Introduction

Clinically, central airway obstruction caused by neck and chest tumors is very dangerous oncological emergency1,2, and difficult to manage for emergency departments (ED)3. Complex anatomical location between trachea and tumors could result in difficult airway4. Acute dyspnea is the most apparent symptom to such patients. Hypoxemia and even asphyxia are major cause of death. Providing effective airway managements and emergency surgical interventions is the key to save these patients5,6.

Traditional airway managements, including nasal oxygen inhalation, respiratory mask, implanted hard and soft endoscopy, laryngeal mask, tracheal intubation, and even tracheotomy, are only suitable for patients with mild obstructed airway7. Traditional approaches usually have only limited effect and even life-threating for patients with critical obstructed airway3,8. Severe central airway obstruction caused by neck and chest tumors show high mortality7,8,9,10. Direct compression of adjacent tumor is the most common cause11,12. Providing adequate ventilation (CO2 removal and oxygenation) and emergency surgical interventions can play a significant role to manage such patients13,14.

Extracorporeal membrane oxygenation (ECMO) has been used to manage cardiac and respiratory failure for more than 40 years. It has also emerged as a useful cares of short-term support for hypoxic patients with nontraditional indications, such as upper airway surgery6,15,16, lung transplantation17, pulmonary embolism18 and airway foreign body19. ECMO can help to ensure adequate ventilation when performing surgical therapies20. American Society of Anesthesiologists (ASA) presented an updated version of the Practice Guidelines for Management of Difficult Airway in 2022. Compared with 2013 version21, ECMO as a novel significant device, has been recommended for managing difficult airway22. However, there is few report of early ECMO initiation to manage difficult airway and provide adequate ventilation for such patients with central airway obstruction caused by neck and chest tumors. We study and present the availability of early ECMO initiation as a bridge for these patients to emergency surgery operations.

Methods

All methods were performed in accordance with the relevant guidelines and regulations, and approved by the Ethics Committee on Biomedical, West China Hospital of Sichuan University (Number: 2021-233). It was a single-center, retrospective small sample study based on real-world. Informed consents were obtained from all patients when they were admitted to our emergency center. The center of West China Hospital, Sichuan University had professional ECMO team and respiratory ICU.

Traditional respiratory supports had extremely limited effect for severe central airway obstruction patients caused by neck and chest tumors.

To explore feasibility of early ECMO initiation as an effective first-aid manner for these patients, we reviewed clinical records of patients between January 2021 and December 2021. Severe central airway obstruction caused by neck and chest tumors, unfeasible traditional respiratory supports and early ECMO intervention were eligible for inclusion. Patients were selected by our respiratory MDT, based on criteria of Practice Guidelines for Management of Difficult Airway (2022 version), presented by American Society of Anesthesiologists (ASA)21,22. 3 patients were completely eligible for inclusion standard. There was no control group. Because it was life-threating for severe central airway obstruction patients caused by neck and chest tumors to use traditional manner. Establishing adequate ventilation was safest for patients. Therefore, we were unable to set control group with traditional manner to compare with ECMO group. We obtained the demographic characteristics, clinical features, blood tests, radiological managements, surgical procedures, pathological examinations, ECMO details and survival outcomes to make a true presentation. Presenting how to build emergency ventilation for severe central airway obstruction patients caused by neck and chest tumors was our primary objective. Central airway obstruction caused by neck and chest tumors is very dangerous oncological emergency with increasing incidence. Discussing an effective first-aid plan to save their life was our secondary objective.

In this part, we showed detailed clinical experience to make that every center could repeat this procedure in the same manner. The primary step was central airway obstruction caused by neck and chest tumors verified by CT performed before treatment. The CT outcomes were interpreted by experienced radiologist or emergency physician. Evaluation and management of difficult airway were performed by anesthesiologist at patient bedside. If traditional managements was useless and even life-threating, ECMO as a significant device could be recommend to provide adequate ventilation. Under ECMO support, surgical procedures were carried out. Conflict between anticoagulation and surgical bleeding should be pay attention. Pharmacokinetics of heparin was important. Kidney played a key role in heparin clearance. Renal function test was significant before using heparin. In our center, firstly, heparin-free was attempted when ECMO was running to provide adequate ventilation. Secondly, coagulation function was tested until reaching surgical standard. Thirdly, surgical procedures were performed during ECMO running without heparin. Lastly, anticoagulation was restarted after operations with acceptable surgical bleeding. All details and variables were recorded.

Results

3 patients with severe central airway obstruction caused by neck and chest tumors were admitted to our center, who received early ECMO support with the Green Passage (Fig. 1).

Figure 1
figure 1

Green passage for patient with possible difficult airway. ED, emergency departments; ER, emergency room; ECG, electrocardiogram; ECMO, extracorporeal membrane oxygenation; MDT, multidisciplinary team.

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Of 3 patients (Table 1), 1 was male, 2 were females. The mean age was 39 (range, 18–52) years. Acute dyspnea was common symptom for all cases. 2 patients presented cyanosis of lips and three concave sign.

Table 1 Clinical characteristics and treatments of patients.
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2 patients showed chest pain. 1 patient had fever. CT scan was performed in 3 patients with imaging abnormal findings. In total, critical central airway stenosis was obvious diagnosis for 3 patients. In detail, case1 was believed to have been caused by neck tumor, case 2 by mediastinal tumor of chest, and case 3 by airway tumor of chest (Fig. 2).

Figure 2
figure 2

CT scans of severe central airway obstruction patients caused by neck and chest tumors before ECMO (Axial view). White arrow shows tumors. Black arrow shows severe central airway obstruction. Thickening of thyroid isthmus, multiple enlarged neck lymph nodes and critical airway stenosis of Case 1 (a, b). Mediastinal huge mass and critical airway stenosis of Case 2 (c, d). Thickening of carina and critical airway stenosis of Case 3 (e–f).

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3 patients (100%) were diagnosed with critical central airway stenosis caused by neck and chest tumors. Acute dyspnea prompted 3 patients to receive adequate ventilation with ECMO. Because traditional respiratory support was life-threating for them (Table 1).

Of note, 3 patients expressed severe respiratory symptoms and did thus undergo arterial blood gas analysis. Descending arterial partial pressure of oxygen (PaO2) value revealed respiratory failure in all cases (Table 2).

Table 2 Arterial blood gas analysis.
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All patients (3/3) were subjected to peripheral venovenous extracorporeal membrane oxygenation (VV ECMO). Femoral and internal jugular vein (FJV) was common cannulation site in 3 patients. Heparin was used as anticoagulant during early ECMO run for all patients. Mean duration of ECMO was 3 h (range: 1.5–4.5 h). All patients were successfully weaned from ECMO without relevant complications (Table 3).

Table 3 Details of early ECMO initiation.
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All patients received surgical operations (Table 4). In detail, 3 patients received mass removal and postoperative assisted ventilation (PAV). Of these, 2 patients received tracheal reconstruction. The mean PAV time was 2.7 days (range: 1–5 days), and no case required prolonged mechanical ventilation due to complications. The mean ICU stay was 3.3 days (range: 1–7 days), and the mean general ward stay was 3.3 days (range: 2–4 days). There was no in-hospital death after surgery.

Table 4 Surgical details of patients.
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Pathology (Fig. 3) demonstrated the tumor dignity including 2 malignant cases (thyroid follicular carcinoma of Case1 and adenoid cystic carcinoma of Case 3) and 1 benign case (mediastinal mature cystic teratoma of Case 2). All patients (3/3) were successfully discharged from hospital.

Figure 3
figure 3

Pathological examination of the tumor dignity (H & E staining, × 100). Thyroid follicular carcinoma of Case 1 (a). Mature cystic teratoma of Case 2 (b). Adenoid cystic carcinoma of Case 3 (c).

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Discussion

Central airway obstruction is dangerous emergency. Airway oppressed by adjacent tumors show high mortality with limited treatments1,2. Asphyxia and respiratory failure are main causes of death in such patients3,7,8,9,10. For these patients with a rapid decline in respiratory status, they must be stabilized before effective treatments17. Effective airway managements are very significant for them23,24,25. Respiratory support to optimize oxygenation is an important issue for critical airway obstruction26,27. When the airway becomes narrowed, the life of the patients is threatened because of impending suffocation. Traditional respiratory supports can be performed quickly11,12. However, in emergency, the traditional respiratory support treatment may be life-threating for patients with severe central airways obstruction caused by neck and chest tumors. Because traditional procedures possibly lead to complete airway obstruction and even death of patients14. Effective airway managements and active surgical intervention are the key to save life of patients11,12,21,22. Although, the process of management and treatment is different to each medical center. For patients with severe central airway obstruction, the thorough knowledge of the pathology, physiology, diagnostic, and therapy options are required with a multidisciplinary team (MDT) approach.

In recent years, the stent placement as an interventional way to palliate the airway obstruction caused by tumor is becoming widely accepted7,8,10,11,12. Because stent placement is safe, minimally invasive, well tolerated, and is increasingly used in various benign and malignant conditions characterized by central airway stenosis13,14,26,28. However, in our cases, using stent is very dangerous. There are two reasons. On the one hand, without adequate ventilation, stent placement can lead to complete obstruction for severe airway stenosis patients. On the other hand, stent touch tumor that may lead to major bleeding because of high intensive vascularity of tumor. For our patients, the mean age is only 39 years. Although, patients can gain short palliation from stent placement, surgical operation is the most effective way to treat tumors. In addition, stent placement may have some unexpected complications, such as stent migration28,29,30,31, fracture28,31, falling off, deformation28, tracheal stent buckling and in-stent stenosis32.

Providing adequate ventilation to support surgical operations is feasible for the 3 patients. However, traditional manners cannot ensure adequate ventilation. Firstly, tracheal intubation is unable to pass the narrow location of severe airway stenosis. Secondly, tracheostomy have high risk of major bleeding because of adjacent tumor with high intensive vascularity. Descending PaO2 value and symptom of hypoxia revealed respiratory failure in our cases. When traditional manner is unfeasible, to ensure adequate ventilation for unstable patients, we used ECMO to manage difficult airway and support surgical procedure.

Previous clinical studies showed that ECMO could be used to ensure adequate ventilation for stent placement in patients with critical airway obstruction13,14,28. However, for severe central airway obstruction patients caused by neck and chest tumors, literature of early ECMO initiation as a bridge to support surgery is rare5. ECMO as a significant device to manage severe central airway obstruction patients caused by neck and chest tumors still need further clinical practice to demonstrate it.

In our study, all patients received early ECMO support with mode of venovenous extracorporeal membrane oxygenation (VV ECMO).

In brief, VV ECMO, cannulation site from femoral vein to internal jugular vein, was preferred for respiratory failure in thoracic surgeries. Previous studies have reported that VV ECMO can help to ensure adequate ventilation (CO2 removal and oxygenation) when performing stent placement in patients with central airway obstruction13,14,28. VV ECMO can provide time to plan and implement adequate treatment, thereby minimizing procedure-related complications28. Furthermore, operating physician feel more comfortable using VV ECMO when performing a high-risk procedure14. There is also clinical study that presented using venoarterial ECMO (VA ECMO) in patients with airway problems20. 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, microembolism, or hemorrhage), cognitive impairment, and major local complications such as arterial dissection, pseudoaneurysm formation, or limb ischemia5,20. For our patients, the VV ECMO may be more suitable than VA ECMO to ensure adequate ventilation for airway management and emergency surgery. ECMO-related complication rates of 24–55% have been reported, including potentially life-threatening complications such as bleeding, hemolysis, air leakage and thrombosis28,33,34. We used Heparin to guard against thrombosis. All cases received coagulation test. We should pay attention to conflict between anticoagulation and surgical bleeding. Finishing operations within time window from Heparin-free staring to membrane blood coagulation appearing is very important.

In our cases, the mean duration of early ECMO was 3 h (range: 1.5–4.5 h), our mean duration was shorter than 15 ± 18 h (range: 1–51 h)5, 20.9 h (range: 2.2–113.4 h)14 and 42 h (range: 5–121 h)28 of published literatures. And there was no any ECMO-related complication in our all cases from early ECMO initiation to weaning off ECMO successfully. This results may associate with short running time of ECMO and adequate prevention of ECMO-related complications. Of note, ECMO-related complications are closely related to the technical proficiency and experience of the operating physician.

Surgery is most effective treatment for tumor disorder. All cases were subjected to surgical procedure. We showed a shorter mean in-hospital time than published papers5,14,28. Hypoxia may increase the potential risk for cardiovascular, pulmonary, central nervous injuries and surgical intolerance. In our study, 2 patients showed chest pain that may revealed the subtler myocardial damage. Early ECMO initiation may protect cardiopulmonary function from hypoxia to increase surgical tolerance. 3 patients were successfully discharged from hospital (Supplementary file).

Interpretation of our results is limited by the single-center, small sample study. There are no comparisons between groups. So, we cannot know for certain whether our surgical procedure could have been accomplished without ECMO support. Setting control group is limited by two reasons. Firstly, traditional manner is unfeasible and even life-threating for patients. Secondly, to compare a lower-risk airway cases would expose the study to selection bias.

The sample size is very small (n = 3), any meaningful comparison would be limited. Although ASA recommended ECMO as a significant device to manage difficult airway in 202222. The paper of using early ECMO to manage severe central airway obstruction patients caused by neck and chest tumor is rare. With increasing number of these patients, when traditional way may be unfeasible and dangerous, finding an effective first-aid is very important. Our study purpose was to discuss the feasibility of using ECMO as a bridge for central airway obstruction patients caused by neck and chest tumors to emergency surgery operations.

However, grass-roots hospitals and some third-level hospitals lack the equipment and operating experience of ECMO, it could be extremely dangerous to transport such patients. So, ECMO-related teaching should be improved. And our center has assigned ECMO groups to help these hospitals. In addition, we have operated prehospital ECMO procedure to transport such patients to our center with professional ECMO team and equipment.

Conclusions

Early ECMO initiation as a bridge can be used to manage difficult airway, provide oxygenation and support surgical procedure for patients with critical central airway stenosis caused by neck and chest tumors. Early ECMO initiation can provide safety and security for airway surgical procedure. Our report further demonstrated the feasibility of ECMO as a significant device to save life of such patients in emergency (Supplementary file).