Gut Dysbiosis With Bacilli Dominance and Accumulation of Fermentation Products Precedes Late-onset Sepsis in Preterm Infants.

BACKGROUND: Gut dysbiosis has been suggested as a major risk factor for the development of late-onset sepsis (LOS), a main cause of mortality and morbidity in preterm infants. We aimed to assess specific signatures of the gut microbiome, including metabolic profiles, in preterm infants <34 weeks of gestation preceding LOS. METHODS: In a single-center cohort, fecal samples from preterm infants were prospectively collected during the period of highest vulnerability for LOS (days 7, 14, and 21 of life). Following 16S rRNA gene profiling, we assessed microbial community function using microbial metabolic network modeling. Data were adjusted for gestational age and use of probiotics. RESULTS: We studied stool samples from 71 preterm infants with LOS and 164 unaffected controls (no LOS/necrotizing enterocolitis). In most cases, the bacteria isolated in diagnostic blood culture corresponded to the genera in the gut microbiome. LOS cases had a decelerated development of microbial diversity. Before onset of disease, LOS cases had specific gut microbiome signatures with higher abundance of Bacilli (specifically coagulase-negative Staphylococci) and a lack of anaerobic bacteria. In silico modeling of bacterial community metabolism suggested accumulation of the fermentation products ethanol and formic acid in LOS cases before the onset of disease. CONCLUSIONS: Intestinal dysbiosis preceding LOS is characterized by an accumulation of Bacilli and their fermentation products and a paucity of anaerobic bacteria. Early microbiome and metabolic patterns may become a valuable biomarker to guide individualized prevention strategies of LOS in highly vulnerable populations.

Regulatory T cell frequencies are increased in preterm infants with clinical early-onset sepsis.

The predisposition of preterm neonates to invasive infection is, as yet, incompletely understood. Regulatory T cells (Tregs ) are potential candidates for the ontogenetic control of immune activation and tissue damage in preterm infants. It was the aim of our study to characterize lymphocyte subsets and in particular CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) Tregs in peripheral blood of well-phenotyped preterm infants (n = 117; 23 + 0 - 36 + 6 weeks of gestational age) in the first 3 days of life in comparison to term infants and adults. We demonstrated a negative correlation of Treg frequencies and gestational age. Tregs were increased in blood samples of preterm infants compared to term infants and adults. Notably, we found an increased Treg frequency in preterm infants with clinical early-onset sepsis while cause of preterm delivery, e.g. chorioamnionitis, did not affect Treg frequencies. Our data suggest that Tregs apparently play an important role in maintaining maternal-fetal tolerance, which turns into an increased sepsis risk after preterm delivery. Functional analyses are needed in order to elucidate whether Tregs have potential as future target for diagnostics and therapeutics.

Increased risk for bronchitis after discharge in non-vaccinated very low birth weight infants.

BACKGROUND: In very low birth weight (VLBW) infants, obstructive bronchitis is a frequent cause of hospital re-admission. For VLBW infants, early vaccinations starting at 2 months after birth have been recommended. OBJECTIVE: To analyze risk factors for bronchitis during the first year after discharge and the effects of in-hospital standard vaccination (hexavalent/pneumococci) and/or RSV immunoprophylaxis with palivizumab. METHODS: A standardized questionnaire was sent to the parents of VLBW infants 7 month after discharge. The reported episodes of bronchitis were correlated with clinically recorded parameters including risk factors for pulmonary morbidity. The effects of in-hospital vaccination were assessed in a subgroup discharged after day 60. RESULTS: A sample of 1 967 responses of infants born 2009-2011 was analyzed. Risk factors for bronchitis were male gender and older siblings. 24% of the population had episodes of bronchitis. In the subgroup discharged after day 60, episodes of bronchitis were reported for 31% of infants who were not vaccinated in-hospital. A significant reduction of the bronchitis rate was found in infants who received palivizumab±standard vaccination (17% bronchitis, p=0.003). Interestingly, in-hospital standard vaccination without RSV immunoprophylaxis was protective (20% bronchitis; p=0.037) as well. CONCLUSIONS: Non-vaccinated male VLBW infants with older siblings are at increased risk for bronchitis during the first year after discharge. Vaccination according to schedule seems to have protective effects, while underlying mechanisms are unknown. The rate of timely vaccination in preterm infants should be increased.

Biophysical activity of animal-derived exogenous surfactants mixed with rifampicin.

Exogenous pulmonary surfactant is a potential delivery system for topical medications via the conducting airways. Due to the sensitivity to inactivation of surfactant, mutual interaction with the shipped drug should be evaluated. Little is known about the interactions between surfactant and antimicrobial drugs. The aim of the present study was to evaluate whether biophysical properties of animal-derived surfactants are modified by the bactericidal antibiotic rifampicin. An intracellular activity and a broad antimicrobiotic spectrum toward Gram-negative and Gram-positive bacteria make rifampicin an interesting substance against pulmonary infections. Curosurf® (porcine surfactant from minced lungs) and Survanta® (bovine surfactant extract) were diluted to 2.5-5.0 mg/ml of phospholipids in 0.9 % NaCl and rifampicin (RIF) was added at 1, 5, and 10 % (w/w). Minimum (γ(min)) and maximum (γ(max)) surface tension of a cyclically compressed bubble in the mixture was assessed with a pulsating bubble surfactometer. After 5 min, γ(min) of Survanta at a concentration of 3 mg/ml was significantly increased after addition of 5 and 10 % RIF (both p < 0.001). At 1 % RIF, the γ(min) of Survanta was ≈10 mN/m and this value was not significantly different to that of Survanta alone. The γ(min) of Curosurf at 3 mg/ml was increased with 10 % RIF (p < 0.001), but not with 1 and 5 %. At 5 mg/ml Survanta was inhibited by 10 % RIF (p < 0.05), while γ(min) of Curosurf was low (<5 mN/m) in all mixtures. In conclusion, Curosurf and Survanta interfere with RIF in a concentration-dependent manner. At the appropriate phospholipid concentration, especially porcine-derived surfactant is able to retain good surface activity when mixed with antibiotics.

Effects of multistrain Bifidobacteria and Lactobacillus probiotics on HMO compositions after supplementation to pregnant women at threatening preterm delivery: design of the randomized clinical PROMO trial.

BACKGROUND: As an indigestible component of human breast milk, Human Milk Oligosaccharides (HMOs) play an important role as a substrate for the establishing microbiome of the newborn. They have further been shown to have beneficial effects on the immune system, lung and brain development. For preterm infants HMO composition of human breast milk may be of particular relevance since the establishment of a healthy microbiome is challenged by multiple disruptive factors associated with preterm birth, such as cesarean section, hospital environment and perinatal antibiotic exposure. In a previous study it has been proposed that maternal probiotic supplementation during late stages of pregnancy may change the HMO composition in human milk. However, there is currently no study on pregnancies which are threatened to preterm birth. Furthermore, HMO composition has not been investigated in association with clinically relevant outcomes of vulnerable infants including inflammation-mediated diseases such as sepsis, necrotizing enterocolitis (NEC) or chronic lung disease. MAIN BODY: A randomized controlled intervention study (PROMO = probiotics for human milk oligosaccharides) has been designed to analyze changes in HMO composition of human breast milk after supplementation of probiotics (Lactobacillus acidophilus, Bifidobacterium lactis and Bifidobacterium infantis) in pregnancies at risk for preterm birth. The primary endpoint is HMO composition of 3-fucosyllactose and 3'-sialyllactose in expressed breast milk. We estimate that probiotic intervention will increase these two HMO levels by 50% according to the standardized mean difference between treatment and control groups. As secondary outcomes we will measure preterm infants' clinical outcomes (preterm birth, sepsis, weight gain growth, gastrointestinal complications) and effects on microbiome composition in the rectovaginal tract of mothers at delivery and in the gut of term and preterm infants by sequencing at high genomic resolution. Therefore, we will longitudinally collect bio samples in the first 4 weeks after birth as well as in follow-up investigations at 3 months, one year, and five years of age. CONCLUSIONS: We estimate that probiotic intervention will increase these two HMO levels by 50% according to the standardized mean difference between treatment and control groups. The PROMO study will gain insight into the microbiome-HMO interaction at the fetomaternal interface and its consequences for duration of pregnancy and outcome of infants.

Comparison of "IN-REC-SUR-E" and LISA in preterm neonates with respiratory distress syndrome: a randomized controlled trial (IN-REC-LISA trial).

BACKGROUND: Surfactant is a well-established therapy for preterm neonates affected by respiratory distress syndrome (RDS). The goals of different methods of surfactant administration are to reduce the duration of mechanical ventilation and the severity of bronchopulmonary dysplasia (BPD); however, the optimal administration method remains unknown. This study compares the effectiveness of the INtubate-RECruit-SURfactant-Extubate (IN-REC-SUR-E) technique with the less-invasive surfactant administration (LISA) technique, in increasing BPD-free survival of preterm infants. This is an international unblinded multicenter randomized controlled study in which preterm infants will be randomized into two groups to receive IN-REC-SUR-E or LISA surfactant administration. METHODS: In this study, 382 infants born at 24+0-27+6 weeks' gestation, not intubated in the delivery room and failing nasal continuous positive airway pressure (nCPAP) or nasal intermittent positive pressure ventilation (NIPPV) during the first 24 h of life, will be randomized 1:1 to receive IN-REC-SUR-E or LISA surfactant administration. The primary outcome is a composite outcome of death or BPD at 36 weeks' postmenstrual age. The secondary outcomes are BPD at 36 weeks' postmenstrual age; death; pulse oximetry/fraction of inspired oxygen; severe intraventricular hemorrhage; pneumothorax; duration of respiratory support and oxygen therapy; pulmonary hemorrhage; patent ductus arteriosus undergoing treatment; percentage of infants receiving more doses of surfactant; periventricular leukomalacia, severe retinopathy of prematurity, necrotizing enterocolitis, sepsis; total in-hospital stay; systemic postnatal steroids; neurodevelopmental outcomes; and respiratory function testing at 24 months of age. Randomization will be centrally provided using both stratification and permuted blocks with random block sizes and block order. Stratification factors will include center and gestational age (24+0 to 25+6 weeks or 26+0 to 27+6 weeks). Analyses will be conducted in both intention-to-treat and per-protocol populations, utilizing a log-binomial regression model that corrects for stratification factors to estimate the adjusted relative risk (RR). DISCUSSION: This trial is designed to provide robust data on the best method of surfactant administration in spontaneously breathing preterm infants born at 24+0-27+6 weeks' gestation affected by RDS and failing nCPAP or NIPPV during the first 24 h of life, comparing IN-REC-SUR-E to LISA technique, in increasing BPD-free survival at 36 weeks' postmenstrual age of life. TRIAL REGISTRATION: ClinicalTrials.gov NCT05711966. Registered on February 3, 2023.

Pregnancy risk factors for very premature delivery: what role do hypertension, obesity and diabetes play?

PURPOSE: Very premature delivery is a major cause of infant morbidity and mortality. Obesity, diabetes and pregnancy hypertension are known risk factors for pregnancy complications. The study aimed to scrutinize differences of pregnancy complications in a cohort of very premature deliveries compared to a national group. METHODS: In a multicenter study performed between January 2009 and December 2010 including 1,577 very low birth weight (VLBW) infants, we compared parental reported pregnancy problems of VLBW infants with a national cohort (KIGGS). We compared reported pregnancy complications to reasons for premature delivery and neonatal outcome within the group of VLBW infants. RESULTS: While parents of the national cohort reported pregnancy-induced hypertension in 8 %, parents of VLBW infants reported this complication more frequently (27 %). Mothers of the national cohort were significantly younger (1 year), suffered less from obesity, anaemia, diabetes. Regression analysis showed that hypertension (OR = 5.11) and advanced maternal age (OR = 1.03) increased the risk for premature birth. Women with hypertension were likely to experience a clinically indicated premature delivery, had more VLBW infants with a moderate growth restriction, but less multiples and their infants had less intraventricular haemorrhages grade 3 or 4. Otherwise, neonatal outcome was correlated with gestational age but not with the pregnancy complications diabetes, hypertension or obesity. CONCLUSION: Premature birth seems to be correlated to gestational hypertension and associated problems in about » of VLBW infants. Further studies should focus on preventing and treating gestational hypertension to avoid premature delivery and associated neonatal morbidity.

Influence of smoking and alcohol during pregnancy on outcome of VLBW infants.

BACKGROUND: Nicotine and alcohol consumption have been associated with premature delivery and adverse neonatal outcome. We wanted to analyze the influence of self-reported nicotine and alcohol consumption on outcome of VLBW infants. MATERIAL AND METHODS: In an ongoing multicenter study 2475 parents of former very low birth weight (VLBW) infants born between January 2009 and December 2011 answered questionnaires about maternal smoking habits and alcohol consumption during pregnancy. 2463 (99.5%) completed questions on alcohol consumption and 2462 (99.5%) on smoking habits. These infants were stratified to reported maternal smoking and alcohol consumption during pregnancy. We compared the reasons for premature delivery, neonatal outcome and parental reports on bronchitis during the first year of life, as well as growth and development at age 2 years to pregnancy exposure. RESULTS: In nicotine exposed infants intrauterine growth restriction (31 vs. 21%, p<0.01), a birth weight below the 10th percentile (26 vs. 17%, p<0.01) and placenta abruption (9.2 vs. 5.8%, p<0.05) was seen more often. Premature rupture of membranes (24 vs. 30%, p<0.05) or HELLP syndrome (6 vs. 11%, p<0.01) was less frequent. A birth weight below the 3rd percentile was seen more frequently in mothers with reported alcohol consumption (13 vs. 6%, p<0.05). We noted an increased rate of BPD and ROP if mothers reported smoking during pregnancy (p<0.05). Growth parameters and scores on Bayley Sscales of infant development at age 2 years did not differ. CONCLUSION: Smoking during pregnancy results in a high rate of growth restricted VLBW infants. Prenatal exposition to nicotine seems to increase postnatal complications such as BPD und ROP.

Galectin-3 in cord blood of term and preterm infants.

In recent years galectin-3 has gained attention as a signalling molecule, mainly in inflammatory diseases. Data on galectin-3 expression in neonates, however, are limited, and expression of this lectin in cord blood has not yet been reported. The aim of this study was to determine galectin-3 levels in cord blood of term and preterm neonates as well as galectin-3 levels in cord blood of term neonates after stimulation with the prevalent pathogen Streptococcus agalactiae. Cord blood samples were incubated for 24 h and galectin-3 levels were assessed by enzyme-linked immunosorbent assay. There is a positive correlation between gestational age and galectin-3 levels in cord blood. Expression of galectin-3 is significantly higher in cord blood of small-for-gestational-age infants compared to appropriate-for-gestational-age infants. Stimulation with an invasive but not with a colonizing strain of S. agalactiae induced expression of galectin-3. Galectin-3 is expressed constitutively in cord blood of neonates and seems to play a role in the innate immunity of this population.

Major contributors to hospital mortality in very-low-birth-weight infants: data of the birth year 2010 cohort of the German Neonatal Network.

The German Neonatal Network (GNN) is a prospective cohort study with the focus on long term development of very-low-birth-weight infants. It was the aim of this study to determine detailed information on causes of mortality in the GNN birth cohort 2010.Major contributors to hospital mortality were recorded by the attending neonatologists for the cohort of very-low-birth-weight (VLBW) infants born in centres of the German Neonatal Network (GNN) in 2010. The data quality was approved by on-site monitoring.2 221 VLBW infants were born in GNN centres in 2010, and death occurred in 221 infants. Male infants carried a higher risk than females (58.8% males among non-survivors vs. 51.7% among survivors, p=0.047). In 11 infants, the major contributor to death was not determined by the attending neonatologist. In 25 infants born at the limit of viability, comfort palliative care was primarily initiated and 14 infants had lethal malformations. The majority of non-survivors suffered from inflammatory diseases including sepsis- or necrotizing enterocolitis (NEC)-associated death (n=56). Respiratory pathology was a major contributor to death in 65 infants including 11 infants who died from pulmonary haemorrhage.Potentially preventable complications of preterm birth such as sepsis, NEC and pulmonary haemorrhage predominate the major contributors to mortality in the GNN 2010 cohort. In order to decrease the rate of these associated deaths, future trials should focus on prophylaxis and therapy optimization strategies for these outcomes.

Surfactant without intubation in preterm infants with respiratory distress: first multi-center data.

BACKGROUND: Recently in a report of a single center a method has been described to apply surfactant via a thin endotracheal catheter to very low birth weight infants spontaneously breathing with nasal continuous positive airway pressure. We now analyzed available multicenter data. PATIENTS AND METHODS: In a multicenter study investigating genetic risk factors, clinical and outcome data and data of antenatal and postnatal treatment of infants with a birth weight below 1,500 g were prospectively recorded. The measures of infants treated with the new method of surfactant application were compared to those of infants who received standard care. The analysis was restricted to infants with a gestational age below 31 weeks (n=1,541). RESULTS: 319 infants were treated with the new method and 1,222 with standard care. The need for mechanical ventilation during the first 72 h (29% vs. 53%, p<0.001), the rate of bronchopulmonary dysplasia defined as oxygen at 36 weeks of postmenstrual age (10.9 % vs. 17.5%, p=0.004) and the rate of death or bronchopulmonary dysplasia were significantly lower in the treatment group than in the standard care group. Surfactant, theophyllin, caffeine and doxapram were significantly more often and analgetics, catecholamines and dexamethasone were significantly less frequently used in the treatment group. CONCLUSIONS: A new method of surfactant application was associated with a lower prevalence of mechanical ventilation and better pulmonary outcome. A prospective controlled trial is required to determine whether this approach is superior to standard care.

Outcome of extremely premature infants at early school age: health-related quality of life and neurosensory, cognitive, and behavioral outcomes in a population-based sample in northern Germany.

PURPOSE: The study aimed at collecting regional data to support and establish evidence-based decision-making. METHODS: We investigated a cohort of 154 preterm infants with gestational age <27+0 weeks born between 1997 and 1999 in a defined region of Northern Germany regarding neurosensory and cognitive outcomes, overall disability status, behavioral problems, and health-related quality of life at the age of seven to nine years (mean: eight years, SD seven months). RESULTS: 92 (60%) infants survived, 75 of these 92 (82%) were followed-up. Rates of disability were high: only 27 (36%) showed 'no dysfunction' of neurosensory status, 33 (44%) 'mild dysfunction', 5 (7%) 'moderate dysfunction' and 10 (13%) 'severe dysfunction', including 8 (11%) with non-ambulatory cerebral palsy. 19 (26%) were mentally retarded. Parents reported behavioral problems in 21 (28%), health-related quality of life was lower in preterm infants compared to a representative normal sample. In multivariate analyses IVH III-IV/PVL was an independent risk factor for adverse outcomes. Behavior problems were predicted by low IQ and lower educational level of the mother. CONCLUSIONS: Overall our results confirm high levels of mortality and morbidity in extremely immature infants. Regional data should include mortality, morbidity and health-related quality of life to adequately inform parents about the prognosis.

Intermediate care units : Recommendations on facilities and structure.

A growing number of patients with increasingly complex or specialized diseases are being treated in hospitals worldwide. The treatment requirements of some of these patients are exceeding the capacity of standard nursing units. However, the severity of these diseases or the treatment requirements for these specific clinical pictures do not always justify admission to an intensive care unit. For this reason, an increasing number of special units (intermediate care units) are being set up to offer highly specialized treatment and close monitoring, in order to fulfil an intermediate role between the standard care unit and the intensive care unit. The recommendations of the German Interdisciplinary Association for Intensive Care and Emergency Medicine (DIVI) on the personnel, capacity, equipment and structure of these units are intended to provide the framework for the setting up and operation of intermediate care units in collaboration with experts on both an evidence-based and an expert-based basis (where scientific evidence is not available). Where only minimal or indirect evidence is available, patient safety is paramount in the formulation of the recommendation.

Length and weight of very low birth weight infants in Germany at 2 years of age: does it matter at what age they start complementary food?

BACKGROUND/OBJECTIVES: We analysed at what age parents start complementary food in very low birth weight infants, determined risk factors for early introduction of complementary food (post-term age) and analysed whether the age at introduction of complementary food influences height or weight at 2 years of age. SUBJECTS/METHODS: Parents of premature infants born in 2009-2011 answered questionnaires regarding introduction of complementary food in the first year of life (N=2262) and were followed up at a post-term age of 2 years (N=981). Length and weight were compared with full-term infants from the KiGGs study. Logistic and linear regression analyses were conducted to study predictors for early introduction of complementary food and the influence of age at introduction of complementary food on later height and weight. RESULTS: Average age at introduction of complementary food was 3.5 months post-term age. The lower the gestational age at birth, the earlier (post-term age) vegetables and meat were introduced. Age at introduction of complementary food was influenced by intrauterine growth restriction, gestational age at birth, maternal education and a developmental delay perceived by the parents. Length and weight at a post-term age of 2 years was not negatively influenced by early introduction of complementary food. CONCLUSIONS: VLBW infants are introduced to complementary food on average before a post-term age of 4 months. There was no negative effect of early introduction of complementary food on height and weight at 2 years of age.

Isolation of cDNA for human epidermal type I transglutaminase.

Keratinocytes of stratified epithelia, including the epidermis, express two distinct forms of transglutaminase, type I and type II. Type I transglutaminase activity is responsible for cell envelope formation in terminally differentiating cultured keratinocytes. Transglutaminase enzymatic activity has been associated with several proteins that are differentially expressed in vivo and in vitro. To elucidate the relationship between the epidermally expressed transglutaminases, cDNA for type I transglutaminase was cloned from a human high-calcium keratinocyte lambda gt11 library. cDNA fragments, generated by PCR primed with a mixture of oligonucleotides coding for five invariant amino acids in the active site, were used as a screening probe. Based on the sequence analysis of 1653 nt contained in the lambda 1-126a clone and on the pattern of expression of a complementary approximately 3-kb transcript, we report cloning of the epidermal type I transglutaminase gene. The expression of this gene is regulated by calcium ions and retinoic acid in cultured human keratinocytes. There are highly conserved regions near the active site cysteine residues that may be important for the enzyme's specialized functions.

Neutrophil elastase and acute pulmonary damage in neonates with severe respiratory distress syndrome.

This study evaluated possible acute effects of neutrophil elastase on neonatal pulmonary morbidity. The activity of free elastase and alpha 1-proteinase inhibitor as well as concentrations of elastase-alpha 1-proteinase inhibitor in tracheal aspirate fluid of neonates with severe respiratory distress syndrome (fraction of inspired oxygen > 0.6, mechanical ventilation) were analyzed between 6 and 36 hours after surfactant replacement therapy. One hundred forty neonates were included in this prospective study. Characteristics, disease severity, and ventilatory requirements were nearly identical in both groups. All patients were treated with natural porcine surfactant (Curosurf) at an age of 2 to 15 hours. In 42 neonates (30%) considerable activities of free elastase were detected (805 micrograms/L; 100 to 1850 [median, 25th to 75th percentile]); in 98 neonates (70%) who had protective levels of alpha 1-proteinase inhibitor, no elastase activity was detected. The average concentrations of elastase-alpha 1-proteinase inhibitor were significantly increased in patients with free elastase activity when compared with those of the nonelastase group. In logistic regression analyses, 28-day outcome data showed a pronounced increase in risk of pulmonary interstitial emphysema for patients with free elastase activity in tracheal aspirate fluid. The incidence of other pulmonary and nonpulmonary complications was very similar in both groups. It is concluded that elastolytic damage and barotrauma may both contribute to acute pulmonary injury in the early stages of respiratory distress syndrome.

Randomized European multicenter trial of surfactant replacement therapy for severe neonatal respiratory distress syndrome: single versus multiple doses of Curosurf.

There is now convincing evidence that the severity of neonatal respiratory distress syndrome can be reduced by surfactant replacement therapy; however, the optimal therapeutic regimen has not been defined. This randomized European multicenter trial was designed to determine whether the beneficial effects of a single large dose of Curosurf (200 mg/kg) in babies with severe respiratory distress syndrome (arterial to alveolar oxygen tension ratio approximately 0.10) could be enhanced by using multiple doses of surfactant. Preterm neonates (birth weight 700 to 2000 g) with severe respiratory distress syndrome requiring artificial ventilation with fraction of inspired oxygen greater than or equal to 0.6 were randomized into two groups at an age of 2 to 15 hours. Both groups received the usual dose of Curosurf (200 mg/kg) immediately after randomization. In neonates randomized to receive multiple-dose treatment, two additional doses of Curosurf (100 mg/kg each) were instilled into the airways (12 and 24 hours after the initial dose) provided that the patients still needed artificial ventilation with fraction of inspired oxygen greater than 0.21. In both groups (single dose: n = 176, multiple doses: n = 167) there was a rapid improvement in oxygenation as reflected by a threefold increase in arterial to alveolar oxygen tension ratio within 5 minutes after surfactant instillation (P less than .001), and peak inspiratory pressure and mean airway pressure could be reduced significantly during the first 6 hours after surfactant treatment. In addition, ventilatory requirement (peak inspiratory pressure, ventilatory efficiency index) was reduced in the multiple-dose group 2 to 4 days after randomization (P less than .05 to .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Exogenous surfactant improves lung compliance and oxygenation in adult rats with meconium aspiration.

We studied the effects of exogenous surfactant on lung function and morphology in an adult rat model of severe meconium aspiration syndrome. Animals ventilated with 100% oxygen received 4-6 ml of human meconium (25 mg/ml) intratracheally. After 30 min, lung-thorax compliance had decreased by > 30% and arterial PO2 was < 10 kPa. Animals were then treated with no material (MECO group), 0.9% NaCl (MECO-saline group), natural porcine surfactant (NPS group) at a dose of 100 mg/kg, or modified porcine surfactant at a dose of either 100 (MPS100 group) or 200 mg/kg (MPS200 group) and were ventilated for another 180 min. Immediate and sustained improvement of arterial PO2 and compliance was observed in the MPS200 group, whereas the MPS100 and NPS groups showed less pronounced effects. There was a significant improvement of quasi-static lung volumes at maximum insufflation pressure and during deflation in the MPS200, MPS100, and NPS groups. Recordings with Wilhelmy balance showed that minimum surface tension of bronchoalveolar lavage fluid from animals receiving either type or dose of surfactant was significantly lower than in the MECO and MECO-saline groups. Meconium aspiration induced diffuse and prominent atelectasis, intra-alveolar edema, and hyaline membranes. These morphological abnormalities were reversed by exogenous surfactant, especially by the high-dose regimen.

Surfactant improves lung function and mitigates bacterial growth in immature ventilated rabbits with experimentally induced neonatal group B streptococcal pneumonia.

AIMS: To study the influence of surfactant on lung function and bacterial proliferation in immature newborn rabbits with experimental group B streptococcal (GBS) pneumonia. METHODS: Preterm rabbit fetuses (gestational age 28 days) underwent tracheotomy and were mechanically ventilated in a warmed body plethysmograph that permitted measurement of lung-thorax compliance. Fifteen minutes after the onset of ventilation the animals received either GBS or saline intratracheally; at 30 minutes, a bolus of saline or 200 mg/kg of a porcine surfactant (Curosurf) was administered via the airway. Bacterial proliferation was evaluated in lung homogenate at the end of the experiments and the results expressed as mean log10 cfu/g lung (SD). Animals receiving only saline (n = 20) or saline and surfactant (n = 20) served as controls. RESULTS: The average survival time was about three hours in all groups. Infected animals receiving surfactant (n = 22) had significantly less bacterial growth (9.09 (0.45) vs 9.76 (0.91)) and improved lung function (compliance: 0.61 (0.14) vs 0.34 (0.19) ml/kg. cm H2O) than infected rabbits receiving saline at 30 minutes (n = 22). CONCLUSION: Surfactant improves lung function and mitigates bacterial growth in preterm rabbits infected with group B streptococci.