Randomized controlled trial of lung lavage with dilute surfactant for meconium aspiration syndrome

Use of surfactant beyond respiratory distress syndrome, what is the evidence?

Surfactant replacement therapy is currently approved by the United States Food and Drug Administration (FDA) for premature infants with respiratory distress syndrome (RDS) caused by surfactant deficiency due to immaturity. There is strong evidence that surfactant decreases mortality and air leak syndromes in premature infants with RDS. However, surfactant is also used "off-label" for respiratory failure beyond classic RDS. This review discusses current evidence for the use of off-label surfactant therapy for (1) term infants with lung disease such as meconium aspiration syndrome (MAS), pneumonia/sepsis, and congenital diaphragmatic hernia (2) premature infants after 72 h for acute respiratory failure, and (3) the use of surfactant lavage. At last, we briefly describe the use of surfactants for drug delivery and the current evidence on evaluating infants for surfactant deficiency.

Neonatal surfactant therapy beyond respiratory distress syndrome

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.

Meconium aspiration syndrome: a comprehensive review

Meconium aspiration syndrome (MAS) is a complex respiratory disease that continues to be associated with significant morbidities and mortality. The pathophysiological mechanisms of MAS include airway obstruction, local and systemic inflammation, surfactant inactivation and persistent pulmonary hypertension of the newborn (PPHN). Supplemental oxygen and non-invasive respiratory support are the main therapies for many patients. The management of the patients requiring invasive mechanical ventilation could be challenging because of the combination of atelectasis and air trapping. While studies have explored various ventilatory modalities, evidence to date does not clearly support any singular modality as superior. Patient's pathophysiology, symptom severity, and clinician/unit expertise should guide the respiratory management. Early identification and concomitant management of PPHN is critically important as it contributes significantly to mortality and morbidities.

Efficacy of synthetic surfactant (CHF5633) bolus and/or lavage in meconium-induced lung injury in ventilated newborn rabbits

BACKGROUND

The pathogenesis of neonatal meconium aspiration syndrome (MAS) involves meconium-induced lung inflammation and surfactant inactivation. Bronchoalveolar lavage (BAL) with diluted surfactant facilitates the removal of meconium. CHF5633, one of the most promising synthetic surfactants, is effective in neonatal respiratory distress syndrome. Here we investigated its efficacy via BAL in an experimental MAS model.

METHODS

Experimental MAS was induced at birth in near-term newborn rabbits by intratracheal instillation of reconstituted human meconium. First, undiluted CHF5633 was compared with a porcine-derived surfactant (Poractant alfa) via intratracheal bolus (200 mg/kg). Second, the efficacy of BAL with diluted CHF5633 (5 mg/mL, 20 ml/kg) alone, or followed by undiluted boluses (100 or 300 mg/kg), was investigated.

RESULTS

Meconium instillation caused severe lung injury, reduced endogenous surfactant pool, and poor survival. CHF5633 had similar benefits in improving survival and alleviating lung injury as Poractant alfa. CHF5633 BAL plus higher boluses exerted better effects than BAL or bolus alone in lung injury alleviation by reversing phospholipid pools and mitigating proinflammatory cytokine mRNA expression, without fluid retention and function deterioration.

CONCLUSIONS

CHF5633 improved survival and alleviated meconium-induced lung injury, the same as Poractant alfa. CHF5633 BAL plus boluses was the optimal modality, which warrants further clinical investigation.

IMPACT

To explore the efficacy of a synthetic surfactant, CHF5633, in neonatal lung protection comparing with Poractant alfa in a near-term newborn rabbit model with meconium-induced lung injury. Similar effects on improving survival and alleviating lung injury were found between CHF5633 and Poractant alfa. Optimal therapeutic effects were identified from the diluted CHF5633 bronchoalveolar lavage followed by its undiluted bolus instillation compared to the lavage or bolus alone regimens. Animals with CHF5633 lavage plus bolus regimen exerted neither substantial lung fluid retention nor lung mechanics deterioration but a trend of higher pulmonary surfactant-associated phospholipid pools.

Ultrasound-guided lung lavage for life-threatening bronchial obstruction due to meconium plug

We present a case of life-threatening airway obstruction caused by meconium aspiration, a condition with significant neonatal mortality and morbidity. Lung ultrasound detected the obstruction and helped in the clinical management allowing to perform a quick and selective bronchoalveolar lavage with diluted surfactant.

European Resuscitation Council Guidelines 2021: Newborn resuscitation and support of transition of infants at birth

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

Neonatal Respiratory Distress Secondary to Meconium Aspiration Syndrome

Infants born through meconium-stained amniotic fluid (MSAF) are 100 times more likely than infants born through clear amniotic fluid to develop respiratory distress in the neonatal period. Meconium aspiration syndrome (MAS) is a common cause of respiratory distress in term and post-mature neonates. MAS is defined as respiratory distress accompanied by a supplemental oxygen requirement in an infant born with MSAF, in the absence of any other identified etiology to explain the symptoms. Therapy for MAS is supportive, and should be tailored to each infant’s specific pathophysiology. In cases of MAS with severe persistent pulmonary hypertension of the newborn (PPHN), patients may remain hypoxic despite aggressive ventilation, and in these cases surfactant, inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO) can be life-saving. Long-term prognosis for MAS is more related to severity of initial hypoxemia and possible neurological insult than to the pulmonary pathology.

Surfactant therapies for pediatric and neonatal ARDS: ESPNIC expert consensus opinion for future research steps

Pediatric (PARDS) and neonatal (NARDS) acute respiratory distress syndrome have different age-specific characteristics and definitions. Trials on surfactant for ARDS in children and neonates have been performed well before the PARDS and NARDS definitions and yielded conflicting results. This is mainly due to heterogeneity in study design reflecting historic lack of pathobiology knowledge. We reviewed the available clinical and preclinical data to create an expert consensus aiming to inform future research steps and advance the knowledge in this area. Eight trials investigated the use of surfactant for ARDS in children and ten in neonates, respectively. There were improvements in oxygenation (7/8 trials in children, 7/10 in neonates) and mortality (3/8 trials in children, 1/10 in neonates) improved. Trials were heterogeneous for patients' characteristics, surfactant type and administration strategy. Key pathobiological concepts were missed in study design. Consensus with strong agreement was reached on four statements: 1. There are sufficient preclinical and clinical data to support targeted research on surfactant therapies for PARDS and NARDS. Studies should be performed according to the currently available definitions and considering recent pathobiology knowledge. 2. PARDS and NARDS should be considered as syndromes and should be pre-clinically studied according to key characteristics, such as direct or indirect (primary or secondary) nature, clinical severity, infectious or non-infectious origin or patients' age. 3. Explanatory should be preferred over pragmatic design for future trials on PARDS and NARDS. 4. Different clinical outcomes need to be chosen for PARDS and NARDS, according to the trial phase and design, trigger type, severity class and/or surfactant treatment policy. We advocate for further well-designed preclinical and clinical studies to investigate the use of surfactant for PARDS and NARDS following these principles.

Early use of combined exogenous surfactant and inhaled nitric oxide reduces treatment failure in persistent pulmonary hypertension of the newborn: a randomized controlled trial

OBJECTIVE

To evaluate whether combined surfactant with inhaled nitric oxide (iNO) use will prevent newborns with hypoxemic respiratory failure (HRF) from developing an Oxygenation Index (OI) > 40.

METHODS

100 term newborns with acute HRF (OI ≥ 20) were randomized to: Surfactant+iNO: received iNO plus up to two doses of surfactant or iNO-Controls: received iNO+placebo. Main outcome was the development of severe HRF (OI > 40) despite iNO use.

RESULTS

Baseline mean ± SD OI was 37.4 ± 14 for the Surfactant+iNO group and 38.2 ± 16 for the controls. Infants receiving surfactant+iNO improved their oxygenation faster, resulting in lower OI at 24 h: 12.9 ± 9 vs 18.7 ± 11 of controls, p < 0.05; and a lower proportion developing OI > 40: 24%(12/50) vs 50%(25/50) of controls, p < 0.02. Fewer infants receiving surfactant+iNO presented the combined outcome of death or ECMO: 16%(8/50) compared to 36%(18/50) of controls, p < 0.05.

CONCLUSIONS

Early use of combined surfactant+iNO improves oxygenation preventing the progression to severe HRF. This may reduce mortality and ECMO need.

TRIAL REGISTRATION NUMBER

ISRCTN13727958.

[Newborn resuscitation and support of transition of infants at birth]

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

Pathophysiological effects of intravenous phosphodiesterase type 4 inhibitor in addition to surfactant lavage in meconium-injured newborn piglet lungs

BACKGROUND

Nonsteroidal anti-inflammatory drugs, such as selective phosphodiesterase type 4 (PDE4) inhibitors have potential anti-inflammatory and respiratory smooth muscle relaxation effects. This study aimed to investigate the pathophysiological effects of an intravenous PDE4 inhibitor (rolipram) and surfactant lavage (SL) in a newborn piglet model of meconium aspiration syndrome (MAS).

METHODS

MAS was induced in 25 newborn piglets, which were randomly divided into control and four SL treatment groups administered with different doses of intravenous rolipram (0, 0.1, 0.5, and 1 mg/kg). Cardiopulmonary variables were monitored and recorded. The experimental time was 4 hours. Serial blood was drawn for blood gas and biomarker analyses. Lung tissue was examined for histological analysis.

RESULTS

All SL-treated groups revealed improved oxygenation during the 4-hour experiments and had significantly lower peak inspiratory pressure levels than the control group at the end of experiments. All SL plus rolipram-treated groups exhibited significantly higher lung compliance than the control group. However, the animals receiving high-dose (0.5 and 1.0 mg/kg) rolipram demonstrated significantly elevated heart rates. Lung histology of the nondependent sites revealed significantly lower lung injury scores in all SL-treated groups compared with that in the control group, but there were no differences among the rolipram-treated groups.

CONCLUSIONS

In addition to SL, intravenous PDE4 inhibitors may further improve lung compliance in treating MAS; however, it is necessary to consider cardiovascular adverse effects, primarily tachycardia. Further investigations are required before the clinical application of intravenous PDE4 inhibitor as an anti-inflammatory agent to treat severe MAS.

Surfactant lavage for neonatal meconium aspiration syndrome-An updated meta-analysis

BACKGROUND

Surfactant lavage seems to have a good application prospect both in experimental models and patients with meconium aspiration syndrome (MAS). Data regarding the effect of surfactant lavage on pulmonary complications of MAS are conflicting. In view of these uncertainties, an updated meta-analysis including the latest literatures is performed.

METHODS

A search was conducted by two investigators involved in this research in PubMed, Embase, and Cochrane databases for studies in English and other languages, in Wanfang, VIP, and Cnki databases for Chinese studies (all last launched on December 18, 2018). Ultimately, we identified 11 original studies, including the surfactant lavage group (n = 189) and the control group (n = 204). 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 MAS: (1) With respect to oxygen index at 48 hours stage and 72 hours stage, data showed significant difference between surfactant lavage/control groups (we/ighted mean difference [WMD] = -3.37, 95% confidence interval [CI], -5.68 ~ -1.06; p = 0.004 and 95% CI, -5.03 ~ -2.37; p < 0.00001). (2) With respect to days on mechanical ventilation, the analysis showed that there was significant difference between surfactant lavage group and control group (WMD = -1.12, 95% CI, -1.40 ~ -0.84; p < 0.00001). (3) Regarding the need for extracorporeal membrane oxygenation, days of oxygen therapy, and hospital stay, no significant differences were found. The comparison of possible complications of MAS: (1) Regarding pneumothorax, the analysis showed there was significant difference between surfactant lavage and control groups (odds ratio [OR] = 0.46, 95% CI, 0.24 ~ 0.85; p = 0.01). (2) With respect to mortality, persist pulmonary hypertension and pulmonary hemorrhage, the results showed no difference between the two groups.

CONCLUSION

With respect to oxygen index and days on mechanical ventilation, surfactant lavage is significantly effective compared with control group, though didn't eventually shorten days of oxygen therapy and hospital stay. In addition, our meta-analysis showed that surfactant lavage does not increase the risk of complications.

Surfactant therapy for meconium aspiration syndrome in neonates: a systematic overview of systematic reviews and recent clinical trials

Aim: To conduct a systematic overview of systematic reviews (SRs) and randomized clinical trials (RCTs) on surfactant therapy in neonatal meconium aspiration syndrome. Methods: We searched EMBASE, PROQUEST and PubMed to summarize the different effects of surfactant lung lavage and bolus surfactant therapies in neonates with meconium aspiration syndrome. Results: With a total of 1377 patients, three SRs and two RCTs were included in analysis. Surfactant effectiveness was concluded by low-quality SRs, with high risk of bias, which was contradicted by high-quality SRs, with low risk of bias. In SRs, the surfactant lung lavage reduced mortality, need for extracorporeal membrane oxygenation and hospitalization, while the bolus surfactant did not. In recent high-quality RCTs, however, the two modalities did not significantly differ. Conclusion: The evidence on surfactant effectiveness and its method of administration is sparse and inconsistent.

Lung Lavage with Dilute Surfactant vs. Bolus Surfactant for Meconium Aspiration Syndrome

OBJECTIVE

To compare the effectiveness of lung lavage with surfactant vs. bolus surfactant treatment in meconium aspiration syndrome (MAS).

PATIENTS AND METHODS

This randomized controlled trial included newborns ventilated with MAS. In lavage group (n = 17) 30 ml/kg of diluted porcine surfactant was instilled into the lung. In bolus group (n = 16) porcine surfactant (100 mg/kg) was administered as bolus. Respiratory outcomes and mortality were compared between groups.

RESULTS

Duration of respiratory support was found to be similar between lavage and bolus groups (3 vs. 3.5 days, p = 0.36). Death or requirement for extracorporeal membrane oxygenation (ECMO) was 12% vs. 6%; respectively (RR: 2, 95% CI 0.16-24.48; p = 1.0). Duration of oxygen therapy, high-frequency ventilation or inhaled nitric oxide requirement did not differ among the groups.

CONCLUSION

Lung lavage did not show any advantage over bolus therapy on duration of respiratory support. The incidence of pneumothorax and surfactant re-administration decreased nonsignificantly in lavage group.

CLINICAL TRIAL REGISTRATION

We registered the trial to ClinicalTrials.gov (http://clinicaltrials.gov) under identifier NCT02041546.

REGISTRY NAME

Lung Lavage With Dilute Poractant Alfa for Meconium Aspiration Syndrome.

Surfactant Lung Lavage vs. Standard Care in the Treatment of Meconium Aspiration Syndrome-A Randomized Trial

OBJECTIVE

The objective of this study was to evaluate the effect of surfactant lung lavage (SLL) on duration of respiratory support in neonates with meconium aspiration syndrome (MAS).

PATIENTS AND METHODS

Sixty term infants with MAS who had moderate to severe respiratory distress (Downes score >4) were randomized toSLL (n = 31) or no lung lavage-NLL (n = 29). Neonates in intervention group underwent lung lavage with dilute surfactant and those in control group were managed as per unit protocol.

RESULTS

The median duration of respiratory support was 34 h in SLL group and 44 h in NLL group (p value = 0.994). The duration of oxygen therapy post-respiratory support decreased by 78% in SLL as compared with NLL group (4 vs. 18 h) (p value = 0.005). Lavage procedure was well tolerated with fall in mean heart rate by just 20/min and in mean saturation drop by just 6% during the procedure.

CONCLUSION

Lung lavage is well tolerated by neonates, but it does not alter overall duration of respiratory support.

Controlled hypothermia may improve surfactant function in asphyxiated neonates with or without meconium aspiration syndrome

Background

Whole-body hypothermia (WBH) is used to improve neurological outcomes in perinatal asphyxia. Recent studies suggested a beneficial effect of hypothermia for some types of acute respiratory failure. However, no data are available about the biophysical function of human surfactant during WBH. We investigated whether WBH improves surfactant biophysical properties in asphyxiated neonates with or without meconium aspiration syndrome (MAS).

Methods

Non-bronchoscopic bronchoalveolar lavage (BAL) has been collected from 10 asphyxiated neonates (2 with MAS, 8 with no lung disease (NLD)) at different time-points (pre-WBH, 24h, 48h, 72h of WBH and post-WBH). Surfactant was extracted and tested by captive bubble surfactometry (CBS) in triplicate, at 37°C and 33.5°C, through initial adsorption and dynamic compression-expansion cycling. Phosphatidylcholine and cholesterol were assayed using enzymatic methods. Clinical data were recorded in real-time.

Results

Minimum surface tension under dynamic testing was significantly improved as assessed at 33.5°C compared with its behavior at 37°C in NLD neonates: the difference was evident after at least 72h of WBH and remained significant at 6h after rewarming (72h: p = 0.009; rewarming: p = 0.040). Similar results were obtained in MAS patients whose surfactant activity improved already at 48h of hypothermia. Total cholesterol showed a trend to increase at the first 24-48h of hypothermia in NLD patients. Conversely, hypothermia seemed to reduce the excess of exogenous cholesterol in MAS surfactant.

Conclusions

Surfactant biophysical properties may improve after 48-72h of WBH in asphyxiated neonates and the improvement is maintained shortly after rewarming. Due to study limitations, further studies are warranted to better clarify the effects of hypothermia on surfactant activity.

Surfactant Replacement Therapy Beyond Respiratory Distress Syndrome in Neonates

BACKGROUND

Surfactant replacement therapy is an established modality of treatment in preterm neonates with respiratory distress syndrome. In addition, there are various neonatal respiratory disorders which are characterized by surfactant deficiency in which surfactant therapy can be a feasible and safe option.

OBJECTIVE

To collate the literature on the use of surfactant replacement therapy in neonates beyond respiratory distress syndrome and examine the evidence and newer developments.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, and EMBASE up to June 2015; and previous reviews, including cross-references, abstracts, and conference proceedings.

RESULTS

Evidence supports surfactant administration via bolus route in neonates with meconium aspiration syndrome, but additional robust evidence is required before its adoption in clinical practice. There is limited evidence to support surfactant therapy in neonates with pneumonia, pulmonary hemorrhage and bronchopulmonary dysplasia. Large multicenter randomized trials are needed to cement or refute the role of surfactant therapy in these disorders.

Current Concepts in the Management of Meconium Aspiration Syndrome

In developing countries, meconium aspiration syndrome (MAS) is an important cause of morbidity and mortality among neonates. The concepts of pathophysiology and management of meconium stained amniotic fluid (MSAF) and meconium aspiration syndrome have undergone tremendous change in recent years. Routine intranatal and postnatal endotracheal suctioning of meconium in vigorous infants is no longer recommended. Recent studies have challenged its role even in non-vigorous infants. Supportive therapy like oxygen supplementation, mechanical ventilation and intravenous fluids are the cornerstone in the management of meconium aspiration syndrome. Availability of surfactant, inhaled nitric oxide, high frequency ventilators and extracorporeal membrane oxygenation has made it possible to salvage more infants with meconium aspiration syndrome. In this review the authors have discussed the current concepts in the pathophysiology and management of MAS. Drugs in trials and future therapeutic targets are also discussed briefly.

Surfactant with and without bronchoalveolar lavage in an experimental model of meconium aspiration syndrome

OBJECTIVES

To assess the effect of surfactant administration, preceded or not by bronchoalveolar lavage (BAL) with dilute surfactant, on pulmonary function in experimental severe meconium aspiration syndrome.

METHODS

Twenty-one newborn pigs received 20% meconium in saline intratracheally and were randomly allocated to one of three groups: I, control; II, surfactant only (poractant alfa, 200 mg/kg); or III, dilute surfactant BAL followed by 125 mg/kg surfactant. Arterial blood gases (ABGs), lung compliance, and resistance were assessed.

RESULTS

Thirty minutes after treatment, mean PaO2 (mm Hg) increased to 72 in group I, to 106 in group II and to 172 in group III (P=0.01). After 3 h, mean PaO2 (mm Hg) was 70 in group I, 95 in group II and 198 in group III (P<0.01). After 6 h, it was 79 in group I, 110 in group II, and 217 in group III (P=0.01). From the 30-min point onward, there were significant differences among treatment groups in all other parameters and at every point of assessment, except for compliance and resistance 3 h after treatment.

CONCLUSIONS

BAL with dilute surfactant, followed by an additional dose of surfactant, produced significant improvements in ABGs and pulmonary mechanics as compared with a single dose of surfactant.

Effects of Surfactant Lavage Combined With Intratracheal Budesonide Instillation on Meconium-Injured Piglet Lungs

OBJECTIVES

To evaluate the combined effects of surfactant lavage and intratracheally instillation of budesonide on meconium-injured piglet lungs.

DESIGN

A prospective, randomized, animal model study.

SETTING

An experimental laboratory.

SUBJECTS

Twenty-four anesthetized and mechanically ventilated newborn piglets.

INTERVENTIONS

Human meconium slurry was intratracheally instilled into piglet lungs to induce lung injury. The injured piglets were randomly assigned to either the sham treatment group (control) or one of the three therapeutic groups: the intratracheally instilled budesonide (Bud) group, the bronchoalveolar lavage with diluted surfactant (dsBAL) group, and the combination therapy of Bud and dsBAL (dsBAL + Bud) group.

MEASUREMENTS AND MAIN RESULTS

Cardiopulmonary profiles were measured hourly. Proinflammatory cytokine (interleukin-1β, interleukin-6, and interleukin-8) levels in bronchoalveolar lavage fluid were measured. Finally, the pulmonary histology of the experimental subjects was examined at the end of experiments. Both of the lavaged groups (dsBAL and dsBAL + Bud) showed significantly better oxygenation than those that had not undergone lavage (control and Bud) (p < 0.05). The dsBAL + Bud group showed a significantly higher lung compliance and required a significantly lower peak inspiratory pressure during the experimental periods than the other three groups (p < 0.05). All treatment groups had significantly lower concentrations of interleukin-1β concentration in the bronchoalveolar lavage fluid than the control group (p < 0.05). The dsBAL + Bud group also had a significantly lower interleukin-6 concentration in the bronchoalveolar lavage fluid (p< 0.05), as well as a significantly lower lung injury score based on pulmonary histology than the control group (p < 0.05).

CONCLUSIONS

Therapeutic bronchoalveolar lavage with diluted surfactant followed by intratracheal instillation of budesonide has a synergistic and beneficial effect when treating severe meconium-injured newborn piglet lungs.

Surfactant therapy and antibiotics in neonates with meconium aspiration syndrome: a systematic review and meta-analysis

Meconium aspiration syndrome (MAS), a common cause of respiratory failure in neonates, is associated with high mortality and morbidity. The objectives of this review were to evaluate the effects of administration of (a) surfactant-either as lung lavage (SLL) or bolus surfactant (BS) and (b) antibiotics on mortality and severe morbidities in neonates with MAS. We searched the following databases: MEDLINE via PubMed, Cochrane CENTRAL, WHOLIS and CABI using sensitive search strategies. We included eight studies on use of surfactant and three studies on use of antibiotics. Neither SLL nor BS reduced the risk of mortality in neonates with MAS (relative risk (RR) 0.38, 95% confidence interval (CI) 0.09 to 1.57; and RR 0.80, 95% CI 0.39 to 1.66, respectively). Both SLL and BS reduced the duration of hospital stay (mean difference -2.0, 95% CI -3.66 to -0.34; and RR -4.68, 95% CI -7.11 to -2.24 days, respectively) and duration of mechanical ventilation (mean difference -1.31, 95% CI -1.91 to -0.72; and mean difference 5.4, 95% CI -9.76 to -1.03 days). Neonates who received BS needed extracorporeal membrane oxygenation (ECMO) less often than the controls (RR 0.64, 95% CI 0.46 to 0.91). Use of antibiotics for MAS did not result in significant reduction in the risk of mortality, sepsis or duration of hospital stay. Surfactant administration either as SLL or BS for MAS was found to reduce the duration of mechanical ventilation and hospital stay; BS also reduced the need for ECMO. Administration of antibiotics did not show any significant clinical benefits in neonates with MAS and no evidence of sepsis. Given the limited number of studies and small number of neonates enrolled, there is an urgent need to generate more evidence on the efficacy and cost-effectiveness of these two treatment modalities before recommending them in routine clinical practice.

Effect of gastric lavage on feeding in neonates born through meconium-stained liquor: a systematic review

OBJECTIVE

To evaluate the efficacy and safety of gastric lavage (GL) in neonates born through meconium-stained liquor (MSL).

DESIGN

A systematic review of randomised controlled trials by searching databases MEDLINE (from 1966), EMBASE (from1980), CINAHL, Cochrane Central Register of Controlled Trials, Google Scholar and proceedings of Pediatric Academic Society meetings (2002-2014).

SETTING

Delivery room/Neonatal ward.

PATIENTS

Neonates with gestation >34 weeks and birth weight ≥1800 g born through MSL.

INTERVENTIONS

Prophylactic GL versus no intervention before first feed.

MAIN OUTCOME MEASURE

Feeding intolerance, defined as inability to initiate/upgrade feeds due to problems such as retching, vomiting, regurgitation and gastric residuals.

RESULTS

A total of six studies (GL: 918, no GL: 966) were included in the review. Meta-analysis using fixed-effects model showed decreased incidence of feed intolerance following GL ((81/918 (8.8%) vs 114/966 (11.8%); risk ratio (RR): 0.71 (95% CI 0.55 to 0.93)). However, the results were not significant when random-effects model was used (RR: 0.78 (95% CI 0.55 to 1.09)). No significant adverse effects of GL were reported.

CONCLUSIONS

Routine GL immediately after birth may improve feed tolerance in neonates born through MSL. However, the evidence is limited, with probable small-study bias and high risk of bias in a number of the included studies. Well-designed studies with adequate sample size are essential to confirm these findings.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

Surfactant for meconium aspiration syndrome in term and late preterm infants

BACKGROUND

Surfactant replacement therapy has been proven beneficial in the prevention and treatment of neonatal respiratory distress syndrome (RDS). The deficiency of surfactant or surfactant dysfunction may contribute to respiratory failure in a broader group of disorders, including meconium aspiration syndrome (MAS).

OBJECTIVES

To evaluate the effect of surfactant administration in the treatment of late preterm and term infants with meconium aspiration syndrome.

SEARCH METHODS

We searched The Cochrane Library (Issue 4, 2006), MEDLINE and EMBASE (1985 to December 2006), previous reviews including cross-references, abstracts, conference and symposia proceedings, expert informants, and journal handsearching, without language restrictions. We contacted study authors for additional data.We ran an updated search in November 2014 and searched the following sites for ongoing or recently completed trials: www.clinicaltrials.gov; www.controlled-trials.com; and www.who.int/ictrp.

SELECTION CRITERIA

Randomised controlled trials which evaluated the effect of surfactant administration in late preterm and term infants with meconium aspiration syndrome are included in the analyses.

DATA COLLECTION AND ANALYSIS

We extracted data on clinical outcomes including mortality, treatment with extracorporeal membrane oxygenation (ECMO), pneumothorax, duration of assisted ventilation, duration of supplemental oxygen, intraventricular haemorrhage (any grade and severe IVH), and chronic lung disease. We conducted data analyses in accordance with the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Four randomised controlled trials met our inclusion criteria. The meta-analysis of four trials (326 infants) showed no statistically significant effect on mortality [typical risk ratio (RR) 0.98, 95% confidence interval (CI) 0.41 to 2.39; typical risk difference (RD) -0.00, 95% CI -0.05 to 0.05]. There was no heterogeneity for this outcome (I² = 0% for both RR and RD). The risk of requiring extracorporeal membrane oxygenation was significantly reduced in a meta-analysis of two trials (n = 208); [typical RR 0.64, 95% CI 0.46 to 0.91; typical RD -0.17, 95% CI -0.30 to -0.04; number needed to treat for an additional beneficial outcome (NNTB) 6, 95% CI 3 to 25]. There was no heterogeneity for RR (1² = 0%) but moderate heterogeneity for RD (I² = 50%). One trial (n = 40) reported a statistically significant reduction in the length of hospital stay (mean difference -8 days, 95% CI -14 to -3 days; test for heterogeneity not applicable). There were no statistically significant reductions in any other outcomes studied (duration of assisted ventilation, duration of supplemental oxygen, pneumothorax, pulmonary interstitial emphysema, air leaks, chronic lung disease, need for oxygen at discharge or intraventricular haemorrhage).

AUTHORS' CONCLUSIONS

In infants with MAS, surfactant administration may reduce the severity of respiratory illness and decrease the number of infants with progressive respiratory failure requiring support with ECMO. The relative efficacy of surfactant therapy compared to, or in conjunction with, other approaches to treatment including inhaled nitric oxide, liquid ventilation, surfactant lavage and high frequency ventilation remains to be tested.

Effects of Natural versus Synthetic Surfactant with SP-B and SP-C Analogs in a Porcine Model of Meconium Aspiration Syndrome

BACKGROUND

Meconium displaces surfactant from the alveolar surface and inhibits its function. The development of active synthetic surfactants is complicated, especially to synthesize the hydrophobic surfactant proteins SP-B and SP-C. A synthetic surfactant, CHF5633 containing SP-B and SP-C analogs, has been designed to act similarly to the natural surfactant poractant alfa.

OBJECTIVE

To test the resistance to meconium inactivation of CHF5633 compared to poractant alfa. Secondary outcome measurements were respiratory and inflammatory parameters.

METHODS

Twenty-six newborn pigs, bodyweight 1.4-2.0 kg were randomized to receive either poractant alfa or CHF5633. After anesthesia, surgery and final stabilization, meconium was instilled endotracheally followed by surfactant. Bronchial lavage fluid was obtained before intervention and every second hour. Respiratory parameters were registered and blood samples drawn before intervention and every hour.

RESULTS

Surfactant was inactivated in both groups 6 h after meconium instillation, but CHF5633 was more resistant than poractant alfa in terms of lipid peroxidation. Respiratory parameters were similar in both groups. Inflammatory and hemostatic parameters differed between groups, suggesting that the surfactants may play different roles in the meconium-induced inflammatory process. Due to the differential effects and complex pattern observed, the data do not indicate that one of the surfactants was superior with respect to inflammatory and hemostatic responses.

CONCLUSION

This study indicates that CHF5633 is as efficient as poractant alfa in experimental meconium aspiration syndrome.

Exogenous surfactant therapy in 2013: what is next? Who, when and how should we treat newborn infants in the future?

Background

Surfactant therapy is one of the few treatments that have dramatically changed clinical practice in neonatology. In addition to respiratory distress syndrome (RDS), surfactant deficiency is observed in many other clinical situations in term and preterm infants, raising several questions regarding the use of surfactant therapy.

Objectives

This review focuses on several points of interest, including some controversial or confusing topics being faced by clinicians together with emerging or innovative concepts and techniques, according to the state of the art and the published literature as of 2013. Surfactant therapy has primarily focused on RDS in the preterm newborn. However, whether this treatment would be of benefit to a more heterogeneous population of infants with lung diseases other than RDS needs to be determined. Early trials have highlighted the benefits of prophylactic surfactant administration to newborns judged to be at risk of developing RDS. In preterm newborns that have undergone prenatal lung maturation with steroids and early treatment with continuous positive airway pressure (CPAP), the criteria for surfactant administration, including the optimal time and the severity of RDS, are still under discussion. Tracheal intubation is no longer systematically done for surfactant administration to newborns. Alternative modes of surfactant administration, including minimally-invasive and aerosolized delivery, could thus allow this treatment to be used in cases of RDS in unstable preterm newborns, in whom the tracheal intubation procedure still poses an ethical and medical challenge.

Conclusion

The optimization of the uses and methods of surfactant administration will be one of the most important challenges in neonatal intensive care in the years to come.

Lung lavage for meconium aspiration syndrome in newborn infants

BACKGROUND

Meconium aspiration syndrome (MAS) can occur when a newborn infant inhales a mixture of meconium and amniotic fluid into the lungs around the time of delivery. Other than supportive measures, little effective therapy is available. Lung lavage may be a potentially effective treatment for MAS by virtue of removing meconium from the airspaces and altering the natural course of the disease.

OBJECTIVES

To evaluate the effects of lung lavage on morbidity and mortality in newborn infants with MAS.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, and EMBASE up to December 2012; previous reviews including cross-references, abstracts, and conference proceedings; and expert informants. We contacted authors directly to obtain additional data. We used the following subject headings and text words: meconium aspiration, pulmonary surfactants, fluorocarbons, bronchoalveolar lavage, lung lavage, pulmonary lavage.

SELECTION CRITERIA

Randomised controlled trials that evaluated the effects of lung lavage in infants with MAS, including those intubated for the purpose of lavage. Lung lavage was defined as any intervention in which fluid is instilled into the lung that is followed by an attempt to remove it by suctioning and/or postural drainage.

DATA COLLECTION AND ANALYSIS

The review authors extracted from the reports of the clinical trial, data regarding clinical outcomes, including mortality, requirement for extracorporeal membrane oxygenation (ECMO), pneumothorax, duration of mechanical ventilation and oxygen therapy, length of hospital stay, indices of pulmonary function, and adverse effects of lavage. Data analysis was done in accordance with the standards of the Cochrane Neonatal Review Group.

MAIN RESULTS

Only four small randomised controlled trials fulfilled the selection criteria. For one of these trials, no data are available for the control group. Two studies compared lavage using diluted surfactant with standard care. Meta-analysis of these two studies did not show a significant effect on mortality (typical relative risk 0.42, 95% confidence interval [CI] 0.12 to 1.46; typical risk difference -0.10, 95% CI -0.24 to 0.04) or the use of ECMO (typical relative risk 0.27, 95% CI 0.04 to 1.86; typical risk difference -0.15, 95% CI -0.35 to 0.04). For the composite outcome of death or use of ECMO, a significant effect favoured the lavage group (typical relative risk 0.33, 95% CI 0.11 to 0.96; typical risk difference -0.19, 95% CI -0.34 to -0.03; number needed to benefit [NNTB] 5). No other benefits were reported. The other published study compared surfactant lavage followed by a surfactant bolus with surfactant bolus therapy alone in MAS complicated by pulmonary hypertension. No significant improvements in mortality, pneumothorax, duration of mechanical ventilation. or duration of hospitalisation were observed.

AUTHORS' CONCLUSIONS

In infants with meconium aspiration syndrome, lung lavage with diluted surfactant may be beneficial, but additional controlled clinical trials of lavage therapy should be conducted to confirm the treatment effect, to refine the method of lavage treatment, and to compare lavage treatment with other approaches, including surfactant bolus therapy. Long-term outcomes should be evaluated in further clinical trials.

Fluid recovery during lung lavage in meconium aspiration syndrome

Lung lavage using two aliquots of 15 mL/kg of dilute surfactant was performed in 30 ventilated infants with severe meconium aspiration syndrome (MAS). Mean recovery of instilled lavage fluid was 46%, with greater fluid return associated with lower mean airway pressure at 24 h and a shorter duration of respiratory support.

CONCLUSION

Recovery of instilled lavage fluid is paramount in effective lung lavage in MAS and must be afforded priority in the lavage technique.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a severe pulmonary disorder which occurs at a rate of one in every 500 live births. About 10-50% of the victims will die of the problem and 7-20% of the survivors develop long-term impairments such as hearing deficit, chronic lung disease, and intracranial bleed. Most adult survivors show evidence of augmented pulmonary vasoreactivity, suggesting a phenotypical change. Several animal models have been used to study the pathophysiology and help to develop new therapeutic modality for PPHN. The etiology of PPHN can be classified into three groups: (1) abnormally constricted pulmonary vasculature as a result of parenchymal diseases; (2) hypoplastic pulmonary vasculature; and (3) normal parenchyma with remodeled pulmonary vasculature. Impaired vasorelaxation of pulmonary artery and reduced blood vessel density in lungs are two characteristic findings in PPHN. Medical treatment includes sedation, oxygen, mechanical ventilation, vasorelaxants (inhaled nitric oxide, inhaled or intravenous prostacyclin, intravenous prostaglandin E1, magnesium sulfate), and inotropic agents. Phosphodiesterase inhibitors have recently been studied as another therapeutic agent for PPHN. Endothelin-1 (ET-1) inhibitors have been studied in animals and a case of premature infant with PPHN successfully treated with an ET-I inhibitor has been reported in the literature. Surfactants have been reported as an adjunct treatment for PPHN as a complication of meconium aspiration syndrome. Even with the introduction of several new therapeutic modalities there has been no significant change in survival rate. Extracorporeal membrane oxygenator is used when medical treatment fails and the patient is considered to have a recoverable cause of PPHN.

Neonatologie

Noch vor 20 Jahren war die häufigste Todesursache Frühgeborener das akute Lungenversagen. Die sensationellen Ergebnisse von Mary Ellen Avery ebneten dann den Weg für eine kausale Therapie des Atemnotsyndroms. M.E. Avery beobachtete, dass die Lungen eines verstorbenen Frühgeborenen luftleer und »schwer« waren und kein »schäumendes Material« (»foam«) enthielten. Wie sie durch Experimente belegen konnte, fehlte diesen Lungen in der Tat eine Substanz, die die Oberflächenspannung in den Alveolen vermindert: das pulmonale Surfactant. Die 1959 publizierten Ergebnisse ihrer Untersuchungen fanden zunächst nicht die ihnen gebührende Aufmerksamkeit. Um die weitere Resonanz auf ihre Entdeckung zu beschreiben, verweist M.E. Avery gerne darauf hin, dass sich neues Wissen in 3 Phasen verbreitet: Die 1. Phase, in der neue Ergebnisse bekannt gegeben werden, wird meist ignoriert. In der 2. Phase rufen die inzwischen von anderen nicht mehr zu leugnenden Ergebnisse Feindseligkeiten hervor, in der 3. und letzten Phase besteht eine generelle Übereinstimmung darüber, dass man schon immer von dieser Tatsache ausgegangen sei.

Comparative effects of bronchoalveolar lavage with saline, surfactant, or perfluorocarbon in experimental meconium aspiration syndrome

OBJECTIVE

Today, in meconium aspiration syndrome, treatment focuses on bronchoalveolar lavage, because it removes meconium and proinflammatory factors from airways. This technique might be more effective if different solutions were used such as saline solution, a protein-free surfactant, or a perfluorocarbon, because these would be less inhibited by meconium proteins.

SETTING

Pulmonary physiology research unit, Cruces Hospital.

DESIGN

Prospective, randomized study.

SUBJECTS

We studied 24 lambs (<6 days) on mechanical ventilation for 180 mins. Catheters were placed and femoral and pulmonary arteries pressures registered (systemic and pulmonary arterial pressures).

INTERVENTIONS

Lambs were instilled with 20% meconium (3-5 mL/Kg) and were randomly assigned to one of the following groups (n = 6): control: only continuous mechanical ventilation; saline bronchoalveolar lavage: bronchoalveolar lavage with 30 mL/kg of saline solution; dilute surfactant bronchoalveolar lavage: bronchoalveolar lavage with 32 mL/kg of diluted surfactant (lucinactant, 10 mg/mL); or perfluorocarbon bronchoalveolar lavage: bronchoalveolar lavage with 30 mL/kg of perfluorocarbon.

MEASUREMENTS AND MAIN RESULTS

Blood gases, cardiovascular parameters, and pulmonary mechanics were assessed. Meconium instillation produced severe hypoxia, hypercapnia, acidosis, and pulmonary hypertension with impairment of pulmonary mechanics (p < .05). Lung lavage with dilute surfactant resulted in the resolution of pulmonary hypertension as well as better gas exchange and pulmonary mechanics than the control group (p < .05). Bronchoalveolar lavage with perfluorocarbon produced a transient improvement in gas exchange and ventilatory indices in comparison with control and saline bronchoalveolar lavage groups.

CONCLUSIONS

In lambs with meconium aspiration syndrome, bronchoalveolar lavage with diluted lucinactant is an effective therapy producing significant improvements in gas exchange, pulmonary hypertension, and pulmonary mechanics. In addition, bronchoalveolar lavage with perfluorocarbon appears to confer some advantages over lavage with equal volumes of saline or no lavage.

Respiratory support in meconium aspiration syndrome: a practical guide

Meconium aspiration syndrome (MAS) is a complex respiratory disease of the term and near-term neonate. Inhalation of meconium causes airway obstruction, atelectasis, epithelial injury, surfactant inhibition, and pulmonary hypertension, the chief clinical manifestations of which are hypoxaemia and poor lung compliance. Supplemental oxygen is the mainstay of therapy for MAS, with around one-third of infants requiring intubation and mechanical ventilation. For those ventilated, high ventilator pressures, as well as a relatively long inspiratory time and slow ventilator rate, may be necessary to achieve adequate oxygenation. High-frequency ventilation may offer a benefit in infants with refractory hypoxaemia and/or gas trapping. Inhaled nitric oxide is effective in those with pulmonary hypertension, and other adjunctive therapies, including surfactant administration and lung lavage, should be considered in selected cases. With judicious use of available modes of ventilation and adjunctive therapies, infants with even the most severe MAS can usually be supported through the disease, with an acceptably low risk of short- and long-term morbidities.

Surfactant lavage therapy for meconium aspiration syndrome: a systematic review and meta-analysis

BACKGROUND

Lung lavage with diluted surfactant has emerged as an innovative treatment for meconium aspiration syndrome (MAS). However, the treatment effect has not yet been fully established.

OBJECTIVE

To investigate the effects of surfactant lavage therapy for MAS by a systematic meta-analysis.

METHODS

Relevant studies were identified by database searches in MEDLINE (from 1950), EMBASE (from 1980), and CENTRAL, up to June 2010, and by additional hand searches. Meta-analyses were separately conducted for randomized controlled trials (RCTs) and non-randomized controlled studies (NRSs). Risk of bias was assessed and clinical as well as statistical heterogeneities were also investigated in explaining the potential bias.

RESULTS

Two RCTs (87 patients) and eight NRSs (178 patients) were identified. From the results of the meta-analysis of RCTs, surfactant lavage significantly decreased death or the need for extracorporeal membrane oxygenation (RR 0.34, 95% CI 0.11, 0.99). An interventional benefit was indicated for other outcomes, although it was not statistically significant based only on the two RCTs. Results from the analysis of outcomes from NRSs are consistent with those from RCTs and demonstrated a beneficial effect, which could be considered as supporting evidence.

CONCLUSIONS

Lung lavage with diluted surfactant appeared to improve the clinical outcome in infants with MAS. Given that less than 100 infants were included in the two RCTs, the findings of this study may still be regarded as insufficient evidence. Further research will be needed to confirm the benefit as well as to refine the lavage technique.

Advances in the management of meconium aspiration syndrome

Meconium aspiration syndrome (MAS) is a common cause of severe respiratory distress in term infants, with an associated highly variable morbidity and mortality. MAS results from aspiration of meconium during intrauterine gasping or during the first few breaths. The pathophysiology of MAS is multifactorial and includes acute airway obstruction, surfactant dysfunction or inactivation, chemical pneumonitis with release of vasoconstrictive and inflammatory mediators, and persistent pulmonary hypertension of newborn (PPHN). This disorder can be life threatening, often complicated by respiratory failure, pulmonary air leaks, and PPHN. Approaches to the prevention of MAS have changed over time with collaboration between obstetricians and pediatricians forming the foundations for care. The use of surfactant and inhaled nitric oxide (iNO) has led to the decreased mortality and the need for extracorporeal membrane oxygenation (ECMO) use. In this paper, we review the current understanding of the pathophysiology and management of MAS.

Secretory phospholipase A2 pathway in various types of lung injury in neonates and infants: a multicentre translational study

BACKGROUND

Secretory phospholipase A2 (sPLA2) is a group of enzymes involved in lung tissue inflammation and surfactant catabolism. sPLA2 plays a role in adults affected by acute lung injury and seems a promising therapeutic target. Preliminary data allow foreseeing the importance of such enzyme in some critical respiratory diseases in neonates and infants, as well. Our study aim is to clarify the role of sPLA2 and its modulators in the pathogenesis and clinical severity of hyaline membrane disease, infection related respiratory failure, meconium aspiration syndrome and acute respiratory distress syndrome. sPLA2 genes will also be sequenced and possible genetic involvement will be analysed.

METHODS/DESIGN

Multicentre, international, translational study, including several paediatric and neonatal intensive care units and one coordinating laboratory. Babies affected by the above mentioned conditions will be enrolled: broncho-alveolar lavage fluid, serum and whole blood will be obtained at definite time-points during the disease course. Several clinical, respiratory and outcome data will be recorded. Laboratory researchers who perform the bench part of the study will be blinded to the clinical data.

DISCUSSION

This study, thanks to its multicenter design, will clarify the role(s) of sPLA2 and its pathway in these diseases: sPLA2 might be the crossroad between inflammation and surfactant dysfunction. This may represent a crucial target for new anti-inflammatory therapies but also a novel approach to protect surfactant or spare it, improving alveolar stability, lung mechanics and gas exchange.

Bronchoalveolar lavage versus bolus administration of lucinactant, a synthetic surfactant in meconium aspiration in newborn lambs

This study was designed to study effects of lung lavage versus the classical bolus instillation with a peptide-based synthetic surfactant (lucinactant) in a model of Meconium Aspiration Syndrome (MAS). Eighteen newborn lambs received meconium and were randomized to: the experimental meconium installation (eMAS) group-lambs with eMAS kept on conventional mechanical ventilation (control); the SF-Bolus group-eMAS receiving a lucinactant bolus (30 mg/ml); or the D-SF-Lavage group-eMAS treated with dilute lucinactant bronchoalveolar lavage (10 mg/ml). Systemic and pulmonary arterial pressures, blood gases, and pulmonary mechanics were recorded for 180 min. In addition, the intrapulmonary distribution of the lucinactant was determined using dye-labeled microspheres. Following meconium instillation, severe hypoxia, hypercapnia, acidosis, and pulmonary hypertension developed, and dynamic compliance decreased (50% from baseline). After lung lavage with dilute lucinactant, gas exchange significantly improved versus bolus instillation (P < 0.05). Further, only in the lavage group did pulmonary arterial pressure return to basal values and dynamic compliance significantly increased. Both lung lavage and bolus techniques for the administration of lucinactant resulted in a non-uniform lung distribution. In conclusion, in newborn lambs with respiratory failure and pulmonary hypertension induced by meconium, lung lavage with dilute lucinactant seems to be an effective and safe alternative for treatment for MAS.