T. Allen Merritt

Exogenous human surfactant for treatment of severe respiratory distress syndrome: A randomized prospective clinical trial

We performed a randomized, prospective clinical trial comparing intratracheal administration of human surfactant with conventional treatment with intermittent mandatory mechanical ventilation alone for treatment of severe respiratory distress syndrome in preterm infants of less than 30 weeks gestation. Twenty-two infants (mean gestational age 27.0 weeks, mean birth weight 987 gm) were given surfactant, and 23 infants (mean gestational age 27.2 week, mean birth weight 1055 gm) received intermittent mandatory ventilation. Infants given surfactant required less FiO2 during the first week, had lower mean airway pressure during the first 48 hours, and had improved ventilatory index and a/A PO2 ratio. Death or the occurrence of bronchopulmonary dysplasia was significantly less among infants given surfactant (P = 0.019). Pneumothorax, pulmonary interstitial emphysema, and need for FiO2 greater than or equal to 0.3 for greater than 30 days was significantly less in the surfactant group. This trial confirms the efficacy of treatment with human surfactant in preterm infants with severe respiratory distress syndrome.

A Multicenter, Randomized, Masked, Comparison Trial of Lucinactant, Colfosceril Palmitate, and Beractant for the Prevention of Respiratory Distress Syndrome Among Very Preterm Infants

Background and Objective. Evidence suggests that synthetic surfactants consisting solely of phospholipids can be improved through the addition of peptides, such as sinapultide, that mimic the action of human surfactant protein-B (SP-B). A synthetic surfactant containing a mimic of SP-B may also reduce the potential risks associated with the use of animal-derived products. Our objective was to compare the efficacy and safety of a novel synthetic surfactant containing a functional SP-B mimic (lucinactant; Discovery Laboratories, Doylestown, PA) with those of a non–protein-containing synthetic surfactant (colfosceril palmitate; GlaxoSmithKline, Brentford, United Kingdom) and a bovine-derived surfactant (beractant; Abbott Laboratories, Abbott Park, IL) in the prevention of neonatal respiratory distress syndrome (RDS) and RDS-related death. Methods. We assigned randomly (double-masked) 1294 very preterm infants, weighing 600 to 1250 g and of ≤32 weeks gestational age, to receive colfosceril palmitate (n = 509), lucinactant (n = 527), or beractant (n = 258) within 20 to 30 minutes after birth. Primary outcome measures were the rates of RDS at 24 hours and the rates of death related to RDS during the first 14 days after birth. All-cause mortality rates, bronchopulmonary dysplasia (BPD) rates, and rates of other complications of prematurity were prespecified secondary outcomes. Primary outcomes, air leaks, and causes of death were assigned by an independent, masked, adjudication committee with prespecified definitions. The study was monitored by an independent data safety monitoring board. Results. Lucinactant reduced significantly the incidence of RDS at 24 hours, compared with colfosceril (39.1% vs 47.2%; odds ratio [OR]: 0.68; 95% confidence interval [CI]: 0.52–0.89). There was no significant difference in comparison with beractant (33.3%). However, lucinactant reduced significantly RDS-related mortality rates by 14 days of life, compared with both colfosceril (4.7% vs 9.4%; OR: 0.43; 95% CI: 0.25–0.73) and beractant (10.5%; OR: 0.35; 95% CI: 0.18–0.66). In addition, BPD at 36 weeks postmenstrual age was significantly less common with lucinactant than with colfosceril (40.2% vs 45.0%; OR: 0.75; 95% CI: 0.56–0.99), and the all-cause mortality rate at 36 weeks postmenstrual age was lower with lucinactant than with beractant (21% vs 26%; OR: 0.67; 95% CI: 0.45–1.00). Conclusions. Lucinactant is a more effective surfactant preparation than colfosceril palmitate for the prevention of RDS. In addition, lucinactant reduces the incidence of BPD, compared with colfosceril palmitate, and decreases RDS-related mortality rates, compared with beractant. Therefore, we conclude that lucinactant, the first of a new class of surfactants containing a functional protein analog of SP-B, is an effective therapeutic option for preterm infants at risk for RDS.

Glutaric aciduria Type II.

Two infants have been studied with glutaric aciduria Type II. The clinical presentation was of an overwhelming illness very early in life; both infants died in the neonatal period. One had dysmorphic features. An acrid odor may be a clue to the diagnosis. Neonatal acidosis, hypoglycemia, and hyperammonemia are characteristic. Organic acid analysis revealed massive lactic aciduria and glutaric aciduria. A variety of other dicarboxylic acids and hydroxy acids and amino acids were found in elevated amounts in body fluids, along with elevated concentrations of butyric, isobutyric, 2-methylbutyric, and isovaleric acids. The pattern of metabolites accumulated is consistent with deficient activity of a number of acyl-CoA dehydrogenases.

Randomized, placebo-controlled trial of human surfactant given at birth versus rescue administration in very low birth weight infants with lung immaturity

A randomized, placebo-controlled trial of human surfactant given intratracheally at birth (prophylactic) versus rescue administration after the onset of severe respiratory distress syndrome (RDS) was conducted among preterm infants born at 24 to 29 weeks of gestation. Singleton fetuses were randomly assigned to receive (1) placebo (air), (2) prophylactic surfactant treatment, or (3) rescue surfactant treatment; infants of multiple births received either (1) prophylactic or (2) rescue treatment. Of 282 potentially eligible fetuses, 246 infants received treatments at birth and 200 infants had RDS. Outcomes are presented both as an intention-to-treat analysis (including infants who met exclusion criteria at or after birth) and as a full treatment protocol analysis for those infants with RDS and likely to benefit from surfactant. Preterm infants (mean 1.0 kg birth weight, 27 to 28 weeks of gestational age) randomly assigned to receive prophylactic treatment received surfactant soon after birth; those assigned to receive rescue surfactant had instillation at a mean age of 220 minutes if the lecithin-sphingomyelin ratio was less than or equal to 2.0 and no phosphatidylglycerol was detected in either amniotic fluid or initial airway aspirate, oxygen requirements were a fraction of inspired oxygen of greater than 0.5, and mean airway pressure was greater than or equal to 7 cm H2O from 2 to 12 hours after birth. Up to four treatment doses (or air) were permitted within 48 hours; approximately 60% of surfactant-treated infants required two or more doses. Surfactant-treated infants had significantly less pulmonary interstitial emphysema than placebo-treated infants (p = 0.02), but there were no other significant differences in mortality rates or morbidity. Indexes of oxygenation and ventilation were improved in surfactant recipients during the first 24 hours. An intention-to-treat analysis found no significant differences between infants given placebo and surfactant-treated infants or between prophylactic- and rescue-treated infants; an improved total mortality rate (p = 0.002) was found among surfactant-treated infants in Helsinki but not in San Diego. Among infants with RDS, the total mortality rate was significantly improved (p = 0.004) with surfactant treatment but not the proportion alive and without bronchopulmonary dysplasia at 28 days (p = 0.052), or the proportion alive and without bronchopulmonary dysplasia at 38 weeks of postconceptional age (p = 0.18) to adjust for differences in prematurity. Deaths caused by RDS or bronchopulmonary dysplasia were significantly reduced among surfactant recipients (p = 0.0001). Neither among singletons nor among multiple-birth infants was there a selective advantage to prophylactic versus rescue treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Bronchoalveolar Lavage with KL4-Surfactant in Models of Meconium Aspiration Syndrome

As a model of the meconium aspiration syndrome (MAS) of human infants, adult rabbits and newborn rhesus monkeys received intratracheal instillation of human meconium to induce pulmonary injury. Injured rabbits were ventilated with 100% O2 and divided into four treatment groups, receiving: 1) bronchoalveolar lavages (BAL) with dilute KL4-Surfactant; 2) lavages with equal volumes of sterile saline; 3) a single intratracheal bolus of KL4-Surfactant, 100 mg/kg; and 4) no treatment. The untreated rabbits developed atelectasis, a fall in pressure-volume levels and in partial pressure of O2 in arterial blood (PaO2) from approximately 500 to <100 mm Hg, and severe pulmonary inflammation between 3 and 5 h after instillation of meconium. Rabbits treated by BAL with dilute KL4-Surfactant showed rapid and sustained recovery of PaO2 to approximately 300 mm Hg within minutes, a return toward normal pressure-volume levels, and diminished inflammation. Rabbits receiving BAL with saline failed to show recovery, and rabbits treated with a bolus of surfactant intratracheally exhibited a transient response by 1-2 h after treatment, but then returned to the initial atelectatic state. Newborn rhesus monkeys, after receiving human meconium intratracheally before the first breath, developed severe loss of pulmonary function. Treatment of these monkeys 1-5 h after birth with BAL with dilute KL4-Surfactant produced clearing of chest radiographs and a rapid improvement in pulmonary function with ratios of partial pressure of O2 in arterial blood to the fraction of O2 in the inspired air rising into the normal range where they remained through the 20-h period of study. The studies indicate that pulmonary function in two models of severe meconium injury respond rapidly to BAL with dilute KL4-Surfactant.

Early closure of the patent ductus arteriosus in very low-birth-weight infants: A controlled trial

A controlled clinical trial comparing early closure (mean = 48.8 hours) of the patent ductus arteriosus using indomethacin to conventional medical management, with intervention only after cardiopulmonary decompensation (mean = 167.4 hours), was undertaken in 24 preterm infants with severe respiratory distress syndrome and evidence of PDA. An interval analysis of one-half the projected sample revealed that infants undergoing early closure of the PDA had significantly reduced occurrence of BPD or mortality by 6 months of age. A comparison of birth weight, Apgar scores, gestational age, age of initial PDA diagnosis, and fluid therapy during the first seven days of life showed no significant differences between early intervention and control groups. At the time of the interval analysis, there were no differences between the groups in duration of intermittent mandatory ventilation or oxygen exposure. Studies will be required to determine whether these and other variables can be altered by early closure of the PDA.

Effect of surfactant substitution on lung effluent phospholipids in respiratory distress syndrome: evaluation of surfactant phospholipid turnover, pool size, and the relationship to severity of respiratory failure.

ABSTRACT. The turnover and pool size of surfactant has been studied in animals, but there is little similar information in humans. In the present investigation lung effluent phospholipids were studied in 29 small preterm infants with severe RDS. Thirteen were treated with mechanical ventilation, and 16 additionally received natural human surfactant. The first dose (60 mg surfactant/kg body wt) was given between 2 and 10 h of age, and the surfactant was given again if there was an insufficient response. Together 260 aspirates, recovered during routine suctioning of the airways, were analyzed for phospholipids. Phosphatidylglycerol, present only in exogenous surfactant, was used as a specific marker to estimate the apparent pool size and the half-life of surfactant phospholipid. In addition, the saturated phosphatidylcholine/sphingomyelin ratios were correlated with the ventilatory index (mean airway pressure x fractional inspiratory oxygen/arterial oxygen tension). There was a linear correlation between the ventilatory index and the saturated phosphatidylcholine/ sphingomyelin (r ~ -0.70) but no consistent correlation between the ventilatory index and the amount of phospholipids in the aspirate. The saturated phosphatidylcholine/ sphingomyelin ratio increased during the surfactant-induced remission of respiratory failure, decreased during the relapse of respiratory failure (present among 50% of the surfactant-treated infants), and increased again during the recovery. The control infants tended to have lower saturated phosphatidylcholine/sphingomyelin ratios during the first week than the surfactant-treated infants. The recipients of surfactant had slightly more severe lung disease than the controls, when the results were adjusted by covariance to remove the differences in the saturated phosphatidylcholine/ sphingomyelin ratio. Exogenous surfactant increased the apparent endogenous pool size at least fivefold. The apparent half-life of phosphatidylglycerol was 30 h (20–36 h). The half-life was independent of the amount of exogenous surfactant (60 versus 120 mg/kg). Therefore, the apparent turnover rate after 120 was higher than after 60 mg/kg surfactant (p<0.01).

An Open Label, Pilot Study of Aerosurf® Combined with nCPAP to Prevent RDS in Preterm Neonates

BACKGROUND Nasal continuous positive airway pressure (nCPAP) is an accepted mode of respiratory support for preterm infants with respiratory insufficiency. To avoid potential sequelae of endotracheal (ET) intubation and mechanical ventilation, prophylactic aerosolization of surfactant delivered via nCPAP has been attempted with limited success. METHODS To determine the feasibility and safety of prophylactic aerosolization of a peptide-containing synthetic surfactant, Aerosurf® (lucinactant for inhalation) was delivered by nCPAP to preterm infants at risk for respiratory distress syndrome (RDS). Neonates were enrolled into treatment group 1 (Aerosurf retreatment separated by at least 3 h) or treatment group 2 (Aerosurf retreatment separated by at least 1 h). A vibrating membrane nebulizer Aeroneb Pro® was used to aerosolize 20 mg/mL Aerosurf. All neonates received the initial 3-h treatment, and three retreatments were permitted within 48 h based on clinical response. RESULTS Seventeen infants were enrolled. Aerosurf was well tolerated, with transient desaturations observed during dosing without bradycardia or hypotension. Variability in output rates of the Aeroneb Pro was observed leading to different average dispensed drug volumes per treatment per patient. All infants survived; 29.4% required subsequent ET surfactant replacement therapy, 23.5% were diagnosed with RDS at 24 h, and 11.8% with bronchopulmonary dysplasia (BPD) at 28 days of life. Mean FiO₂ was 0.4 at baseline, and 0.32 at 4 h posttreatment. CONCLUSIONS Aerosurf can be safely administered via nCPAP in preterm infants at risk for RDS and may provide an alternative to surfactant administration via an ET tube. Further studies are required to evaluate this delivery approach.

The Use of Synthetic Peptides in the Formation of Biophysically and Biologically Active Pulmonary Surfactants

ABSTRACT: Synthetic pulmonary surfactants consisting of mixtures of phospholipids with synthetic peptides based on the amino acid sequence of human surfactant apoprotein SP-B were prepared. These surfactants were analyzed for their ability to lower surface tension on a pulsating bubble surfactometer and for their capacity to improve lung compliance and increase alveolar expansion in a fetal rabbit model of surfactant deficiency. The data demonstrate that several peptides, ranging from 17 to 45 residues in length, matching the carboxy-terminal sequence of the SP-B protein, when appropriately recombined with the phospholipids dipalmitoylphosphatidycholine and phosphatidylglycerol (3:1), are capable of producing a synthetic surfactant with biophysical and biologic activity approaching that of human surfactant derived from amniotic fluid.

Ventriculoperitoneal Shunts in Low Birth Weight Infants with Intracranial Hemorrhage: Neurodevelopmental outcome

Fifty preterm infants (mean birth weight, 1266 +/- 303 g; mean gestational age, 30 +/- 2 weeks) who required a ventriculoperitoneal (VP) shunt for posthemorrhagic hydrocephalus (92% with Grade III or IV hemorrhage) were followed for neurodevelopmental problems. VP shunts were placed at a median age of 29 days (range, 18 to 87 days) after serial lumbar punctures failed to control progressive and symptomatic ventriculomegaly. A total of 34 infants (68%) required one shunt revision or more, and the overall infection rate per patient was 50%. Seven infants died, 2 from shunt infections. The infants were evaluated with audiological, ophthalmological, and neurodevelopmental examinations. Of the survivors, 11 (28%) have severe visual loss and 10 (24%) have hearing impairment. Of the infants, 21 (49%) have severe motor handicaps and 19 (38%) have seizure disorders. Developmental and motor scores were obtained using the Bayley or Knobloch-Gesell scales. Seven infants (18%) have normal developmental outcomes; 26 (60%) have multiple handicaps. Grade IV hemorrhage or the occurrence of seizures was a predictor of poor neurodevelopmental outcome. We conclude that progressive posthemorrhagic hydrocephalus in low birth weight infants is associated with multiple handicaps despite early VP shunt placement.