Discussion:
Critical tracheal stenosis caused by endotracheal tumors or extrinsic compression by mediastinal masses, if not recognized preoperatively and inadequately managed intraoperatively, may lead to loss of airway control; in the absence of alternative means of ventilation/oxygenation such as ECMO, this is often associated with significant morbidity/mortality. A high index of suspicion based on the preoperative imaging coupled with clinical presentation of respiratory stridor and significant dyspnea at rest should alert treating physicians of a potential airway emergency and the need for appropriate preoperative planning. This includes discussion with anesthesiology colleagues and consultation with members of the ECMO team, either for standby in the operating room at the time of endotracheal intubation or elective placement of a VV ECMO circuit and institution of flow to achieve total ventilatory/oxygenation support, prior to safe endotracheal intubation, as we presented in this case. Heparin-coated VV ECMO circuits may mitigate the need for systemic heparinization, which can facilitate surgery with minimal blood loss4. The indications for VV ECMO have expanded and currently include ARDS, lung rest (e.g. airway obstruction or pulmonary contusion), lung transplantation, lung hyperinflation (i.e. status asthmatics), pulmonary hemorrhage and congenital diaphragmatic hernia1. The expanding use of ECMO as life support for patients with acute respiratory failure was popularized after the 2009 randomized controlled CESAR trial demonstrating patients with acute respiratory distress syndrome (ARDS) who were allocated to the VV ECMO group (n = 90 patients) had higher 6 month survival rates without disability versus conventional ventilator-based strategies (n = 90 patients; 63% vs. 47%, p = 0.03, respectively)5. A case report and systemic review by Malpas and colleagues demonstrated the essential role of ECMO or cardiopulmonary bypass (CPB) as the a priori method of oxygenation during difficult airway management6. They identified 45 cases of critical airway obstruction caused by a wide range of airway pathologies including tracheal tumors, tracheal stenosis, head-neck cancers and mediastinal masses being the most common. All patients underwent ECMO or CPB prior to induction of anesthesia and the extracorporeal support was either used only for establishment of tracheal intubation and ventilation or the entire operative case.
In summary, appropriate coordination with an ECMO team at a tertiary referral center allows for careful preoperative planning to resect tumors causing critical airway stenosis. The planned use of VV ECMO, not as a rescue option, but as part of an algorithm for difficult airways provides security in the surgical resection of mediastinal tumors.