A 40 year old woman with no past medical history presented with 1 week of upper respiratory symptoms and viral prodrome (extremity swelling, myalgias, arthralgias). Left thoracoscopic lung biopsy confirmed cryptogenic organizing pneumonia but was complicated by left bronchopleural fistula and worsening severe hypoxemia/hypercarbia (arterial blood gas (ABG), 7.34; pCO2, 74; paO2, 44) despite rescue strategies (inhaled nitric oxide, prone positioning) and systemic corticosteroids. She was transferred to our institution and required emergent veno-venous extracorporeal membrane oxygenation (VV-ECMO) for respiratory failure (right femoral 28Fr Avalon cannula, right internal jugular vein [IJ] 23Fr Biomedicus cannula) with 2 Quadrox-ID adult oxygenators and Levitronix Centrimag device. Initial ECMO settings were sweep 2 L/min, flow 4.6 L/min, 3,500 RPM, heparin infusion (goal activated partial thrombosis time (aPTT) 40–50 sec), target hemoglobin 10 mg/dl, and platelets greater than 100,000. The ECMONet score before ECMO cannulation was 4 (cutoff 4.5 for mortality risk prediction).1 Tracheostomy was performed 8 days later.
To facilitate early mobility and reconditioning for possible lung transplantation, the right IJ catheter was exchanged for a bicaval dual-lumen Avalon cannula2 on ECMO day 35 (827 hours). Transient bi-femoral ECMO was initiated via a new left femoral 23Fr Biomedicus cannula which facilitated guidewire exchange via the existing right IJ 23Fr single lumen cannula to a 27Fr Avalon ECMO cannula (flow 3.5–4.0 L/min).
The patient remained neurologically fully intact with no evidence of hypoxic injury. Given her age and lack of pre-existing comorbidities, the patient and family requested continuation of all critical care support. She was able to tolerate moderate exercise with bicycle reconditioning. Chest computed tomography scans confirmed decreasing diffuse lung parenchymal consolidation consistent with resolving acute respiratory distress syndrome. Transient pulmonary hypertension (estimated right ventricle systolic pressure 73 mm Hg) required medical management; follow-up transthoracic echocardiogram showed an ejection fraction greater than 70% with hyperdynamic left ventricle, mild-to-moderate tricuspid regurgitation, right ventricular enlargement with moderately decreased right ventricular systolic function, and right ventricular systolic pressure of 37 mm Hg.
Serial evaluations were performed by the multidisciplinary lung transplant team for possible lung transplantation,3,4 but she was not deemed a transplant candidate due to high panel reactive antibody (PRA) (93%) and possible pulmonary infection; desensitization therapy was also considered.5 Infectious complications included enterococcus bacteremia and fungemia (Candida parapsilosis/glabrata); however, bronchoscopic alveolar lavage cultures demonstrated only mixed oral flora, and peripheral/ECMO circuit blood cultures were negative. No prophylactic antimicrobials were used.
Although oxygenation improved, refractory hypercapnia persisted. Additional discussions were held with the patient/family regarding medical futility, and trials off ECMO were started on ECMO day 240 (5,772 hours). Increasing respiratory acidosis remained the limiting factor to ECMO independence. The patient was trialed off VV-ECMO on day 260 (6,244 hours), and remained off support for 5 days. Decannulation was performed on ECMO day 265 (6,364 hours). She died 4 days later due to pulseless electrical activity (PEA) arrest due to severe hypercapnia and respiratory acidosis. Autopsy confirmed densely fibrotic lungs with multiple pneumatoceles and sequelae of severe acute respiratory distress syndrome.
No circuit or cannula complications occurred during prolonged ECMO. Both oxygenators were exchanged twice, on ECMO days 105 (2,516 hours) and 175 (4,188 hours) due to decreased flows and poor oxygenation gradients due to clot burden. One bigger better bladder exchange was required on ECMO day 90 (2,149 hours). All component exchanges occurred without complication. Despite transitioning to the Avalon cannula and the prolonged duration of ECMO, no complete circuit exchange was ever required (Figure 1; Table 1). No prior report, to the best of our knowledge, has documented such prolonged use of ECMO support with a single bicaval cannula. The cannula site (right IJ) was managed with purse-string sutures at the insertion site and stabilizing sutures superior to this, chlorhexidine-alcohol cleansing, dry gauze dressing, and coban self-adherent wrap around the forehead. No infection at the cannula insertion site occurred.
This case demonstrates that current technological advances in ECMO circuit safety and simplicity6 can result in prolonged ECMO support for respiratory failure without technical complications. This case highlights the challenges encountered with prolonged ECMO support in a patient who initially had evidence of partial native lung recovery, but failed to demonstrate further improvement. Transitioning patients to the Avalon cannula to improve early mobility7,8 is one strategy to optimize recovery in prolonged ECMO.9
Prolonged ECMO poses unique ethical issues in patients who are not lung transplant candidates. We currently lack optimal diagnostic modalities for critical assessment of native lung recovery. In patients supported by left ventricular assist devices for cardiac failure, assessment of myocardial viability and native cardiac structure/function is feasible using noninvasive testing10 although it does not always equate with clinical recovery.11 Future studies are warranted to determine reversibility of lung injury.
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Keywords:Copyright © 2015 by the American Society for Artificial Internal Organs
extracorporeal membrane oxygenation; acute respiratory distress syndrome; circuit exchange; futility; prolonged; lung recovery