Acute dyspnea is a common manifestation of oncologic emergency caused by tumor invasion or compression of central airway [1, 2]. Furthermore, asphyxia and respiratory failure, can result from central airways obstruction and is the cause of significant mortality [3, 7–10]. For those patients who usually present with a rapid decline in respiratory status, they must be stabilized before surgical procedure can be established [17]. These patients have a high rate of in-hospital mortality. Effective airway managements is very significant [23–25]. Respiratory support to optimize oxygenation is an important issue for critical airway obstruction [26, 27]. When the airway becomes narrowed, the life of the patients is threatened because of impending suffocation. In this emergency, traditional airway managements can be carried out quickly and provides immediate palliation for patients with symptomatic airway obstruction [11, 12]. However, the traditional airway managements and respiratory support treatment may be impossible and even dangerous for critical airway obstruction. Because traditional procedures possibly lead to complete airway obstruction and even the death of patients in this critical condition [14]. The life of patients can be saved by effective airway managements and quick surgical intervention [11, 12, 21, 22]. Although, the process of management and treatment is different to each medical center, for patients with severe central airway obstruction, the thorough knowledges of the pathology, physiology, diagnostic, and therapy options is required along with a multidisciplinary team (MDT) approach.
In recent years, the stent placement as an interventional treatment to palliate the critical airway obstruction caused by tumor is becoming widely accepted [7, 8, 10–12]. Because stent placement is safe, minimally invasive, well tolerated, and is increasingly used in various benign and malignant conditions characterized by central airway stenosis [13, 14, 26, 28]. However, stent placement also have defects, for example, it can increase the risk of major bleeding or complete bilateral obstruction of the main bronchus [29]. In our study, all cases have rapid onset with quick progress of tumor. Therefore, stent placement may have some unexpected risks, such as migration [28, 30, 31], fracture [28,31,], falling off and deformation [28] of stent, which can be caused by direct compression and extension of tumor. In addition, tracheal stent buckling and in-stent stenosis is also potential complications [32].
For our patients, the mean age is only 39 (range, 18–52) years. Although, patients can gain brief palliation from stent placement, surgical procedure is radical approach for young patients of tumor. MDT come up with an available approach: first, effectively managing airway to palliate dyspnea and improve hypoxia, simultaneously, providing adequate ventilatory (CO2 removal and oxygenation) to support surgical procedure.
However, in our all cases, conventional manners cannot solve the problem of hypoxia. Because of critical airway stenosis, tracheal intubation is unable to pass the narrow location of airway. Tracheostomy have high risk of major bleeding, and even suffocation to death of patient, due to high intensive vascularity of tumor.
Descending PaO2 value and clinical pictures of hypoxia revealed acute respiratory failure in all cases (3/3). To ensure adequate ventilation (CO2 removal) and oxygenation in unstable patients with difficult airway, ECMO as a novel significant device, had been recommended by ASA in 2022 [22]. According to Practice Guidelines for Management of Difficult Airway (2022 Edition) updated by ASA, ECMO is regarded as final lifeline for patient with difficult airway. In our cases(3/3), definite difficult airway was evaluated by emergency physicians and anesthesiologist. Immediately, we used early ECMO to manage difficult airway and support surgical procedure in ED. Previous clinical studies presented that use ECMO to ensure adequate ventilatory function (CO2 removal and oxygenation) in stent placement and bronchoscopy for patients with critical airway obstruction [13, 14, 28]. Their starting time of ECMO was intraoperative, and mainly solved the problem of intraoperative hypoxia. However, for central airway obstruction patients with difficult airway caused by neck and chest tumor, literature of using early ED-ECMO to manage difficult airway and support surgery is rare [5]. ECMO as a novel significant device for difficult airway management still need further clinical practice to demonstrate after 2022. In our study, all cases (3/3) received early ED-ECMO support with mode of venovenous extracorporeal membrane oxygenation (VV ECMO).
In brief, VV ECMO, cannulation site from femoral vein to internal jugular vein (or subclavian vein), was preferred for respiratory failure in thoracic surgeries. Previous studies have shown that VV ECMO can help to ensure adequate ventilatory function (CO2 removal and oxygenation) when performing stent placement in patients with central airway obstruction [13, 14, 28]. VV ECMO can provide time to plan and implement adequate treatment, thereby minimizing procedure-related complications [28]. Furthermore, surgeons feel more comfortable using VV ECMO when performing a high-risk procedure [14]. There is also clinical study that presented using venoarterial ECMO (VA ECMO) in patients with airway problems [20]. VA ECMO, cannulation site from femoral vein to femoral artery, was used usually when patients need circulatory support based on clinical and echocardiogram assessment in addition to respiratory support. The VA approach is recommended if the patient show cardiac arrest or shock, whereas the VV technique may be sufficient when only ventilation and oxygenation are required. Compared with VV ECMO, the VA ECMO reduces pulmonary blood flow and is associated with a higher incidence of neurologic events (eg, cerebral infarction, microemboli, or hemorrhage), cognitive impairment, and major local complications such as arterial dissection, pseudoaneurysm formation, or limb ischemia [5, 20]. For our cases, the VV ECMO may be more suitable than VA ECMO to manage difficult airways for patients who require adequate oxygenation and ventilation to emergency surgery. ECMO-related complication rates of 24–55% have been reported, including potentially life-threatening complications such as bleeding, hemolysis, air leakage and thrombosis [28, 33, 34]. Our all cases received disseminated intravascular coagulation (DIC) test. 2 patients (2/3) showed rising D-dimer value. We preventively used anticoagulation (Heparin and futhan) to guard against thrombosis. In our cases, the mean duration of ECMO was 3 hours (range: 1.5–4.5 hours), our mean duration time was shorter than 15 ± 18 hours (range: 1–51 hours) [5], 20.9 hours (range: 2.2−113.4 hours) [14] and 42 hours (range: 5−121 hours) [28] of published literature. And there was no any ECMO-related complication in our all cases from early ED-ECMO initiation to weaning off ECMO successfully. This results may associate with short running time of ECMO and adequate prevention of ECMO-related complications.
Surgery is important treatment for oncological emergencies. All cases (3/3) were subjected to surgical procedure and then pathological examination demonstrated the etiology of critical airway stenosis caused by tumors. We showed a shorter mean in-hospital time than published studies [5, 14, 28]. Hypoxia may increases the potential risk for cardiovascular, pulmonary, central nervous injuries and surgical intolerance. In our study, 2 patients (2/3) showed chest pain and positive myocardial markers that may revealed the subtler myocardial damage. Early ED-ECMO initiation may protect cardiopulmonary function from hypoxia to increase intraoperative tolerance. All patients were successfully discharged from hospital. However, the data of using early ED-ECMO to manage difficult airway for central airway obstruction caused by neck and chest tumor is rare after ASA recommended ECMO as a novel significant device to manage difficult airway [22]. Our study further demonstrated the feasibility of ECMO in difficult airway management, and showed that ECMO can provide security for airway surgical procedure.
Interpretation of our results is limited by the single-centre study design and small sample size. There are no comparisons between groups, limiting our ability to understand the effect of early ED-ECMO support during difficult airway management. Given the preemptive nature of ED-ECMO initiation in nearly all cases and the lack of a control group, we cannot know for certain whether our surgical procedure could have been accomplished without ECMO support. Our data was offered by single-medical team. For difficult airway management, such as critical airway stenosis caused by neck and chest tumor, no control group can be generated retrospectively as ECMO was provided to all critical airway stenosis cases at our centre. To compare a lower-risk airway cases would expose the study to selection bias. Furthermore, the sample size is very small (n = 3), any meaningful comparison would be limited. Given our small sample size, and the rare oncological emergencies, our study purpose was to demonstrate safety and feasibility for using early ED-ECMO to manage difficult airway and support surgery. ECMO incurs risk and is resource intensive. Meanwhile, our study showed emergency of critical airway stenosis caused by tumor is high-risk, grassroots hospitals lacked ECMO device and experience, quickly transfer patient to superior hospital is very important.