P . Anton-Martin et al .: J Extra Corpor Technol 2025 , 57 , 2 – 8 3
pediatric heart disease patients with respiratory failure , its use is limited in this population due to the potential for worsening cardiopulmonary interactions [ 14 ]. Furthermore , the outcomes of pediatric patients with heart disease who received HFOV as a ventilatory strategy for PH before ECMO cannulation remain unclear . Our study aimed to evaluate predictors of survival to hospital discharge in pediatric cardiac patients with PH requiring ECMO .
Materials and methods Study setting and design
This study was an observational , retrospective cohort study that utilized the Extracorporeal Life Support Organization ( ELSO ) registry database . The Institutional Review Board at the University of Tennessee Health Science Center reviewed the study and determined it to be Not Human Subjects Research status .
Study population and data collection
All neonatal and pediatric cardiac patients 18 years of age with PH supported on ECMO between January 1 , 2011 , and December 31 , 2020 , were included in this study . PH was identified using the International Classification of Diseases 9 and 10 codes utilized to identify secondary diagnoses in the ELSO database . ECMO runs with inaccurate data as well as secondary and subsequent runs were excluded . We also excluded those patients who developed PH as an ECMO complication . The data extracted from the ELSO registry database included information regarding demographics , cardiac diagnoses , use of cardiopulmonary bypass ( CPB ) before cannulation , preextracorporeal life support , ECMO support , complications , and outcomes . Cardiac diagnoses were dichotomized as CHD and heart failure ( cardiomyopathy , myocarditis , heart transplant , etc .). Ventilator support was grouped as conventional ventilation , HFOV , and other ventilator modes . The severity of illness indicators available in the dataset at the time of ECMO initiation included pH , oxygenation index ( OI ), mean blood pressure , arrest before ECMO , nitric oxide use , and renal replacement therapy use . ECMO type was grouped into venovenous and veno-arterial ( VA ) and ECMO indication was categorized into pulmonary , cardiac , and extracorporeal cardiopulmonary resuscitation ( ECPR ). Year of ECMO data was also available . However , since most of the patients were clustered over the last 5 years , we did not perform any analysis to evaluate the influence of temporal trends on the outcomes ( Fig . 1 ).
Aims , hypothesis , and outcomes
We aimed to characterize the population of neonatal and pediatric cardiac patients with PH supported on ECMO and to describe factors associated with improved survival . We hypothesized that these patients would benefit from HFOV before cannulation . The primary outcome was survival to hospital discharge . Secondary outcomes were ECMO duration , hospital length of stay ( LOS ), and mechanical ventilation ( MV ) duration .
Statistical analysis
Continuous variables were described using medians and interquartile ranges ( IQR ) while frequencies and proportions were used for categorical variables . Bivariate analyses were conducted using Chi-squared tests and Wilcoxon-Mann- Whitney tests to ascertain the association between covariates and outcomes . Multivariable logistic regression models were used to analyze the effects of potential variables on survival to hospital discharge . Backward selection with an alpha level of removal of 0.05 was utilized . Odds ratios ( OR ) and 95 % confidence intervals were calculated . All p-values were 2-sided and p < 0.05 was considered statistically significant . Statistical analyses were performed using SAS ( version 9.4 , SAS Institute Inc ., NC , USA ).
Results Patient population A total of 161 cardiac neonates and children with PH supported on ECMO between January 2011 and December 2020 were included in this study . The median age and weight of the cohort were 40 days ( IQR 7.3 – 452 ) and 4.06 kg ( IQR 3 – 9.36 ). Neonates (< 30 days old ) accounted for 48.1 % of patients . Males were predominant ( 59 %). CHD accounted for 77.2 % of diagnoses . The most frequent cardiac diagnoses were transposition of the great arteries ( 17.3 %), hypoplastic left heart syndrome ( 15.4 %), double outlet right ventricle ( 10 %), cardiomyopathy ( 8.6 %), and heart transplant ( 6.2 %). Survival to hospital discharge reached 36 % ( Table 1 ). Support before ECMO , characteristics , and complications
Before ECMO cannulation , most patients were ventilated in conventional modes ( 79.7 %), followed by HFOV ( 11 %) and other ventilator types ( 6.8 %). VA support was the most frequent ECMO mode ( 94.4 %) and cannulation via ECPR occurred in 23.5 % of patients . The most frequent ECMO complications in the cohort included the need for renal replacement therapy ( 44 %) and surgical site bleeding ( 25.3 %). Table 1 summarizes the above data .
Patients ventilated on conventional vs HFOV before ECMO
Patients ventilated on HFOV before ECMO had a higher OI ( p < 0.001 ), were more often classified as pulmonary ECMO type ( p < 0.001 ) and exhibited reduced utilization of CPB ( p = 0.018 ) and central cannulation ( p = 0.041 ). Table 2 provides a comparison of pre-ECMO support , characteristics , and complications between patients who received conventional ventilation vs HFOV prior to ECMO cannulation .
Survivors and non-survivors to hospital discharge No differences were observed in demographic and diagnostic characteristics between both groups . There was a significantly higher use of HFOV pre-cannulation in survivors