One-year outcome in 232 premature infants with birth weights of 750 to 1249 grams and respiratory distress syndrome randomized to rescue treatment with two doses of synthetic surfactant or air placebo. Canadian Exosurf Neonatal Study Group

In vitro evaluation of inhalable isoniazid-loaded surfactant liposomes as an adjunct therapy in pulmonary tuberculosis

In this study, exogenous pulmonary surfactant was evaluated as an inhalable drug carrier for antitubercular drug isoniazid (INH). Isoniazid-entrapped liposomes of dipalmitoylphosphatidylcholine (DPPC) (the most abundant lipid of lung surfactant and exogenous surfactant) were developed and evaluated for size, drug entrapment, release, in vitro alveolar deposition, biocompatibility, antimycobacterial activity, and pulmonary surfactant action. Isoniazid-entrapped DPPC liposomes were about 750 nm in diameter and had entrapment efficiency of 36.7% +/- 1.8%. Sustained release of INH from DPPC liposomes was observed over 24 h. In vitro alveolar deposition efficiency using the twin impinger exhibited approximately 25-27% INH deposition in the alveolar chamber upon one minute nebulization using a jet nebulizer. At 37 degrees C, the formulation had better pulmonary surfactant function with quicker reduction of surface tension on adsorption (36.7 +/- 0.4 mN/m) than DPPC liposomes (44.7 +/- 0.6 mN/m) and 87% airway patency was exhibited by the formulation in a capillary surfactometer. The formulation was biocompatible and had antimycobacterial activity. The isoniazid-entrapped DPPC liposomes could fulfill the dual purpose of pulmonary drug delivery and alveolar stabilization due to antiatelectatic effect of the surfactant action which can improve the reach of antitubercular drug INH to the alveoli.

Evaluation of antitubercular drug-loaded surfactants as inhalable drug-delivery systems for pulmonary tuberculosis

Pulmonary tuberculosis is associated with a year-long chemotherapy, poor alveolar drug levels, drug-related systemic toxicity, and patient noncompliance. In this study, exogenous pulmonary surfactant is proposed as a drug carrier for antitubercular drugs. Dipalmitoylphosphatidylcholine (DPPC), the major lung-surfactant lipid, has been combined with antitubercular drugs isoniazid (INH), rifampicin (RFM), and ethambutol (ETH) in 1:1 ratio by weight, in which drugs had a ratio of 1:2:3 by weight. At 37 degrees C, the formulation had better surfactant function with quicker reduction of surface tension on adsorption (32.71 +/- 0.65 mN/m) than DPPC liposomes (44.67 +/- 0.57 mN/m) and maintained 100% airway patency in a capillary surfactometer. Drug-loaded surfactant liposomes were about 2 microm and had entrapment efficiency of 30.04% +/- 2.05%, 18.85% +/- 2.92%, and 61.47% +/- 3.32% for INH, RFM, and ETH, respectively. Sustained release of the drugs from surfactants was observed over 24 h. In vitro alveolar deposition efficiency using the twin impinger showed 12.06% +/- 1.87% of INH, 43.30% +/- 0.87% of RFM, and 22.07% +/- 2.02% of ETH deposited in the alveolar chamber upon nebulization for a minute using a jet nebulizer. The formulation was biocompatible and stable with physicochemical properties being retained even after storage for a month at 4 degrees C. Antitubercular drug-loaded surfactants developed could serve dual purposes of alveolar stabilization due to surfactant action and better reach of these drugs to the alveoli due to antiatelectatic effect of the surfactant.

Relationship between perinatal and neonatal indices and intelligence quotient in very low birth weight infants at the age of 6 or 8 years

BACKGROUND

The majority of children born with very low birth weight (VLBW; < 1500g) enter mainstream schools. They experience significant neurodevelopmental disabilities during childhood. The specific aims of our study were to evaluate the neonatal outcomes of VLBW infants and whether they would influence intelligence quotient (IQ), cognitive function and learning disabilities at the age of 6 or 8 years.

METHODS

We enrolled VLBW neonates who weighed less than 1500g and who were delivered at Shin-Kong Wu Ho-Su Memorial Hospital in 1996 and 1999. The psychological assessments were applied with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) for age 6 and Wechsler Intelligence Scale for Children-Third Edition (WISC-III) for age 8. We recorded their demographic data, ventilation duration by days, length of stay, use of surfactant, respiratory distress syndrome (RDS), and other complications.

RESULTS

According to whether the full scale intelligence quotient (FSIQ) was above or below the average score (FSIQ = 90), we divided VLBW children into two groups (< 90, n = 17; > or = 90, n = 21). The children with lower gestational age had lower FSIQ (p = 0.013). The higher FSIQ group (> or = 90) showed more prenatal steroid use (5/17, 29.4% vs. 14/21, 66.7%; p = 0.049). There were more boys in the lower FSIQ group (< 90, 13/17, 76.5% vs. > or = 90, 7/21, 33.3%; p = 0.011). The average IQ scores were 78.11 +/- 9.05 and 102.57 +/- 8.89 in the FSIQ < 90 and FSIQ > or = 90 groups, respectively. The groups were similar in ventilation duration by days, use of surfactant, frequency of sepsis, RDS, bronchopulmonary dysplasia, patent ductus arteriosus, intraventricular hemorrhage and retinopathy of prematurity.

CONCLUSION

In our study, the children with lower gestational age had lower FSIQ. There was no significant association between small for gestational age and IQ performance. The neonatal outcomes of VLBW infants did have less impact on IQ performance later in life.

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.

Change in cognitive function over time in very low-birth-weight infants

CONTEXT

Preterm very low-birth-weight (VLBW) infants have a high prevalence of neurodevelopmental disability when evaluated during the first several years of life. However, recent experimental data suggest that the developing brain may recover from or compensate for injury.

OBJECTIVE

To determine if there is cognitive improvement throughout early and middle childhood following VLBW birth.

DESIGN, SETTING, AND PARTICIPANTS

Follow-up data of 296 infants born weighing 600 to 1250 g who participated in a prospective, randomized, placebo-controlled intraventricular hemorrhage (IVH) prevention study performed at 3 northeastern US hospitals between September 1989 and August 1992 and who were serially evaluated at 36, 54, 72, and 96 months of corrected age (CA).

MAIN OUTCOME MEASURES

The age-normed Peabody Picture Vocabulary Test-Revised (PPVT-R) score and measures of intelligence.

RESULTS

Overall, the median PPVT-R score increased from 88 at 36 months of CA to 99 at 96 months of CA; when data from 36 and 96 months of CA were compared, 45% of children gained 10 points or more and 12.5% showed a 5- to 9-point increase in test scores. Similar findings were noted for full-scale and verbal IQ scores. Multivariate analyses demonstrated that increasing age, residence in a 2-parent household, and higher levels of maternal education were all significantly associated with higher PPVT-R scores (for each, P<.001). In addition, early intervention led to greater increases over time in PPVT-R scores among children whose mothers had less than a high school education compared with those with a high school education level or greater (P =.03 by test for interaction). Although most children showed improvement in PPVT-R scores with increasing CA, children with early-onset IVH and subsequent significant central nervous system injury had the lowest PPVT-R scores initially and the scores declined over time (P =.009 by test for interaction).

CONCLUSIONS

The majority of VLBW children had improvement in verbal and IQ test scores over time. Only children with early-onset IVH followed by significant central nervous system injury had low PPVT-R scores that declined over time.

Developmental outcome of preterm infants after surfactant therapy: systematic review of randomized controlled trials

OBJECTIVES

To review neuro-developmental outcome at 1 and 2 years of age following randomized controlled trials (RCT) of neonatal surfactant therapy.

METHODS

A systematic review of the MEDLINE, Embase and Cochrane Controlled Trial Register databases, searching for RCT of surfactant replacement therapy with follow-up outcomes, was carried out. The main outcome measures were severe and mild disability at 1 and 2 years plus composite adverse outcome of death and/or severe disability.

RESULTS

A meta-analysis using odds ratios was carried out on 13 RCT. There were a total of 2218 treated and 2090 control infants who underwent follow up at 1 year of age. There were 303 treated and 292 control infants with follow up at between 18 months and 2 years of age. Surfactant therapy was associated with a lower rate of mild disability at 1 year (OR 0.79; 95% CI 0.66-0.95). There was a reduction in the combined adverse outcome (death or severe disability rate) at 1 year (OR 0.8; 95% CI 0.72-0.89). Neither the 1 year nor the 2 year follow-up examination showed a statistical difference in the severe disability rate between the control and treated group.

CONCLUSION

Surfactant therapy increases survival without an increase in subsequent morbidity at 1 and 2 years of age.

Measurement of health status and quality of life in neonatal follow-up studies

Mortality and neuro-developmental outcome can be precisely measured but in order to interpret the significance of changes in them, further information is needed about health status, the effect of health status on lifestyle of survivors and their families, the quality of life experienced by survivors and the value placed by the public and survivors on different health states. The ability to measure such aspects of health now allows more relevant follow-up studies to be designed. This article discusses concepts of health status and quality of life and the problems in applying these to children. There follows a critique of modern instruments for measuring health status and quality of life and their application in neonatal follow-up studies. We recommend that only a small number of well-established instruments should be considered so that results are valid and can be compared with other studies.

Synthetic surfactant for respiratory distress syndrome in preterm infants

BACKGROUND

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

OBJECTIVES

To assess the effect of intratracheal administration of synthetic surfactant in premature newborns with established respiratory distress syndrome (RDS).

SEARCH STRATEGY

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

SELECTION CRITERIA

Randomized controlled trials which compared the effect of synthetic surfactant treatment to routine management in the treatment of preterm infants with respiratory distress syndrome.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcome including the incidence of pneumothorax, pulmonary interstitial emphysema, pulmonary hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, apnea of prematurity, intraventricular hemorrhage (any grade, and severe intraventricular hemorrhage), bronchopulmonary dysplasia, neonatal mortality, bronchopulmonary dysplasia or death, retinopathy of prematurity (any retinopathy, and retinopathy greater than Stage 3), mortality at hospital discharge, mortality to one year of age, and cerebral palsy (any, and moderate/severe 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

Six randomized controlled trials of synthetic surfactant treatment of established respiratory distress syndrome were identified. Five of the studies used Exosurf Neonatal (a synthetic surfactant composed of dipalmitoylphosphatidylcholine, hexadecanol and tyloxapol); one small study utilized a mixture of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylglycerol (PG). Treatment with intratracheal Exosurf Neonatal in premature infants with established respiratory distress syndrome improves pulmonary gas exchange and decreases the requirement for ventilatory support. In individual trials, the use of Exosurf Neonatal resulted in a statistically significant reduction in pneumothorax, patent ductus arteriosus, bronchopulmonary dysplasia (BPD), BPD or death at 28 days, and mortality. Similar results are seen when these large trials of Exosurf Neonatal are analyzed in conjunction with the smaller trial of dry powdered DPPC and phosphatidylglycerol (PG). The meta-analysis supports a decrease in the risk of pneumothorax (typical relative risk 0.64, 95% CI 0.55, 0.76, typical risk difference -0.09, 95% CI -0.12,-0.06), a decrease in the risk of pulmonary interstitial emphysema (typical relative risk 0.62, 95% CI 0.54, 0.71, typical risk difference -0.12, 95% CI -0.16, -0.09), a decrease in the risk of patent ductus arteriosus (typical relative risk 0.90, 95% CI 0.84, 0.97; typical risk difference -0.06 95% CI -0.10, -0.02), a decrease in the risk of intraventricular hemorrhage (typical relative risk 0.88, 95% CI 0.77, 0.99; typical risk difference -0.04, 95% CI -0.08, -0.00), a decrease in the risk of bronchopulmonary dysplasia (typical relative risk 0.75, 95% CI 0.61, 0.92; typical risk difference -0.04, 95% CI -0.06, -0.01), a decrease in the risk of neonatal mortality (typical relative risk 0. 73, 95% CI 0.61, 0.88; typical risk difference -0.05, 95% CI -0.07, -0.02), a decrease in the risk of bronchopulmonary dysplasia or death at 28 days (typical relative risk 0.73, 95% CI 0.65, 0.83; typical risk difference -0.06, 95% CI -0.11, -0.05), a decrease in the risk of mortality prior to hospital discharge (typical relative risk 0.79, 95% CI 0.68, 0.92; typical risk difference -0.05, 95% CI -0.07, -0.02) and a decrease in the risk of mortality during the first year of life (typical relative risk 0.80, 95% CI 0.69, 0.94; typical risk difference -0.04, 95% CI -0.07, -0.01). (ABS

Neuromotor ability in 5- to 7-year-old children with very low or extremely low birthweight

This study was intended to determine the effects of extremely low birthweight (ELBW, 500 to 999 g) and very low birthweight (VLBW, 1000 to 1499 g) on neuromotor ability in 5- to 7-year-old children. Fourteen ELBW and 20 VLBW children were compared with 24 term control children of normal birthweight (NBW, >2500 g). Using quantitative assessment instruments, the following data were collected: maximal cycling speed during 30 seconds of cycling at 'zero' resistance, simple reaction time of the legs, and performance on components of a whole-body coordination test. The main findings were a slower reaction time, lower maximal cycling speed, and lower coordination scores in the ELBW group compared with the NBW group and, for some variables, with the VLBW group. The reduced motor performance in these children appears for the most part to be a reflection of impaired neuromotor control and motor development, rather than merely a smaller body or muscle size.

Role of lipid polymorphism in pulmonary surfactant

The development of artificial surfactants for the treatment of respiratory distress syndrome (RDS) requires lipid systems that can spread rapidly from solution to the air-water interface. Because hydration-repulsion forces stabilize liposomal bilayers and oppose spreading, liposome systems that undergo geometric rearrangement from the bilayer (lamellar) phase to the hexagonal II (HII) phase could hasten lipid transfer to the air-water interface through unstable transition intermediates. A liposome system containing dipalmitoylphosphatidylcholine was designed; the system is stable at 23 degrees C but undergoes transformation to the HII phase as the temperature increases to 37 degrees C. The spreading of lipid from this system to the air-water interface was rapid at 37 degrees C but slow at 23 degrees C. When tested in vivo in a neonatal rabbit model, such systems elicited an onset of action equal to that of native human surfactant. These findings suggest that lipid polymorphic phase behavior may have a crucial role in the effective functioning of pulmonary surfactant.