Neonatal ECMO: Current controversies and trends

Complications Associated with Subsequent Vascular Access in Pediatric ECMO Patients

INTRODUCTION

Following ECMO decannulation, intensivists and surgeons must consider whether to reuse the cannulation site for central venous catheters (CVC) or seek remote access. This study investigates the risk of infectious complication associated with the reuse of peripheral ECMO cannulation sites for subsequent central venous access.

METHODS

A retrospective review was conducted for patients aged 0-18 years, who underwent peripheral ECMO cannulation between 2009 and 2021 at a single children's hospital.

RESULTS

Of the 227 charts reviewed, after ECMO decannulation, 53 patients received a CVC at the same location, 25 received a CVC at a different location, 62 received a peripherally inserted central catheter (PICC), and 87 had no subsequent vascular access placed within 30 days of decannulation. Patients with secondary access placed at the same site experienced 1 CLABSI, or 0.94 CLABSIs per 1000 line days. Patients with PICC lines after ECMO decannulation had 1 CLABSI, or 0.43 CLABSIs per 1000 line days. In comparison, the institution's hospital-wide CLABSI rate was 1.46 per 1000 line days during this same period. Although the rate of CLABSI among patients with secondary access at the site of decannulation was higher than the rate among patients with PICC lines (p = 0.79) it was lower than the institutional rate (p = 0.54), these differences did not rise to the level of statistical significance.

CONCLUSION

Compared with ECMO patients with subsequent CVCs placed at an alternative access site or via PICC after decannulation, patients with contemporaneous CVC placement at the site of decannulation do not experience a significantly higher rate of CLABSIs.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Retrospective comparative study.

Frequency of Extracorporeal Membrane Oxygenation Support and Outcomes After Implementation of a Structured PICU Network in Neonates and Children: A Prospective Population-Based Study in the West of France

OBJECTIVES

To describe the frequency and outcomes on the use of extracorporeal membrane oxygenation (ECMO) among critically ill neonates and children within a structured pediatric critical care network in the West of France. To assess the optimality of decision-making process for patients primarily admitted in non-ECMO centers.

DESIGN

Observational prospective population-based study from January 2015 to December 2019.

PATIENTS

Neonates over 34 weeks of gestational age, weighing more than 2,000 g and children under 15 years and 3 months old admitted in one of the 10 units belonging to a Regional Pediatric Critical Care Network.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Eight-thousand one hundred eighty-nine children and 3,947 newborns were admitted within one of the 10 units of the network over the study period. Sixty-five children (8.1% [95% CI, 6.2-10‰]) and 35 newborns (9.4% [95% CI, 6.4-12%]) required ECMO support. Of these patients, 31 were first admitted to a non-ECMO center, where 20 were cannulated in situ (outside the regional ECMO center) and 11 after transfer to the ECMO regional center. Cardiogenic shock, highest serum lactate level, and cardiac arrest prior to first phone call with the regional ECMO center were associated with higher rate of in situ cannulation. During the study period, most of the patients were cannulated for underlying cardiac issue (42/100), postoperative cardiac surgery instability (38/100), and pediatric (10/100) and neonatal (10/100) respiratory distress syndrome. Patients primarily admitted in non-ECMO centers or not had similar 28-day post-ICU survival rates compared with those admitted in the referral ECMO center (58% vs 51%; p = 0.332). Pre-ECMO cardiac arrest, ECMO, and lower pH at ECMO onset were associated with lower 28-day post-ICU survival.

CONCLUSIONS

Our local results suggest that a structured referral network for neonatal and pediatric ECMO in the region of Western France facilitated escalation of care with noninferior (or similar) early mortality outcome. Our data support establishing referral networks in other equivalent regions.

Neonatal respiratory and cardiac ECMO in Europe

Neonatal extracorporeal membrane oxygenation (ECMO) is a life-saving procedure for critically ill neonates suffering from a potentially reversible disease, causing severe cardiac and/or respiratory failure and refractory to maximal conventional management. Since the 1970s, technology, management, and clinical applications of neonatal ECMO have changed. Pulmonary diseases still represent the principal neonatal diagnosis, with an overall 74% survival rate, and up to one-third of cases are due to congenital diaphragmatic hernia. The overall survival rate in cardiac ECMO is lower, with congenital heart defect representing the main indication. This review provides an overview of the available evidence in the field of neonatal ECMO. We will address the changing epidemiology, basic principles, technologic advances in circuitry, and monitoring, and deliver a current multidisciplinary management framework, focusing on ECMO applications, complications, and long-term morbidities. Lastly, areas for further research will be highlighted.Conclusions: ECMO is a life support with a potential impact on long-term patients' outcomes. In the next years, advances in knowledge, technology, and expertise may push neonatal ECMO boundaries towards more premature and increasingly complex infants, with the final aim to reduce the burden of ECMO-related complications and improve overall patients' outcomes. What is Known: • ECMO is a life-saving option in newborns with refractory respiratory and/or cardiac failure. • The multidisciplinary ECMO management is challenging and may expose neonates to complications with an impact on long-term outcomes. What is New: • Advances in technology and biomaterials will improve neonatal ECMO management and, eventually, the long-term outcome of these complex patients. • Experimental models of artificial placenta and womb technology are under investigation and may provide clinical translation and future research opportunities.

Outcomes and factors associated with early mortality in pediatric and neonatal patients requiring extracorporeal membrane oxygenation for heart and lung failure

BACKGROUND

Mortality and morbidity after surgical repair for complex congenital heart defects and severe cardiopulmonary failure on extracorporeal membrane oxygenation (ECMO) support remain high despite significant advances in medical management and technological improvements. We report on outcomes and factors after using ECMO in our surgical pediatric population including short- and long-term survival.

METHODS

A total of 45 neonatal and pediatric patients were identified who needed ECMO in our department between January 2008 and December 2016. In 41 cases (91%) a vaECMO (ECLS) was implemented, whereas 4 patients (9%) received vvECMO treatment for respiratory failure. In 33 cases vaECMO was implanted following cardiac surgery for congenital heart disease (CHD), whereas in 8 patients ECMO was utilized by means of extracorporeal cardiopulmonary resuscitation (eCPR) following refractory cardiac arrest. The primary endpoint of the present study was survival to discharge and long-term survival free from neurological impairments. Univariate and bivariate analysis was performed to address predictors for outcome. Kaplan-Meier survival analysis was used to address mid- and long-term survival.

RESULTS

Median [IQR] duration of ECMO support was 3 [2, 5] days (range, 1-17 days). Median age at ECMO implantation was 128 [14, 1,813] days, median weight of patients was 5.4 [3.3, 12] kg. Totally 10 patients included in this study were diagnosed with concomitant genetic conditions. A total of 20 (44%) patients were successfully weaned off ECMO (survived >24 h after ECMO explantation), whereas 15 (33%) of them survived to discharge. Single ventricle (SV) repair was performed in 14, biventricular repair in 19 patients. Neonates (<30 days of age), female patients, patients with genetic conditions, SV repair patients, and eCPR patient cohort showed lower odds of survival on ECMO. Failed myocardial recovery (P=0.001), profound circulatory failure despite a high dose of catecholamines (P<0.001), neurological impairment pre-ECMO and post-ECMO (P=0.04 and P<0.001, respectively), and severe pulmonary failure despite high respiratory pressure settings were most common mortality reasons.

CONCLUSIONS

ECMO provides efficient therapy opportunities for life-threatening conditions. Nevertheless, neonates and pediatric patients who underwent ECMO were at high risk for cerebrovascular events and poor survival. Appropriate patient selection using predictors of outcome reducing complications might improve outcomes of this patient cohort.

Interhospital Transport on Extracorporeal Membrane Oxygenation of Neonates-Perspective for the Future

In recent years the number of extracorporeal membrane oxygenation (ECMO) cases in neonates has been relatively constant. Future expansion lays in new indications for treatment. Regionalization to high-volume ECMO centers allows for optimal utilization of resources, reduction in costs, morbidity, and mortality. Mobile ECMO services available "24-7" are needed to provide effective logistics and reliable infrastructure for patient safety. ECMO transports are usually high-risk and complex. To reduce complications during ECMO transport communication using time-out, checklists, and ECMO A-B-C are paramount in any size mobile program. Team members' education, clinical training, and experience are important. For continuing education, regular wet-lab training, and simulation practices in teams increase performance and confidence. In the future the artificial placenta for the extremely premature infant (23-28 gestational weeks) will be introduced. This will enforce the development and adaptation of ECMO devices and materials for increased biocompatibility to manage the high-risk prem-ECMO (28-34 weeks) patients. These methods will likely first be introduced at a few high-volume neonatal ECMO centers. The ECMO team brings bedside competence for assessment, cannulation, and commencement of therapy, followed by a safe transport to an experienced ECMO center. How transport algorithms for the artificial placentae will affect mobile ECMO is unclear. ECMO transport services in the newborn should firstly be an out-reach service led and provided by ELSO member centers that continuously report transport data to an expansion of the ELSO Registry to include transport quality follow-up and research. For future development and improvement follow-up and sharing of data are important.

Impact of an inline extracorporeal membrane oxygenation hemofilter system in neonatal acute kidney injury

Extracorporeal membrane oxygenation (ECMO) is considered a recognized lifesaving support for patients with cardiorespiratory failure. Acute kidney injury (AKI) and fluid overload are significant morbidity factors resulting in serious complications. The inline hemofilter system (IHS) and the continuous renal replacement therapy (CRRT) machine are different methods of renal replacement therapy for patients with ECMO. IHS is the alternate, safe dialysis modality of choice because it is user-friendly, inexpensive, and efficiently removes fluid overload and renal diffusive clearance. We report on a 20-day-old male neonate with multiple congenital cardiac defects who needed venoarterial ECMO and had AKI necessitating renal replacement therapy using IHS. The patient had stable electrolyte parameters, good ultrafiltration, and efficient diffusive clearance. He was decannulated from ECMO therapy after 9 days without any related complications. Therefore, neonatal IHS is a safe and efficient alternative approach to AKI.

Current trends in neonatal ECMO

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for patients with respiratory and cardiac failure refractory to maximal medical management. The extracorporeal life support organization registry is the largest available resource for describing the population and outcomes of patients treated with this therapy. The use of ECMO for neonatal patients is decreasing in proportion to the total annual ECMO runs most likely due to advancements in medical management. Although the overall survival for neonatal ECMO has decreased, this is likely a reflection of the increasingly complex neonatal patients treated with this therapy. Although many patient and mechanical complications are decreasing over time, there remains a high percentage of morbidities and risks associated with ECMO. Continued refinements in management strategies are important to improving overall patient outcomes.

Extracorporeal Membrane Oxygenation Support in Neonates: A Single Medical Center Experience in Taiwan

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) was used in neonates with severe cardiopulmonary failure who failed to respond to conventional therapy. We started to apply neck venoarterial ECMO (VA-ECMO) in neonatal patients from 2000. In this study, we have focused on neonates who received ECMO support and described the current status of ECMO in neonates for both cardiac and pulmonary support and the risk factors associated with their outcomes.

METHODS

Data were retrieved from our ECMO database for the neonates (age < 28 days) who received neck VA-ECMO support from January 2005 to June 2015.

RESULTS

In total, 27 neonates, including 21 with respiratory support and six with cardiac support, were enrolled in this study. Sixteen (59.2%) patients survived to hospital discharge, and only one patient had a poor neurological outcome. The survival rate for respiratory support was 61.9% in which meconium aspiration syndrome with persistent pulmonary hypertension of a newborn had a superior outcome (11/13, 84.6%) and congenital diaphragmatic hernia had the worst outcome (4/7, 57.1%). The survival rate in the cardiac support group was only 50%. The median ECMO duration and hospital stay were 6 (1∼35.8) days and 37 (23∼232) days, respectively, for survivors. Furthermore, 11 (52.3%) neonates of 21 outborn patients were put on ECMO in other hospitals by our mobile ECMO team for respiratory support, and their survival (81.8%) was significantly better than those from in-house ECMO institution (40%).

CONCLUSION

This is the first report for ECMO in neonatal disease in Taiwan. We achieved an overall survival rate of 59.2% with good neurological outcomes in this 10-year experience. ECMO could be a useful transportation tool for critical neonates who have a poor response to ventilator support.

A novel minimal invasive mouse model of extracorporeal circulation

Extracorporeal circulation (ECC) is necessary for conventional cardiac surgery and life support, but it often triggers systemic inflammation that can significantly damage tissue. Studies of ECC have been limited to large animals because of the complexity of the surgical procedures involved, which has hampered detailed understanding of ECC-induced injury. Here we describe a minimally invasive mouse model of ECC that may allow more extensive mechanistic studies. The right carotid artery and external jugular vein of anesthetized adult male C57BL/6 mice were cannulated to allow blood flow through a 1/32-inch external tube. All animals (n = 20) survived 30 min ECC and subsequent 60 min observation. Blood analysis after ECC showed significant increases in levels of tumor necrosis factor α, interleukin-6, and neutrophil elastase in plasma, lung, and renal tissues, as well as increases in plasma creatinine and cystatin C and decreases in the oxygenation index. Histopathology showed that ECC induced the expected lung inflammation, which included alveolar congestion, hemorrhage, neutrophil infiltration, and alveolar wall thickening; in renal tissue, ECC induced intracytoplasmic vacuolization, acute tubular necrosis, and epithelial swelling. Our results suggest that this novel, minimally invasive mouse model can recapitulate many of the clinical features of ECC-induced systemic inflammatory response and organ injury.

The impact of leukoreduced red blood cell transfusion on mortality of neonates undergoing extracorporeal membrane oxygenation

BACKGROUND

Blood products containing leukocytes have been associated with negative immunomodulatory and infectious effects. Transfusion-related acute lung injury is partially explained by leucocyte agglutination. The Food and Drug Administration has therefore recommended leukoreduction strategies for blood product transfusion. Our institution has been using leukocyte-reduced blood via filtration for neonates on Extracorporeal Membrane Oxygenation (ECMO). We hypothesized that the use of leukocyte-reduced blood would decrease mortality and morbidity of neonatal ECMO patients.

METHODS

Retrospective review of noncardiac ECMO in neonates from 1984-2011, stratified into year groups I and II (≤1996 and ≥1997). Demographics, duration and type of ECMO, complications, and outcome data were collected. Blood product use data was collected. Univariate, bivariate, and multivariate analyses determined predictors of risk-adjusted mortality by year group.

RESULTS

Patients (827) underwent ECMO with 65.3% (540) in group I. Overall median blood product use in mL/kg/d was 36.2 packed red blood cells (pRBC), 8.1 platelets, and 0 cyroprecipitate and/or fresh-frozen plasma. Overall mortality was 16.4%. Median pRBC used or transfused was 42.1 mL/kg/d in group I versus 19.1 mL/kg/d group II (P <0.001). On bivariate analysis, there was no difference in crude mortality between the 2 year groups (17.2% versus 16.0%, P = 0.66). However, on multivariate analysis adjusting for demographics, diagnosis, complications, and blood product use other than pRBCs, each additional transfusion of 10 mL/kg/d of pRBC was associated with a 33% increase in mortality in group I (P <0.05). Group II also showed an increase in mortality with each additional transfusion (21%) but this was not statistically significant (P = 0.07). Days on ECMO were not associated with pRBC transfusion in group I but increased in group II (additional 3 d for each 10 mL/kg/d transfused). There was no difference in infectious complications between groups I and II.

CONCLUSIONS

Blood transfusion requirement has diminished in newborns undergoing ECMO at our institution. Transfusion of non leukocyte-reduced blood is associated with an increase in mortality whereas transfusion of leukocyte-reduced blood provided no benefit with a trend toward increased mortality. Further research is recommended to understand these trends.

Chest tube placement in children during extracorporeal membrane oxygenation (ECMO)

BACKGROUND

Pleural collections of air and fluid are frequent in infants and children treated with extracorporeal membrane oxygenation (ECMO). In this anticoagulated population, chest tube placement is potentially hazardous, and catastrophic hemorrhage has been reported. We sought to define the risks associated with chest tube placement in a large population of children managed with ECMO.

METHODS

The records of 189 consecutive children managed with ECMO at two children's hospitals were reviewed. Demographics, indications for ECMO, and ECMO courses were reviewed. In particular, the occurrence of pleural collections and the frequency and technique of chest tube placement were evaluated. The incidence of complications and mortality were determined.

RESULTS

The median age of the subjects was 2days. The overall mortality was 26.5%. A pneumothorax was found in 19 (10.1%), a pleural effusion in 26 (13.8%), and a hemothorax in 2 (1.0%). A chest tube was placed in 27 (19 by a needle-guide wire technique and 8 by cut-down). Major bleeding complications occurred in 6 subjects (22%).

CONCLUSIONS

There was a significant incidence of major bleeding complications and death in subjects in whom chest tubes were placed. The placement of a chest tube during ECMO should be done only if it is likely to improve pump flow or promote weaning of support.

The changing population of the United States and use of extracorporeal membrane oxygenation

BACKGROUND

Neonatal extracorporeal membrane oxygenation (ECMO) has been widely used for the last 25 y. The impact of ethno-demographic changes on ECMO outcomes has not been fully examined. We evaluated the Extracorporeal Life Support Organization registry over a 21-y period to understand these trends.

METHODS

A retrospective review of all neonates undergoing noncardiac ECMO in the United States between the years 1990 and 2010 was conducted based on the years of available live birth census data. Demographic, clinical, and outcome data were collated. Patient specifics, ECMO type, ECMO length, arterial blood gases, and mortality were analyzed. Univariate, bivariate, and multivariate analyses were then performed. Changes in ethnic composition of neonates on ECMO were compared with similar ethnic trend in available U.S. live birth data.

RESULTS

Data were available for 18,130 neonates. Comparing ethnicity by year, the proportion of Caucasian neonates requiring ECMO dropped from 64.3% in 1990 to 49.5% in 2010, while African-American and Hispanic neonates on ECMO increased from 21.1% and 11.1% to 26.1% and 17.4%, respectively (P < 0.001). By diagnosis, congenital diaphragmatic hernia surpassed meconium aspiration syndrome as the leading indication for ECMO compared with 1990 (congenital diaphragmatic hernia, 21.5%-28.4%; meconium aspiration syndrome, 47.0%-15.7%; P < 0.05). ECMO mortality nearly doubled, from 18.5% to 34.0% over the study period. On adjusted analysis, African-Americans were 17% less likely to die on ECMO compared with Caucasian neonates.

CONCLUSIONS

Neonates of ethnic minorities continue to disproportionally require ECMO support in comparison to their birth rates. Although ethnicity alone does not impact the outcome of these newborns, the increased requirement of ECMO may highlight the need for targeted education, improved prenatal care, and decision making in these groups.

Adapted ECMO criteria for newborns with persistent pulmonary hypertension after inhaled nitric oxide and/or high-frequency oscillatory ventilation

PURPOSE

Early prediction of extracorporeal membrane oxygenation (ECMO) requirement in term newborns with persistent pulmonary hypertension (PPHN), partially responding to inhaled nitric oxide (iNO) and/or high-frequency oscillatory ventilation (HFOV), based on oxygenation parameters.

METHODS

This was a retrospective cohort study in 53 partial responders from among 133 term newborns with PPHN born between 2002 and 2007. Alveolar-to-arterial oxygen gradient (AaDO₂) values were determined in these 53 partial responders during the initial 72 h of iNO and/or HFOV treatment and compared between newborns who ultimately did (n = 11) and did not (n = 42) need ECMO.

RESULTS

Over 72 h, partial responders not requiring ECMO showed a more profound AaDO₂ decrease than those who needed ECMO (median decline 242.5 mmHg, IQR 144 to 353 mmHg, vs. 35 mmHg, IQR -15 to 123 mmHg; p = 0.0007). A decline of <123 mmHg over 72 h predicted the need for ECMO (sensitivity 82 %, specificity 79 %). At 72 h, AaDO₂ was significantly lower in partial responders without the need for ECMO than in those who did need ECMO (median 369 mmHg, IQR 258 to 478 mmHg, vs. 570 mmHg IQR 455 to 590 mmHg; p = 0.0008). An AaDO₂ >561 mmHg at 72 h predicted the need for ECMO (sensitivity 64 %, specificity 95 %, positive predictive value 78 %).

CONCLUSIONS

In term newborns with PPHN partially responding to iNO and/or HFOV, oxygenation-based prediction of the need for ECMO appears to be possible after 72 h. ECMO centers are encouraged to develop their own prediction model in order to prevent both lung damage and unnecessary ECMO runs.

Continuous renal replacement therapy to reduce inflammation in a piglet hemorrhage-reperfusion extracorporeal membrane oxygenation model

BACKGROUND

During extracorporeal membrane oxygenation (ECMO), circulation of blood across synthetic surfaces triggers an inflammatory response. Therefore, we evaluated the ability of continuous renal replacement therapy (CRRT) to remove cytokines and reduce the inflammatory response in a piglet hemorrhage-reperfusion ECMO model.

METHODS

Three groups were studied: (i) uninjured controls (n = 11); (ii) hemorrhage-reperfusion while on venoarterial ECMO (30% hemorrhage with subsequent blood volume replacement within 60 min) (n = 8); (iii) treatment with CRRT after hemorrhage-reperfusion while on ECMO (n = 7). Hemodynamic parameters, oxygen utilization, and plasma and broncho-alveolar lavage (BAL) cytokine levels were recorded and lung tissue samples collected for histologic comparison.

RESULTS

Whereas mean arterial pressures decreased among hemorrhage-reperfusion piglets, ECMO with CRRT did not significantly alter mean arterial pressures or systemic vascular resistance and was able to maintain blood flow as well as oxygen delivery after hemorrhage-reperfusion. Plasma interleukin (IL)-6 and IL-10, and BAL tumor necrosis factor (TNF)-α, IL-1β, IL-6, IL-8, and IL-10 increased as a result of hemorrhage-reperfusion while on ECMO. After a 6-h period of CRRT, plasma IL-6 and BAL TNF-α, IL-6, and IL-8 levels decreased.

CONCLUSION

Data suggest CRRT may decrease inflammatory cytokine levels during the initial phase of ECMO therapy following hemorrhage-reperfusion while maintaining cardiac output and oxygen utilization.

The impact of ethnic population dynamics on neonatal ECMO outcomes: a single urban institutional study

INTRODUCTION

Neonatal extracorporeal membrane oxygenation ECMO has been clinically used for the last 25 y. It has been an effective tool for both cardiac and non cardiac conditions. The impact of ethno-demographic changes on ECMO outcomes however remains unknown. We evaluated a single institution's experience with non cardiac neonatal ECMO over a 28-y period.

METHODS

A retrospective review of all neonates undergoing noncardiac ECMO between the y 1984 and 2011 was conducted and stratified into year groups I, II, III (≤1990, 1991-2000, and ≥2001). Demographic, clinical, and outcome data were collected. The patient specifics, ECMO type, ECMO length, blood use, complications, and outcomes were analyzed. Univariate, bivariate, and multivariate analyses were then performed.

RESULTS

Data was available for 827 patients. The number of African-American and Hispanic patients increased over the last 27 y (27.5% versus 45.0% and 3.3% versus 21.5%, year group I versus year group III, respectively). The proportion of congenital diaphragmatic hernia (CDH) patients by ethnicity also increased for African-Americans and Hispanics between the two year groups (22.0% to 33.0% and 4.9% to 33.0%, respectively). Similar pattern was noted for non-CDH diagnoses. Low birth weight, low APGAR scores, CDH, primary pulmonary hypertension, central nervous system hemorrhage, and ECMO were independent predictors of mortality. Ethnicity, in itself however, was not associated with mortality on adjusted analysis.

CONCLUSION

More African-Americans and Hispanics have required ECMO over the years with a concurrent decrease in the number of Caucasians. While ethnicity was not an independent predictor of mortality, it appears to be a surrogate for fatal but sometime preventable diagnoses among minorities. Further investigations are needed to better delineate the reason behind this disparity.

Plasma concentrations of inflammatory cytokines rise rapidly during ECMO-related SIRS due to the release of preformed stores in the intestine

Extracorporeal membrane oxygenation (ECMO) is a life-saving support system used in neonates and young children with severe cardiorespiratory failure. Although ECMO has reduced mortality in these critically ill patients, almost all patients treated with ECMO develop a systemic inflammatory response syndrome (SIRS) characterized by a 'cytokine storm', leukocyte activation, and multisystem organ dysfunction. We used a neonatal porcine model of ECMO to investigate whether rising plasma concentrations of inflammatory cytokines during ECMO reflect de novo synthesis of these mediators in inflamed tissues, and therefore, can be used to assess the severity of ECMO-related SIRS. Previously healthy piglets (3-week-old) were subjected to venoarterial ECMO for up to 8 h. SIRS was assessed by histopathological analysis, measurement of neutrophil activation (flow cytometry), plasma cytokine concentrations (enzyme immunoassays), and tissue expression of inflammatory genes (PCR/western blots). Mast cell degranulation was investigated by measurement of plasma tryptase activity. Porcine neonatal ECMO was associated with systemic inflammatory changes similar to those seen in human neonates. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) concentrations rose rapidly during the first 2 h of ECMO, faster than the tissue expression of these cytokines. ECMO was associated with increased plasma mast cell tryptase activity, indicating that increased plasma concentrations of inflammatory cytokines during ECMO may result from mast cell degranulation and associated release of preformed cytokines stored in mast cells. TNF-alpha and IL-8 concentrations rose faster in plasma than in the peripheral tissues during ECMO, indicating that rising plasma levels of these cytokines immediately after the initiation of ECMO may not reflect increasing tissue synthesis of these cytokines. Mobilization of preformed cellular stores of inflammatory cytokines such as in mucosal mast cells may have an important pathophysiological role in ECMO-related SIRS.

Effective lavage volume of diluted surfactant improves the outcome of meconium aspiration syndrome in newborn piglets

Meconium aspiration syndrome (MAS) is one of the top causes of severe respiratory failure in neonates. This study was designed to investigate the effective volume of therapeutic bronchoalveolar lavage (BAL) with diluted surfactant in the treatment of MAS in newborn piglets. Human meconium was instilled in 24 piglets to induce MAS, and the piglets were randomly divided into four groups: 1) control, no lavage; 2) lavage-10, BAL with diluted surfactant (5 mg/mL, Survanta) 10 mL/kg in two aliquots; 3) lavage-20, 20 mL/kg in two aliquots; 4) lavage-30, 30 mL/kg in two aliquots. Cardiopulmonary parameters were monitored, and the lung tissue was histologically examined after experiments. The changes in oxygenation and lung compliance of lavage-20 and lavage-30 groups were significantly better than control and lavage-10 groups (p < 0.05), but there was no significant difference between lavage-20 and lavage-30 groups. The lung injury scores were significantly lower in the dependent site of lavage-20 and lavage-30 groups than the other two groups. In conclusion, using 20 mL/kg diluted surfactant in two aliquots to perform therapeutic BAL was as effective as 30 mL/kg in improving the pathophysiological outcomes in MAS and may warrant consideration clinically in treating MAS.