Surfactant application during extracorporeal membrane oxygenation improves lung volume and pulmonary mechanics in children with respiratory failure

Advances in pulmonary management and weaning from ECLS

ECMO for neonatal and pediatric respiratory failure provides gas exchange to allow lung recovery from reversible pulmonary ailments. This is a comprehensive discussion on the various strategies and advances utilized by pediatric ECLS specialists today. ECMO patients require continual monitoring, serial gasses and radiographs, near-infrared spectroscopy (NIRS - to monitor oxygen delivery to regional tissue beds), and more quality ECLS directed care. As the foundation to lung recovery, good EMCO closely monitors ECLS flow rates, sweep gasses, and membrane lung function. Mixed venous oxygen saturation (Sv02) greater than 65% indicates good oxygen delivery and sweep gas adjustments maintain PaCO2 of 40-45 mm Hg. Lung recovery ventilatory settings do not fully rest the lungs but maintain normal or nontoxic pressure and oxygen levels. Neonatal recovery settings are PIP (cm H20) of 15-20, PEEP of 5-10, ventilator rate of 12-20 and an inspiratory time of 0.5-1 s, and FiO2 of 0.3-0.5. Pediatric recovery settings are PIP (cm H20) < 25, PEEP of 5-15, ventilator rate of 10-20 and an inspiratory time of 0.8-1 s, and FiO2 of <0.5. Some studies demonstrate a higher recovery PEEP level decreases duration of ECMO, but do not demonstrate a mortality difference. Multiple adjunctive therapies such as surfactant, routine pulmonary clearance and respiratory physiotherapy, iNO, prone positioning, bronchoscopy, POCUS, CT imaging, and extubation or "awake ECLS" can significantly affect pulmonary recovery. Patience is necessary as lung recovery may take weeks or even months on the nontoxic settings. On these settings, dynamic recovery will be revealed by improvement in tidal volume, minute ventilation and radiographic pulmonary aeration, prompting discussion about weaning. When this pulmonary compliance recovery becomes evident, decreasing ECLS flow while also decreasing circuit FiO2 and/or sweep gas are common components to ECMO weaning strategies.

Extracorporeal membrane oxygenation in critically ill neonatal and pediatric patients with acute respiratory failure: a guide for the clinician

Intro: Extracorporeal membrane oxygenation for neonatal and pediatric respiratory failure continues to demonstrate improving outcomes, largely due to advances in technology along with refined management strategies despite mounting patient acuity and complexity. Successful use of ECMO requires thoughtful initiation and candidacy strategies, along with reducing the risk of ventilator induced lung injury and the progression to multiorgan failure.Areas Covered: This review describes current ECMO management strategies for neonatal and pediatric patients with acute refractory respiratory failure and summarizes relevant published literature. ECMO initiation and candidacy, along with ventilator and sedation management, are highlighted. Additionally, rapidly expanding areas of interest such as anticoagulation strategies, transfusion thresholds, rehabilitation on ECMO, and drug pharmacokinetics are described.Expert Opinion: Over the last few decades, published studies supporting ECMO use for acute refractory respiratory failure, along with institutional experience, have resulted in increased utilization although more randomized-controlled trials are needed. Future research should focus on filling the knowledge gaps that remain regarding anticoagulation, transfusion thresholds, ventilator strategies, sedation, and approaches to rehabilitation to subsequently implement into clinical practice. Additionally, efforts should focus on well-designed trials, including population pharmacokinetic studies, to develop dosing recommendations.

Surfactant therapy to facilitate weaning in paediatric patients dependent on extacorporeal membrane oxygenation

We are reporting two paediatric cases with severe adenoviral acute respiratory distress syndrome with viral counts of 308 and 119 million copies/mL respectively, who required venoarterial extracorporeal membrane oxygenation (ECMO) support for nearly 3 weeks. They were static on ECMO and had shown a complete lack of response to all therapeutic interventions aimed at decreasing ECMO support. To facilitate weaning from ECMO, they received 2-3 doses of surfactant. This led to dramatic improvement in pulmonary compliance, oxygenation and chest X-ray. They were both weaned off ECMO within 24 hours of receiving surfactant. Surfactant was well tolerated, with no adverse effects. In both cases, weaning from ECMO was possible only after surfactant administration. From our experience, we conclude that surfactant administration is a potentially safe and effective treatment modality that helps weaning from ECMO and should be considered in patients who are dependent on ECMO for long duration.

Veno-venous ECMO as a platform to evaluate lung lavage and surfactant replacement therapy in an animal model of severe ARDS

BACKGROUND

There are limited therapeutic options directed at the underlying pathological processes in acute respiratory distress syndrome (ARDS). Experimental therapeutic strategies have targeted the protective systems that become deranged in ARDS such as surfactant. Although results of surfactant replacement therapy (SRT) in ARDS have been mixed, questions remain incompletely answered regarding timing and dosing strategies of surfactant. Furthermore, there are only few truly clinically relevant ARDS models in the literature. The primary aim of our study was to create a clinically relevant, reproducible model of severe ARDS requiring extracorporeal membrane oxygenation (ECMO). Secondly, we sought to use this model as a platform to evaluate a bronchoscopic intervention that involved saline lavage and SRT.

METHODS

Yorkshire pigs were tracheostomized and cannulated for veno-venous ECMO support, then subsequently given lung injury using gastric juice via bronchoscopy. Animals were randomized post-injury to either receive bronchoscopic saline lavage combined with SRT and recruitment maneuvers (treatment, n = 5) or recruitment maneuvers alone (control, n = 5) during ECMO.

RESULTS

PaO₂/FiO₂ after aspiration injury was 62.6 ± 8 mmHg and 60.9 ± 9.6 mmHg in the control and treatment group, respectively (p = 0.95) satisfying criteria for severe ARDS. ECMO reversed the severe hypoxemia. After treatment with saline lavage and SRT during ECMO, lung physiologic and hemodynamic parameters were not significantly different between treatment and controls.

CONCLUSIONS

A clinically relevant severe ARDS pig model requiring ECMO was established. Bronchoscopic saline lavage and SRT during ECMO did not provide a significant physiologic benefit compared to controls.

Surfactant Administration During Pediatric Cardiac Extracorporeal Membrane Oxygenation

We investigated the safety and efficacy of surfactant during extracorporeal membrane oxygenation (ECMO) in children with cardiac disease. ECMO patients administered surfactant (surfactant group) were compared with patients who did not receive (control). Criteria to administer surfactant were based on a decreased lung compliance of <0.5 ml/kg/cm H2O. Efficacy was determined on pulmonary compliance change and the radiography-based respiratory distress severity (RDS) score. For the surfactant group, lung compliance measurements and RDS scores were obtained just before the first surfactant administration (T0), 24 hours after the last dose of surfactant (T1), and 24 hours after ECMO decannulation (T2). For the control group, measurements were obtained at baseline (T0), day of ECMO decannulation (T1), and 24 hours after ECMO decannulation (T2). Eighty were on ECMO, 29 in the surfactant, and 51 in the control group. Surfactant group was younger 20 (6-140) vs. 28 (8-928) days old (p = 0.03), had longer ECMO duration 110 (58-192) vs. 46 (29-84) hours (p = 0.001), and had longer mechanical ventilation 16 (11-26) vs. 7 (5-9) days (p = 0.003). The lung compliance and RDS scores in the surfactant group improved significantly between baseline and 24 hours after decannulation, 0.36 ± 0.13 vs. 0.5 ± 0.12 ml/kg/cm H2O (p = 0.002) and 13 ± 3 vs. 12 ± 2 (p = 0.04), respectively. None developed pneumothorax. Mild pulmonary hemorrhage occurred twice (one in each group). Hospital duration and survival were similar 36 (19-48) vs. 31 (18-48) days and 69% vs. 78% in surfactant and control groups, respectively. Although this is a relatively small study, surfactant appears to be safe in pediatric cardiac ECMO patients.

Surfactant Administration During Pediatric Extracorporeal Membrane Oxygenation

Administering surfactant during pediatric extracorporeal membrane oxygenation (ECMO) may influence important clinical variables but has been insufficiently described. Ninety-six courses of ECMO from our center were retrospectively assessed, and 89 surfactant doses were identified during 37 ECMO courses. Surfactant administration was associated with a respiratory indication for ECMO and increased durations of ECMO and positive pressure ventilation. Hospital survival was 64.9% (24) in surfactant-treated ECMO courses and 72.9% (43) otherwise (p = 0.41). Dynamic compliance of the respiratory system (Cdyn; shown as least squares mean [standard error] in ml/cm H2O/kg by mixed-effects modeling) increased significantly from 0.34 (0.03) before surfactant to 0.40 (0.03) within 12 hours (p = 0.023) and to 0.45 (0.03) within 24 hours (p < 0.001) of surfactant administration. Other mechanical ventilator parameters, ECMO settings, and arterial blood gas results did not differ significantly after surfactant administration. Among surfactant recipients, significantly increased Cdyn was observed in the nonsurgical group (n = 20) but not in the cardiac surgery group (n = 17). In conclusion, respiratory system compliance is increased after surfactant administration and noncardiac surgical patients may preferentially benefit from this therapy. Surfactant administration was associated with longer durations of mechanical support, but not with unfavorable mortality.

Extracorporeal membrane oxygenation for neonatal and pediatric respiratory failure: an evidence-based review of the past decade (2002-2012)

OBJECTIVE

To provide a comprehensive evidence-based review of extracorporeal membrane oxygenation for neonatal and pediatric respiratory failure.

DATA SOURCE

A thorough computerized bibliographic search of the clinical literature regarding the use of extracorporeal membrane oxygenation in the neonatal and pediatric populations.

STUDY SELECTION

Clinical trials published between January 1, 2002, and October 1, 2012, including "extracorporeal membrane oxygenation" or "ECMO" and limited to studies involving humans aged 0-18 years. Trials focused on extracorporeal membrane oxygenation for cardiac indications were excluded from this study, unless the study was evaluating ancillary therapies in conjunction with extracorporeal membrane oxygenation.

DATA EXTRACTION

Studies were evaluated for inclusion based on reporting of patient outcomes and/or strategic considerations, such as cannulation strategies, timing of extracorporeal membrane oxygenation utilization, and ancillary therapies.

DATA SYNTHESIS

Pertinent data are summarized, and the available data are objectively classified based on the value of the study design from which the data are obtained.

CONCLUSIONS

Despite a large number of published extracorporeal membrane oxygenation studies, there remains a paucity of high-quality clinical trials. The available data support continued use of extracorporeal membrane oxygenation for respiratory failure refractory to conventional therapy for neonatal and pediatric patients without significant comorbidities. Further research is needed to better quantify the benefit of extracorporeal membrane oxygenation and the utility of many therapies commonly applied to extracorporeal membrane oxygenation patients.

What's new in surfactant? A clinical view on recent developments in neonatology and paediatrics

Surfactant therapy has significantly changed clinical practice in neonatology over the last 25 years. Recent trials in infants with respiratory distress syndrome (RDS) have not shown superiority of any natural surfactant over another. Advancements in the development of synthetic surfactants are promising, yet to date none has been shown to be superior to natural preparations. Ideally, surfactant would be administered without requiring mechanical ventilation. An increasing number of studies investigate the roles of alternative modes of administration and the use of nasal continuous positive airway pressure to minimise the need for mechanical ventilation. Whether children with other lung diseases benefit from surfactant therapy is less clear. Evidence suggests that infants with meconium aspiration syndrome and children with acute lung injury/acute respiratory distress syndrome may benefit, while no positive effect of surfactant is seen in infants with congenital diaphragmatic hernia. However, more research is needed to establish potential beneficial effects of surfactant administration in children with lung diseases other than RDS. Furthermore, genetic disorders of surfactant metabolism have recently been linked to respiratory diseases of formerly unknown origin. It is important to consider these disorders in the differential diagnosis of unexplained respiratory distress although no established treatment is yet available besides lung transplantation for the most severe cases.

CONCLUSION

Research around surfactant is evolving and recent developments include further evolution of synthetic surfactants, evaluation of surfactant as a therapeutic option in lung diseases other than RDS and the discovery of genetic disorders of surfactant metabolism. Ongoing research is essential to continue to improve therapeutic prospects for children with serious respiratory disease involving disturbances in surfactant.

Year in review 2005: Critical Care--respirology: mechanical ventilation, infection, monitoring, and education

We summarize all original research in the field of respiratory intensive care medicine published in 2005 in Critical Care. Twenty-seven articles were grouped into the following categories and subcategories to facilitate rapid overview: mechanical ventilation (physiology, spontaneous breathing during mechanical ventilation, high frequency oscillatory ventilation, side effects of mechanical ventilation, sedation, and prone positioning); infection (pneumonia and sepsis); monitoring (ventilatory monitoring, pulmonary artery catheter and pulse oxymeter); and education (training and health outcome).