Controlled trial of a single dose of synthetic surfactant at birth in premature infants weighing 500 to 699 grams. The American Exosurf Neonatal Study Group I

Success of blinding a procedural intervention in a randomised controlled trial in preterm infants receiving respiratory support

BACKGROUND

Blinding of treatment allocation from treating clinicians in neonatal randomised controlled trials can minimise performance bias, but its effectiveness is rarely assessed.

METHODS

To examine the effectiveness of blinding a procedural intervention from treating clinicians in a multicentre randomised controlled trial of minimally invasive surfactant therapy versus sham treatment in preterm infants of gestation 25-28 weeks with respiratory distress syndrome. The intervention (minimally invasive surfactant therapy or sham) was performed behind a screen within the first 6 h of life by a 'study team' uninvolved in clinical care including decision-making. Procedure duration and the study team's words and actions during the sham treatment mimicked those of the minimally invasive surfactant therapy procedure. Post-intervention, three clinicians completed a questionnaire regarding perceived group allocation, with the responses matched against actual intervention and categorised as correct, incorrect, or unsure. Success of blinding was calculated using validated blinding indices applied to the data overall (James index, successful blinding defined as > 0.50), or to the two treatment allocation groups (Bang index, successful blinding: -0.30 to 0.30). Blinding success was measured within staff role, and the associations between blinding success and procedural duration and oxygenation improvement post-procedure were estimated.

RESULTS

From 1345 questionnaires in relation to a procedural intervention in 485 participants, responses were categorised as correct in 441 (33%), incorrect in 142 (11%), and unsure in 762 (57%), with similar proportions for each of the response categories in the two treatment arms. The James index indicated successful blinding overall 0.67 (95% confidence interval (CI) 0.65-0.70). The Bang index was 0.28 (95% CI 0.23-0.32) in the minimally invasive surfactant therapy group and 0.17 (95% CI 0.12-0.21) in the sham arm. Neonatologists more frequently guessed the correct intervention (47%) than bedside nurses (36%), neonatal trainees (31%), and other nurses (24%). For the minimally invasive surfactant therapy intervention, the Bang index was linearly related to procedural duration and oxygenation improvement post-procedure. No evidence of such relationships was seen in the sham arm.

CONCLUSION

Blinding of a procedural intervention from clinicians is both achievable and measurable in neonatal randomised controlled trials.

An Update on the Prevention and Management of Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common morbidity affecting preterm infants and is associated with substantial long-term disabilities. There has been no change in the incidence of BPD over the past 20 years, despite improvements in survival and other outcomes. The preterm lung is vulnerable to injuries occurring as a result of invasive ventilation, hyperoxia, and infections that contribute to the development of BPD. Clinicians caring for infants in the neonatal intensive care unit use multiple therapies for the prevention and management of BPD. Non-invasive ventilation strategies and surfactant administration via thin catheters are treatment approaches that aim to avoid volutrauma and barotrauma to the preterm developing lung. Identifying high-risk infants to receive postnatal corticosteroids and undergo patent ductus arteriosus closure may help to individualize care and promote improved lung outcomes. In infants with established BPD, outpatient management is complex and requires coordination from several specialists and therapists. However, most current therapies used to prevent and manage BPD lack solid evidence to support their effectiveness. Further research is needed with appropriately defined outcomes to develop effective therapies and impact the incidence of BPD.

A systematic review of randomized controlled trials for the prevention of bronchopulmonary dysplasia in infants

OBJECTIVE

Bronchopulmonary dysplasia (BPD) is the most common cause of pulmonary morbidity in premature infants and is associated with life-long morbidities. Developing drugs for the prevention of BPD would improve public health. We sought to determine characteristics of favorable randomized controlled trials (RCTs) of drugs for BPD prevention.

STUDY DESIGN

We searched MEDLINE and EMBASE from 1992 to 2014 using the MeSH terms 'BPD' and 'respiratory distress syndrome, newborn'. We included a Cochrane Library search to ensure inclusion of all available RCTs. We identified RCTs with BPD as a primary or secondary outcome and determined the definition of BPD used by the study. We determined whether a phase I or phase II study-to determine drug safety, efficacy or optimal dose-was performed before the RCT. Finally, we searched the Cochrane Library for meta-analyses for each drug and used the results of available meta-analyses to define a favorable versus unfavorable RCT.

RESULT

We identified 2026 articles; 47 RCTs met our inclusion criteria encompassing 21 drugs; 5 of the drugs reduced the incidence of BPD. We found data from phase I or II studies for 16 of the drugs, but only 1 demonstrated a reduction of BPD.

CONCLUSION

The majority of the drugs studied in RCTs failed to reduce the incidence of BPD. Performing early-phase studies before phase III trials might provide necessary information on drugs and drug doses capable of preventing BPD, thus informing the development of future RCTs.

Short-term outcome of pulmonary hemorrhage in very-low-birth-weight preterm infants

BACKGROUND

Severe pulmonary hemorrhage is a serious complication with a high mortality rate in preterm infants with respiratory distress syndrome (RDS) after surfactant therapy. The aim of this study is to evaluate the efficacy of our current management strategy for neonates with severe pulmonary hemorrhage.

MATERIALS AND METHODS

Very-low-birth-weight (VLBW) infants who developed severe pulmonary hemorrhage were studied from January 2006 to August 2011. Treatment for severe pulmonary hemorrhage in our neonatal intensive care unit (NICU) included intratracheal epinephrine spraying/irrigation, blood component therapy, and as necessary, surfactant supplement therapy was administered in cases that secondary RDS was diagnosed. High frequency oscillatory ventilation (HFOV) was utilized when hypoxia or respiratory acidosis persisted under conventional mechanical ventilation (CMV). We then described the clinical courses of severe pulmonary hemorrhage following our management.

RESULTS

A total of 18 (3.2%) out of 469 VLBW infants developed severe pulmonary hemorrhage. The mean gestational age was 27 weeks, the mean birth weight was 822 g, and the onset age was 2.5 days after birth. There was no severe pulmonary hemorrhage-associated mortality during this period with the exception of one case, in which an infant died after the parents refused to do further therapy. Sixteen (88.8%) neonates had RDS and 13 received surfactant therapy. Twelve (66.6%) cases developed secondary RDS following the onset of severe pulmonary hemorrhage, and four cases received surfactant supplement therapy. In the surfactant supplement group, alveolar-arterial oxygen difference (AaDO2) and oxygenation index (OI) during the 2-4 hours postpulmonary hemorrhage period showed statistically significant improvement, whereas the other group only showed a tendency toward improvement without reaching statistical significance when compared to the baseline data. Duration of high oxygen requirement [defined as fraction of inspired oxygen (FiO2) > 40%] was also less in the surfactant supplement group.

CONCLUSION

This data suggests that our current strategy is effective for treating severe pulmonary hemorrhage in VLBW infants. Surfactant therapy for severe pulmonary hemorrhage may also be beneficial for improving lung function and may shorten the duration of high oxygen requirement.

Role of prophylactic surfactant in preterm infants

BACKGROUND

Respiratory distress syndrome (RDS) in preterm neonates is caused by a deficiency or dysfunction of pulmonary surfactant. The physiological function of surfactant includes the ability to lower surface tension, as well as the ability to rapidly adsorb and spread. A wide variety of surfactant products have been formulated and studied in clinical trials. The present study was designed to find out whether prophylactic administration of surfactant leads to a significant decrease in the risk of neonatal mortality and neonatal morbidity.

METHODS

This was an experimental study in which a total of 125 preterm newborns less than 34 weeks gestation were studied. One hundred preterm newborns (controls) less than 34 weeks gestation were managed in the conventional manner as per the existing protocols in the neonatal intensive care unit. Twenty-five consecutively delivered preterm newborns less than 34 weeks gestation were administered surfactant. Data regarding clinical outcomes including mortality and morbidity profile was collected and analysed.

RESULTS

The mean duration of ventilation in the ventilated babies in the control group and the surfactant group was 129.8 ± 43 hours and 85.7 ± 46 hours, respectively; the difference being statistically significant. In the surfactant group, four babies (16%) died and in the control group, 27 babies (27%) died. The difference was not statistically significant. The number of babies developing retinopathy of prematurity and needing laser treatment for retinopathy of prematurity was greater in the surfactant group.

CONCLUSION

Prophylactic administration of surfactant in preterm newborns of gestational age < 34 weeks is associated with a significant decrease in mean duration of ventilation and an increase in the incidence of retinopathy of prematurity.

Prophylactic protein free synthetic surfactant for preventing morbidity and mortality in preterm infants

BACKGROUND

Respiratory distress syndrome (RDS) is caused by a deficiency or dysfunction of pulmonary surfactant. A variety of surfactant products including protein free synthetic surfactant have been developed and tested in the prevention and treatment of RDS.

OBJECTIVES

To assess the effect of prophylactic administration of protein free synthetic surfactant (SS) on mortality, chronic lung disease and other morbidities associated with prematurity in preterm newborns at risk for developing RDS. Subgroup analysis were planned according to the degree of prematurity, surfactant product and dosage schedule.

SEARCH STRATEGY

Searches were made of the The Cochrane Library, MEDLINE, OVID, EMBASE, CINAHL from 1966 to 2009. In addition, previous reviews including cross references and abstracts from the Society for Pediatric Research were searched. No language restrictions were applied.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials that compared the effect of protein free SS administered to high risk preterm newborns at or shortly after birth in order to prevent RDS, mortality and complications of prematurity.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes was excerpted from the clinical trials by the reviewers. Data were analyzed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Studies of prophylactic administration of protein free SS note a variable improvement in the respiratory status and a decrease in respiratory distress syndrome in infants who receive prophylactic protein free SS. The meta-analysis supports a decrease in the risk of pneumothorax (typical relative risk 0.67, 95% CI 0.50, 0.90), pulmonary interstitial emphysema (typical relative risk 0.68, 95% CI 0.50, 0.93), and neonatal mortality (typical relative risk 0.70, 95% CI 0.58, 0.85). No differences were seen in the risk of intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and cerebral palsy. The meta-analysis supports an increase in the risk of patent ductus arteriosus associated with prophylactic SS administration (typical relative risk 1.11, 95% CI 1.00, 1.22), and an increase in the risk of pulmonary hemorrhage (typical relative risk 3.28, 95% CI 1.50, 7.16).

AUTHORS' CONCLUSIONS

Prophylactic intratracheal administration of protein free synthetic surfactant to infants at risk of developing respiratory distress syndrome has been demonstrated to improve clinical outcome. Infants who receive prophylactic protein free SS have a decreased risk of pneumothorax, a decreased risk of pulmonary interstitial emphysema, and a decreased risk of neonatal mortality. Infants who receive prophylactic protein free SS have an increased risk of developing patent ductus arteriosus and pulmonary hemorrhage.

Adsorption and direct probing of fibrinogen and sodium myristate at the air/water interface

Fibrinogen (FB), a serum protein, is considered a major inhibitor of lung surfactant function at the lining layer of the alveoli. In this study, the adsorption of aqueous bovine FB at the air/water interface was investigated with tensiometry and directly probed for the first time with ellipsometry and infrared reflection adsorption spectroscopy (IRRAS). The tension results show that FB has moderate surface activity. The surface densities of FB were calculated by using two different ellipsometry models to range from 3+/-0.2 to 17+/-2 mg/m2, for 7.5 to 750 ppm of FB in water at 25 degrees C. Although FB at concentrations from 75 to 750 ppm reached about the same steady surface tension value, the surface densities at 750 ppm FB were substantially larger. The same techniques were used for studying aqueous mixtures of 7.5 to 750 ppm FB with 2 mM of sodium myristate (SM) to investigate a possible interaction of the SM with the protein. The behavior of the FB/SM mixtures was found to be close to that of SM alone. The surface tension of the FB/SM mixtures reached values less than 10 mN/m under surface area oscillation at 20 or 80 rpm. These results and the ellipsometry and the IRRAS results indicate that at a concentration of 2 mM SM, FB, up to 750 ppm, does not inhibit the surfactant surface-tension-lowering function. In certain cases the results demonstrate that FB and SM may act cooperatively in lowering the surface tension.

Surfactant era (1990-2002) 2-year outcomes of infants less than 1500 g from a Community Level 3 Neonatal Intensive Care Unit

OBJECTIVE

To report Bayley scores of 572 twenty-four-month corrected age infants whose birth weights (BWs) were less than 1500 g cared for in a Community Level 3 Neonatal Intensive Care Unit (NICU) between 1990 and 2002 when surfactant was routinely used.

STUDY DESIGN

Survival, "normal" defined as both Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI)>84, MDI>69 and MDI>84 were analyzed by gestational age (GA) and BW. Comparisons were made between infants born pre- and post-1996 when high-frequency oscillatory ventilation came into frequent use, Medicaid and non-Medicaid infants, multiples and singletons, outborn and inborn infants, boys and girls and infants with intrauterine growth retardation (IUGR) and those appropriate for gestational age (AGA).

RESULTS

There was a correlation between GA and BW and improving outcomes. Scores do not approach those of normal standardization sample populations (60% for "normal", 68% for MDI>84 and 95% for MDI>69) until 1400 g and 30 weeks. Medicaid, outborn and IUGR infants, and boys did worse in some aspects.

CONCLUSION

There was a correlation between both GA and BW and improving outcomes. Availability of these developmental data on a laminated pocket card can facilitate presentation of outcome experience to families by pediatric and obstetric caregivers.

Interaction of an artificial surfactant in human pulmonary epithelial cells

Surfaxin (lucinactant), a peptide-based surfactant consisting of dipalmitoylphosphatidylcholine (DPPC) plus KL(4) (sinapultide) (a synthetic peptide modeled after human surfactant protein-B), is effective in treating respiratory distress syndrome in preterm infants. Our goal was to determine the uptake and effects of Surfaxin on human pulmonary type II cells isolated from fetal tissue and other lung cell types. Based on previous published reports, we hypothesized that this exogenous synthetic surfactant would have little effect on type II cell surfactant-related physiological features. Human type II cells and A549 and NCI-H441 adenocarcinoma cells incorporated (3)H-KL(4) and (14)C-DPPC components in Surfaxin, but with different kinetics. Fractionation of NCI-H441 and A549 cellular components indicated that the highest specific activity of (3)H-KL(4) was present in the 18,000g cellular fraction (which contains vesicles and lysosomes). The number of lamellar bodies (LBs) appears to increase in human type II cells incubated in the presence of Surfaxin when visualized by light microscopy, while LB structure (determined by electron microscopy) was not altered. Expression of endogenous surfactant protein (SP-A, SP-B, and SP-C) mRNA levels in human type II cells was not altered by the presence of Surfaxin. We conclude that while human type II cells and other lung cell types can incorporate the components of Surfaxin, the surfactant-related physiological functions of these cells are not altered.

Fetal infants: the fate of 4172 infants with birth weights of 401 to 500 grams--the Vermont Oxford Network experience (1996-2000)

OBJECTIVE

Improvement in the survival of extremely low birth weight infants requires that we evaluate the limits of our care and assess the impact of treatment on a population of infants who previously rarely survived.

METHODS

A review was conducted of demographic and clinical data of infants who had birth weight 401 to 500 g and were entered in the Vermont Oxford Network Database between 1996 and 2000.

RESULTS

A total of 4172 infants who weighed 401-500 g (mean gestational age: 23.3 +/- 2.1 weeks) were born at 346 participating centers. Overall, 17% survived until discharge. A total of 2186 (52%) died in the delivery room (DR), and 1986 (48%) were admitted to a neonatal intensive care unit (NICU). Compared with infants who died in the DR, infants who survived the DR and were admitted to the NICU were more likely to be female (58% vs 49%), to be small for gestational age (56% vs 11%), to have received prenatal steroids (61% vs 12%), and to have been delivered by cesarean section (55% vs 5%). Thirty-six percent of NICU admissions survived to discharge. Mean gestational age of the 690 NICU survivors was 25.3 +/- 2.0 weeks. These survivors experienced significant morbidity in the NICU.

CONCLUSIONS

An appreciable number of these marginally viable fetal infants survive. They experienced a high rate of serious morbidities while in the NICU. There is very little information about long-term outcomes, as the medical and developmental status of few of these infants has been followed carefully. Parents should be made aware of the high incidence of serious problems, and concerted efforts should be made to follow the status of these infants.

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.

Comparison of low and high dose of vitamin D treatment in nutritional vitamin D deficiency rickets

In this study, we compared three different therapy modes (150,000 IU, 300,000 IU, and 600,000 IU vitamin D p.o.) in infants with nutritional vitamin D deficiency rickets (VDR). Our purpose was to determine the most effective dosage of vitamin D with least side effects for treating VDR. The study included 56 patients, 3-36 months of age, with nutritional VDR and 20 age-matched control infants. In all infants, serum calcium, phosphorus, alkaline phosphatase, magnesium, serum 25-hydroxycholecalciferol, plasma intact parathormone levels and urinary Ca/creatine ratio were determined. Of 56 patients, 52 were able to be followed long-term. These patients were reexamined on the 3rd day, 7-10th day, and 25-30th day after treatment. On the 30th day post-treatment, we did not find any difference between the doses in the improvement of rickets. However, hypercalcemia was present in eight infants who had been administered 300,000 IU (two infants) and 600,000 IU (six infants) of vitamin D. In conclusion, our findings showed that 150,000 IU or 300,000 IU of vitamin D was adequate in the treatment of VDR, but 600,000 IU of vitamin D may carry the risk of hypercalcemia.

Increased fragility of pulmonary capillaries in newborn rabbit

The pulmonary capillaries of neonatal lungs are potentially vulnerable to stress failure because of the complex changes in the pulmonary circulation that occur at birth. We perfusion fixed the lungs from nine anesthetized newborn rabbits at capillary transmural pressures (P(tm)) of 5 +/- 5, 10 +/- 5, and 15 +/- 5 cmH(2)O. Normal microscopic appearances were seen at P(tm) values of 5 +/- 5 and 10 +/- 5 cmH(2)O, but massive airway edema was observed in lungs perfused at a P(tm) of 15 +/- 5 cmH(2)O. Consistent with this, no disruptions of the alveolar epithelium were observed at P(tm) values of 5 +/- 5 cmH(2)O, but mean values of 0.11 and 1.22 breaks/mm epithelium were found at P(tm) of 10 +/- 5 and 15 +/- 5 cmH(2)O, respectively (P < 0.05 for 5 +/- 5 vs. 15 +/- 5 cmH(2)O). These pressures are in striking contrast to those in the adult rabbit in which, by a similar procedure, a P(tm) of 52.5 cmH(2)O, is required before stress failure is consistently seen. We conclude that stress failure of pulmonary capillaries in newborn rabbit lungs can occur at P(tm) values of less than one-third of those that are required in adult lungs.

Function and inhibition sensitivity of the N-terminal segment of surfactant protein B (SP-B1-25) in preterm rabbits

BACKGROUND

Surfactant protein B (SP-B) is an essential component of pulmonary surfactant, but shorter SP-B sequences may exert equivalent surface activity.

METHODS

We synthesised a peptide based on the amino-terminal domain of SP-B (SP-B1-25), a full length SP-B1-78, and a full length palmitoylated SP-C peptide (SP-C1-35) and compared the in vivo function and sensitivity to plasma inhibition of preparations consisting of mixtures of phospholipids with SP-B1-25 or SP-B1-78 and/or SP-C1-35 to Survanta. Preterm rabbits born at 27 days of gestation were treated at birth with surfactant and ventilated for 60 minutes. At 15 minutes half of them received plasma intratracheally. Dynamic compliance was monitored every 15 minutes and postmortem pressure-volume curves were measured to define lung mechanics.

RESULTS

Dynamic compliance and postmortem lung volumes were highest after treatment with a surfactant consisting of an SP-B peptide and SP-C1-35 or Survanta. Plasma instillation decreased dynamic compliance and lung volumes sharply, but the most effective activity was by prior instillation of surfactants containing SP-B1-25.

CONCLUSION

These experiments suggest that the N-terminal domain of SP-B (SP-B1-25) exhibits in vitro and in vivo surface activity and is relatively insensitive to plasma inhibition.

Outcomes of children of extremely low birthweight and gestational age in the 1990s

Advances in perinatal care have improved the chances for survival of extremely low birthweight (<800 grams) and gestational age (<26 weeks) infants. A review of the world literature reveals that among regional populations, survival at 23 weeks' gestation ranges from 2 to 35%, at 24 weeks' gestation 17 to 62% and at 25 weeks' gestation 35 to 72%. These wide variations may be accounted for by differences in population descriptors, in the criteria used for starting or withdrawing treatment, in the reported duration of survival and differences in care. Major neonatal morbidity increases with decreasing gestational age and birthweight. At 23 weeks' gestation, chronic lung disease occurs in 57 to 86% of survivors, at 24 weeks in 33 to 89% and at 25 weeks' gestation in 16 to 71% of survivors. The rates of severe cerebral ultrasound abnormality range from 10 to 83% at 23 weeks' gestation, 9 to 64% at 24 weeks and 7 to 22% at 25 weeks' gestation Of 77 survivors at 23 weeks' gestation, 26 (34%) have severe disability (defined as subnormal cognitive function, cerebral palsy, blindness and/or deafness). At 24 weeks' gestation, the rates of severe neurodevelopmental disability range from 22 to 45%, and at 25 weeks' gestation 12 to 35%. When compared with children born prior to the 1990s, the rates of neurodevelopmental disability have, in general, remained unchanged. We conclude that, with current methods of care, the limits of viability have been reached. The continuing toll of major neonatal morbidity and neurodevelopmental handicap are of serious concern.

Mortality and time to death in very low birth weight infants: California, 1987 and 1993

BACKGROUND

Recent advances in perinatal technology have dramatically increased the survival of very low birth weight (VLBW) infants (<1500 g). The possibility that these advances may also prolong the time to death and increase pain and suffering has been of concern, but there have been no population-based evaluations of this issue.

METHODS

Infant, neonatal, and postneonatal mortality rates and time to death for infants 500 to 749 g, 750 to 999 g, 1000 to 1499 g, and all VLBW infants born during 1987 were compared with those outcomes for infants born in 1993 using statewide California linked birth/death cohort files. To assess the effects of improved survival and changes in time until death, we calculated the total days of life preceding an infant death per 1000 live born infants (TDD).

RESULTS

VLBW infants comprised.96% of California's live births in 1987 and.92% of those in 1993. Between 1987 and 1993, VLBW infant mortality rate decreased 28.4% (from 290.7 to 208.3 per 1000 live born VLBW infants), VLBW neonatal mortality rate decreased 30. 3% (from 244.5 to 170.4), and VLBW postneonatal mortality rate decreased 25.3% (from 61.2 to 45.7 per 1000 VLBW alive at 28 days; P <.05 for each rate). Infant mortality rates decreased by 18.8% (718. 1 to 583.0 per 1000) for infants 500 to 749 g, 43.3% (375.1 to 202. 6) for infants 750 to 999 g, and 40.1% (127.9 to 76.7) for infants 1000 to 1449 g (P <.05 for each group). Neonatal mortality and postneonatal mortality rates also decreased in all 3 VLBW subgroups. These reductions in mortality rates were not accompanied by a significant difference in the distribution of times to death or a significant increase in the average time to death for all VLBW infants (22.0 vs 23.6 days) or for those with birth weights of 500 to 749 g (12.7 vs 71.5 days). Reduced mortality in larger infants was accompanied by an increase in the average time to death, from 24. 3 to 32.5 days in infants 750 to 999 g and from 32.3 to 47.0 days in infants 1000 to 1449 g. TDD decreased from 6410 to 4908 days for all VLBW infants. TDD was also reduced 26.4% (2401 days), 24.3% (2115 days), and 22.5% (1043 days) for the 3 VLBW birth weight groups.

CONCLUSIONS

Both mortality rate and timing of death are important when assessing the impact of advances in perinatal technology. Although the average time to death was significantly increased in VLBW infants weighing >750 g, between 1987 and 1993, advances in perinatal technology dramatically decreased VLBW mortality. In the State of California in 1993, this resulted in 452 fewer VLBW deaths and 8233 fewer days preceding a VLBW death than expected.

Prophylactic synthetic surfactant for preventing morbidity and mortality in preterm infants

BACKGROUND

This section is under preparation and will be included in the next issue.

OBJECTIVES

To assess the effect of prophylactic administration of synthetic surfactant in preterm newborns at risk for developing respiratory distress syndrome (RDS).

SEARCH STRATEGY

Searches were made of the Oxford Database of Perinatal Trials, Medline (MeSH terms: pulmonary surfactant; limits: age groups, newborn infants; publication type, clinical trial), previous reviews including cross-references, abstracts, conference and symposia proceedings, expert informants, and journal hand searching in the English language.

SELECTION CRITERIA

Randomized, controlled trials which compared the effect of prophylactic synthetic surfactant administered to high risk preterm newborns at or shortly after birth in order to prevent respiratory distress syndrome and other complications of prematurity.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes including the incidence of pneumothorax, pulmonary interstitial emphysema, patent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage (any grade and severe intraventricular hemorrhage), bronchopulmonary dysplasia, mortality, bronchopulmonary dysplasia or death, retinopathy of prematurity (any retinopathy, and retinopathy stages 3-4) mortality to one year of age, and cerebral palsy was excerpted from the report of the clinical trials by the reviewer. Data were analyzed according to the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Studies of prophylactic administration of synthetic surfactant note a variable improvement in the respiratory status and a decrease in respiratory distress syndrome in infants who receive prophylactic synthetic surfactant. The meta-analysis supports a decrease in the risk of pneumothorax (typical relative risk 0.67, 95% CI 0.50, 0.90; typical risk difference -0.05, 95% CI -0.09, -0. 02), a decrease in the risk of pulmonary interstitial emphysema (typical relative risk 0.68, 95% CI 0.50, 0.93; typical risk difference -0.06, 95% CI -0.11, -0.01), and a decrease in risk of neonatal mortality (typical relative risk 0.70, 95% CI 0.58, 0.85; typical risk difference -0.07, 95% CI -0.11, -0.03). No differences were seen in the risk of intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and cerebral palsy. The meta-analysis supports an increase in the risk of patent ductus arteriosus associated with prophylactic synthetic surfactant administration (typical relative risk 1.11, 95% CI 1.00, 1.22; typical risk difference 0.05, 95% CI 0. 00,0.10), and an increase in the risk of pulmonary hemorrhage (typical relative risk 3.28, 95% CI 1.50, 7.16; typical risk difference 0.03, 95% CI 0.01, 0.05).

REVIEWER'S CONCLUSIONS

Prophylactic intratracheal administration of synthetic surfactant to infants judged to be at risk of developing respiratory distress syndrome has been demonstrated to improve clinical outcome. Infants who receive prophylactic synthetic surfactant have a decreased risk of pneumothorax, a decreased risk of pulmonary interstitial emphysema, and a decreased risk of neonatal mortality. Infants who receive prophylactic synthetic surfactant have an increased risk of developing patent ductus arteriosus and pulmonary hemorrhage.

Outcomes of children of extremely low birthweight and gestational age in the 1990's

Advances in perinatal care have improved the chances for survival of extremely low birthweight (< 800 g) and gestational age (< 26 weeks) infants. A review of the world literature and our own experience reveals that at 23 weeks gestation survival ranges from 2% to 35%. At 24 weeks gestation the range is 17% to 58%, and at 25 weeks gestation 35% to 85%. Differences in population descriptors, in the initiation and withdrawal of treatment and the duration of survival considered may account for the wide variations in the reported ranges of survival. Major neonatal morbidity increases with decreasing gestational age and birthweight. The rates of severe cerebral ultrasound abnormality range at 23 weeks gestation from 10% to 83%, at 24 weeks from 17% to 64% and at 25 weeks gestation from 10% to 22%. At 23 weeks gestation, chronic lung disease occurs in 57% to 70% of survivors, at 24 weeks in 33% to 89%, and at 25 weeks gestation in 16% to 71% of survivors. When compared to children born prior to the 1990's, the rates of neurodevelopmental disability have, in general, remained unchanged. Of 30 survivors reported at 23 weeks gestation nine (30%) are severely disabled. At 24 weeks gestation the rates of severe neurodevelopmental disability (including subnormal cognitive function, cerebral palsy, blindness and deafness) range from 17% to 45%, and at 25 weeks gestation 12% to 35% are similarly affected. In Cleveland, Ohio, we compared the outcomes of 114 children with birthweight 500-749 g born 1990-1992 to 112 infants born 1993-1995. Twenty month survival was similar (43% vs 38%). The use of antenatal and postnatal steroids increased (10% vs 54% and 43% vs 84%, respectively, P< 0.001), however the rates of chronic lung disease increased from 41% to 63% (P = 0.06). There was a significant increase in the rate of subnormal cognitive function at 20 months corrected age (20% vs 48%, P < 0.02) and a trend to an increase in the rate of cerebral palsy (10% vs 16%) and neurodevelopmental impairment. We conclude that, with current methods of care, the limits of viability have been reached. The continuing toll of major neonatal morbidity and neurodevelopmental handicap are of serious concern.

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.

Bronchopulmonary dysplasia. Impact of surfactant replacement therapy

Bronchopulmonary dysplasia is a major contributor to the morbidity and mortality of infants born prematurely. Surfactant replacement therapy has had a significant impact on the death rate from respiratory distress syndrome, yet the impact on bronchopulmonary dysplasia is minimal. Despite these findings, the overall incidence and severity of bronchopulmonary dysplasia are likely to decline over time as neonatal care continues to advance.

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.

Survival and developmental disability in infants with birth weights of 501 to 800 grams, born between 1979 and 1994

OBJECTIVE

Because the survival rate has increased for extremely low birth weight neonates, many have raised the concern that the rate of developmental disability among survivors will also increase. To address this concern, we analyzed changes over time in survival and major neurosensory impairment in a sample of extremely low birth weight infants born between July 1, 1979, and June 30, 1994.

METHODS

The study sample included 513 infants with birth weights of 501 to 800 g who were cared for in either of the two neonatal intensive care units that serve a 17-county region in northwest North Carolina and who were born to mothers residing in that region. At 1 year of age (corrected for gestation), survivors were examined by a pediatrician and were tested using the Bayley Scales of Infant Development. Major neurosensory impairment was defined as cerebral palsy, a Bayley Mental Developmental Index <68, or blindness. A total of 209/216 (97%) of survivors were examined at 1 year of age. Epoch of birth was defined as follows: epoch 1, July 1, 1979 to June 30, 1984; epoch 2, July 1, 1984 to June 30, 1989; and epoch 3, July 1, 1989 to June 30, 1994.

RESULTS

Survival rates for epochs 1, 2, and 3 were, respectively, 24/120 (20%), 63/175 (36%), and 129/218 (59%). In contrast, the proportions with a major neurosensory impairment did not increase over time; rates for successive epochs were 6/24 (25%), 17/61 (28%), and 26/124 (21%). Rates of cerebral palsy were 3/24 (13%), 12/61 (20%), and 9/124 (7%); rates of delayed mental development were 4/24 (17%), 12/61 (20%), and 17/124 (14%); and rates of blindness were 2/24 (8%), 0/62, and 5/124 (4%), respectively.

CONCLUSIONS

This analysis suggests that the increasing survival of extremely low birth weight neonates since the late 1970s has not resulted in an increased rate of major developmental problems identifiable at 1 year of age.

Synthetic or natural surfactants

Surfactant replacement therapy is one of the most studied interventions in neonatal medicine, with many thousands of infants having been enrolled in randomized clinical trials. It is clear that surfactant therapy reduces neonatal mortality and the risk of pulmonary air leaks in babies with or at risk of developing respiratory distress syndrome. Yet some doubts linger over other aspects of this therapy, despite it having been an acceptable and proven therapy for the past 7-10 years. As regards timing of treatment, the earlier the better, with true prophylaxis being reserved for babies of less than 28 week's gestation. Natural surfactant preparations containing surfactant proteins B and C act more rapidly than their synthetic protein-free counterparts and probably also have a greater impact on reducing neonatal mortality and pulmonary air leaks. Fears raised about immunological effects, prion transmission and chemical contamination of natural surfactants have not been substantiated. Long-term follow-up studies do not show any differences in outcome between treated and non-treated infants, except that the incidence and severity of retinopathy of prematurity might be reduced by treatment with natural surfactant. Further research is needed and this will include more detailed follow-up studies, newer indications for surfactant therapy and the testing of newer preparations with synthetic peptides or protein analogues added.

Pulmonary hemorrhage: a novel complication after extracorporeal life support

Pulmonary hemorrhage (PH) occurs infrequently as a complication in neonates with respiratory failure. Major PH has been observed at the authors' institution in several neonates after "successful" completion of extracorporeal life support (ECLS) therapy. The authors sought to determine the incidence of PH and the risk factors associated with this unique and newly described morbidity after ECLS. The hospital records of all patients who had PH after ECLS were reviewed. The control patients were the first three infants who underwent ECLS just before each PH case. PH was defined as the occurrence of bloody tracheal secretions associated with a deterioration in pulmonary status. Demographics, ventilator/ECLS parameters, fluid management, coagulation, and laboratory studies were evaluated in the pre-ECLS, during ECLS, and in the post-ECLS period. From 1985 to 1993, 13 (6%) of 214 neonates suffered major PH, at a mean time of 43.2 +/- 9.2 hours after the ECLS course. The overall mortality rate for children with PH was 38%, compared with 5% among the control patients. In the pre-ECLS phase, patients with PH required more fluid (153.6 +/- 20.2 mL/kg/d v 106.8 +/- 10.2 mL/kg/d) and were acidemic for a longer period (2.3 +/- 1.2 hours v 0.6 +/- 0.2 hours; pH < 7.25). No differences were noted in AaDo2 or oxygenation index criteria. During ECLS, inotropes were required more often (23% v 0%; P < .01) because hypotension was more common (77% v 33%; P < .05). Activated clotting times (ACT) and heparin requirements were equivalent for the two groups. After ECLS the patients with PH required longer ventilatory assistance (184.9 +/- 48.2 hours v 83.4 +/- 16.7 hours) and supplemental oxygen (24.3 +/- 3.0 days v 17.2 +/- 1.9 days). No coagulation abnormalities were identified at the time of PH. Higher SGPT (185.4 +/- 146.4 U/L v 22.6 +/- 3.5 U/L; P < .05) and BUN (69.3 +/- 7.5 mg/dL v 47.2 +/- 5.9 mg/dL; P < .05) also were noted for the patients with PH. PH represents an important and novel morbidity in neonates after ECLS. Prolonged acidosis, a high fluid requirement before ECLS, the need for blood pressure support during ECLS, and evidence of renal and/or hepatic dysfunction serve to identify patients who have a high risk for the development of this complication.

Exogenous surfactant use in neonates

OBJECTIVE

To review exogenous surfactant use in the treatment of respiratory distress syndrome (RDS) in premature neonates.

DATA SOURCES

A MEDLINE search and extensive review of journals was conducted to identify the information for this review from 1983 to 1995 using the following key words: prematurity, surfactant, clinical trials, beractant, Survanta, colfosceril, Exosurf, and neonatal respiratory distress syndrome.

STUDY SELECTION AND DATA EXTRACTION

All articles were considered for possible inclusion in the review. Emphasis was placed on controlled studies involving beractant and colfosceril palmitate.

DATA SYNTHESIS

Results of published clinical trials using beractant or colfosceril palmitate in premature infants at risk for RDS have shown improvement in the need for supplemental oxygen and ventilatory support over the course of RDS and a reduction in pneumothorax. However, there was little impact on the incidence of intraventricular hemorrhage. Clinical trials studying the treatment of established RDS have also shown similar improvements. In a comparison of prophylactic versus late treatment, no distinct advantage of preventive treatment was found, except among infants less than 26-28 weeks gestation. Single versus multiple-dose studies have shown no specific advantage of more than two doses of colfosceril palmitate. A comparison trial of beractant and colfosceril palmitate has shown no difference in outcome. Long-term follow-up studies have been encouraging among infants being treated with exogenous surfactant.

CONCLUSIONS

The use of beractant and colfosceril palmitate in premature infants has clearly decreased morbidity and mortality associated with RDS. Only one trial has compared the efficacy of beractant with that of colfosceril in the treatment of RDS. There does not appear to be a distinct advantage of one product over another. Early treatment of infants at highest risk for RDS, those less than 26-28 weeks gestation, seems to be beneficial over waiting for RDS to progress in severity. Further research needs to be performed to determine the optimal dosing and timing of these agents, as well as comparative trials studying efficacy. Criteria for use of these products need to be further defined to decrease the incidence of unnecessary treatment.

[Natural or artificial surfactants? Arguments in favour of natural surfactants]

The use of exogenous surfactant (ES) is an essential component for prevention and treatment of hyaline membrane disease (HMD). The ES available for clinical use are of two therapeutic classes: natural surfactants prepared from mammalian lung and artificial surfactants. The choice between these two classes of ES is controversial. In this overview, we present the arguments in favour of the preferential use of natural ES. The presence of hydrophobic specific proteins (SP-B and SP-C) provides to natural ES better surface tension properties than artificial ES. The in vitro greater efficacy of natural ES has been confirmed in vivo in experimental models of surfactant deficiency, human pharmacodynamic studies, and comparative clinical trials. Furthermore, the excellent clinical tolerance and harmlessness of natural ES has been firmly established. A meta-analysis of the comparative clinical trials between natural ES and one artificial ES (enrolling as many as 4400 babies treated for HMD) suggests that the use of natural ES compared to this artificial ES significantly reduces the neonatal mortality by 20%. In conclusion, all these arguments are in favor of the preferential use of natural ES for prevention and treatment of HMD.

Controversies: synthetic or natural surfactant. The case for natural surfactant

Surfactant replacement therapy for respiratory distress syndrome (RDS) is not new, the first trials having been performed over 30 years ago. These early trials used synthetic protein-free surfactants administered as aerosols and were unsuccessful. Since 1980 a variety of natural and synthetic surfactant preparations have been used to treat or prevent RDS, and both demonstrate clinical effects. I have used evidence derived from 3 areas to demonstrate the superiority of natural surfactants: in vitro physical properties, in vivo physiological effects and the results of comparative clinical trials. using the pulsating bubble surfactometer, the surface tension at maximum and minimum bubble size are significantly lower for natural compared to synthetic surfactants (31 and 0 mN/m versus 53 and 29 mN/m respectively). Physiological effects of surfactants have been compared in immature rabbits and lambs and both models demonstrate the superiority of natural surfactants. For example in immature rabbits lung compliance values after 60 minutes of ventilation are 0.60 ml/cmH2O in natural surfactant treated animals, 0.44 ml/cmH2O in synthetic surfactant treated animals and 0.34 ml/cmH2O in controls (p < 0.01). The technique of meta-analysis was used to analyse the outcome of 6 comparative clinical trials of natural and synthetic surfactants. These 6 studies included 3536 babies and 5 of them compared Survanta (a bovine natural surfactant) and Exosurf (a synthetic protein-free surfactant). One study compared Infasurf (another bovine natural surfactant with Exosurf). Meta-analysis shows a 19% reduction in the odds of neonatal death for natural compared to synthetic surfactant treated babies (OR, 0.81; 95% CI 0.66-0.98). For bronchopulmonary dysplasia there was a non-significant reduction in risk for Survanta-treated babies (OR, 0.93; 95% CO 0.78-1.10). In summary, there is now clear evidence of physiological and clinical superiority of natural compared to synthetic surfactants. Surfactant proteins B and C are needed to facilitate rapid adsorption and spreading of phospholipids. They also account for the more rapid clinical action allowing oxygen and ventilator pressures to be lowered soon after administration. The odds of neonatal mortality are reduced by about 20% if natural surfactants are preferred to their synthetic protein-free counterparts. Long-term follow-up studies of babies treated with both types of surfactant should be a top priority.

Double-blind, randomized trial of one versus three prophylactic doses of synthetic surfactant in 826 neonates weighing 700 to 1100 grams: effects on mortality rate. American Exosurf Neonatal Study Groups I and IIa

At 33 hospitals in the United States, a double-blind, randomized clinical trial was performed to compare one versus three prophylactic doses of synthetic surfactant in 700 to 1100 gm inborn infants. All 826 infants received an initial prophylactic dose of surfactant within 30 minutes of birth. Subsequently 410 infants received two doses of placebo (air) 12 and 24 hours later, and 416 infants received two additional doses of surfactant. By the age of 28 days, 70 infants who received one dose of surfactant and 40 infants who received three doses were dead, a 43% relative reduction in the mortality rate (30 fewer deaths; p = 0.002). By the age of 1 year after term, 87 infants who received one dose and 62 infants who received three doses were dead: a 29% relative reduction in the mortality rate (25 fewer deaths; p = 0.027). Infants who received three doses of surfactant required significantly less oxygen and less mean airway pressure for the first week of life. Necrotizing enterocolitis (9 vs 25 infants; p = 0.005), and use of high-frequency ventilation (13 vs 26 infants; p = 0.037); pancuronium (43 vs 62 infants; p = 0.045); and leukocyte transfusions (0 vs 4 infants; p = 0.042) were less frequent in the three-dose group, but air leak, bronchopulmonary dysplasia, intraventricular hemorrhage, patent ductus arteriosus, pulmonary hemorrhage, and infections were not different. These results indicate that physiologic findings, mortality rates, and probably morbidity rates are improved by two additional prophylactic doses of synthetic surfactant.

Surfactant replacement therapy

Surfactant replacement therapy for treatment or prevention of the respiratory distress syndrome (RDS) has been studied intensively over the past decade. Randomized controlled trials have demonstrated a reduction in the odds of neonatal death of about 40% and of pulmonary air leaks of 35 to 70% depending upon the type of surfactant used. Prophylaxis or very early treatment is superior to later treatment, especially for the very preterm (< 28 week) infant. Natural (derived from animal lungs) surfactants have a more rapid onset of action than synthetic surfactants and may also provide better long-term benefits, but further comparative trials will be needed to demonstrate this conclusively. Surfactant treatment should not be viewed as a substitute for prenatal steroid therapy to enhance fetal lung maturity; the treatments are synergistic.

Extensive intraalveolar pulmonary hemorrhage in infants dying after surfactant therapy

To assess the possible relationship between exogenous surfactant therapy and pulmonary hemorrhage in premature infants, we compared autopsy findings in 15 infants treated with exogenous surfactant and in 29 who died before the introduction of surfactant therapy. Infants who met the following criteria were included: birth weight 501 to 1500 gm, survival 4 hours to 7 days, and no congenital anomalies. Average birth weight, gestational age, and age at death were equivalent for the two groups. High rates of pulmonary hemorrhage were present in both groups (treated 80% vs untreated 83%). The untreated group had higher incidences of interstitial hemorrhage and lung hematomas and significantly more large interstitial hemorrhages: 31% untreated versus 0% treated (p < 0.05). The overall rate of intraalveolar hemorrhage was similar in the two groups, but surfactant-treated infants were more likely to have extensive intraalveolar hemorrhage: 53% versus 14% (p < 0.05). Most surfactant-treated infants who survived more than 24 hours had extensive intraalveolar hemorrhage (8/9). Patients who had extensive intraalveolar hemorrhage, with or without prior surfactant therapy, frequently had clinically significant pulmonary hemorrhage (7/12). These findings indicate that infants who die after surfactant therapy have higher rates of a specific type of pulmonary hemorrhage--extensive intraalveolar hemorrhage.

High-dose versus low-dose bovine surfactant treatment in very premature infants

The aim of the study was to determine if high-dose bovine surfactant (Alveofact, initially 100 mg/kg birth weight) would improve oxygenation compared with low-dose surfactant (50 mg/kg birth weight) administered intratracheally within 1 h after birth. Inclusion criteria included gestational age 24-29 weeks and birth weight 500-1500 g, intubation and mechanical ventilation, absence of congenital malformations and bacterial infections. Retreatment was considered if the fraction of inspired oxygen (FiO2) was > 0.4 (dose 50 mg/kg birth weight). The primary endpoint was level of oxygenation (PaO2/FiO2) 2 h after treatment. The study design was a sequential analysis using a triangular test with alpha = 0.05 and 95% power to detect a 25% improvement in the endpoint. Oxygenation was improved significantly with high-dose (n = 42) compared to low-dose treatment (n = 48): 30.9 +/- 15.0 kPa (231.5 +/- 112.7 mmHg) versus 24.1 +/- 15.7 kPa (180.6 +/- 118.0 mmHg) (mean +/- SD). The survival rate was 83% in both groups and the incidence of pulmonary interstitial emphysema was 33% versus 14% with the high-dose treatment. We conclude that high-dose surfactant significantly improved oxygenation and reduced lung barotrauma. An initial dose greater than 50 mg/kg birth weight of surfactant is required for optimal acute response.

Survival and follow-up of infants born at 23 to 26 weeks of gestational age: effects of surfactant therapy

Little information is available regarding the effect of surfactant on outcome for infants born at or before 26 weeks of gestation. We addressed this issue by reviewing records of 310 infants born at gestational ages of 23 through 26 weeks who were admitted to our nursery from 1986, when surfactant was introduced, through 1990. Surfactant was administered to 154 infants (5 during a single-dose prevention study, 25 during a multiple-dose prevention study, 124 while receiving a Food and Drug Administration treatment investigational new drug); 156 infants were not treated with surfactant. Seventy-three percent of the treated infants survived, compared with 55% of the nontreated infants. Increased survival occurred at all gestational ages between 23 and 26 weeks but were greatest in infants born at 23 and 24 weeks. At follow-up, no differences in neurologic outcome were detected between surfactant-treated and nontreated infants. We conclude that surfactant use in extremely premature infants improves survival rates without increasing the proportion of impaired survivors.

Effects of surfactant therapy on outcome of extremely premature infants

Limits of viability of extremely premature infants have recently been addressed both in Europe and the United States. These reports, which demonstrate frequent adverse outcome of infants born before 26 weeks of gestation, have not considered the impact of surfactant therapy. We reviewed records of 445 infants born between 23 and 36 weeks gestation who were admitted to our nursery following the availability of surfactant treatment in 1986 through 1992. Two hundred and eighty-five infants were treated with surfactant (Survanta, Ross Laboratories) as part of controlled, prospective trials or as routine treatment under Food and Drug Administration approval. One hundred and fifty-six infants were unable to be treated with surfactant, as either they received placebo therapy during prospective trials or were born prior to approval of routine surfactant use in the United States. Four additional infants born following the commercial availability of surfactant did not receive surfactant therapy. Survival of untreated infants was 56% compared to 75% in treated infants (P < 0.001). Infants born at all gestational ages between 23 and 26 weeks had an increased likelihood of survival as a result of surfactant treatment. No differences in neurologic outcome between surfactant treated and non-treated infants were demonstrated at subsequent follow-up. We conclude that survival of extremely premature infants is improved following surfactant therapy and that subsequent neurologic outcome is not compromised as a result of this therapy.

Surfactant replacement therapy in neonates less than 32 weeks gestation: effect on neonatal intensive care resource utilization

The effect of synthetic surfactant (Exosurf) replacement on complications from hyaline membrane disease (HMD) in infants < 32 weeks gestation and their resource utilization within a neonatal intensive care unit was studied in 1991-92. A control group was selected from infants admitted to the same unit during the preceding 3 years when Exosurf was not available. The infants were controlled for gestation, weight and severity of HMD. Infants given Exosurf had a significant reduction in the incidence of pulmonary interstitial emphysema (PIE), and a marginal decrease in the incidence of pneumothorax. They required fewer days on the ventilator and consumed less of the scarce financial resources. There was no difference in the mortality rate among the two groups. The changes seen were more evident among those infants between 30 and 31 weeks gestation, compared to those < 28 weeks.

Cost effects of surfactant therapy for neonatal respiratory distress syndrome

OBJECTIVE

To examine the cost effects of a single dose (5 ml/kg) of a protein-free synthetic surfactant (Exosurf) as therapy for neonatal respiratory distress syndrome, for both rescue and prophylactic therapy.

RESEARCH DESIGN

Nonblinded, randomized clinical trials of both rescue and prophylactic therapy. Regression analyses were used to control for the independent effects of sex, multiple birth, delivery method, birth weight, and surfactant therapy.

SETTING

The prophylactic trial was conducted at a university medical center only; the rescue trial also included a tertiary community hospital.

PATIENTS

Prophylaxis was administered immediately after birth to 36 infants (38 control subjects) with birth weights between 700 and 1350 gm. Rescue therapy was administered at 4 to 24 hours of age to 53 infants (51 control subjects) with established respiratory distress syndrome and birth weights > or = 650 gm (no upper limit). Infants in the prophylactic trial were not eligible for the rescue trial.

RESULTS

For the rescue trial, there was a $16,600 reduction in average hospital costs (p = 0.18), which was larger than the cost of the surfactant ($450 to $900), yielding a probable net savings. For the prophylactic trial, hospital costs were larger for treated infants versus control subjects who weighed less than about 1100 gm at birth and lower for treated infants versus control subjects who weighed more than 1100 gm at birth (p < 0.05). For the prophylactic sample, the result was an average cost per life saved of $71,500.

CONCLUSIONS

Single-dose rescue surfactant therapy is probably a cost-effective therapy because it produced a lower mortality rate for the same (and probably lower) expenditure. Single-dose prophylactic therapy for smaller infants (< or = 1350 gm) appeared to yield a reduction in mortality rate for a small additional cost. The use of multiple-dose therapy in infants who do not respond to initial therapy may alter the effects described above to either increase or decrease the observed cost-effectiveness of surfactant therapy. Regardless, surfactant therapy will remain a cost-effective method of reducing mortality rates, relative to other commonly used health care interventions.

The limit of viability--neonatal outcome of infants born at 22 to 25 weeks' gestation

BACKGROUND

With improved survival of preterm infants, questions have been raised about the limit of viability. To provide better information and counseling for parents of infants about to be delivered after 22 to 25 weeks' gestation, we evaluated the mortality and neonatal morbidity of preterm infants born at these gestational ages.

METHODS

We studied retrospectively all 142 infants born at 22 to 25 weeks' gestation (as judged by best obstetrical estimate) from May 1988 through September 1991 in a single hospital. Mortality in the first six months, including stillbirths, and neonatal morbidity (i.e., the presence of intracranial pathologic conditions, chronic lung disease, and retinopathy of prematurity) were analyzed.

RESULTS

Fifty-six infants (39 percent) survived for six months. Survival improved with increasing gestational age; none of 29 infants born at 22 weeks' gestation survived, as compared with 6 of 40 (15 percent) born at 23 weeks, 19 of 34 (56 percent) born at 24 weeks, and 31 of 39 (79 percent) born at 25 weeks. There were seven stillbirths at 22 weeks' gestation and four stillbirths at 23 weeks. The more immature the infant, the higher the incidence of neonatal complications as determined by the number of days of mechanical ventilation, the length of the hospital stay, and the presence of retinopathy of prematurity, periventricular or intraventricular hemorrhage, or periventricular leukomalacia. Only 2 percent of infants born at 23 weeks' gestation survived without severe abnormalities on cranial ultrasonography, as compared with 21 percent of those born at 24 weeks and 69 percent of those born at 25 weeks.

CONCLUSIONS

We believe that aggressive resuscitation of infants born at 25 weeks' gestation is indicated, but not of those born at 22 weeks. Whether the occasional child who is born at 23 or 24 weeks' gestation and does well justifies the considerable mortality and morbidity of the majority is a question that should be discussed by parents, health care providers, and society.

Pulmonary hemorrhage and exogenous surfactant therapy: a metaanalysis

A metaanalysis of surfactant clinical trials was carried out to assess whether or not an association exists between exogenous surfactant therapy and pulmonary hemorrhage. Trials that reported the pulmonary hemorrhage occurrence (group 1) and those that did not (group 2) were analyzed. Thirty-three treatment strategies were tested in 29 publications from 1980 through 1992. Eleven of these were group 1 trials, which reported a 3% overall incidence of pulmonary hemorrhage. The rates were significantly higher in both the treated and the control groups of natural surfactant trials than in synthetic surfactant trails (5.87% and 5.36% in the natural surfactant trials vs 2.51% and 1.04% in the synthetic surfactant trials, respectively). The pooled estimate of relative risk for pulmonary hemorrhage with any surfactant therapy was 1.47 (95% confidence interval 1.05, 2.07; p < 0.05). Logistic regression modeling revealed that the nature of surfactant, treatment strategy, and lower mean birth weight had a significant influence on the relative risk of pulmonary hemorrhage; a similar trend was seen with higher mortality rates. Variation in the rates of patent ductus arteriosus did not have an independent effect on the estimated pulmonary hemorrhage risk. Most group 2 trials were published before 1990, and the median total sample size was 73, compared with 402 for the group 1 trials (p < 0.05), most of which were published in the 1990s. In 10 (50%) of 20 group 2 trials, pulmonary hemorrhage data were collected methodically, in comparison with all group 1 trials, most of which collected data prospectively. We conclude that pulmonary hemorrhage is a rare complication of respiratory distress syndrome. An awareness of the possible association of pulmonary hemorrhage with surfactant use in later trials and the differences in definitions and reporting practices probably explain variations in the reported incidence among the trials. The risk of pulmonary hemorrhage increases slightly, on an average of 47%, with any surfactant therapy. This increased risk is small compared with the documented benefits of surfactant therapy in respiratory distress syndrome.

Surfactant replacement therapy for pulmonary diseases

Surfactant therapy has clearly been a meaningful addition to the therapeutic armamentarium in the management of premature infants with RDS. Pediatricians and others involved in the care of newborn infants should familiarize themselves with the various surfactant preparations, the indications for their use, the techniques of administration, and the possible side effects. All such care provides should also be skilled in endotracheal intubation and ventilation of neonates; recognition of the clinical and radiographic signs of RDS; and have the appropriate equipment to monitor cardiopulmonary status, oxygenation, and ventilation in these infants until transport to a tertiary care facility can be accomplished. In addition to the two current FDA-approved surfactants, several other surfactants are in various stages of evaluation. When administered to infants with established RDS, both natural and synthetic surfactants have clearly been shown to improve survival, decrease requirements for ventilatory support, and reduce the incidence of air leak complications. Although by no means conclusively demonstrated, certain infants, particularly those delivered at < 30 week gestation, may benefit from immediate treatment in the delivery room. It should be emphasized that, except under extenuating but controlled circumstances and except in the hands of an experienced physician, surfactant treatment should not be viewed as an integral part of neonatal resuscitation. Adequate treatment requires the administration of a minimum of two surfactant doses, although some infants may benefit from additional doses or treatment with an alternative preparation. Massive pulmonary hemorrhage, although rare, is observed with prophylactic and rescue treatment protocols and may result from hemorrhagic pulmonary edema due to a hemodynamically significant PDA. Currently there are no data to recommend the use of one surfactant preparation over another. The short- and long-term benefits may be similar with different products. Therefore, we must await results of trials with then necessary power (large number of subjects) and unbiased design to discern any clinically relevant differences. Results of studies directly comparing the relative efficacy of Survanta and Exosurf, conducted under the auspices of the National Institutes of Health, are expected in 1993. Multicenter trials comparing prophylactic and rescue administration of Exosurf versus CLSE and Survanta versus CLSE are currently underway. It is encouraging to note that follow-up studies up to 2 years of age do not reveal an increase in physical or neurodevelopmental handicaps, BPD, or other problems in preterm infants who received surfactant preparations either for prophylaxis or rescue therapy. Results of long-term follow-up studies, however, are not yet available.(ABSTRACT TRUNCATED AT 400 WORDS)