Effects of different surfactant administrations on cerebral autoregulation in preterm infants with respiratory distress syndrome

Surfactant administration and cerebral oxygenation and perfusion in preterm neonates - A systematic review of literature

BACKGROUND

Surfactant replacement is standard for preterm neonates with respiratory distress syndrome, improving survival and outcomes. Less invasive surfactant administration (LISA) and intubation-surfactant-extubation (INSURE) are preferred methods for surfactant replacement in spontaneously breathing preterm neonates. Despite the undeniable benefits of surfactant implementation in neonatal care, surfactant administration can affect vital parameters and cerebral oxygenation and perfusion, assessed by near-infrared spectroscopy (NIRS).

OBJECTIVE

This review systematically examined the literature on surfactant administration in preterm neonates and its impact on NIRS-measured cerebral oxygenation.

METHODS

A systematic search of PubMed, Embase, CINAHL, Clinical Trials, and Ovid Medline was conducted using following terms: newborn, infant, neonate, preterm, premature, prematurity, surfactant, LISA, less-invasive surfactant administration, INSURE, near-infrared-spectroscopy, NIRS, oximetry, spectroscopy, cerebral oxygenation, cerebral tissue oxygen saturation (crSO2), crSO2, cerebral perfusion. Only studies in human preterm neonates were included.

RESULTS

Sixteen studies were identified that described cerebral oxygenation measured by NIRS in the context of surfactant administration demonstrating a decrease in crSO2 during surfactant administration, followed by a subsequent increase. Three studies specifically described the course of crSO2 in neonates while receiving LISA, whereby in two of these LISA was compared to INSURE describing differences in crSO2 behaviour. Two additional studies described surfactant administration using the INSURE procedure and the influence on cerebral oxygenation. Ten studies investigated surfactant administration in intubated neonates receiving mechanical ventilation. One study described crSO2 in neonates receiving aerosolised surfactant.

CONCLUSION

This systematic review indicates that surfactant administration is associated with a transient decrease in crSO2 followed by a return to baseline levels, whereby differences between the LISA and INSURE methods were observed.

Surfactant therapy - The conundrum of which infant should be given, when, which drug in what dose via which route of administration?

Surfactant therapy in preterm and term born infants has been a huge success story. In the meantime, we have very detailed answers to the five essential questions of each medical therapy: which infant should be treated, when, with which drug, in/at what dose, and via which route of administration. The answers to these questions depend on the gestational age of the infant. We have focused on preterm infants <28 weeks of gestation as they are the most vulnerable and may have the maximum benefit of appropriate treatment. Therefore, we performed a sub-group analysis for data available from the published trials in infants less than 28 weeks who received less/minimal invasive surfactant administration/therapy [LISA/MIST] versus intubation-surfactant-extubation (INSURE). The need for mechanical ventilation (MV) was significantly reduced by 28 % (RR:0.72, 95%CI:0.64-0.80, n = 548 infants) after LISA/MIST. The incidence of bronchopulmonary dysplasia (BPD) was significantly decreased by 30 % (RR:0.70, 95%CI:0.66-0.75, n = 6528 infants) after LISA/MIST. No difference in mortality was noted between the two groups. In the current review, we discuss the applicability of guidelines to individual patient groups like the infants <28 weeks and emphasize the individual assessment of published data by the treating physician.

Cerebral autoregulation in pediatric and neonatal intensive care: A scoping review

Deranged cerebral autoregulation (CA) is associated with worse outcome in adult brain injury. Strategies for monitoring CA and maintaining the brain at its 'best CA status' have been implemented, however, this approach has not yet developed for the paediatric population. This scoping review aims to find up-to-date evidence on CA assessment in children and neonates with a view to identify patient categories in which CA has been measured so far, CA monitoring methods and its relationship with clinical outcome if any. A literature search was conducted for studies published within 31st December 2022 in 3 bibliographic databases. Out of 494 papers screened, this review includes 135 studies. Our literature search reveals evidence for CA measurement in the paediatric population across different diagnostic categories and age groups. The techniques adopted, indices and thresholds used to assess and define CA are heterogeneous. We discuss the relevance of available evidence for CA assessment in the paediatric population. However, due to small number of studies and heterogeneity of methods used, there is no conclusive evidence to support universal adoption of CA monitoring, technique, and methodology. This calls for further work to understand the clinical impact of CA monitoring in paediatric and neonatal intensive care.

Do Different Amounts of Exogenous Surfactant Differently Influence Cerebrovascular Instability in a Consecutive Group of Preterm Babies? Preliminary Results from a Single-Center Experience

BACKGROUND

Thirty years ago, the first attempt by Saliba and colleagues was made to reduce the negative effects (hypercarbia) of exogenous surfactant (ES) by slowing its administration. Sixteen years later, we observed the first less invasive surfactant administration (LISA) attempt by Kribs and colleagues. Many studies, since that time, have tried to minimize the invasiveness of ES and subsequent cerebral blood flow perturbations through studies using near-infrared spectroscopy (NIRS). We sought to address this medical challenge by identifying a less problematic modality of ES administration by delivering multiple aliquots of ES instead of a single one, as typically performed. The aim of this study was to test the hypothesis that a different way of administering ES using more aliquots could be a safe alternative that should be assessed in further studies.

METHODS

Patients between 26 + 0 and 35 + 6 weeks of gestational age (GA) requiring ES administration were enrolled (April 2023-February 2024). Differently fractioned doses were delivered according to an arbitrary standard dosage (0.3 mL per aliquot in babies < 29 weeks; 0.6 mL in babies ≥ 29 weeks), while NIRS and transcutaneous CO2 (tCO2) monitoring were always performed. ES's effectiveness was assessed based on the reduction in the Oxygen Saturation Index (OSI) after administration. Persistent desaturation, bradycardia, and airway obstruction were defined as adverse effects and used to evaluate safety during ES administration, as well as variability in NIRS-rSO2 values and tCO2.

RESULTS

Twenty-four patients were enrolled with a median GA of 29 weeks (IQR 4.5) and BW of 1223 ± 560 g. In addition, 50% of the cohort received fewer than three aliquots, whereas the other 50% received more than three. Monitoring was started before the procedure and continued 30' after the last ES aliquot administration. The variability in NIRS-SpO2 values was significantly higher in the group (p = 0.007) with a lower number of aliquots administered. Similarly, increased NIRS-rSO2 values (p = 0.003) and increased tCO2 levels (p = 0.005) were observed in infants who underwent an ES split after the administration of a low number of aliquots.

CONCLUSIONS

Our data obtained from the group with > 3 fractionated doses of ES seem to justify the preparation of a more robust study, as the combination of reduced NIRS variability and reduced tCO2 maximum levels is consistent with more stable cerebral blood flow during the challenging time of ES administration.

Less invasive surfactant administration versus intubation-surfactant-extubation in the treatment of neonatal respiratory distress syndrome: a systematic review and meta-analyses

OBJECTIVES

To compare LISA with INSURE technique for surfactant administration in preterm with gestational age (GA) < 36 weeks with RDS in respect to the incidence of pneumothorax, bronchopulmonary dysplasia (BPD), need for mechanical ventilation (MV), regional cerebral oxygen saturation (rSO2), peri‑intraventricular hemorrhage (PIVH) and mortality.

METHODS

A systematic search in PubMed, Embase, Lilacs, CINAHL, SciELO databases, Brazilian Registry of Randomized Clinical Trials (ReBEC), Clinicaltrials.gov, and Cochrane Central Register of Controlled Trials (CENTRAL) was performed. RCTs evaluating the effects of the LISA technique versus INSURE in preterm infants with gestational age < 36 weeks and that had as outcomes evaluation of the rates of pneumothorax, BPD, need for MV, rSO2, PIVH, and mortality were included in the meta-analysis. Random effects and hazard ratio models were used to combine all study results. Inter-study heterogeneity was assessed using Cochrane Q statistics and Higgin's I2 statistics.

RESULTS

Sixteen RCTs published between 2012 and 2020 met the inclusion criteria, a total of 1,944 preterms. Eleven studies showed a shorter duration of MV and CPAP in the LISA group than in INSURE group. Two studies evaluated rSO2 and suggested that LISA and INSURE transiently affect brain autoregulation during surfactant administration. INSURE group had a higher risk for MV in the first 72 h of life, pneumothorax, PIVH and mortality in comparison to the LISA group.

CONCLUSION

This systematic review and meta-analyses provided evidence for the benefits of the LISA technique in the treatment of RDS, decreasing CPAP time, need for MV, BPD, pneumothorax, PIVH, and mortality when compared to INSURE.

Surfactant administration methods for premature newborns: LISA vs. INSURE comparative analysis

INTRODUCTION

Respiratory Distress Syndrome (RDS) is the most common respiratory disorder among premature infants. The use of surfactant has significantly reduced respiratory complications and mortality. There are two conventional methods for administering surfactant: Intubate-Surfactant-Extubate (INSURE) and Less Invasive Surfactant Administration (LISA). This study aims to compare the effects of surfactant administration using these two methods on the treatment outcomes of premature newborns.

MATERIALS AND METHODS

In this retrospective cohort study, we included 100 premature newborns with RDS and spontaneous breathing who were admitted to the Neonatal Intensive Care Unit of Besat Hospital in Sanandaj city in 2021. Exclusion criteria comprised congenital anomalies and the needing for intubation for resuscitation at birth. The outcomes of epmericaly trated with two methods were compared: the LISA (50 neonates) and the INSURE (50 neonates). Our interesting outcomes were needing for mechanical ventilation, duration of ventilation, pneumothorax, pulmonary hemorrhage, severe retinopathy, CPAP duration, and bronchopulmonary dysplasia. Finally, we entered the data into STATA-14 statistical software and analyzed it using chi-square and t-tests.

RESULTS

In this study, 69% of the neonates were boys. The LISA group exhibited significantly lower rates of need for mechanical ventilation (P = 0.003) and ventilation duration (P < 0.001) compared to the INSURE group. Conversely, there were no significant differences between the two groups (P > 0.05) in terms of pneumothorax, pulmonary hemorrhage, severe retinopathy, CPAP duration, and bronchopulmonary dysplasia rates.

CONCLUSION

The results of this study suggest that the LISA method is a safe and non-invasive approach for surfactant administration. Notably, it resulted in a reduced need for mechanical ventilation and decreased ventilation duration compared to the INSURE method.

Surfactant and neonatal hemodynamics during the postnatal transition

Surfactant replacement therapy (SRT) has revolutionized the management of respiratory distress syndrome (RDS) in premature infants, leading to improved survival rates and decreased morbidity. SRT may, however, be associated with hemodynamic changes, which can have both positive and negative effects on the immature cardiovascular system, during the transitional adaptation from fetal to extrauterine environment. However, there is a relative paucity of evidence in this domain, with most of them derived from small heterogeneous observational studies providing conflicting results. In this review, we will discuss the hemodynamic changes that occur with surfactant administration during this vulnerable period, focusing on available evidence regarding changes in pulmonary and systemic blood flow, cerebral circulation and their clinical implications.

Clinical decision thresholds for surfactant administration in preterm infants: a systematic review and network meta-analysis

Background

The ideal threshold at which surfactant administration in preterm neonates with respiratory distress syndrome (RDS) is most beneficial is contentious. The aim of this systematic review was to determine the optimal clinical criteria to guide surfactant administration in preterm neonates with RDS.

Methods

The systematic review was registered in PROSPERO (CRD42022309433). Medline, Embase, CENTRAL and CINAHL were searched from inception till 16th May 2023. Only randomized controlled trials (RCTs) were included. A Bayesian random effects network meta-analysis (NMA) evaluating 33 interventions was performed. The primary outcome was requirement of invasive mechanical ventilation (IMV) within 7 days of life.

Findings

58 RCTs were included. In preterm neonates ≤30 weeks after adjusting for the confounding factor of modality of surfactant administration, an arterial alveolar oxygen tension ratio (aAO2) <0.36 (FiO2: 37-55%) was ranked the best threshold for decreasing the risk of IMV, very low certainty. Further, surfactant administration at an FiO2 40-45% possibly decreased mortality compared to rescue treatment when respiratory failure was diagnosed, certainty very low. The reasonable inference that could be drawn from these findings is that surfactant administration may be considered in preterm neonates of ≤30 weeks' with RDS requiring an FiO2 ≥ 40%. There was insufficient evidence for the comparison of FiO2 thresholds: 30% vs. 40%. The evidence was sparse for surfactant administration guided by lung ultrasound. For the sub-group >30 weeks, nebulized surfactant administration at an FiO2 < 30% possibly increased the risk of IMV compared to Intubate-Surfactant-Extubate at FiO2 < 30% and 40%, and less invasive surfactant administration at FiO2 40%, certainty very low.

Interpretation

Surfactant administration may be considered in preterm neonates of ≤30 weeks' with RDS if the FiO2 requirement is ≥40%. Future trials are required comparing lower FiO2 thresholds of 30% vs. 40% and that guided by lung ultrasound.

Funding

None.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

Structural and haemodynamic evaluation of less invasive surfactant administration during nasal intermittent positive pressure ventilation in surfactant-deficient newborn piglets

The most recent approaches to the initial treatment of respiratory distress syndrome (RDS)- involve non-invasive ventilation (NIV) and less-invasive surfactant (SF) administration (LISA). Combining these techniques has been proven a useful treatment option for SF-deficient neonates. The objective of this study was to explore the impact on the brain (using cerebral near infrared spectroscopy, NIRS) of different LISA methods during NIV, using nasal intermittent positive pressure ventilation (NIPPV) for treating neonatal RDS. For this, we used five groups of spontaneously breathing newborn piglets (n = 6/group) with bronchoalveolar lavage (BAL)-induced respiratory distress which received NIPPV only (controls), poractant-alfa using the INSURE-like method (bolus delivery) followed by NIPPV, or poractant-alfa using one of three LISA devices, 1) a nasogastric tube (NT), 2) a vascular catheter (VC) or 3) the LISAcath® catheter. We assessed pulmonary, hemodynamic and cerebral effects, and performed histological analysis of lung and brain tissue. Following BALs, the piglets developed severe RDS (pH<7.2, PaCO2>70 mmHg, PaO2<70 mmHg, dynamic compliance<0.5 ml/cmH2O/kg at FiO2 = 1). Poractant-alfa administration using different LISA techniques during NIPPV was well tolerated and efficacious in newborn piglets. In our study, although all groups showed normal physiological ranges of total lung injury score and biochemical lung analysis, VC and LISAcath® catheters were associated with better values of lung compliance and lower values of lung damage than NIPPV, NT or INSURE-like methods. Moreover, neither of the SF administration methods used (LISA or INSURE-like) had a significant impact on the histological neonatal brain injury score. Of note, the LISAcath® has been recently withdrawn from the market.

Surfactant without Endotracheal Tube Intubation (SurE) versus Intubation-Surfactant-Extubation (InSurE) in Neonatal Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

Neonatal respiratory distress syndrome (NRDS) is generally treated with surfactant by intubation-surfactant-extubation (InSurE) technique, an invasive method of surfactant administration. Surfactant without endotracheal tube intubation (SurE) is a noninvasive technique that avoids intubation and has been found to have improved the delivery of exogenous surfactants, thereby decreasing lung damage in neonates. This systematic review aimed to provide insights into the efficacy of SurE over InSurE in neonates who received respiratory support and to evaluate the progression and onset of concurrent diseases after treatment. The CENTRAL, PubMed, and Embase databases were searched for data collection. In all, 21 research articles were eligible, comprising 19,976 study participants. The data showed a significant reduction in the composite outcome of stage 2 necrotizing enterocolitis, bronchopulmonary dysplasia, and onset of hemodynamically significant patent ductus arteriosus when treated with SurE. The trend towards lower pneumothorax rates with SurE was also evident. These findings were robust due to the sensitivity analyses performed. There were no differences in the outcome of death or rates of other neonatal morbidities. Overall, SurE was identified as a better substitute for InSurE to treat neonates with RDS.

Thin-catheter Surfactant Application for Respiratory Distress Syndrome in Spontaneously Breathing Preterm Infants: A Meta-analysis of Randomized Clinical Trials

BACKGROUND

Surfactant application by a thin catheter represented by the term less invasive surfactant administration (LISA) for respiratory distress syndrome in spontaneously breathing preterm infants was developed as an alternative to endotracheal intubation.

METHODS

We conducted a meta-analysis to assess the effects of LISA when compared to the socalled intubation-surfactant-extubation (INSURE) and the standard endotracheal intubation and mechanical ventilation (MV). The primary outcome was the composite incidence of death or bronchopulmonary dysplasia at a postmenstrual age of 36 weeks. The secondary outcome was the composite incidence of seven other severe adverse events. On 06 October 2021, we searched randomized clinical trials (RCTs) in PubMed, the Cochrane Library, ClinicalTrials.gov, and the ICTRP Registry.

RESULTS

We included 18 RCTs. The pooled data on the primary outcome favored LISA when compared to either INSURE (risk ratio 0.67; 95% CI, 0.51 to 0.88) or MV (risk ratio 0.78; 95% CI, 0.61 to 0.99). The pooled data on the second outcome also favored LISA when compared to INSURE (risk ratio 0.75; 95% CI, 0.60 to 0.94) and MV (risk ratio 0.73; 95% CI, 0.55 to 0.96).

CONCLUSION

The findings showed that surfactant application by non-intubation respiratory support and the use of a thin catheter may decrease the composite risk of death or bronchopulmonary dysplasia. The included data support the view that LISA should be considered the preferred treatment option in eligible infants.

Surfactant delivery via thin catheters: Methods, limitations, and outcomes

Various less invasive surfactant administration strategies like surfactant replacement therapy via thin catheters, laryngeal mask airway, pharyngeal instillation, and nebulized surfactant are increasingly being practiced to avoid the harmful effects of endotracheal intubation and ventilation. Numerous studies have been done to study surfactant replacement via thin catheters whereas little data is available for other methods. However, there are variations in premedication policies, type of respiratory support used in these studies. Surfactant delivery using thin catheters has been reported to be associated with decrease in the need for mechanical ventilation (MV), duration of MV, bronchopulmonary dysplasia and neonatal mortality. With the current evidence, among all the available surfactant delivery methods, the one using thin catheters appears to be the most feasible and beneficial to improve clinical neonatal outcomes.

Comparative efficacy of methods for surfactant administration: a network meta-analysis

OBJECTIVES

To compare surfactant administration via thin catheters, laryngeal mask, nebulisation, pharyngeal instillation, intubation and surfactant administration followed by immediate extubation (InSurE) and no surfactant administration.

DESIGN

Network meta-analysis.

SETTING

Medline, Scopus, CENTRAL, Web of Science, Google-scholar and Clinicaltrials.gov databases were systematically searched from inception to 15 February 2020.

PATIENTS

Preterm neonates with respiratory distress syndrome.

INTERVENTIONS

Less invasive surfactant administration.

MAIN OUTCOME MEASURES

The primary outcomes were mortality, mechanical ventilation and bronchopulmonary dysplasia.

RESULTS

Overall, 16 randomised controlled trials (RCTs) and 20 observational studies were included (N=13 234). For the InSurE group, the median risk of mortality, mechanical ventilation and bronchopulmonary dysplasia were 7.8%, 42.1% and 10%, respectively. Compared with InSurE, administration via thin catheter was associated with significantly lower rates of mortality (OR: 0.64, 95% CI: 0.54 to 0.76), mechanical ventilation (OR: 0.43, 95% CI: 0.29 to 0.63), bronchopulmonary dysplasia (OR: 0.57, 95% CI: 0.44 to 0.73), periventricular leukomalacia (OR: 0.66, 95% CI: 0.53 to 0.82) with moderate quality of evidence and necrotising enterocolitis (OR: 0.67, 95% CI: 0.41 to 0.9, low quality of evidence). No significant differences were observed by comparing InSurE with administration via laryngeal mask, nebulisation or pharyngeal instillation. In RCTs, thin catheter administration lowered the rates of mechanical ventilation (OR: 0.39, 95% CI: 0.26 to 0.60) but not the incidence of the remaining outcomes.

CONCLUSION

Among preterm infants, surfactant administration via thin catheters was associated with lower likelihood of mortality, need for mechanical ventilation and bronchopulmonary dysplasia compared with InSurE. Further research is needed to reach firm conclusions about the efficacy of alternative minimally invasive techniques of surfactant administration.

LISA/MIST: Complex clinical problems almost never have easy solutions

Over the last 10 years, new techniques to administer surfactant have been promoted, based on their presumed lesser invasiveness and they have been generally called LISA (less invasive surfactant administration). We believe that the clinical potential of LISA techniques is currently overestimated. LISA lacks biological and pathophysiological background justifying its potential benefits. Moreover, LISA has been investigated in clinical trials without previous translational data and these trials are affected by significant flaws. The available data from these trials only allow to conclude that LISA is better than prolonged, unrestricted invasive ventilation with loosely described parameters, a mode of respiratory support that should be anyway avoided in preterm infants. We urge the conduction of high-quality studies to understand how to choose and titrate analgesia/sedation and optimize surfactant administration in preterm neonates. We offer a comprehensive, evidence-based review of the clinical data on LISA, their biases and the lack of physiopathology background.

Systematic review found that using thin catheters to deliver surfactant to preterm neonates was associated with reduced bronchopulmonary dysplasia and mechanical ventilation

AIM

Surfactant delivery is a cornerstone for managing respiratory distress in preterm neonates, but data on the best surfactant delivery methods have been conflicting.

METHODS

A systematic literature review using the PubMed, Embase, Cochrane Library and Web of Science databases identified papers published up to November 5, 2019. Additional studies were identified from trial registries, conference proceedings and the reference lists of the selected papers.

RESULTS

We identified 15 studies covering 4926 preterm infants. The randomised controlled trials (RCTs) and observational studies both showed significant reductions in early intubation rates with use of thin catheters. The relative risk (RR) was 0.63 and the 95% confidence interval (95% CI) was 0.55-0.72 (P < .01), with an odds ratio (OR) of 0.40 and 95% CI of 0.35-0.45 (P < .0001). The collective results from the RCTs revealed a significant decrease in bronchopulmonary dysplasia (BPD) rates in the thin catheter group (RR, 0.47; 95% CI 0.33-0.66; P < .01). These findings were consistent with the observational studies (OR 0.47; 95% CI 0.43-0.52; P < .01).

CONCLUSION

Using thin catheters to deliver surfactant in comparison with intubate-surfactant-extubate (INSURE) to newborn preterm infants with respiratory distress was associated with a reduced incidence of BPD and less need for mechanical ventilation.

Cerebral Autoregulation in Sick Infants: Current Insights

Cerebrovascular autoregulation is the ability to maintain stable cerebral blood flow within a range of cerebral perfusion pressures. When cerebral perfusion pressure is outside the limits of effective autoregulation, the brain is subjected to hypoperfusion or hyperperfusion, which may cause vascular injury, hemorrhage, and/or hypoxic white matter injury. Infants born preterm, after fetal growth restriction, with congenital heart disease, or with hypoxic-ischemic encephalopathy are susceptible to a failure of cerebral autoregulation. Bedside assessment of cerebrovascular autoregulation would offer the opportunity to prevent brain injury. Clinicians need to know which patient populations and circumstances are associated with impaired/absent cerebral autoregulation.

Less invasive surfactant administration: a word of caution

Surfactant is a cornerstone of neonatal critical care, and the presumed less (or minimally) invasive techniques for its administration have been proposed to reduce invasiveness of neonatal critical care interventions. These techniques are generally known as less invasive surfactant administration (LISA) and have quickly gained popularity in some neonatal intensive care units. Despite the increase in the use of LISA, we believe that the pathobiological background supporting its possible clinical benefits is unclear. Similarly, it is unclear whether there are any ignored drawbacks, as LISA has been tested in only a few trials and some physiopathological issues seem to have gone unnoticed. Active research is warranted to fill these knowledge gaps before LISA can be firmly recommended. In this Viewpoint, we provide an in-depth analysis of LISA techniques, based on physiological and pathobiological factors, followed by a critical appraisal of available clinical data, and highlight some possible future research directions.

Less invasive surfactant administration in preterm infants with respiratory distress syndrome-an updated meta-analysis

BACKGROUND

Less invasive surfactant administration (LISA) seems to have a good application prospect both in experimental models and patients with respiratory distress syndrome (RDS). Data regarding the effect of LISA procedure on RDS are conflicting.

METHODS

A search was conducted by two investigators involved in this research in PubMed, Embase, and Cochrane databases for studies in English and in Wanfang, VIP, and Cnki databases for Chinese studies (all last launched on December 18, 2018). Odds ratio and weighted mean difference were calculated using a random-effects or fixed-effects model, depending on the data type and heterogeneity of the included studies.

RESULTS

The comparison of effectiveness on RDS: (1) with respect to mechanical ventilation (<72 hours) and mechanical ventilation (all time periods). Data showed significant differences between LISA/control groups. (2) With respect to days of mechanical ventilation, data showed no significant differences between LISA/control groups. (3) With respect to bronchopulmonary dysplasia, the analysis showed that there was significant difference between LISA group and control group. (4) Regarding days of supplementary oxygen therapy and hospital stay, no significant differences were found. The comparison of possible complications of RDS: (1) data for mortality, pneumothorax and pulmonary hemorrhage showed no differences in the two groups. (2) Data for retinopathy of preterm comparison showed significant difference between the two groups. (3) Regarding intraventricular hemorrhage/periventricular leukomalacia, significant differences were found between the two groups.

CONCLUSION

Based on the above evidences, LISA is an effective and safe treatment for preterm infants with RDS.

The effect of less invasive surfactant administration on cerebral oxygenation in preterm infants

AIM

To determine the regional cerebral tissue oxygenation saturation (rcSO₂ ) 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 rcSO₂ . During the first 120 hours of life, rcSO₂ values of CPAP were similar to those of infants in the LISA group, that is median rcSO₂ values 90% vs 85%, respectively (P = .126). Episodes with rcSO₂ 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 rcSO₂ values of infants in the LISA group were similar to the CPAP group.

Cerebral oxygenation associated with INSURE versus LISA procedures in surfactant-deficient newborn piglet RDS model

BACKGROUND

Nasal continuous-positive airway pressure (nCPAP) with the INSURE (INtubation-SURfactant-Extubation) or LISA (Less-Invasive Surfactant Administration) procedures are increasingly being chosen as the initial treatment for neonates with surfactant deficiency. Our objective was to compare the effects on cerebral oxygenation of different methods for surfactant administration: INSURE and LISA, using a nasogastric tube (NT) or a LISAcath® catheter, in spontaneously breathing SF-deficient newborn piglets.

METHODS

Eighteen newborn piglets with SF-deficient lung injury produced by repetitive bronchoalveolar lavages were randomly assigned to INSURE, LISA-NT, or LISAcath® groups. We assessed pulmonary (gas exchange, lung mechanics, lung histology) and hemodynamic (mean arterial blood pressure, heart rate) changes, cerebral oxygenation (cTOI) and cerebral fractional tissue extraction (cFTOE), with near-infrared spectroscopy, carotid blood flow and brain histology.

RESULTS

SF-deficient piglets developed respiratory distress (F_iO2  = 1, pH <7.2, P_aCO2 >70 mmHg, P_aO2 <70 mmHg, C_dyn <0.5 mL/cmH₂ O/kg). Rapid improvements in pulmonary status were observed in all surfactant-treated groups without hemodynamic alterations. In the INSURE group, a transient decrease in cTOI occurred during and immediately after surfactant administration, while cTOI only decreased during surfactant administration in the LISA-NT group and did not change significantly in the LISAcath® group. Brain injury scores were low in all surfactant-treated groups.

CONCLUSION

In spontaneously breathing SF-deficient newborn piglets, short-lasting decreases in cerebral oxygenation are associated with surfactant administration by the INSURE method or LISA using an NT, while no cerebral oxygenation changes occurred with LISA using a LISAcath®. Notably, none of treatments studied seems to have a negative impact on the neonatal brain.

The use of less invasive surfactant administration (LISA) in the United States with review of the literature

BACKGROUND

The majority of extremely low gestational age neonates undergo intubation for surfactant therapy. Less invasive surfactant administration (LISA) uses a thin catheter inserted into the trachea to deliver the surfactant. During the procedure, the infant is breathing spontaneously while supported with continuous positive airway pressure. Although LISA is widely adapted in Europe and Australia, the rate of LISA use in the United States is unknown.

STUDY DESIGN

The aim of this study is to evaluate the use of LISA in the US. A web-based survey was distributed via SurveyMonkey to 2550 neonatologists from AAP's SoNPM mailing list.

RESULTS

Of the 472 neonatologists who answered the survey, 15% used LISA either as a part of routine care (8%) or as part of research (7%).

CONCLUSION

Unlike several regions of Europe, LISA is not widely used in the US. Future studies should address ambiguities regarding infant selection, procedure training and "roadblocks" to its broader application.

Measuring Near-Infrared Spectroscopy Derived Cerebral Autoregulation in Neonates: From Research Tool Toward Bedside Multimodal Monitoring

Introduction: Cerebral autoregulation (CAR), the ability of the human body to maintain cerebral blood flow (CBF) in a wide range of perfusion pressures, can be calculated by describing the relation between arterial blood pressure (ABP) and cerebral oxygen saturation measured by near-infrared spectroscopy (NIRS). In literature, disturbed CAR is described in different patient groups, using multiple measurement techniques and mathematical models. Furthermore, it is unclear to what extent cerebral pathology and outcome can be explained by impaired CAR. Aim and methods: In order to summarize CAR studies using NIRS in neonates, a systematic review was performed in the PUBMED and EMBASE database. To provide a general overview of the clinical framework used to study CAR, the different preprocessing methods and mathematical models are described and explained. Furthermore, patient characteristics, definition of impaired CAR and the outcome according to this definition is described organized for the different patient groups. Results: Forty-six articles were included in this review. Four patient groups were established: preterm infants during the transitional period, neonates receiving specific medication/treatment, neonates with congenital heart disease and neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia. Correlation, coherence and transfer function (TF) gain are the mathematical models most frequently used to describe CAR. The definition of impaired CAR is depending on the mathematical model used. The incidence of intraventricular hemorrhage in preterm infants is the outcome variable most frequently correlated with impaired CAR. Hypotension, disease severity, dopamine treatment, injury on magnetic resonance imaging (MRI) and long term outcome are associated with impaired CAR. Prospective interventional studies are lacking in all research areas. Discussion and conclusion: NIRS derived CAR measurement is an important research tool to improve knowledge about central hemodynamic fluctuations during the transitional period, cerebral pharmacodynamics of frequently used medication (sedatives-inotropes) and cerebral effects of specific therapies in neonatology. Uniformity regarding measurement techniques and mathematical models is needed. Multimodal monitoring databases of neonatal intensive care patients of multiple centers, together with identical outcome parameters are needed to compare different techniques and make progress in this field. Real-time bedside monitoring of CAR, together with conventional monitoring, seems a promising technique to improve individual patient care.