) and surfactant treatment. The approach may be supplemented with caffeine citrate and non-invasive positive pressure ventilation for apnoea. The low incidence of BPD seen as a consequence of the treatment strategy is mainly due to a reduced need for mechanical ventilation (MV).

CONCLUSION

Early-postnatal treatment with nCPAP and surfactant decreases the severity and mortality of RDS and BPD. This is mainly due to a diminished use of MV in the first days of life.

Nasal CPAP has become an indispensable part of the primary treatment of newborns with respiratory distress syndrome

Prenatal steroids, early nasal CPAP combined with early surfactant treatment followed by extubation to nasal CPAP, and if necessary mechanical ventilation is a very effective treatment of respiratory distress syndrome. This treatment package is part of the 'Scandinavian model' for treatment of very-low-birthweight infants which also comprises gentle ventilation at birth; minimal handling; 'neonatal individualized development care and assessment program'; high priority of breast feeding; and use of kangaroo method and which facilitates observation and nursing of sick premature infants and optimizes the possibility for early mother-child contact. The incidence of bronchopulmonary dysplasia seems to be less of a problem in centres preferring nasal CPAP as the primary treatment for respiratory distress syndrome.

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.

A multicenter, randomized, controlled trial of lucinactant versus poractant alfa among very premature infants at high risk for respiratory distress syndrome

BACKGROUND

Available therapeutic surfactants are either animal-derived or non-protein-containing synthetic products. Animal-derived surfactants contain variable amounts of surfactant apoproteins, whereas the older-generation synthetic products contain only phospholipids and lack surfactant proteins (SPs). Both decrease morbidity and mortality rates associated with respiratory distress syndrome (RDS) among preterm infants, compared with placebo. However, excess mortality rates have been observed with non-protein-containing synthetic surfactants, compared with the animal-derived products. Evidence suggests that synthetic surfactants consisting solely of phospholipids can be improved with the addition of peptides that are functional analogs of SPs. Lucinactant is a new synthetic peptide-containing surfactant that contains sinapultide, a novel, 21-amino acid peptide (leucine and lysine repeating units, KL4 peptide) designed to mimic human SP-B. It is completely devoid of animal-derived components.

OBJECTIVE

We hypothesized that the outcomes for premature infants treated with lucinactant and poractant alfa would be similar. Therefore, we compared lucinactant (Surfaxin; Discovery Laboratories, Doylestown, PA) with porcine-derived, poractant alfa (Curosurf; Chiesi Farmaceutici, Parma, Italy) in a trial to test for noninferiority.

METHODS

A total of 252 infants born between 24 and 28 weeks of completed gestation, with birth weights between 600 and 1250 g, were assigned randomly in a multicenter, multinational, noninferiority, randomized, controlled study to receive either lucinactant (n = 124) or poractant alfa (n = 128) within 30 minutes of life. The primary outcome was the incidence of being alive without bronchopulmonary dysplasia (BPD) through 28 days of age. Key secondary outcomes included death at day 28 and 36 weeks postmenstrual age (PMA), air leaks, neuroimaging abnormalities, and other complications related to either prematurity or RDS. An independent, international, data and safety monitoring committee monitored the trial.

RESULTS

The treatment difference between lucinactant and poractant alfa for survival without BPD through 28 days was 4.75% (95% confidence interval [CI]: -7.3% to 16.8%) in favor of lucinactant, with the lower boundary of the 95% CI for the difference, ie, -7.3%, being greater than the prespecified noninferiority margin of -14.5%. At 28 days, 45 of 119 infants given lucinactant were alive without BPD (37.8%; 95% CI: 29.1-46.5%), compared with 41 of 124 given poractant alfa (33.1%; 95% CI: 24.8-41.3%); at 36 weeks PMA, the rates were 64.7% and 66.9%, respectively. The corresponding mortality rate through day 28 for the lucinactant group was lower than that for the poractant alfa group (11.8% [95% CI: 6.0-17.6%] vs 16.1% [95% CI: 9.7-22.6%]), as was the rate at 36 weeks PMA (16% and 18.5%, respectively). There were no differences in major dosing complications. In addition, no significant differences were observed in the incidences of common complications of prematurity, including intraventricular hemorrhage (grades 3 and 4) and cystic periventricular leukomalacia (lucinactant: 14.3%; poractant alfa: 16.9%).

CONCLUSIONS

Lucinactant and poractant alfa were similar in terms of efficacy and safety when used for the prevention and treatment of RDS among preterm infants. The ability to enhance the performance of a synthetic surfactant with the addition of a peptide that mimics the action of SP-B, such as sinapultide, brings potential advantages to exogenous surfactant therapy.

Randomized trial comparing two natural surfactants (Survanta vs. bLES) for treatment of neonatal respiratory distress syndrome

Exogenous surfactants have been used as an effective treatment of neonatal respiratory distress syndrome (RDS). Different preparations of surfactant carry different biophysical and clinical properties. To study the response pattern and treatment outcome of two natural surfactants (bLES and Survanta) for the treatment of RDS, we conducted a randomized clinical trial at the neonatal unit of a university teaching hospital. Premature babies with birth weight between 500-1,800 g who developed RDS requiring mechanical ventilation with an oxygen requirement of more than 30% within 6 hr of life were randomized into two treatment groups. Oxygenation indices (OIs) within 12 hr of treatment were compared as primary outcomes, while neonatal complications were analyzed as secondary outcomes of the study. Sixty babies were recruited, with 29 in the bLES and 31 in the Survanta treatment group. Both groups had significant and sustained improvements in OI after surfactant replacement therapy (SRT), while the bLES group was associated with a significantly lower OI throughout the initial 12 hr after treatment compared with the Survanta group. There was no difference in secondary outcomes including mortality, ventilator days, and occurrence of chronic lung disease. We conclude that infants with RDS respond favorably to both types of surfactant replacement, and that bLES achieved a faster clinical response in terms of improvement in OI than Survanta.

Pathophysiology of Neonatal Respiratory Distress Syndrome

Neonatal respiratory distress syndrome (RDS) remains one of the major causes of neonatal mortality and morbidity despite advances in perinatal care. The initial management of infants with RDS has almost become 'too routine' with little thought about the pathophysiological processes that lead to the disease and how the clinician can use the existing therapeutic interventions to optimize care. The transition from fetus to infant involves many complex adaptations at birth; the most important is the function of the lungs as a gas exchange organ. Preterm surfactant-deficient infants are less well equipped to deal with this transition. Optimum gas exchange is achieved through matching of ventilation and perfusion. In RDS, ventilation may be affected by homogeneity of the airways with atelectasis and over distension, as hyaline membranes block small airways. In turn this contributes to the inflammation that becomes bronchopulmonary dysplasia. Exogenous surfactant given early, particularly with positive end-expiratory pressure and, where necessary, gentle ventilation, would seem to be the optimum way to prevent atelectasis. How this can be achieved in neonates after surfactant therapy is explored through a review of the normal physiology of the newborn lung and how this is affected by RDS. The therapeutic interventions of resuscitation, exogenous surfactant, ventilation and inhaled nitric oxide are discussed in relation to their effects and what are currently the optimum ways to use these. It is hoped that with a better understanding of the normal physiology in the newborn lung, and the effects of both disease and interventions on that physiology, the practising clinician will have a greater appreciation of management of preterm infants with, or at risk of, RDS.

The short-term outcome of a large cohort of very preterm infants treated with poractant alfa (Curosurf) for respiratory distress syndrome. A postmarketing phase IV study

OBJECTIVES

To determine the effect of a porcine-derived lung surfactant, poractant alfa (Curosurf), on the respiratory outcome of very preterm infants with established neonatal respiratory distress syndrome (RDS), and to identify risk factors for severe bronchopulmonary dysplasia (BPD) in this population.

DESIGN

A multicenter prospective longitudinal cohort study of 924 very preterm infants with RDS, born between 23 and 32 weeks gestation, and treated with at least one dose of poractant alfa during the first 48 hours of life.

RESULTS

The median gestational age and the mean birthweight were 29 weeks and 1210 g, respectively; babies born at <28 weeks accounted for 27.1% of the cohort. Infants were treated with poractant alfa 7.9 hours after birth on average. Approximatively 32% of them required at least one additional dose. The mortality rate was 23.5%. The rates of survival without BPD at 28 days postnatal age and 36 weeks postmenstrual age were 38.9% and 54.0%, respectively. In the univariate analysis, factors associated with a higher risk of BPD at 36 weeks postmenstrual age (severe BPD) were low gestational age, low birthweight, poor response to the first dose, and the presence of pneumothorax, interstitial emphysema, pulmonary hemorrhage, patent ductus arteriosus requiring treatment, acquired pulmonary infection, or necrotizing enterocolitis. In the multivariate analysis, significant risk factors for severe BPD were low gestational age, low birthweight, and the presence of interstitial emphysema, pulmonary infection, or necrotizing enterocolitis.

CONCLUSION

The rate of RDS-related complications in this high-risk cohort was comparable to the rates observed in the pivotal trials. In very premature infants treated with poractant alfa for established RDS, early barotrauma and postnatal local and/or systemic inflammation are strongly associated with the subsequent development of severe BPD.

Surfactant therapy for respiratory distress syndrome in premature neonates: a comparative review

Exogenous surfactant therapy has been part of the routine care of preterm neonates with respiratory distress syndrome (RDS) since the beginning of the 1990s. Discoveries that led to its development as a therapeutic agent span the whole of the 20th century but it was not until 1980 that the first successful use of exogenous surfactant therapy in a human population was reported. Since then, randomized controlled studies demonstrated that surfactant therapy was not only well tolerated but that it significantly reduced both neonatal mortality and pulmonary air leaks; importantly, those surviving neonates were not at greater risk of subsequent neurological impairment. Surfactants may be of animal or synthetic origin. Both types of surfactants have been extensively studied in animal models and in clinical trials to determine the optimum timing, dose size and frequency, route and method of administration. The advantages of one type of surfactant over another are discussed in relation to biophysical properties, animal studies and results of randomized trials in neonatal populations. Animal-derived exogenous surfactants are the treatment of choice at the present time with relatively few adverse effects related largely to changes in oxygenation and heart rate during surfactant administration. The optimum dose of surfactant is usually 100 mg/kg. The use of surfactant with high frequency oscillation and continuous positive pressure modes of respiratory support presents different problems compared with its use with conventional ventilation. The different components of surfactant have important functions that influence its effectiveness both in the primary function of the reduction of surface tension and also in secondary, but nonetheless just as important, role of lung defense. With greater understanding of the individual surfactant components, particularly the surfactant-associated proteins, development of newer synthetic surfactants has been made possible. Despite being an effective therapy for RDS, surfactant has failed to have a significant impact on the incidence of chronic lung disease in survivors. Paradoxically the cost of care has increased as surviving neonates are more immature and consume a greater proportion of neonatal intensive care resources. Despite this, surfactant is considered a cost-effective therapy for RDS compared with other therapeutic interventions in premature infants.

A theoretical study of chemical delivery within the lung using exogenous surfactant

A mathematical model is developed for lung injury treatments involving the delivery of therapeutic chemicals, such as drugs and gene vectors, into the lung using simultaneous tracheal instillation of exogenous pulmonary surfactant. The influence of exogenous surfactant dose, flow rate, bulk liquid viscosity, pulmonary absorption rate and chemical molecular diffusivity on the chemical delivery to the lung is investigated. Our results reveal that different pulmonary absorption rates lead to significantly different distribution patterns and change the time taken for the total amount of chemical to be absorbed along the airways. The various factors can also influence where the majority of the chemical is placed within the lung and this is relevant to the targeting of drugs to particular lung generations.

[The Europe against immature lung (EURAIL) project. Strategies for the prevention and treatment of lung immaturity in neonates]

OBJECTIVE

To determine clinical practice variability in the prevention and postnatal treatment of lung immaturity in Spain.

PATIENTS AND METHODS

Cross-sectional study within a larger study in 13 European countries. Data were obtained from the medical records of all very low birth weight (VLBW) infants born in participating centers, without other instrumentation.

RESULTS

A questionnaire was sent to 213 centers. Seventy-two (34 %) responded, with 162,157 births (40 % of total births in 1999). Eight percent of infants were of low birth weight, 1.2 % (2,015) of very low birth weight and 0.45 % were of extremely low birth weight. A total of 52.2 % of VLBW infants received at least one dose of prenatal steroids, 28.8 % received a full course and 9.3 % received more than one cycle. All centres used surfactant and 76.8 % had a written protocol. Forty-one percent of VLBW infants were intubated, 47.6 % required mechanical ventilation for more than 6 hours, and 5 % underwent continuous positive airway pressure. A total of 80.4 % used postnatal steroids, half of them for chronic lung disease prevention, and 83.4 % used steroids to treat this disease. Steroids were most frequently indicated at 7-14 days of life for 3-9 days. The most important causes of neonatal morbidity were chronic lung disease in 14 %, ductus arteriosus in 16.7 %, intraventricular hemorrhage in 8.5 %, and necrotizing enterocolitis in 7.3 %.

CONCLUSIONS

Prenatal exposure to steroids was low. Repeat cycles and postnatal steroid use to prevent chronic lung disease was high. Recent scientific evidence on the use of pre- and postnatal steroids should be more widely disseminated.

A multicenter, randomized open study of early corticosteroid treatment (OSECT) in preterm infants with respiratory illness: comparison of early and late treatment and of dexamethasone and inhaled budesonide

AIM

To compare early (<3 days) with late (>15 days) steroid therapy and dexamethasone with inhaled budesonide in very preterm infants at risk of developing chronic lung disease.

METHODS

Five hundred seventy infants from 47 neonatal intensive care units were enrolled. Criteria for enrollment included gestational age <30 weeks, postnatal age <72 hours, and need for mechanical ventilation and inspired oxygen concentration >30%. Infants were randomly allocated to 1 of 4 treatment groups in a factorial design: early (<72 hours) dexamethasone, early budesonide, delayed selective (>15 days) dexamethasone, and delayed selective budesonide. Dexamethasone was given in a tapering course beginning with 0.50 mg/kg/day in 2 divided doses for 3 days reducing by half until 12 days of therapy had elapsed. Budesonide was administered by metered dose inhaler and a spacing chamber in a dose of 400 microg/kg twice daily for 12 days. Delayed selective treatment was started if infants needed mechanical ventilation and >30% oxygen for >15 days. The factorial design allowed 2 major comparisons: early versus late treatment and systemic dexamethasone versus inhaled budesonide. The primary outcome was death or oxygen dependency at 36 weeks and analysis was on an intention-to-treat basis. Secondary outcome measures included death or major cerebral abnormality, duration of oxygen treatment, and complications of prematurity. Adverse effects were also monitored daily.

RESULTS

There were no significant differences among the groups for the primary outcome. Early steroid treatment was associated with a lower primary outcome rate (odds ratio [OR]: 0.85; 95% confidence interval [CI]: 0.61,1.18) but even after adjustment for confounding variables the difference remained nonsignificant. Dexamethasone-treated infants also had a lower primary outcome rate (OR: 0.86; 95% CI: 0.62,1.20) but again this difference remained not significant after adjustment. For death before discharge, dexamethasone and early treatment had worse outcomes than budesonide and delayed selective treatment (OR: 1.42; 95% CI: 0.93,2.16; OR: 1.51; 95% CI: 0.99,2.30 after adjustment, respectively) with the results not quite reaching significance. Duration of supplementary oxygen was shorter in the early dexamethasone group (median: 31 days vs 40-44 days). Early dexamethasone was also associated with increased weight loss during the first 12 days of treatment (52 g vs 3 g) compared with early budesonide, but over 30 days there was no difference. In the early dexamethasone group, there was a reduced incidence of persistent ductus arteriosus (34% vs 52%-59%) and an increased risk of hyperglycemia (55% vs 29%-34%) compared with the other 3 groups. Dexamethasone was associated with an increased risk of hypertension and gastrointestinal problems compared with budesonide but only the former attained significance.

CONCLUSIONS

Infants given early treatment and dexamethasone therapy had improved survival without chronic lung disease at 36 weeks compared with those given delayed selective treatment and inhaled budesonide, respectively, but results for survival to discharge were in the opposite direction; however, none of these findings attained statistical significance. Early dexamethasone treatment reduced the risk of persistent ductus arteriosus. Inhaled budesonide may be safer than dexamethasone, but there is no clear evidence that it is more or less effective.

Quantitative determination of dipalmitoylphosphatidylcholine and palmitic acid in porcine lung surfactants used in the treatment of respiratory distress syndrome

A high-performance liquid chromatography (HPLC) method was developed that can separate and quantify dipalmitoylphosphatidylcholine and its degradation product, palmitic acid from various phospholipids contained in a porcine lung surfactant used in the treatment of respiratory distress syndrome, which was recently approved for use by the FDA. The method used a C8 reversed-phase HPLC column with a (50:45:10) acetonitrile/methanol/acetic acid mobile phase, and refractive index detection. The active component of the lung surfactant, dipalmitoylphosphatidylcholine (DPPC) and palmitic acid (PA), could be quantified following a liquid-liquid extraction procedure along with an internal standard, dimyristoylphosphatidylcholine (DMPC). The assay was validated for linearity, accuracy, precision, reproducibility and ruggedness. Column stability was measured by performing the assay over time and monitoring the system suitability parameters. The extraction procedure has a 90% recovery and the assay is linear over a range of 5 microg/ml to 300 microg/ml. The assay is used to release commercial product and monitor stability of existing lots of material.

Nasal continuous positive airway pressure and early surfactant therapy for respiratory distress syndrome in newborns of less than 30 weeks' gestation

OBJECTIVE

To determine whether early versus late treatment with porcine surfactant (Curosurf) reduces the requirement of mechanical ventilation in very preterm infants primarily supported by nasal continuous positive airway pressure (nasal CPAP).

DESIGN

Multicenter randomized, controlled trial.

PATIENTS

The study population comprised 60 infants <30 weeks' gestation with respiratory distress syndrome (RDS) who had an arterial to alveolar oxygen tension ratio (a/APO2) of 0.35 to 0.22. The cohort from which the study population was generated comprised 397 infants.

RESULTS

The need for mechanical ventilation or death within 7 days of age was reduced from 63% in the late-treated infants to 21% in early-treated infants. Increasing numbers of antenatal steroid doses also improved the outcome, especially in the early-treated infants. Six hours after randomization mean a/APO2 rose to 0.48 in the early-treated infants compared with 0.36 in the late-treated. The need of mechanical ventilation before discharge was reduced from 68% in the late-treated to 25% in the early-treated infants.

CONCLUSIONS

Nasal CPAP in combination with early treatment with Curosurf significantly improves oxygenation and reduces the subsequent need for mechanical ventilation in infants <30 weeks' gestational age with RDS.

Current perspectives on the drug treatment of neonatal respiratory distress syndrome

Respiratory distress syndrome (RDS) in preterm neonates is caused by a lack of alveolar surfactant, which leads to decreased pulmonary compliance and increased work of breathing. Effective therapy for RDS has reduced mortality at the expense of increasing the number of preterm survivors with chronic lung disease. Drugs such as corticosteroids, proterelin (thyrotropin-releasing hormone) and ambroxol have all been administered to mothers to promote fetal lung maturation, but of these only corticosteroids have been proven to be of benefit. The management of RDS includes assisted ventilation and surfactant replacement therapy. There are several surfactant preparations, some synthetic and others derived from animal lungs, and recent research has been directed at finding which, if any, is superior. The timing of the first dose has also been studied. Prophylactic surfactant administration within the first 15 minutes of life appears to be more efficacious than later treatment for very preterm babies, but could lead to some neonates being treated unnecessarily and perhaps being exposed to adverse effects. Newer treatments for neonates with RDS are aimed at reducing the pulmonary inflammation that occurs as a result of ventilatory barotrauma and oxygen toxicity. Superoxide dismutase, along with other antioxidants, may be beneficial as a free radical scavenger to reduce oxygen toxicity. Inhaled nitric oxide may reduce oxygen requirements by reducing ventilation-perfusion mismatching, and early treatment with corticosteroids may reduce pulmonary inflammation. All of these treatments are currently undergoing clinical trials.

Principles of surfactant replacement

Surfactant therapy is an established part of routine clinical management of babies with respiratory distress syndrome. An initial dose of about 100 mg/kg is usually needed to compensate for the well documented deficiency of alveolar surfactant in these babies, and repeated treatment is required in many cases. Recent experimental and clinical data indicate that large doses of exogenous surfactant may be beneficial also in conditions characterized by inactivation of surfactant, caused by, for example, aspiration of meconium, infection, or disturbed alveolar permeability with leakage of plasma proteins into the airspaces. The acute response to surfactant therapy depends on the quality of the exogenous material (modified natural surfactants are generally more effective than protein-free synthetic surfactants), timing of treatment in relation to the clinical course (treatment at an early stage of the disease is better than late treatment, and may reduce the subsequent need for mechanical ventilation), and mode of delivery (rapid instillation via a tracheal tube leads to more uniform distribution and is more effective than slow airway infusion). Treatment with aerosolized surfactant improves lung function in animal models of surfactant deficiency or depletion, but is usually associated with large losses of the nebulized material in the delivery system. Furthermore, data from experiments on immature newborn lambs indicate that treatment response may depend on the mode of resuscitation at birth, and that manual ventilation with just a few large breaths may compromise the effect of subsequent surfactant therapy. The widespread clinical use of surfactant has reduced neonatal mortality and lowered costs for intensive care in developed countries. The hydrophobic surfactant proteins SP-B and SP-C are probably essential for optimal biophysical and physiological activity of exogenous surfactants isolated from mammalian lungs, and the dose-effectiveness (in part reflecting resistance to inactivation) can be further improved by enrichment with SP-A. The development of new artificial surfactant substitutes, based on synthetic analogues of the native surfactant proteins, is an important challenge for future research.

Limited comparability of classifications of levels of neonatal care in UK units. The ECSURF (Economic Evaluation of Surfactant) Collaborative Study Group

AIM

To assess whether different classifications of neonatal care or dependency scales are comparable when used in multicentre studies of cost effectiveness.

METHODS

A survey of classifications was used in a nationally representative group of 57 units in 1990-1, with a retrospective study of 10 354 cot days using patient records from a 5% random sample of 1042 admissions. Local and national classifications were correlated with medical and nursing procedures recorded for up to 26 days after each admission.

RESULTS

Classifications varied substantially. Of the 57 units in our sample, 26 used one of two national classifications, sometimes modified; 17 used the Northern Neonatal Network dependency scale; and the other 14 did not record daily levels of care. In each classification, the highest level was having respiratory support by ventilation or continuous distending pressure through an endotracheal tube, nasal prongs, facemask or negative pressure device. This level of care was consistently comparable between classifications; lower levels were not.

CONCLUSIONS

Retrospective comparisons between units with different classifications can only reliably differentiate between days with and without respiratory support. There is a pressing need to develop and validate more appropriate scales for prospective multicentre studies. These should relate activity to costs and outcome.

A risk-benefit assessment of natural and synthetic exogenous surfactants in the management of neonatal respiratory distress syndrome

Alveolar surfactant is central to pulmonary physiology. Quantitative and qualitative surfactant abnormalities appear to be the primary aetiological factors in neonatal respiratory distress syndrome (RDS) and exogenous replacement of surfactant is a rational treatment. Available exogenous surfactants have a natural (mammal-derived lung surfactants) or synthetic origin. Pharmacodynamic and clinical studies have demonstrated that exogenous surfactants immediately improve pulmonary distensibility and gas exchange; however, this is achieved more slowly and with more failures with synthetic surfactants. The ensuing advantageous haemodynamic effects are not so striking and they include an inconvenient increased left to right ductal shunt. Two strategies of administration have been used: prophylactic or rescue therapy to treat declared RDS. All methods of instillation require intubation. In addition to the early benefits (improved gas exchange and reduced ventilatory support) the incidence of classical complications of RDS, especially air leak events, is decreased except for the uncommon problem of pulmonary haemorrhage. The incidence of bronchopulmonary dysplasia is neither uniformly nor significantly reduced although the severity appears to be lessened. The overall incidence of peri-intraventricular haemorrhages is not diminished although separate trials have shown a decreased rate. The most striking beneficial effect of exogenous surfactants is the increased survival (of about 40%) of treated very low birthweight neonates. A small number of adverse effects has been described. The long term outcome of survivor neonates with RDS treated with surfactants versus control neonates with RDS not treated with surfactants is similar in terms of physical growth, at least as good in terms of respiratory status, with a similar or slightly better neurodevelopmental outcome. There is not clear benefit of exogenous surfactant therapy in extremely premature infants (< 26 weeks gestational age, birthweight < 750 g). The potential risks of contamination, inflammatory and immunogenic reaction and the inhalation of platelet activating factor remain a theoretical concern of surfactant therapy which has not been confirmed in clinical practice. The optimal timing of treatment favours prophylaxis over rescue treatment and early rescue treatment rather than delayed therapy. Meta-analyses suggest the clinical superiority of natural surfactant extracts over a synthetic one (colfosceril palmitate). The economic impact of surfactant therapy is favourable and the costs per quality-adjusted life year (QALY) for surviving surfactant treated infants are low. In conclusion, the mid and long term benefit/risk ratio clearly favours the use of exogenous surfactants to prevent or to treat RDS in neonates who have a gestational age of > 26 weeks or a birthweight of > 750 g, especially with the prophylactic strategy using natural surfactant extracts.

Lyso-phosphatidylcholine and outcome of preterm babies with respiratory distress syndrome treated with surfactant

Phosphatidylcholine (PC) is the predominant phospholipid in natural surfactant preparations. A metabolic intermediate, lyso-PC, is potentially injurious to the lungs. In the present study, tracheal aspirates from preterm babies with respiratory distress syndrome treated with surfactant were examined for the presence of lyso-PC to determine if there was any correlation with outcome. Eighteen babies were assigned to receive initially either 100 or 200 mg/kg Curosurf followed by up to three further 100-mg/kg doses if required. Lyso-PC was present in aspirates taken 12-24 h after the last treatment from nine of 11 infants who initially received 200 mg/kg but in only one from seven receiving 100 mg/kg initially, and was dependent on the total dose of phospholipid administered. Three babies in the low-dose group developed bronchopulmonary dysplasia, whereas two in the high-dose group were non-survivors, however we could not correlate the presence of lyso-PC with adverse long-term outcome in this group of preterm infants.

[Early continuous positive pressure in the labor room]

BACKGROUND

Indication for intubation and mechanical ventilation in premature infants may be reduced by initiating continuous positive airway pressure (CPAP) in delivery room.

POPULATION AND METHODS

Immediately after birth, respiratory support with CPAP was given to all infants with gestational age less than 32 weeks. In case of apnea or progressing symptoms with hypoxemia or carbonic acidosis, with PCO2 increasing to more than 60 mmHg, infants were treated with nasotracheal intubation and ventilation.

RESULTS

One hundred and fifty one infants, with mean gestational age 29.6 +/- 1.9 weeks and mean birth weight 1,326 +/- 378 g were delivered in the obstetrical department of Marseille. In delivery room, 63% were treated with CPAP, and only 13% with nasotracheal intubation. The need for subsequent mechanical ventilation was reduced to 40% of the population. Surfactant therapy was used in 17% of this cohort. Two infants were given surfactant and extubated. Three of 14 deaths (9.2%) were caused by respiratory disease.

CONCLUSIONS

Early CPAP reduces the indication of mechanical ventilation in premature infants. Incidence of pulmonary complications such as pneumothorax or bronchopulmonary dysplasia is low among those infants who require mechanical ventilation later. Early CPAP takes place in a general policy to decrease neonatal morbidity.

Babies born under 1000 g--perinatal outcome

Improved survival of very pre-term infants is a result of advances in obstetric and neonatal medicine. To provide relevant data for a Northern Ireland population group, we evaluated mortality and morbidity of extremely low birthweight (ELBW; < 1000 g) infants from a tertiary referral neonatal unit. Seventy-seven ELBW infants were admitted on the first day of life during the period April 1990 to April 1992. Mean (SD) gestational age (GA) was 26.2 (2.1) weeks and birthweight (BW) was 781 (132) g. The degree of severity of initial illness was high, with a mean (SD) CRIB (clinical risk index for babies) score of 7.4 (4.2). Fifty (65%) babies survived, being discharged home at a mean (SD) age of 95 (34) days. Survivors were more likely to have received maternal steroid therapy or been born in this hospital. Ten (20%) of the survivors had evidence of severe neonatal brain injury or cranial ultrasonography--Papile grade 3 or 4 intraventricular haemorrhage (IVH) or periventricular leucomalacia (PVL). Survival rate of ELBW infants without severe brain injury was 54% overall; this ranged from 0% in ELBW infants born at 23 weeks GA and 33% at 24 weeks GA to 85% at 27 weeks GA.

Appropriate surfactant usage in 1996

Surfactant therapy has been proven effective in the prevention and treatment of respiratory distress syndrome. Over 6,000 infants have been studied in randomized controlled trials. These studies have demonstrated that both prophylactic administration of surfactant and administration of surfactant to premature infants with established respiratory distress syndrome will decrease the risk of pneumothorax and decrease the risk of mortality. Currently, over 50% of very low birth weight infants in North America receive some sort of surfactant preparation. However, many questions remain regarding optimal usage of surfactant preparations. Recent randomized controlled trials have evaluated issues regarding surfactant dosage, treatment strategy, method of administration, and surfactant preparation. Initial doses in the range of 100-200 mg/kg with repeat doses to selected infants who relapse appears to be the best approach to therapy. Prophylactic surfactant therapy leads to a small but statistically significant reduction in the risk of pneumothorax and mortality. The clinical relevance of these advantages and the cost effectiveness of this care remains under debate. A variety of methods of administration have been used in randomized controlled trials. Trials which compare these methods of administration demonstrate the adequacy of currently tested bolus administration. However, other methods of administration, such as slow infusion of surfactant leads to uneven distribution of surfactant and poor response. Both synthetic surfactants and natural surfactant extracts have been proven effective in the care of these infants. However, randomized controlled trials which directly compare these two preparations demonstrate a small advantage to the use of natural surfactant extracts. Natural surfactant extracts improve initial ventilatory status and decrease the risk of pneumothorax. Surfactant replacement therapy has proven to be effective in the treatment of very low birth weight premature infants. Current clinical trials support the early institution of treatment either prophylactically or as soon as possible in intubated babies with signs of respiratory distress syndrome. Repeat treatment may be important in optimizing outcome due to surfactant inactivation. Currently available natural surfactant extracts improve early clinical outcome and decrease pneumothorax compared to the available synthetic preparations.

Trends and variations in use of antenatal corticosteroids to prevent neonatal respiratory distress syndrome: recommendations for national and international comparative audit. Scottish Neonatal Consultants' Collaborative Study Group, International Neonatal Network

OBJECTIVES

In 1990 a meta-analysis of randomised trials showed 70% lower mortality after antenatal corticosteroid therapy for 24 h or more for infants born before 31 weeks gestation. We investigated whether antenatal corticosteroid therapy has increased in these infants since 1990 and studied variations in use by hospital of birth.

DESIGN

Retrospective cohort study in 1601 infants in nine neonatal units.

SUBJECTS

Neonatal admissions before 31 weeks of gestation from January 1988 to October 1993. MEASURE OF OUTCOME: Corticosteroids administered for 24 h or more before delivery.

RESULTS

Data were obtained in 1579 (99%) infants. The proportion (range) in each hospital whose mothers had antenatal corticosteroids for 24 h or more was 16% (0-43) in 1988-89 and 29% (0-36) in 1990-93 (P < 0.001). In post hoc analyses, 65/347 (20%) births in district hospitals had treatment for 24 h or more compared with 354/1254 (28%) in teaching hospitals (P = 0.001).

CONCLUSIONS

Antenatal corticosteroid therapy increased but varied by hospital of birth. This may reflect varying performance, or bias from reporting, selection or referral. Ideally, corticosteroid therapy should be compared in women at risk of preterm delivery, but standardising risk or indications for delivery between hospitals and accurate ascertainment presents major difficulties. To minimise selection or referral bias, hospitals should publish, for all mothers delivering between 24 and 33 weeks and 6 days gestation 48 h or more after admission, the proportions treated 1. for 24 h or more (target: > 70%), or 2. at all (target: > 90%).

[Outcome of blood gas parameters during the first 24 years after Exosurf administration]

BACKGROUND

There is now good evidence that the clinical course of infants with respiratory distress syndrome can be improved by treatment with exogenous surfactant. However, optimal methods of giving such a treatment are still debated.

POPULATION AND METHODS

The arterial blood gases and the arterial/alveolar oxygen tension ratio (a/A) were recorded during the 24 hours following artificial surfactant (Exosurf) treatment in 400 newborns aged 25 to 42 gestational weeks. A positive response was defined by an a/A ratio > 0.22 or an increase in a/A ratio up to 25%.

RESULTS

After administration of the first dose, a positive response was obtained in 63% of cases during the first 6 hours and 11% during the 6 following hours. The response after the second dose was favourable in 75% of cases. At 24 hours after treatment, 36% of the infants had obtained an a/A ratio > 0.22.

CONCLUSION

Because of the 18% of infants who responded positively only after the second dose, administration of this dose seems justifiable even in case of non-response to the first dose. The quality of the response is related to the severity of the pulmonary illness but is independent of the gestational age.

Prophylaxis of respiratory distress syndrome by treatment with modified porcine surfactant at birth: a multicentre prospective randomized trial

The objective of this prospective, multicentre trial, carried out at 18 third level hospitals in Italy, was to evaluate efficacy of modified porcine surfactant (Curosurf), administered at birth to prevent the development of respiratory distress syndrome (RDS) in premature infants. 287 babies with a gestational age of 24-30 weeks were randomized to prophylactic treatment with Curosurf (80 mg/ml; dose 20 mg/kg) or to a control group receiving no surfactant treatment in the delivery-room. Babies in both groups were eligible for rescue treatment with surfactant (200 mg/kg) if they developed clinical symptoms of RDS and required mechanical ventilation. The main end-point was to obtain, in the prophylaxis group, a 30% reduction in the incidence of grade 3-4 RDS. Median gestational age was 28 weeks in both groups and mean birth weight 1010 and 1002 g, respectively for prophylaxis and control babies. There was a 32% reduction in the incidence of grade 3-4 RDS in the prophylaxis group (p < 0.05). This was associated with a significant reduction in mean maximum fraction of inspired oxygen (0.57 vs 0.66%; p < 0.01), a decreased incidence of pulmonary interstitial emphysema (7 vs 14%; p < 0.05) and a lowered mortality (21 vs 35%; p < 0.01). Combined unfavourable outcome (mortality + bronchopulmonary dysplasia and/or grade 3-4 intraventricular hemorrhage and/or grade 2-4 retinopathy of prematurity) was significantly lower in the prophylaxis than in the second group (41 vs 58%; p < 0.01). The favourable effects of prophylactic treatment were equally recorded in all the age groups, including the babies with the lowest gestational age (24-25 weeks). Multiple and logistic regression analysis confirmed that high gestational age and surfactant prophylaxis were, independently, associated with a lower degree of RDS (p = 0.0001 and p = 0.0008, respectively) and a lower mortality (p = 0.0001 and p = 0.0045, respectively). We conclude that prophylaxis with modified natural surfactant effectively prevents RDS in newborn babies between 24 and 30 weeks' gestation.