Veno-Venous Extra-Corporeal Membrane Oxygenation (ECMO) in a Child with Hemoptysis and Fontan Circulation

Background: Extracorporeal membrane oxygenation is a rescue life support technique used in life threatening conditions of refractory respiratory and/or cardiac distress. Indication for extracorporeal life support in children depends on age and varies from pulmonary to cardiac pathologies. In some cases, it may be used as a bridge to a therapeutic procedure. We described here the management of respiratory failure due to hemoptysis in a child with a Fontan circulation and veno-venous extracorporeal membrane oxygenation which served as a bridge to angio-embolization. Hemoptysis can be a life threatening condition which can lead to hypovolemic shock and impaired gio-embolization. Results: Hemoptysis due to diffuse intra-alveolar hemorrhage from collateral circulation was successfully treated in this young patient with pulmonary vascular embolization. This allowed to wean the patient from extra-corporeal membrane oxygenation. Conclusion: Veno-venous ECMO can be life-saving as a bridge to angio-embolization for severe hemoptysis in patients with Fontan circulation. The reported case allows to underline that our multidisciplinary approach in this complex pediatric patient surely participated to improve outcome.


Introduction
Extracorporeal membrane oxygenation (ECMO) in the neonatal and pediatric population has been developed more than 45 years ago [1]. This extracorporeal life support (ECLS) technique has been used in life threatening situations of respiratory and/or cardiac failure as a rescue therapy. Several indications for ECMO implantation have been reported and depend on patient age [1]. These included asthma, bronchiolitis, pneumonia, non-pulmonary infection, drowning, inhalation, foreign body, trauma, congenital heart disease, congenital diaphragmatic hernia, meconium aspiration syndrome, persistent pulmonary hypertension of the newborn, respiratory distress syndrome and sepsis [1].
Other indications for ECLS are endotracheal tumor resection, tracheal resection, complex tracheoesophageal fistulae, dislodged stents, foreign body removal, control of hemoptysis, debridement of papillomatosis, relief of external compression, difficult or impossible one lung ventilation, mediastinal masses and lung transplantation [2].
Survival rate at discharge from hospital when ECMO is used for cardiac disease in neonates and older children is 42% and 41% respectively [3]. Survival at hospital discharge for respiratory disease, when ECMO is used in neonates and older children, is 74% and 58%, respectively [3]. Veno-venous ECMO is used for primary refractory respiratory failure. ECMO system is constituted by a centrifugal pump, a membrane oxygenator and an integrated circuit of tubing connected to the patient by two canulas, drainage and infusion.
In the veno-venous ECMO (VVECMO), the drainage canula is inserted through the right femoral vein into the inferior vena cava in order to drain patient blood for oxygenation and carbon dioxide (CO 2 ) removal by the membrane Open Journal of Pediatrics oxygenator; the infusion canula is inserted through the right jugular vein and to the right atrium in order to reinject oxygenated blood into the patient and to the left heart and systemic circulation [2].
Veno-arterial ECMO (VAECMO) is used for hemodynamic and circulatory support with or without respiratory dysfunction. In this setting, the drainage canula is usually inserted through the femoral vein in order to bring patient blood to the membrane oxygenator; the arterial canula is usually inserted through the common femoral artery to reinject oxygenated blood coming from membrane oxygenator into the aorta. With this ECLS, the lungs and the right ventricle are unloaded [2]. VVECMO and VAECMO have been used as a bridge to palliative or corrective surgery in children with congenital heart disease and demonstrated a survival rate at discharge from hospital of more than 60% [4].
VVECMO has been used in children with diffuse intra-alveolar hemorrhage as a bridge to treatment with successful results [5] [6].
We report here the management of hemoptysis with VVECMO in a 16 year-old boy with a univentricular heart and a Fontan circulation. In this particular setting, both vena cava, disconnected from the heart, drain systemic venous blood directly into the pulmonary arteries.

Case Report
A 16 year-old boy was admitted for hemoptysis in the pediatric intensive care unit (PICU) on 24 January 2019 in Reims. History was characterized by a type IC tricuspid atresia. He had a partial cavo-pulmonary anastomosis with section-ligation of the main pulmonary artery at the age of 3 months and Fontan completion surgery with a fenestrated 18 mm extracardiac conduit at the age 18 months. Before the present one, he had already experienced 4 episodes of hemoptysis 5, 2.5 and 1.5 years earlier for which he had underwent 3 successful angio-embolizations. The fourth episode of hemoptysis which had occurred 1.5 years before the present one spontaneously resolved after antivitamin K therapy withdrawal, previously administered because of a right atrial thrombus. He had no history of allergy and was taking 75 mg of aspirin as sole medication.
At admission to the PICU the patient was hemodynamically stable with normal hemoglobin levels and coagulation laboratory tests. A thoracic computed tomographic scan (CT-scan) showed intra-alveolar hemorrhage of the lingula, inferior and superior lobes and three right intra-atrial partially calcified thrombi.
Vascular embolization was decided as treatment to stop bleeding. Just before going to the interventional radiologic ward, the patient suddenly presented massive hemoptysis requiring selective intubation of the left bronchus with a left Carlens tube to exclude the left bleeding lung; this was realized under general anesthesia with etomidate and after topic anesthesia of the glottis with lidocaine.
The patient was then transferred to the interventional ward for angio-embolization.
He was spontaneously breathing with mild pressure support under sedation with Open Journal of Pediatrics propofol and ketamine which was switched to volume control ventilation because of fatigue.
At this time, angio-embolization did not succeed to control the bleeding. The patient developed severe respiratory acidosis with a pH of 6.9 and PaCO 2 of 145 mmHg, despite mechanical ventilation with volume control and adequate sedation. Taking into account the cardiac surgical history, the complex congenital heart disease, the risk of severe hypercarbia and the ongoing hemoptysis, we decided to urgently assist patient with ECMO. A veno-venous ECMO implantation was realized by the cardiac surgeon with canulation of the right femoral vein for blood drainage and the right internal jugular vein for blood reinjection. Finally, the patient had a favorable outcome and was discharged home with 100 mg per day of aspirin and 1000 mg twice daily of levetiracetam.

Discussion
Although major aorto-pulmonary collateral arteries (MAPCAs) are usually found in pulmonary atresia with ventricular septal defect, they are not uncommon in univentricular hearts [7] and can be responsible for severe hemoptysis [8] as it was the case in our patient.
Angio-embolization was the first therapeutic choice in this patient because In the present case, the left lung was not ventilated because of massive hemorrhage for which a selective bronchial intubation was necessary to exclude the bleeding lung but also to protect the non-bleeding lung.
Hypercarbia can occur due to the non-ventilated but perfused lung. In the Fontan circulation mild hypercarbia of 40 -45 mmHg may be beneficial because it increases cerebral blood flow and thus can increase flow to the pulmonary circulation [9]. However, severe hypercarbia can increase pulmonary vascular resistance and thus compromise blood oxygenation. If hypoxemia occurs, it may cause hypoxic pulmonary vasoconstriction which increases pulmonary resistance and compromises Fontan circulation [9].
Veno-venous ECMO was performed to reduce hypercarbia, respiratory acidosis and prevent hypoxemia due to intra-alveolar hemorrhage which could have had serious adverse outcome in this patient's hemodynamic status. The extracorporeal life support in this setting was used as a bridge to treatment of the pulmonary hemorrhage with angio-embolization. Veno-venous ECMO has been described as a bridge treatment in diffuse intra-alveolar hemorrhage and has been shown to be efficient in this setting [7] [10]. This technique has also been used in other primary respiratory failures with good results in children [11].
Veno-arterial ECMO has been used for ECLS in Fontan circulation with cardiac failure described as "failing Fontan" [12]. This condition can have different etiologies such as arrhythmias, thrombosis of cavo-pulmonary anastomosis, increase in pulmonary vascular resistance and diastolic and systolic univentricular dysfunction. The efficiency of ECMO in the failing Fontan depends on venous drainage [12]. Survival after ECMO in a failing Fontan varies from 35% to 50% depending on the studies [12]. The patient described in the present case report did not have a failing Fontan circulation as demonstrated by our echocardiographic findings prior to ECMO instauration. Diastolic and systolic functions were normal. There was no arrythmia and the cavo-pulmonary anastomoses were widely permeable.
Indication for ECMO was primary respiratory failure secondary to hemopty-  [13].
In Fontan patients, a high VVECMO output is necessary to maintain a venous pressure high enough to ensure pulmonary circulation and single ventricle preload. We believe that echocardiographic monitoring of pulmonary blood flow and ventricular filling is mandatory for proper VVECMO settings in these patients. It has been previously reported that if veno-venous ECMO is not effective it can be converted to a veno-arterial ECMO [12].
In the present case, VVECMO was efficient to bridge the patient to angioem-  [2]. Incidence of bleeding is 70.2% and 37.5% for thrombosis [18] in children under ECMO.
In the present case, the patient had seizures and peripheral ischemic lesions with favorable outcome. Although MRI and CT-scan cerebral imaging did not show evidence of ischemic lesions, emboli remain highly suspected. ECMO, repeated catheterization sessions and intracardiac thrombus were potential causes of emboli which could have explained the clinical presentation.

Conclusions
We reported a complex and critical congenital case of a young patient successfully treated with VVECMO during severe hemoptysis in a context of a univentricular heart with Fontan circulation. In this particular and critical situation, a multidisciplinary therapeutic approach of this patient was mandatory to improve his outcome. Open Journal of Pediatrics The innovating aspect of this case report was the use of a VVECMO as a bridge to angioembolization in a patient with a Fontan circulation presenting hemoptysis and the use of transthoracic echocardiographic aortic blood flow peak velocity time integral variation to monitor fluid responsiveness for fluid and hemodynamic therapy in a complex congenital heart disease.

Funding
There was no funding.

Ethic Approval
The parents give informed consent and permission to publish this case report.