Am J Transplant. 2015 Aug;15(8):2256-60.

Successful Semi-Ambulatory Veno-Arterial Extracorporeal Membrane Oxygenation Bridge to Heart–Lung Transplantation in a Very Small Child

Wong JY1, Buchholz H2, Ryerson L3, Conradi A4, Adatia I4, Dyck J5, Rebeyka I2, Lien D6, Mullen J2.
  • 1Department of Pediatrics, Division of Pediatric Respiratory Medicine, McMaster University, Hamilton, Ontario, Canada.
  • 2Department of Cardiac Surgery, University of Alberta, Edmonton, Alberta, Canada.
  • 3Department of Pediatrics, Pediatric Cardiac Intensive Care Unit, University of Alberta, Edmonton, Alberta, Canada.
  • 4Department of Pediatrics, Pediatric Intensive Care Unit, University of Alberta, Edmonton, Alberta, Canada.
  • 5Department of Pediatrics, Division of Pediatric Cardiology, University of Alberta, Edmonton, Alberta, Canada.
  • 6Department of Medicine, Division of Respiratory Medicine, University of Alberta, Edmonton, Alberta, Canada.

 

Correspondence:

Dr. Jackson Wong
Division of Pediatric Respiratory Medicine
Department of Pediatrics
Faculty of Health Sciences
1280 Main Street West, HSC 3A
Hamilton, ON, Canada  L8S 4K1
wongjack@mcmaster.ca

 

Abstract

Lung transplantation (LTx) may be denied for children on extracorporeal membrane oxygenation (ECMO) due to high risk of cerebral hemorrhage. Rarely has successful LTx been reported in children over 10 years of age receiving awake or ambulatory veno-venous ECMO. LTx following support with ambulatory veno-arterial ECMO (VA ECMO) in children has never been reported to our knowledge. We present the case of a 4-year-old, 12-kg child with heritable pulmonary artery hypertension and refractory right ventricular failure. She was successfully bridged to heart-lung transplantation (HLTx) using ambulatory VA ECMO. Initial resuscitation with standard VA ECMO was converted to an ambulatory circuit using Berlin heart cannulae. She was extubated and ambulating around her bed while on VA ECMO for 40 days. She received an HLTx from an oversized marginal lung donor. Despite a cardiac arrest and Grade 3 primary graft dysfunction, she made a full recovery without neurological deficits. She achieved 104% force expiratory volume in 1 s 33 months post-HLTx. Ambulatory VA ECMO may be a useful strategy to bridge very young children to LTx or HLTx. Patient tailored ECMO cannulation, minimization of hemorrhage, and thrombosis risks while on ECMO contributed to a successful HLTx in our patient.

KEYWORDS: Clinical research; extracorporeal membrane oxygenation (ECMO); lung disease; lung transplantation; pediatrics; practice; pulmonology

PMID: 25872800

 

Supplement

Extracorporeal membrane oxygenation (ECMO) is a form of extracoporeal life support. The veno-arterial (VA) configuration is designed to support the entire cardiopulmonary circulation in the event of a combined cardiopulmonary failure. In our patient, her arterial pulmonary arterial hypertension (PAH) was at an advanced state and she failed to respond to all medical treatment. A sudden pulmonary hypertensive crisis necessitated an emergency VA ECMO support via a conventional right neck approach (right carotid artery and internal jugular vein cannulation). Children supported on ECMO routinely require considerable sedation[1], [2] as accidental decannulation can result in immediate cardiopulmonary arrest and death. Prolonged sedation and mechanical ventilation on ECMO however have many drawbacks: pulmonary atelectasis, ventilator-associated pneumonia, myopathy, and inability to participate in rehabilitation, cogitative and emotional assessment in preparation of transplantation.

Many questions emerged during the care of our patient. Should young children with severe PAH be candidates for ECMO? Once a patient with PAH is put on ECMO the chance of a sustained recovery is remote even if weaning from ECMO is possible. Kirshbom[3] reported 14 patients supported on VA ECMO waiting for lung/heart-lung transplantation; only 1 survived to transplant. Another report by Puri[4] showed 40% of 15 children waiting for lung transplantation (LTx) could be weaned off VA ECMO. However, all needed to proceeded to LTx given the high stake of mortality without it. Overall survival post-LTx to discharge was only 40% and 63% experienced major complications (bleeding, reexploration, major infection, and stroke). VA ECMO bridged to LTx was therefore discouraged. The appropriateness of treating a child with severe PAH with ECMO is therefore questionable as without LTx their outlook would be dismal.

Will our patient survive to transplantation given the scarcity of young donors? The longer the wait on ECMO to transplant the more likely complications will happen. Overall mortality in patients waiting for LTx is around 25%[5] with increased risks in those who are treated on ICU[6] and those with raised pulmonary vascular resistance[7]. If organs become available from a marginal donor what would be the lowest limit of acceptability given the urgency for transplant? A second donor organ offer may never happen. What level of experience is required before a pediatric transplant center should offer ECMO to LTx? Would our patient survive an inter-hospital transfer on ECMO to another centre with greater experience? Will other transplant institutions accept a small child on VA ECMO for LTx at all?

Sudden death[8], [9] is a recognized complication of PAH. Our patient was fortunate that she was put on VA ECMO successfully even though it was unplanned. Should PAH patients not responding to maximum medical therapy be treated electively with VA ECMO and listed for urgent LTx? Weaning these patients from ECMO may not be possible and they may die on ECMO without transplant due to organ shortage. Some believe ECMO should only be used for patients needing emergency ECMO. Emergency ECMO may only be possible for patients who are already treated in the cardiac ICU/OR environment. Patients succumbed elsewhere may never have a chance. Furthermore, patients may sustain irreversible damage despite CPR while emergency ECMO equipment and personnel are being mobilized.

Ambulatory ECMO has many advantages. To allow this in a small child, the ECMO cannulae and connections need to be secure and small enough. This was made possible for our patient using cannulae for artificial heart connecting the right atrium and the ascending aorta with an in series centrifugal pump and an adult oxygenator. Risk of clots in the circuit was reduced by eliminating all shunts, bridges, connectors, or pig tails from the circuit and by using intravenous bivalirudin (not commonly used in ECMO). As hemorrhage is a main cause of mortality4, coagulation status was checked throughout the day and a heart-lung transplant was preferred as it can be performed more quickly – hence shorter anticoagulation with cardiopulmonary bypass.

A marginal heart-lung block became available for our patient but it had many unfavourable features: double size mismatch, bruised left lung with low pulmonary venous pO2 and prolonged ischaemic time. Contused lungs are considered highly unfavourable for transplantation[10] and most transplant center would refuse such organs. Post implantation, partial volvulus of the left lung occurred and necessitated further cardiopulmonary bypass and intensive resuscitation. The chest was stented open in order to accommodate the oversized organs. Soon after returned to PICU the patient had a prolonged cardiac arrest. She also developed severe primary graft dysfunction responded to bronchoscopic surfactant treatments. We also had to ventilate the patient using parameters for the double sized donor in order to achieve adequate ventilation.

Our case had numerous hurdles in the pre-, peri- and post-operative period. The ability to employ a semi-ambulatory VA ECMO was unusual and despite that it was not a fix-it-all treatment. It was part of a series of innovative and inter-dependent treatments. Finally, for a trouble-free ambulatory ECMO, the patient must be developmentally mature enough to co-operate and be able to walk. At age 4 years, our patient is likely the youngest child that could meet these requirements. Considerable effort was also made to encourage play therapy during ECMO to maintain morale and cooperation. To our knowledge she is the first pediatric patient, and the second human case, reported on successful ambulatory VA ECMO treatment. We had one chance to save a life in a creative and audacious manner; it was successful with a touch of serendipity.

 

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[8] D. M. Ackermann and W. D. Edwards. Sudden death as the initial manifestation of primary pulmonary hypertension. Report of four cases. American Journal of Forensic Medicine & Pathology 8 (2):97-102, 1987.

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[10] Mallory GB, Jr., Schecter MG, Elidemir O. 2009. Management of the pediatric organ donor to optimize lung donation. Pediatr Pulmonol 44(6):536-46.

 

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