Pediatric extracorporeal life support in specialized situations

Nitric Oxide on Extracorporeal Membrane Oxygenation in Neonates and Children (NECTAR Trial): Protocol for a Randomized Controlled Trial

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) provides support for the pulmonary or cardiovascular function of children in whom the predicted mortality risk remains very high. The inevitable host inflammatory response and activation of the coagulation cascade due to the extracorporeal circuit contribute to additional morbidity and mortality in these patients. Mixing nitric oxide (NO) into the sweep gas of ECMO circuits may reduce the inflammatory and coagulation cascade activation during ECMO support.

OBJECTIVE

The purpose of this study is to test the feasibility and safety of mixing NO into the sweep gas of ECMO systems and assess its effect on inflammation and coagulation system activation through a pilot randomized controlled trial.

METHODS

The Nitric Oxide on Extracorporeal Membrane Oxygenation in Neonates and Children (NECTAR) trial is an open-label, parallel-group, pilot randomized controlled trial to be conducted at a single center. Fifty patients who require ECMO support will be randomly assigned to receive either NO mixed into the sweep gas of the ECMO system at 20 ppm for the duration of ECMO or standard care (no NO) in a 1:1 ratio, with stratification by support type (veno-venous vs veno-arterial ECMO).

RESULTS

Outcome measures will focus on feasibility (recruitment rate and consent rate, and successful inflammatory marker measurements), the safety of the intervention (oxygenation and carbon dioxide control within defined parameters and methemoglobin levels), and proxy markers of efficacy (assessment of cytokines, chemokines, and coagulation factors to assess the impact of NO on host inflammation and coagulation cascade activation, clotting of ECMO components, including computer tomography scanning of oxygenators for clot assessments), bleeding complications, as well as total blood product use. Survival without ECMO and the length of stay in the pediatric intensive care unit (PICU) are clinically relevant efficacy outcomes. Long-term outcomes include neurodevelopmental assessments (Ages and Stages Questionnaire, Strength and Difficulties Questionnaire, and others) and quality of life (Pediatric Quality of Life Inventory and others) measured at 6 and 12 months post ECMO cannulation. Analyses will be conducted on an intention-to-treat basis.

CONCLUSIONS

The NECTAR study investigates the safety and feasibility of NO as a drug intervention during extracorporeal life support and explores its efficacy. The study will investigate whether morbidity and mortality in patients treated with ECMO can be improved with NO. The intervention targets adverse outcomes in patients who are supported by ECMO and who have high expected mortality and morbidity. The study will be one of the largest randomized controlled trials performed among pediatric patients supported by ECMO.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12619001518156; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376869.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/43760.

Lung transplantation for pediatric pulmonary arterial hypertension-quo vadis?

In children with pulmonary arterial hypertension, lung transplantation illustrates a feasible treatment option once pharmacological therapy is exhausted. Timing of listing for lung transplantation in children remains difficult since hemodynamic deterioration often occurs abruptly and the time on the waiting list is usually hard to predict. Clear contraindications for lung transplantation are recent history of malignancies as well as irreversible end-organ failure. Generally, patients with pulmonary arterial hypertension in the absence of structural cardiac defects can safely undergo bilateral lung transplantation, combined heart-lung transplantation remains a procedure with a higher perioperative risk and should only be performed in selected cases with irreversible structural defects. Donor selection in recent years shows donors with extended criteria as well as lobar transplantation with good outcome, having the positive effect of broadening of the donor pool. Bridging to lung transplantation with veno-arterial ECMO treatment is feasible and has a good outcome in experienced transplant centers. Surgical considerations should include the risk of hemodynamic decompensation upon anesthesia induction and the need for extracorporeal support pre-, intra- and postoperative. Lung transplantation should be performed on veno-arterial ECMO support with either peripheral (>20 kg) or central cannulation (<20 kg). The surgical transplantation procedure includes the bronchial anastomosis as well as anastomoses of the pulmonary artery and the left atrium. Postoperative prolonged veno-arterial ECMO treatment for the immediate postoperative period allows for left ventricular remodeling given the new hemodynamic circumstances with lower pulmonary vascular resistance. Standard triple immunosuppression in most lung transplant programs currently includes steroids, mycophenolate mofetil and tacrolimus. Survival after pediatric lung transplantation for IPAH is comparable to pediatric lung transplants for other underlying diseases with a 1-year survival of approx. 80% and a 5-year survival of 64-65%. Therefore, evolving techniques in the field of lung transplantation led to overall improved survival prospects in children with end-stage pulmonary vascular disease.

Diagnostic Accuracy of Infection Markers to Diagnose Infections in Neonates and Children Receiving Extracorporeal Membrane Oxygenation

BACKGROUND

Infections represent one of the most common complications in patients managed on Extracorporeal Membrane Oxygenation (ECMO) and are associated with poorer outcomes. Clinical signs of infection in patients on ECMO are non-specific. We assessed the diagnostic accuracy of Procalcitonin (PCT), C-reactive protein (CRP) and White cell count (WCC) to diagnose infection on ECMO.

METHODS

Retrospective single center observational study including neonates and children <18 years treated with ECMO in 2015 and 2016. Daily data on PCT, CRP and WCC were assessed in relation to microbiologically confirmed, and clinically suspected infection on ECMO using operating characteristics (ROC) curves.

RESULTS

Sixty-five ECMO runs in 58 patients were assessed. CRP had the best accuracy with an area under the ROC curve (AUC) of 0.79 (95%-CI 0.66-0.92) to diagnose confirmed infection and an AUC of 0.72 (0.61-0.84) to diagnose confirmed and suspected infection. Abnormal WCC performed slightly worse with an AUC of 0.70 (0.59-0.81) for confirmed and AUC of 0.66 (0.57-0.75) for confirmed and suspected infections. PCT was non-discriminatory.

CONCLUSION

The diagnosis of infections acquired during ECMO remains challenging. Larger prospective studies are needed that also include novel infection markers to improve recognition of infection in patients on ECMO.

Perioperative complications in a paediatric cardiac surgery program with limited systemic resources

BACKGROUND

The perioperative complications rate in paediatric cardiac surgery, as well as the failure-to-rescue impact, is less known in low- and middle-income countries.

AIM

To evaluate perioperative complications rate, mortality related to complications, different patients' demographics, and procedural risk factors for perioperative complication and post-operative death.

METHODS

Risk factors for perioperative complications and operative mortality were assessed in a retrospective single-centre study which included 296 consecutive children undergoing cardiac surgery.

RESULTS

Overall mortality was 5.7%. Seventy-three patients (24.7%) developed 145 perioperative complications and had 17 operative mortalities (23.3%). There was a strong association between the number of perioperative complications and mortality - 8.1% among patients with only 1 perioperative complication, 35.3% - with 2 perioperative complications, and 42.1% - with 3 or more perioperative complications (p = 0.007). Risk factors of perioperative complications were younger age (odds ratio 0.76; (95% confidence interval 0.61, 0.93), previous cardiac surgery (odds ratio 3.5; confidence interval 1.33, 9.20), extracardiac structural anomalies (odds ratio 3.03; confidence interval 1.27, 7.26), concomitant diseases (odds ratio 3.23; confidence interval 1.34, 7.72), and cardiopulmonary bypass (odds ratio 6.33; confidence interval 2.45, 16.4), whereas the total number of perioperative complications per patient was the only predictor of operative death (odds ratio 1.89; confidence interval 1.06, 3.37).

CONCLUSIONS

In a program with limited systemic resources, failure-to-rescue is a major contributor to operative mortality in paediatric cardiac surgery. Despite the comparable crude mortality, the operative mortality among patients with perioperative complications in our series was significantly higher than in the developed world. A number of initiatives are needed in order to improve failure-to-rescue rates in low- and middle-income countries.

Venoarterial extracorporeal membrane oxygenation support for neonatal and pediatric refractory septic shock: more than 15 years of learning

The objective of the study was to report our institutional experience in the management of children and newborns with refractory septic shock who required venoarterial extracorporeal membrane oxygenation (VA ECMO) treatment, and to identify patient-and infection-related factors associated with mortality. This is a retrospective case series in an intensive care unit of a tertiary pediatric center. Inclusion criteria were patients ≤ 18 years old who underwent a VA ECMO due to a refractory septic shock due to circulatory collapse. Patient conditions and support immediately before ECMO, analytical and hemodynamic parameter evolution during ECMO, and post-canulation outcome data were collected. Twenty-one patients were included, 13 of them (65%) male. Nine were pediatric and 12 were newborns. Median septic shock duration prior to ECMO was 29.5 h (IQR, 20-46). Eleven patients (52.4%) suffered cardiac arrest (CA). Neonatal patients had worse Sepsis Organ Failure Assessment (SOFA) score, Oxygenation Index and PaO₂/FiO₂ ratio, blood gas analysis, lactate levels, and left ventricular ejection fraction compared to pediatric patients. Survival was 33.3% among pediatric patients (60% if we exclude pneumococcal cases) and 50% among newborns. Hours of sepsis evolution and mean airway pressure (MAP) prior to ECMO were significantly higher in the non-survivor group. CA was not a predictor of mortality. Streptococcus pneumoniae infection was a mortality risk factor. There was an improvement in survival during the second period, from 14.3 to 57.2%, related to shorter sepsis evolution before ECMO placement, better candidate selection, and greater ECMO support once the patient was placed.

CONCLUSION

Patients with refractory septic shock should be transferred precociously to a referral ECMO center. However, therapy should be used with caution in patients with vasoplegic pattern shock or S. pneumoniae sepsis. What is Known: • Children with refractory septic shock have significant mortality rates, and although ECMO is recommended, overall survival is low. • There are no studies regarding characteristics of infections as predictors of pediatric survival in ECMO. What is New: • Septic children should be transferred precociously to referral ECMO centers during the first hours if patients do not respond to conventional therapy. • Treatment should be used with caution in patients with vasoplegic pattern shock or S. pneumoniae sepsis.

Early changes in coagulation profiles and lactate levels in patients with septic shock undergoing extracorporeal membrane oxygenation

Background

To investigate the impact of coagulation profiles and lactate levels in patients with septic shock undergoing extracorporeal membrane oxygenation (ECMO).

Methods

A retrospective analysis of coagulation profiles, including disseminated intravascular coagulation (DIC) score, before and during 48 h of ECMO support [on day 0 (pre-ECMO), day 1, and day 2], was conducted in patients with septic shock undergoing ECMO.

Results

A total of 37 patients were included, and 15 (40.5%) patients survived. The initial DIC scores did not change in either the pre-ECMO overt-DIC (n=15) or non-overt-DIC (n=22) group after ECMO commencement. However, the DIC scores were significantly higher, at all three time-points, in non-survivors than in survivors. Additionally, the lactate levels improved considerably in the pre-ECMO non-overt-DIC group and in survivors during ECMO support, but not in the pre-ECMO overt DIC group or non-survivors. On a multivariate analysis, the pre-ECMO DIC score was significantly associated with hospital death [odds ratio (OR), 3.935; 95% confidence interval (CI), 1.170-13.230]. Receiver operating characteristic (ROC) curves revealed that the combination of pre-ECMO DIC score plus lactate level was the best predictor of hospital death (area under the curve, 0.879; 0.771-0.987); patients with combined scores >9.35 (the optimal cut-off) exhibited a three-fold higher mortality rate than did those with lower scores (81.8% vs. 26.7%, P=0.001).

Conclusions

During the early period of ECMO support, the coagulation profiles and lactate levels exhibited different trajectories in survivors and non-survivors. Furthermore, the pre-ECMO DIC score plus lactate level was the best predictor of hospital death.

Extracorporeal membrane oxygenation support for refractory septic shock in liver transplantation recipients

Purpose

This study was designed to assess the outcome of the extracorporeal membrane oxygenation (ECMO) in liver transplantation (LT) recipients with refractory septic shock and predict the prognosis of those cases.

Methods

From February 2005 to October 2012, ECMO was used in 8 cases of refractory septic shock. Laboratory values including lactate and total bilirubin level just before starting ECMO were obtained and sepsis-related organ failure assessment (SOFA) score, acute physiology and chronic health evaluation (APACH) II score and simplified acute physiology score (SAPS) 3 were calculated. Subsequent peak serum lactate and total bilirubin level, and SOFA score after 24 hours of starting ECMO were measured.

Results

Comparisons were made between survivors and nonsurvivors. ECMO was weaned off successfully in 3 patients (37.5%) and 2 patients (25%) survived to hospital discharge. Clinical scores including SOFA, APACH II, and SAPS3 and laboratory results including lactate, total bilirubin and CRP were not significantly different between survivor and nonsurvivor groups. Lactate level and SOFA score tended to decrease after ECMO support in survivor group and total bilirubin and CRP level tended to increase in nonsurvivor group.

Conclusion

Our findings suggest that the implantation of ECMO might be considered in highly selected LT recipients with refractory septic shock.

Venovenous Extracorporeal Life Support in Single-Ventricle Patients with Acute Respiratory Distress Syndrome

There is new and growing experience with venovenous extracorporeal life support (VV ECLS) for neonatal and pediatric patients with single-ventricle physiology and acute respiratory distress syndrome (ARDS). Outcomes in this population have been defined but could be improved; survival rates in single-ventricle patients on VV ECLS for respiratory failure are slightly higher than those in single-ventricle patients on venoarterial ECLS for cardiac failure (48 vs. 32-43%), but are lower than in patients with biventricular anatomy (58-74%). To that end, special consideration is necessary for patients with single-ventricle physiology who require VV ECLS for ARDS. Specifically, ARDS disrupts the balance between pulmonary and systemic blood flow through dynamic alterations in cardiopulmonary mechanics. This complexity impacts how to run the VV ECLS circuit and the transition back to conventional support. Furthermore, these patients have a complicated coagulation profile. Both venous and arterial thrombi carry marked risk in single-ventricle patients due to the vulnerability of the pulmonary, coronary, and cerebral circulations. Finally, single-ventricle palliation requires the preservation of low resistance across the pulmonary circulation, unobstructed venous return, and optimal cardiac performance including valve function. As such, the proper timing as well as the particular conduct of ECLS might differ between this population and patients without single-ventricle physiology. The goal of this review is to summarize the current state of knowledge of VV ECLS in the single-ventricle population in the context of these special considerations.

Extracorporeal Life Support for Pediatric Heart Failure

Extracorporeal life support (ECLS) represents an essential component in the treatment of the pediatric patient with refractory heart failure. Defined as the use of an extracorporeal system to provide cardiopulmonary support, ECLS provides hemodynamic support to facilitate end-organ recovery and can be used as a salvage therapy during acute cardiorespiratory failure. Support strategies employed in pediatric cardiac patients include bridge to recovery, bridge to therapy, and bridge to transplant. Advances in extracorporeal technology and refinements in patient selection have allowed wider application of this therapy in pediatric heart failure patients.

Nature of the underlying heart disease affects survival in pediatric patients undergoing extracorporeal cardiopulmonary resuscitation

OBJECTIVE

To describe the use of extracorporeal membrane oxygenation (ECMO) in acute resuscitation after cardiac arrest in pediatric patients with heart disease, with reference to patient selection and predictors of outcome.

METHODS

A retrospective medical record review was performed of all patients aged ≤21 years with heart disease who had undergone ECMO for cardiopulmonary resuscitation (ECPR) at Texas Children's Hospital from January 2005 to December 2012. The most recent Pediatric Overall Performance Category score was determined from the patients' medical records.

RESULTS

During the study period, 62 episodes of ECPR occurred in 59 patients, with 27 (46%) surviving to hospital discharge and 25 (43%) alive at the most recent follow-up visit. The overall survival to discharge for patients with myocardial failure (myocarditis, cardiomyopathy, or after transplantation) and structural heart disease was similar (40% vs 50%, P=.6). No patient with restrictive cardiomyopathy survived; 1 patient (13%) in ECPR group after late cardiac graft failure survived to discharge. Survival to discharge was greater for patients who were intubated (70%) at cardiac arrest (P=.001). The presence of pre-existing acute kidney injury at cardiac arrest (62%) was associated with greater mortality (P=.059). A Pediatric Overall Performance Category score of ≤2 (indicating good neurologic performance) was present in 68% of the survivors; 7 patients (87%) with a score>2 had abnormal imaging findings (P=.01).

CONCLUSIONS

ECPR was associated with modest survival in pediatric patients with heart disease; however, this was associated in part with the underlying disease and pre-existing comorbidities, including the presence of acute kidney injury.