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.