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Background: Less invasive surfactant administration (LISA) has become the preferred method of surfactant administration for spontaneously breathing babies on continuous positive airway pressure (CPAP)., Summary: The development of LISA followed the need to combine CPAP and surfactant replacement as mainstay treatment options for respiratory distress syndrome, thereby avoided exposure to positive pressure ventilation., Key Messages: This review summarises the current knowns and unknowns of LISA including the physiological concept, its relevance for short-term and long-term outcomes and the challenges for practical implementation of LISA as part of a less invasive respiratory care bundle. Further, we provide an update of the evidence on alternatives to LISA, for example, nebulised surfactant administration, pharyngeal deposition of surfactant and delivery via supraglottic airway., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

Lung surfactant is the first drug so far designed for the special needs of the newborn. In 1929, Von Neergard described lung hysteresis and proposed the role of surface forces. In 1955-1956, Pattle and Clements found direct evidence of lung surfactant. In 1959, Avery discovered that the airway's lining material was not surface-active in hyaline membrane disease (HMD). Patrick Bouvier Kennedy's death, among half-million other HMD-victims in 1963, stimulated surfactant research. The first large surfactant treatment trial failed in 1967, but by 1973, prediction of respiratory distress syndrome using surfactant biomarkers and promising data on experimental surfactant treatment were reported. After experimental studies on surfactant treatment provided insight in lung surfactant biology and pharmacodynamics, the first trials of surfactant treatment conducted in the 1980s showed a striking amelioration of severe HMD and its related deaths. In the 1990s, the first synthetic and natural surfactants were accepted for treatment of infants. Meta-analyses and further discoveries confirmed and extended these results. Surfactant development continues as a success-story of neonatal research., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Whilst exogenous surfactant therapy is central to the management of newborn infants with respiratory distress syndrome, its use in other neonatal lung diseases remains inconsistent and controversial. Here we discuss the evidence and experience in relation to surfactant therapy in newborns with other lung conditions in which surfactant may be deficient or dysfunctional, including meconium aspiration syndrome, pneumonia, congenital diaphragmatic hernia and pulmonary haemorrhage. We find that, for all of these diseases, administration of exogenous surfactant as bolus therapy is frequently associated with transient improvement in oxygenation, likely related to temporary mitigation of surfactant inhibition in the airspaces. However, for none of them is there a lasting clinical benefit of surfactant therapy. By virtue of interrupting disease pathogenesis, lavage therapy with dilute surfactant in MAS offers the greatest possibility of a more pronounced therapeutic effect, but this has yet to be definitively proven. Lavage therapy also involves a greater degree of procedural risk., (Copyright © 2023. Published by Elsevier Ltd.)

Background: Respiratory distress syndrome is the main cause of mortality and morbidity in preterm infants. "Less invasive surfactant administration" (LISA), which describes intratracheal surfactant administration to spontaneously breathing infants via a small diameter tube, is recommended as the first-line treatment in preterm infants with more than 30% supplemental oxygen. Prophylactic use of LISA in preterm infants with less than 30% supplemental oxygen was not tested in randomised controlled trials yet, and long-term outcome data of the procedure are scarce., Methods: Preterm infants with a gestational age between 25 weeks + 0 days and 28 weeks + 6 days who are breathing spontaneously on continuous positive airway pressure with supplemental oxygen at or below 30% in the first hour of life will be randomised to a prophylactic LISA treatment with 100-200 mg surfactant intratracheally per kilogramme bodyweight (intervention group) or will continue the continuous positive airway pressure treatment (control group). Participants will have follow-up until age 5 years. At that time, the children will be tested by spirometry, and forced expiratory volume within 1-s z-scores will be compared between the intervention and control groups as the primary outcome parameter of the trial. Secondary endpoints include additional lung function parameters, endurance, motor development, intelligence, and sensitivity for infectious lung diseases. Short-term safety assessment will be done after completed enrolment (n = 698) and discharge of all infants. This safety assessment will include in-hospital mortality and short-term complications., Discussion: Robust data concerning the possible long-term benefits of prophylactic LISA treatment are lacking. The current observational data from the German Neonatal Network indicate that approximately 50% of preterm infants with supplemental oxygen at or below 30% within the first hour of life are treated with LISA. The pro.LISA trial will provide short- and long-term outcomes of preterm infants receiving prophylactic treatment and will clarify if prophylactic treatment should be given to all preterm infants or if the current practice of selective treatment if supplemental oxygen exceeds 30% is more appropriate., Trial Registration: German Clinical Trials Register DRKS00028086. Prospectively registered on 8 February 2022., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Aim: We explored whether subnormal forced expiratory volume within 1 s (FEV 1 ) at 5-9 years of age was lower in children born preterm who received less invasive surfactant administration (LISA) rather than surfactant via an endotracheal tube., Methods: The multi-centre, randomised Nonintubated Surfactant Application trial enrolled 211 preterm infants born at 23-26 weeks of gestation from 13 level III neonatal intensive care units from April 2009 to March 2012. They received surfactant via LISA (n = 107) or after conventional endotracheal intubation (n = 104). The follow-up assessments were carried out by a single team blinded to the group assignments. The main outcome was FEV 1  < 80% of predicted values., Results: Spirometry was successful in 102/121 children. The other children died or were lost to follow-up. Median FEV 1 was 93% (interquartile range 80%-113%) of predicted values in the LISA group and 86% (interquartile range 77-102%) in the control group (p = 0.685). Rates of FEV 1  < 80% were 11/57 (19%) and 15/45 (33%), respectively, which was an absolute risk reduction of 14% (95% confidence interval -3.1% to 31.2%, p = 0.235). There were no differences in other outcome measures., Conclusion: The proportion of children aged 5-9 years with subnormal FEV 1 was not significantly different between the groups., (© 2022 The Authors. Acta Paediatrica published by John Wiley & Sons Ltd on behalf of Foundation Acta Paediatrica.)

Importance: The inclusion of less invasive surfactant administration (LISA) in the care of preterm infants has been found to be beneficial for respiratory outcomes. Recently, the OPTIMIST trial found higher mortality rates in the subgroup of infants born at 25 to 26 weeks' gestational age (GA) who received surfactant treatment while spontaneously breathing., Objective: To analyze outcomes among LISA-exposed, highly vulnerable babies born at less than 27 weeks' GA within the large-scale observational cohort of the German Neonatal Network., Design, Setting, and Participants: In this cohort study of data from 68 tertiary level neonatal intensive care units in Germany of infants born between 22 weeks 0 days to 26 weeks 6 days of gestation between April 1, 2009, and December 31, 2020, short-term outcomes among infants receiving LISA vs infants not receiving LISA were compared., Exposure: Use of LISA within the first 72 hours of life., Main Outcomes and Measures: The main outcomes were rates of LISA use, use of mechanical ventilation within the first 72 hours (considered failure of LISA), and association of LISA with outcomes, including death from all causes, bronchopulmonary dysplasia (BPD), death and BPD combined, pneumothorax, retinopathy of prematurity, intracerebral hemorrhage, and periventricular leukomalacia. To address potential confounding factors, multivariate logistic regression models were used., Results: A total of 6542 infants (3030 [46.3%] female and 3512 [53.7%] male; mean [SD] GA, 25.3 (1.1) weeks; mean [SD] birth weight, 715 [180] g) were analyzed; 2534 infants (38.7%) received LISA, which was most frequently given quasi-prophylactically during delivery room management. Among the infants who received LISA, 1357 (53.6%) did not require mechanical ventilation in the first 72 hours compared with 331 infants (8.3%) of 4008 who did not receive LISA. In a multivariate logistic regression model that adjusted for GA, small-for-GA status, sex, multiple birth, inborn status, antenatal steroid use, and maximum fraction of inspired oxygen in the first 12 hours of life, LISA was associated with reduced risks of all-cause death (odds ratio [OR], 0.74; 95% CI, 0.61-0.90; P = .002), BPD (OR, 0.69; 95% CI, 0.62-0.78; P < .001), and BPD or death (OR, 0.64; 95% CI, 0.57-0.72; P < .001) compared with infants without LISA exposure., Conclusions and Relevance: The results of this long-term multicenter cohort study suggest that LISA may be associated with reduced risks of adverse outcomes in extremely preterm infants.

Aim: The aim of this study was to evaluate neurocognitive outcome at 24 months of corrected age after less invasive surfactant application (LISA) in preterm infants born at 23-26 weeks of gestational age., Methods: Surviving participants of a LISA trial conducted in 13 German level III neonatal intensive care units were reviewed for assessment of developmental outcome, hearing and vision problems, growth and rehospitalisation days. Maternal depression, breastfeeding rates and socio-economic factors were evaluated as potentially confounding factors., Results: In total, 156/182 infants took part in the study, 78 had received surfactant via LISA and 78 via endotracheal intubation. 22% of LISA infants compared to 42% of intubated infants had a psychomotor development index (PDI) <70 (0.012). A significant difference in mental development index (MDI) was observed in the stratum of more mature infants (25 and 26 weeks of GA). For this group, MDI < 70 was observed in 4% of LISA infants vs 21% of intubated infants (P = 0.008)., Conclusion: At 24 months of age, the LISA-treated infants scored less often PDI < 70 and had similar results in MDI. Infants born at 25 and 26 weeks treated with LISA had lower rates of severe disability. LISA is safe and may be superior., (© 2020 The Authors. Acta Paediatrica published by John Wiley & Sons Ltd on behalf of Foundation Acta Paediatrica.)

Less invasive surfactant administration (LISA) is a method to deliver surfactant to spontaneously breathing premature infants via a thin catheter. Here we report the two-year outcome from the AMV (avoid mechanical ventilation) study, the first randomized controlled trial on this mode of surfactant delivery. No statistically significant differences in weight, length or neurodevelopmental outcome (Bayley II scores) were found between the LISA intervention group (n = 95) and the control group (n = 84) that received standard treatment.Conclusion: No differences in outcome were observed at 2 years. LISA seems safe in that aspect. What is Known: • LISA is a method that is in increasing use for surfactant delivery to spontaneously breathing infants. LISA reduces the need for mechanical ventilation. What is New: • Outcome data at 2 years from the first randomized study with LISA raise no safety concerns in comparison to a group of infants that received standard treatment.

Purpose of Review: The purpose of this review is to describe current concepts in the field of Less Invasive Surfactant Administration (LISA). The use of continuous positive airway pressure (CPAP) has become standard for the treatment of premature infants with respiratory problems throughout the world. However, if CPAP fails, technologies like LISA are needed that can combine surfactant delivery and spontaneous breathing with the support of noninvasive modes of ventilation., Recent Findings: LISA with thin catheters has been in use in Germany for more than 15 years. In the last 5 years, there was substantial interest in this method around the world. Randomized studies and recent metaanalyses indicate that the LISA technique helps to avoid mechanical ventilation especially in emerging respiratory distress syndrome (RDS). LISA is also associated with improved outcomes of preterm infants, specifically in the prevention of bronchopulmonary dysplasia (BPD) and intracranial hemorrhage (ICH). By now, a variety of different LISA catheters, devices and techniques have been described. However, most of the technologies are still connected with the unpleasant experience of laryngoscopy for the affected infants, so that the search for even less invasive techniques, for example, surfactant application by nebulization, goes on., Summary: Maintenance of spontaneous breathing with support by the LISA technique holds big promise in the care of preterm infants. Patient comfort and lower complication rates are strong arguments to further investigate and promote the LISA approach. Open questions include exact indications for different patient groups, the usefulness of devices/catheters that have recently been built for the LISA technique and -- perhaps most urgently -- the issue of analgesia/sedation during the procedure. Studies on long-term outcome after LISA are under way.

Aim: To determine the regional cerebral tissue oxygenation saturation (rcSO 2 ) in a group of infants requiring less invasive surfactant administration (LISA) as compared to infants with continuous positive airway pressure (CPAP) only., Methods: In preterm infants with a gestational age 26 0/7-31 6/7 weeks, we conducted an observational study using near-infrared spectroscopy (NIRS) in the first 120 hours of life., Results: We analysed the data of 22 infants who never received surfactant (CPAP), 22 infants had LISA and CPAP (LISA) and 6 infants received surfactant via endotracheal tube (ETT). Four infants had both surfactant application modes including six LISA applications. In total, there were 32 successful LISA applications but 44 attempts; 13/44 (30%) of LISA attempts resulted in a 20% decrease of rcSO 2 . During the first 120 hours of life, rcSO 2 values of CPAP were similar to those of infants in the LISA group, that is median rcSO 2 values 90% vs 85%, respectively (P = .126). Episodes with rcSO 2 values <65% were 0.4% in the CPAP group as compared to 4.8% in the LISA group (P < .001)., Conclusion: Our observational data indicate that rcSO 2 values of infants in the LISA group were similar to the CPAP group., (©2019 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Non-invasive ventilation and especially the application of continuous positive airway pressure (CPAP) has become standard for the treatment of premature infants with respiratory problems. However, CPAP failure may occur due to respiratory distress syndrome, that is, surfactant deficiency. Less invasive surfactant administration (LISA) aims to provide an adequate dose of surfactant while the infant is breathing spontaneously, thus avoiding positive pressure ventilation support. Using a thin catheter for surfactant application allows infants to maintain function of the glottis and continue spontaneous breathing, whereas the INtubate-SURfactant-Extubate (INSURE) procedure is connected with sedation/analgesia, regular intubation and a (brief) period of positive pressure ventilation. Individual studies and meta-analyses summarised in this review point in the direction that LISA is more effective than standard treatment or INSURE both in terms of short-term (avoidance of mechanical ventilation) and long-term (intracerebral haemorrhage and bronchopulmonary dysplasia) outcomes. Open questions include exact treatment thresholds for different gestational ages, the usefulness of devices/catheters that have recently been purpose-built for the LISA technique and especially the question of analgesia/sedation during the procedure. The current technology still demands laryngoscopy with all its unpleasant effects for infants. Therefore, studies with pharyngeal surfactant deposition immediately after delivery, the use of laryngeal airways for surfactant administration and attempts to nebulise surfactant are under way. Finally, LISA is not simply an isolated technical procedure for surfactant delivery but rather part of a comprehensive non-invasive approach supporting the concept of a gentle transition to the extrauterine world enabling preterm infants to benefit from the advantages of spontaneous breathing., Competing Interests: Competing interests: EH, CH and WG have received study support, honoraria for presentations and travel support from Chiesi Farmaceutici, a surfactant producer. EH and CH served as advisors for Draeger Medical, a company producing incubators, monitors and ventilators., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Exogenous surfactant replacement is the most effective evidence-based therapy for respiratory distress syndrome in preterm infants. The mode of administration has evolved in the last decade towards less invasive techniques that aim to effectively provide an adequate dose of surfactant, while allowing spontaneous respiration to continue, and with the support of continuous positive airway pressure. Surfactant delivery via aerosolisation, pharyngeal instillation, and laryngeal mask are being actively pursued in research, but have not yet been adopted to any significant degree in clinical practice. Surfactant administration via thin catheter, on the other hand, is becoming more widely used in neonatal intensive care units worldwide and is now an acknowledged alternative to the standard mode of surfactant delivery. Different devices, including nasogastric tubes, vascular catheters, and purpose-built surfactant instillation catheters are used. We present here a contemporary review of surfactant administration via thin catheter, in a practical guide format that reflects the individual and collective scientific opinions of the clinicians who participated in formulating the guide., (© 2019 S. Karger AG, Basel.)

In a large cohort study of the German Neonatal Network (GNN) we aimed to evaluate whether less invasive surfactant administration (LISA) strategy is associated with complications of preterm birth. Within the observational period n = 7533 very-low-birth-weight infants (VLBWI) with gestational age 22 0/7 to 28 6/7 weeks were enrolled in GNN; n = 1214 VLBWI never received surfactant, n = 2624 VLBWI were treated according to LISA procedure, n = 3695 VLBWI had surfactant via endotracheal tube (ETT). LISA was associated with a reduced risk for adverse outcome measures including mortality [odds ratio (OR) 0.66 (95% CI: 0.51-0.84), p < 0.001] bronchopulmonary dysplasia [BPD; OR 0.55 (95% CI: 0.49-0.62), p < 0.001], intracerebral hemorrhage (ICH) grade II-IV [OR 0.55 (95% CI: 0.48-0.64), p < 0.001] and retinopathy of prematurity [ROP; OR 0.62 (95% CI: 0.45-0.85), p < 0.001]. Notably, LISA was associated with an increased risk for focal intestinal perforation [FIP; OR 1.49 (95% CI: 1.14-1.95), p = 0.002]. The differences in FIP rates were primarily observed in VLBWI born <26 weeks (LISA: 10.0 vs. ETT: 7.4%, p = 0.029). Our observational data confirm that LISA is associated with improved outcome. In infants <26 weeks we noted an increased risk for FIP. Future randomized controlled trials including LISA need to integrate safety analyses for this particular subgroup.

Surfactant treatment of neonatal respiratory distress syndrome (RDS) was introduced in Europe during the 1990s. Meta-analyses have indicated that using less invasive surfactant administration techniques on preterm neonates receiving continuous positive airway pressure (CPAP) results in improved survival rates without bronchopulmonary dysplasia. Surfactant should be administered early and ventilator settings adapted to changing oxygen requirements and lung mechanics. Side effects including initial bradycardia, oxygen desaturation, tube obstruction and isolated cases of pulmonary haemorrhage have been reported., Conclusion: Less invasive surfactant therapy improves pulmonary outcomes in preterm neonates with RDS and should ideally be administered in combination with CPAP., (©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Importance: Treatment of respiratory distress syndrome in premature infants with continuous positive airway pressure (CPAP) preserves surfactant and keeps the lung open but is insufficient in severe surfactant deficiency. Traditional surfactant administration is related to short periods of positive pressure ventilation and implies the risk of lung injury. CPAP with surfactant but without any positive pressure ventilation may work synergistically. This randomized trial investigated a less invasive surfactant application protocol (LISA)., Objective: To test the hypothesis that LISA increases survival without bronchopulmonary dysplasia (BPD) at 36 weeks' gestational age in extremely preterm infants., Design, Setting, and Participants: The Nonintubated Surfactant Application trial was a multicenter, randomized, clinical, parallel-group study conducted between April 15, 2009, and March 25, 2012, in 13 level III neonatal intensive care units in Germany. The final follow-up date was June 21, 2012. Participants included 211 of 558 eligible (37.8%) spontaneously breathing preterm infants born between 23.0 and 26.8 weeks' gestational age with signs of respiratory distress syndrome. In an intention-to-treat design, infants were randomly assigned to receive surfactant either via a thin endotracheal catheter during CPAP-assisted spontaneous breathing (intervention group) or after conventional endotracheal intubation during mechanical ventilation (control group). Analysis was conducted from September 6, 2012, to June 20, 2013., Intervention: LISA via a thin catheter., Main Outcomes and Measures: Survival without BPD at 36 weeks' gestational age., Results: Of 211 infants who were randomized, 104 were randomized to the control group and 107 to the LISA group. Of the infants who received LISA, 72 (67.3%) survived without BPD compared with 61 (58.7%) of those in the control group. The reduction in absolute risk was 8.6% (95% CI, -5.0% to 21.9%; P = .20). Intervention group infants were less frequently intubated (80 infants [74.8%] vs 103 [99.0%]; P < .001) and required fewer days of mechanical ventilation. Significant reductions were seen in pneumothorax (5 of 105 intervention group infants [4.8%] vs 13 of 103 12.6%]; P = .04) and severe intraventricular hemorrhage (11 infants [10.3%] vs 23 [22.1%]; P = .02), and the combined survival without severe adverse events was increased in the intervention group (54 infants [50.5%] vs 37 [35.6%]; P = .02; absolute risk reduction, 14.9; 95% CI, 1.4 to 28.2)., Conclusions and Relevance: LISA did not increase survival without BPD but was associated with increased survival without major complications. Because major complications are related to lifelong disabilities, LISA may be a promising therapy for extremely preterm infants., Trial Registration: isrctn.org Identifier: ISRCTN64011614.

Aim: Providing less invasive surfactant administration (LISA) to spontaneously breathing preterm infants has been reported to reduce mechanical ventilation and bronchopulmonary dysplasia (BPD) in randomised controlled trials. This large cohort study compared these outcome measures between LISA-treated infants and controls., Methods: Infants receiving LISA, who were born before 32 gestational weeks and enrolled in the German Neonatal Network, were matched to control infants by gestational age, umbilical cord pH, Apgar-score at 5 min, small for gestational age status, antenatal treatment with steroids, gender and highest supplemental oxygen during the first 12 h of life. Outcome data were compared with chi-square and Mann-Whitney U-tests and adjusted for multiple comparisons., Results: Between 2009 and 2012, 1103 infants were treated with LISA at 37 centres. LISA infants had lower rates of mechanical ventilation (41% versus 62%, p < 0.001), postnatal dexamethasone treatment (2.5% versus 7%, p < 0.001), BPD (12% versus 18%, p = 0.001) and BPD or death (14% versus 21%, p < 0.001) than the controls., Conclusion: Surfactant treatment of spontaneously breathing infants was associated with lower rates of mechanical ventilation and BPD. Additional large-scale randomised controlled trials are needed to assess the possible long-term benefits of LISA., (©2014 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Unlabelled: Very low birth weight (VLBW) infants frequently receive analgesia and/or sedation for painful procedures and mechanical ventilation to avoid negative stress. Yet, concerns remain regarding potential adverse long-term effects of these drugs on VLBW infants' neurocognitive outcome. Recent studies have shown that less invasive surfactant application (LISA) and early nasal CPAP treatment reduce the need for mechanical ventilation and painful procedures. Therefore, these measures might also reduce the application of analgesic and/or sedative drugs in VLBW infants. To evaluate this hypothesis and to identify potential changes in analgesic treatment concepts in recent years, we retrospectively analyzed data on analgesia and sedation, respiratory support, and the method of surfactant application in VLBW infants enrolled in the German Neonatal Network (GNN) trial between 2003 and 2009 (period 1) and compared it with data from infants participating in GNN in 2010 (period 2). In both periods, about one third of all infants were treated with analgesic and/or sedative drugs using a wide variety of substances. The administration of novel drugs such as propofol, sufentanil, or intravenous paracetamol was higher in 2010 (6.7 vs. 12.2 %). Infants who were treated with CPAP only received significantly less analgesic/sedative medication than infants who were mechanically ventilated (12 vs. 65 %, p=<0.001). Similarly, infants treated with LISA received less analgesic or sedative drugs as compared to infants who received surfactant via endotracheal intubation (36 vs. 63 %, p=0.001)., Conclusion: Although both avoidances of mechanical ventilation and less invasive surfactant application are associated with reduced analgesic or sedative treatment, the percentage of VLBW infants who received analgesia and/or sedation remained unchanged in Germany in recent years.

The idea to deliver surfactant to spontaneously breathing premature infants is not new. The spectrum of methods reported reaches from aerosol administration over pharyngeal deposition, the use of laryngeal masks, short term intubation, surfactant administration and rapid extubation (INSURE) to an approach of keeping premature neonates on spontaneous breathing with continuous positive airway pressure support and administering surfactant by laryngoscopy via a small diameter tube. This way of Less Invasive Surfactant Administration (LISA) is in increasing use in the last decade in Germany. More than 1000 babies have been included in clinical studies on LISA by now. A first prospective randomized controlled trial (AMV-trial) demonstrated a significant reduction in the use of mechanical ventilation in LISA patients compared to standard treatment with intratracheal bolus administration of surfactant. Another recent study (Take Care study) indicates, that LISA may even be superior to INSURE. The search for even more "gentle" methods (e.g. nebulization) to deliver surfactant continues., (© 2013.)

Background: Exogenous surfactant derived from animal lungs is applied for treatment of surfactant deficiency. By means of its rapid spreading properties, it could transport pharmaceutical agents to the terminal air spaces. The antimicrobial peptide Polymyxin B (PxB) is used as a topical antibiotic for inhalation therapy. Whereas it has been shown that PxB mixed with surfactant is not inhibiting surface activity while antimicrobiotic activity is preserved, little is known concerning the effects on synthesis of endogenous surfactant in alveolar type II cells (ATIIC)., Objective: To investigate ATIIC viability and surfactant-exocytosis depending on PxB and/or surfactant exposure., Methods: ATIIC were isolated from rat lungs as previously described and were cultivated for 48 h. After incubation for a period of 1-5 h with either PxB (0.05 or 0.1 mg/ml), modified porcine surfactant (5 or 10 mg/ml) or mixtures of both, viability and exocytosis (spontanously and after stimulation) were determined by fluorescence staining of intracellular surfactant., Results: PxB 0.1 mg/ml, but not porcine surfactant or porcine surfactant plus PxB reduces ATIIC-viability. Only PxB alone, but not in combination with porcine surfactant, rapidly reduces fluorescence in ATIIC at maximum within 3 h, indicating stimulation of exocytosis. Subsequent ionomycin-stimulation does not further increase exocytosis of PxB incubated ATIIC. In presence of surfactant, stimulating effects of PxB and ionomycin on exocytosis are reduced., Conclusion: PxB alone shows negative effects on ATIIC, which are counterbalanced in mixtures with surfactant. So far, our studies found no results discouraging the concept of a combined treatment with PxB and surfactant mixtures.

Background: Surfactant is usually given to mechanically ventilated preterm infants via an endotracheal tube to treat respiratory distress syndrome. We tested a new method of surfactant application to spontaneously breathing preterm infants to avoid mechanical ventilation., Method: In a parallel-group, randomised controlled trial, 220 preterm infants with a gestational age between 26 and 28 weeks and a birthweight less than 1·5 kg were enrolled in 12 German neonatal intensive care units. Infants were independently randomised in a 1:1 ratio with variable block sizes, to standard treatment or intervention, and randomisation was stratified according to centre and multiple birth status. Masking was not possible. Infants were stabilised with continuous positive airway pressure and received rescue intubation if necessary. In the intervention group, infants received surfactant treatment during spontaneous breathing via a thin catheter inserted into the trachea by laryngoscopy if they needed a fraction of inspired oxygen more than 0·30. The primary endpoint was need for any mechanical ventilation, or being not ventilated but having a partial pressure of carbon dioxide more than 65 mm Hg (8·6 kPa) or a fraction of inspired oxygen more than 0·60, or both, for more than 2 h between 25 h and 72 h of age. Analysis was by intention to treat. This study is registered, number ISRCTN05025922., Findings: 108 infants were assigned to the intervention group and 112 infants to the standard treatment group. All infants were analysed. On day 2 or 3 after birth, 30 (28%) infants in the intervention group were mechanically ventilated versus 51 (46%) in the standard treatment group (number needed to treat 6, 95% CI 3-20, absolute risk reduction 0·18, 95% CI 0·30-0·05, p=0·008). 36 (33%) infants in the intervention group were mechanically ventilated during their stay in the hospital compared with 82 (73%) in the standard treatment group (number needed to treat: 3, 95% CI 2-4, p<0·0001). The intervention group had significantly fewer median days on mechanical ventilation, (0 days. IQR 0-3 vs 2 days, 0-5) and a lower need for oxygen therapy at 28 days (30 infants [30%] vs 49 infants [45%], p=0·032) compared with the standard treatment group. We recorded no differences between groups for mortality (seven deaths in the intervention group vs five in the standard treatment group) and serious adverse events (21 vs 28)., Interpretation: The application of surfactant via a thin catheter to spontaneously breathing preterm infants receiving continuous positive airway pressure reduces the need for mechanical ventilation., Funding: German Ministry of Research and Technology, University of Lübeck, and Chiesi Pharmaceuticals., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In neonatal pneumonia, the surface activity of pulmonary surfactant is impaired and microorganisms may invade by passing the air-liquid interface. Previously, we have shown that addition of the antimicrobial peptide polymyxin B (PxB) to modified porcine surfactant (pSF) improves resistance to surfactant inactivation in vitro while antimicrobial activity of PxB is maintained. In this study, we investigated pSF/PxB in vivo. Neonatal near-term rabbits were treated with intratracheal pSF and/or PxB. Rabbits treated with only saline served as controls. Animals were ventilated with standardized tidal volumes and received ∼10(7) Escherichia coli intratracheally. Plethysmographic pressure-volume curves were recorded every 30 min. After 240 min, animals were killed, the right lung and left kidney were excised, and bacterial growth was determined. The left lung was used for histologic analysis. Intratracheal administration of PxB ± pSF significantly reduced the growth of E. coli compared with control animals or animals receiving only pSF. This was accompanied by reduction of severe inflammatory tissue destruction and significantly reduced bacterial translocation to the left kidney. Animals receiving pSF + PxB had no difference in lung compliance compared with the pSF- or PxB-treated group. Mixtures of PxB and pulmonary surfactant show antimicrobial effects in neonatal rabbits and prevent systemic spreading of E. coli.

Objective: Surface activity of pulmonary surfactant is impaired by exposure to syringes lubricated with silicone oil (SO). These syringes are used daily in clinical practice., Design: In vitro experiments were used for detection of SO, determination of surface activity, and semiquantitative measurement of surfactant protein (SP)-B and -C in SO/surfactant mixtures. Randomized, controlled animal studies were applied for determination of in vivo activity., Setting: University research laboratory., Interventions: Mass spectrometry of SO originating from syringes with and without surfactant was performed. The surface activity of SO plus surfactant phospholipids (PLs) or modified natural surfactant (Curosurf) was measured. SO/Curosurf preparations were further analyzed for changes in the content of SP-B and SP-C using immunoblotting. Neonatal rabbits received mixtures of SO/Curosurf (ratio 0-1.3 mg/mg PL) intratracheally and were then ventilated with a standardized sequence of peak insufflation pressures. Tidal volume curves were recorded, gas volumes of excised lungs were measured, and histologic analysis was performed., Measurements and Main Results: Dissolved SO was found after rinsing syringes with organic solvents or Curosurf. Surface activity of Curosurf was significantly reduced after addition of 0.13-1.3 mg SO/mg PL. Immunoblotting revealed interference of SO with SP-B, but not with SP-C. With increasing SO/Curosurf ratios, patchy alveolar air expansion was observed, lung gas volumes were reduced, and time to inflate the lungs was increased, whereas compliance and tidal volumes remained unimpaired., Conclusions: In vitro SO impairs surface activity of Curosurf and leads to interference with SP-B. SO contamination of exogenous surfactant impairs lung function in animal studies and should be avoided.

Background: Surfactant dysfunction due to inhibition is involved in the pathophysiology of meconium aspiration syndrome. Dextran addition has been shown to reverse exogenous surfactant inactivation by meconium, but the precise mechanisms and the morphological correlate of this effect are yet unknown. Morphological surfactant analysis by transmission electron microscopy (TEM) and stereology allows the differentiation of active (large aggregates = LA) and inactive (small aggregates = SA) subtypes., Methods: To determine the in vitro effects of meconium and dextran addition on the morphology of a modified porcine natural surfactant (Curosurf), Curosurf samples were either incubated alone or together with meconium or with meconium and dextran, fixed and processed for TEM. Volume fractions of surfactant subtypes [lamellar body-like forms (LBL), multilamellar vesicles (MV), unilamellar vesicles (UV)] were determined stereologically., Results: All preparations contained LBL and MV (corresponding to LA) as well as UV (corresponding to SA). The volume fraction of UV increased with addition of meconium and decreased with further addition of dextran. Correspondingly, the UV/(LBL+MV) ratio (resembling the SA/LA ratio) increased when meconium was added and decreased when dextran was added to the surfactant-meconium mixture., Conclusion: Meconium causes alterations in the ultrastructural composition of Curosurf that can be visualized and analyzed by TEM and stereology. These alterations resemble an increase in the SA/LA ratio and are paralleled by an increase in minimum surface tension. Dextran prevents these effects and may therefore be a useful additive to exogenous surfactant preparations to preserve their structural and functional integrity, thereby improving their resistance to inactivation.

Pulmonary surfactant is inactivated in meconium aspiration syndrome and neonatal pneumonia. Development of an exogenous surfactant less sensitive to inactivation might be useful for treating these diseases. We investigated in vitro whether addition of the cationic cyclic membrane cross-linking peptide polymyxin B (PxB) and/or calcium chloride (CaCl2) to modified porcine surfactant Curosurf increases resistance to meconium-induced inactivation of surface activity while antimicrobial activity of PxB is maintained. To study bacterial proliferation, Escherichia coli, group B streptococci (GBS), or Staphylococcus aureus were incubated 0-5 h in saline or in meconium in the presence or absence of Curosurf with or without PxB. PxB and CaCl2 improved spreading and adsorption of Curosurf. Curosurf plus CaCl2/PxB needed a 4-fold increase of meconium concentration to increase dynamic surface tension significantly compared with Curosurf plus CaCl2 alone, indicating that PxB further increases the resistance of Curosurf to meconium-induced inactivation. Meconium alone like meconium/Curosurf promoted growth of E. coli and GBS, but addition of Curosurf/PxB or PxB alone significantly reduced the growth of E. coli. Biophysical and antibacterial properties of Curosurf and PxB may be combined into a useful adjunct in the treatment of neonatal Gram-negative pneumonia and/or meconium aspiration syndrome.

The antibacterial activities of the cathelicidin peptides LL-37 and an 18-residue C-terminal fragment of prophenin, corresponding to positions 62 to 79 of native prophenin (PF-18), were analyzed in the presence of a modified surfactant preparation isolated from minced porcine lungs. At low micromolar concentrations, both LL-37 and PF-18 showed significant activities against different serotypes of group B streptococci, with LL-37 being more active on a molar basis. The surfactant preparation at a concentration of 10 mg/ml partly blocked the antibacterial activity of 9 microM LL-37 and completely blocked the antibacterial activity of 9 microM PF-18. However, 10 mg of the surfactant preparation per ml had only minor inhibitory effects on LL-37 and PF-18 at 90 microM. Addition of up to 900 microM PF-18 did not affect the surface properties of the surfactant preparation. These data suggest that surfactant preparations containing antimicrobial peptides could be useful for the local treatment of pulmonary infections.

Besides being one of the mechanisms responsible for ventilator-induced lung injury, atelectasis also seems to aggravate the course of experimental pneumonia. In this study, we examined the effect of reducing the degree of atelectasis by natural modified surfactant and/or open lung ventilation on bacterial growth and translocation in a piglet model of Group B streptococcal pneumonia. After creating surfactant deficiency by whole lung lavage, intratracheal instillation of bacteria induced severe pneumonia with bacterial translocation into the blood stream, resulting in a mortality rate of almost 80%. Treatment with 300 mg/kg of exogenous surfactant before instillation of streptococci attenuated both bacterial growth and translocation and prevented clinical deterioration. This goal was also achieved by reversing atelectasis in lavaged animals via open lung ventilation. Combining both exogenous surfactant and open lung ventilation prevented bacterial translocation completely, comparable to Group B streptococci instillation into healthy animals. We conclude that exogenous surfactant and open lung ventilation attenuate bacterial growth and translocation in experimental pneumonia and that this attenuation is at least in part mediated by a reduction in atelectasis. These findings suggest that minimizing alveolar collapse by exogenous surfactant and open lung ventilation may reduce the risk of pneumonia and subsequent sepsis in ventilated patients.

In addition to its biophysical functions, surfactant plays an important role in pulmonary host defense. In this investigation we studied the influence of various commercially available surfactants on the phagocytosis of bacteria that are common pathogens in the neonatal period. Group B streptococci (GBS), Escherichia coli and Staphylococcus aureus were cultured with isolated human polymorphonuclear leucocytes (PMN) and non-specific serum in the presence or absence of different modified natural (Curosurf, Alveofact, Survanta) or totally synthetic, protein-free surfactant preparations (Exosurf, Pumactant). Prior to and after 30 and 60 min of incubation with PMN at different surfactant concentrations (1, 10 or 20 mg/ml), the number of viable bacteria was determined by colony counting. Killing of S. aureus by PMN was not influenced by any of the surfactants. Alveofact and Curosurf had no significant negative impact on phagocytosis. At 20 mg/ml, Curosurf even reduced the number of viable E. coli. Survanta at 10 and 20 mg/ml and Exosurf at all concentrations impaired the killing of non-encapsulated GBS and E. coli. Pumactant at 1-20 mg/ml interfered with the phagocytosis of E. coli. In further experiments we demonstrated that Curosurf did not interfere with the phagocytosis of an encapsulated GBS-strain opsonised by a specific antiserum either. In additional experiments we analysed the influence of the different surfactants on the release of reactive oxygen metabolite by PMN and found that the changes in nitroblue tetrazolium reduction did not necessarily correlate with the findings of the studies on killing. In conclusion, we found that killing by PMN was influenced by the bacterial species and the composition and concentration of the different surfactant preparations. The strongest impairment in phagocytic function of PMN was observed with the protein-free synthetic surfactant Exosurf, a phospholipid preparation that contains the alcohols hexadecanol and tyloxapol as spreading agents.

Injectable drugs are generally administered to newborns with 1 mL syringes. During in-vitro measurements of surface tension with a pulsating bubble surfactometer, we noticed that surfactant was inactivated after repeated aspiration into a 1 mL syringe with a rubber-coated plunger. Inactivation did not take place, however, when we used rubber-free two-part syringes with polyethylene pistons. Results of further studies showed that the silicone fluid used to lubricate the rubber surface of the syringe was inactivating the surfactant. Our findings suggest that contact with rubber surfaces should be avoided in the handling of surfactant material for biophysical assessment or clinical use.

Surfactant has been shown to influence a variety of immune functions. However, for in vitro studies most investigators used a single surfactant concentration often far below what has to be expected in bronchoalveolar fluid following surfactant replacement therapy. We studied the chemotactic activity and the oxygen metabolite release of human polymorphonuclear leukocytes (PMN) following incubation with Curosurf, a porcine modified natural surfactant preparation, at concentrations ranging from 1 to 16 mg/ml. In the presence of 1% bovine serum albumin, surfactant at 1 and 4 mg/ml enhanced anaphylatoxin C5a-related chemotaxis, whereas a higher dose of 16 mg/ml was inhibitory. Furthermore, Curosurf itself demonstrated a concentration-dependent chemotactic effect. Oxygen metabolite release, as measured by nitroblue tetrazolium reduction, was significantly diminished at surfactant concentrations of 8 and 16 mg/ml. This effect was most pronounced when group B streptococci at concentrations 5 x 10(9) CFU/ml were applied for PMN stimulation. We conclude that the effects of surfactant on PMN immune functions are not only concentration-dependent but also influenced by the degree of PMN stimulation.