Central Airway
Strictures (CAS) are stenoses caused by lesions of the trachea, main bronchus and right middle bronchus. Patients with central airway strictures present clinically with progressive wheezing symptoms that often lead to respiratory failure or asphyxia, resulting in death. Diagnosis is often confirmed by imaging and bronchoscopy. Patients with benign airway stenosis have a long survival period, and patients and families have high expectations, often hoping to obtain long-term symptom relief. Surgery is the traditional treatment, but surgery itself carries many risks, and many patients are unsuitable or unable to tolerate surgery due to their lesion characteristics or cardiopulmonary insufficiency. With the continuous development of bronchoscopic interventions, many airway stenosis lesions that previously required surgery or could not be treated surgically can be treated satisfactorily with the help of bronchoscopic interventions [1].
1. Data and methods
1.1 Clinical data A total of 135 patients with benign airway stenosis treated systematically from January 2006 to December 2011 in the Department of Respiratory Medicine, Coal General Hospital were retrospectively analyzed. There were 76 males and 59 females. The age ranged from 5 to 84 years, with an average of 42.2 years. There were 29 (21.5%) endotracheal stenoses, 91 (67.4%) wall stenoses, 5 (3.7%) extra-tracheal stenoses, and 10 (7.4%) mixed stenoses. All patients had severe dyspnea before surgery, and the presence of tracheal stenosis was confirmed by CT and bronchoscopy.
1.2 Materials and methods Devices and methods used for tracheoscopic intervention: (1) bendable bronchoscope: bendable electronic bronchoscope made by Pentax, Japan; (2) argon plasma coagulation: APC 300 treatment instrument made by ERBE, Germany. Argon plasma coagulation treatment to adjust the flow rate of O.3-2 L/min, output power of 0.03-0.05 J / s; each cautery time of 2-5 seconds. (3) High-pressure balloon: mainly using the U.S. Boston
Scientific company 5833 and 5835 high-pressure balloon and 5061 high-pressure gun pump, balloon expansion gradually increase the size and pressure of the balloon, each expansion choose 8-10 atmospheres, each time l-3 min, each operation can be repeated 3-4 times; (4) freezing: using the German ERBE company production of freezing (4) freezing: using the freezing apparatus produced by the German company ERBE, the lesion is frozen, each treatment selects 5 to 6 points, generally each point freezing lasts about 1-2
(5) stent: Jiangsu Sigma Z-type overlapping stent was used, and the appropriate stent was selected according to the degree of stenosis and length of the lesion. Under direct tracheoscopic view, the middle section of the stent is aligned with the total section of the stenosis to release the stent, and then the stent position and dilatation are checked by tracheoscopy, and the stent position can be adjusted by biopsy forceps if necessary.
1.3 Stenosis typing criteria 1. Endotracheal type: intraluminal benign tumor or granuloma, foreign body, necrotic material. 2. Wall type: (1) twisted or bent (2) scarred stenosis (3) conical (hourglass-like) stenosis (4) web-like stenosis (5) scabbard-like (6) membrane collapse (7) airway fistula (8) tracheal cartilage calcification. 3. Extra-tracheal type: external pressure stenosis, caused by extra-tracheal lesions compressing the trachea, if it is malignant 4. mixed type: granuloma + scarring (or hourglass-like), airway fistula + scarring/ hourglass-like/granuloma.
1.4 Efficacy evaluation
The shortness of breath index was scored according to the American Thoracic Society’s shortness of breath rating scale: grade 0: normal; grade 1: shortness of breath during brisk walking; grade 2: shortness of breath during usual walking; grade 3: stopping due to shortness of breath during usual walking; grade 4: shortness of breath during light activity.
Complete remission (CR): stenosis remission of 100-70% for 1 month; significant effect (SR): stenosis remission of 69-40% or more for 1 month; marginally effective (MR): stenosis remission of 39-10% for 1 month; not effective (NR): stenosis remission of less than 10%. Clinical effectiveness rate = CR+SR/total number of cases. Clinical benefit rate = CR+SR+MR/total number of cases.
2 , Results
2.1 Stenosis typing and etiological analysis There were 29 cases of intraductal stenosis, 91 cases of wall stenosis, 5 cases of extraductal stenosis, and 10 cases of mixed stenosis in this group of patients with benign central airway stenosis. Among the endotracheal stenosis, 10 cases (34.5%) were benign masses, 9 cases (31.0%) were foreign bodies, and 10 cases (34.5%) were sarcoid stenosis; the classification of endotracheal stenosis is shown in Table 1; scar stenosis was the main cause of endotracheal stenosis, and its etiology is shown in Table 2. 40%). Among the mixed stenosis, 5 cases (50%) were post-pneumonectomy, 4 cases (40%) were tuberculosis in airway stenosis, and 1 case of intradistal neurofibrillary tumor invaded the airway.
Table 1
Wall-type airway stenosis
Type of tubular wall airway stenosis type typing n (%)
Wall-type airway stenosis type typing n (%)
Twisting or bending
2 (2.2)
Scabbard-like
2 (2.2)
Scar-like stenosis
61 (67.0)
Membrane collapse
5 (5.5)
Conical (hourglass-like) stenosis
12 (13.1)
Airway fistula
4 (4.4)
Web-like stenosis
4 (4.4)
Calcification of tracheal cartilage
1 (1.2)
Table 2 Etiology of scarred airway stenosis
Classification of scarred airway stenosis etiology n (%)
Classification of scarred airway stenosis etiology n (%)
After tracheal intubation, tracheotomy
33 (54.1)
After bare stent placement
9 (14.7)
Tuberculosis
10 (16.3)
Radiotherapy
2 (3.2)
Burns
2 (3.2)
Post bronchial anastomosis
4 (6.5)
2.2 Treatment methods and efficacy Treatment was based on the bronchoscopic manifestations of benign central airway stenosis, and single or combined endoluminal interventional treatment methods were selected. 120 patients (94.5%) were cured by bronchoscopic interventional treatment methods in the cases that have ended treatment so far. The bronchoscopic interventions used in this group were: APC, CO2 cryo-thaw, balloon dilation, and endoprosthesis (all overlapping stents). Among the cured patients, the different types of stenosis treated are shown in Table 3. Among the cases with failed tracheoscopic interventions, T-tube placement was performed in all cases of mixed stenosis that failed with 3-4 treatments; surgical treatment failed in 2 cases of hourglass stenosis. Among the fatal cases, one died of acute myocardial infarction, one died of hemoptysis, and one died of infectious toxic shock, the latter two were tracheotomized and in a vegetative state after a car accident. Four of the cases still under treatment were mixed stenoses and four were wall stenoses (three were scar stenoses and one was an hourglass-like stenosis).
Table 3 Treatment of cured cases
Intraductal type
Wall type
Canal shape
Mixed type
Total
Single treatment method
2
17
5
0
24
Two treatments
27
54
0
0
81
Three treatments
0
13
0
4
17
Four treatments
0
7
0
0
7
Specific treatments for each type of stenosis: 1. Intraductal stenosis: all patients cured by single treatment were treated with CO2 freezing, the remaining 27 were cured by CO2 freezing combined with APC. 2. Wall stenosis: scar stenosis: 9 patients treated by single treatment (CO2 freezing: 5, internal stenting: 2, balloon dilation: 2), 32 patients treated by two treatments (APC+freezing: 14, freezing+balloon dilation: 10, freezing+stenting: 2), 18 patients treated by three treatments (APC+CO2 freezing+balloon dilation: 4, CO2 freezing+balloon dilation: 2). (APC+freezing 14, freezing+balloon dilation 10, freezing+stenting 2), three treatments 18 (APC+CO2 freezing+balloon 4, CO2 freezing+balloon dilation+stenting 8, APC+CO2 freezing+stenting 6), four treatments 2 (APC+CO2 freezing+balloon dilation+stenting); conical (hourglass) stenosis (hourglass-like) stenosis: 3 with APC + CO2 freezing, 3 with balloon dilation + CO2 freezing, and 3 with combined stenting; web-like stenosis: all cured by balloon dilation; scabbard-like, membrane collapse, airway fistula, and calcification of tracheal cartilage: all treated with endoprosthesis and widened tracheal lumen; some patients were treated with CO2 freezing and freeze-thawing or freeze-thawing combined with APC due to granulomatous hyperplasia after stent placement. 3. extra-tubular stenosis was treated by endostenting. 4. mixed stenosis: all were treated by a combination of three treatment methods (APC + CO2 freezing + balloon in 3 patients and APC + CO2 freezing + stent in 2 patients). The efficacy of various types of airway stenosis treated by bronchoscopic intervention is shown in Table 4
Table 4
Efficacy evaluation (x+s)
Endotracheal stenosis
Wall stenosis
Extraductal stenosis
Mixed stenosis
Degree of improvement of stenosis (%)
91.3+3.86
55.6+2.17
82.0+3.74
47.3+6.80
Treatment time (m)
0.59+0.10
3.34+0.4
*
4.75+0.85
Preoperative shortness of breath score (points)
2+0.166
3.23+0.08
3.6+0.25
4.0+0.0
How long postoperative shortness of breath score (points)
0.37+0.09
1.16+0.053
0.8+0.2
1.75+0.45
Complete remission (CR) (cases)
24
17
5
0
Significant effect (SR) (cases)
4
47
0
3
Minimally effective (MR) (cases)
1
14
0
1
Null (NR) (cases)
0
2
0
2
Clinical effective rate (%)
96.6
80
100
50
Clinical benefit rate (%)
100
97.5
100
66.7
*All patients with extraductal stenosis had improvement of airway stenosis after endoprosthesis placement, followed by treatment for the primary disease.
3. Discussion
Benign airway stenosis is mostly caused by compression of the airway itself or by extra-airway lesions. Despite the benign origin of the lesion, the stenosis can seriously affect respiratory function or cause obstructive pneumonia or pulmonary atelectasis, resulting in recurrent coughing, coughing and wheezing, which can seriously affect the patient’s quality of life and even lead to death because the stenosis is located in the central airway. The development of interventional pulmonology has led to a rapid change in the treatment of benign airway stenosis and has allowed patients to avoid the risk of open-heart surgery.
For the etiological typing of the cases in this group, 45 (33.3%) were post-tracheal intubation and tracheotomy, 28 (20.7%) were tuberculosis, 15 (11.1%) were benign masses, 14 (10.4%) were bare stents, 11 (8.1%) were foreign bodies, 4 (3%) were burns, 4 (3%) were post-bronchial anastomosis, 2 were post-radiotherapy,, recurrent poly chondromalacia 2, tracheal chondromalacia 2, amyloidosis 2, congenital tracheal stenosis 1, goiter 3, and mediastinal masses 2.
By analyzing the cases in this group, we can see that the majority of patients with benign airway stenosis can be cured with tracheoscopic interventions and do not require surgical treatment. Most of them could be cured with one or two treatments, and a small number of them required a combination of three or more treatments. The endotracheal stenosis is the most improved and can usually be cured with CO2 cryopreservation or combined with APC therapy, with a short treatment time and good prognosis. However, granulomatous stenosis can be transformed into walled scar stenosis if it is a wide basal lesion. The most common causes of wall stenosis are scar stenosis, post-tracheal intubation, tracheotomy and endobronchial tuberculosis. In our group, there were 33 cases (68.7%) of post-tracheotomy and 8 cases (16.7%) of tuberculosis. Scar stenosis usually requires a combination of two or more methods of treatment, with carbon dioxide freezing being the primary treatment. Among the canal wall stenoses, scarred stenoses and conical stenoses required the longest treatment time, mostly required a combination of multiple methods, and had the worst prognosis. Purulent stenosis requires the shortest treatment time and is usually cured by balloon dilation followed by CO2 freezing and thawing, while a few patients require short-term endotracheal stenting, which has the best prognosis. Endotracheal stents are preferred for the treatment of tubular stenosis, and can be removed when the compression is released. The treatment of mixed stenosis mostly requires a combination of three or more treatments, which requires the longest treatment time and has the worst prognosis.
With the improvement of various critical care resuscitation techniques and respiratory support treatment in China, the survival time of critically ill patients is prolonged, and the proportion of patients with long-term tracheal intubation or tracheotomy is gradually increasing, so tracheal stenosis caused by these medical factors is common, and this group ranks first in the etiology of benign central airway stenosis. Therefore, how to prevent tracheal intubation and tracheotomy-induced airway stenosis should be taken seriously. Wu Xuan et al. reported the analysis of risk factors for tracheal stenosis complicating tracheotomy with mechanical ventilation in 560 patients, in the order of their influence: intubation time, respiratory tract infection, and diabetes. It was found that intubation beyond 7 d resulted in post-intubation tracheal injury in 94.5% of patients and significant injury resulting in tracheal stenosis in 9% of patients. Balloon to tracheal mucosal injury depends mainly on the relationship between balloon pressure and tracheal mucosal perfusion pressure (normal value 22-32 mmHg), Payne et al [2] reported that when balloon pressure was 30 cmH2O, mucosal blood flow was partially blocked and mucosal perfusion pressure decreased by 30-60%; when it reached 40 cmH2O, perfusion was significantly reduced and mucosa was pale; when balloon pressure reached 45 cmH2O, the mucosal blood flow is completely blocked, to tracheal mucosal injury, and long-term postoperative complications. In order to avoid ischemic injury to the tracheal mucosa due to overinflation of the balloon, many scholars suggest that the balloon pressure should be less than 25 mmHg (34 cmH2O). Liang Hua et al [3] found through animal tests that balloon deflation for 20 minutes had a protective effect on tracheal mucosal injury, and continued prolongation of deflation time on the basis of again had no practical significance for improving prognosis. The current solutions to mucosal injury caused by tracheal intubation mainly include: 1. taking minimum closure (MOP) and minimum closure volume (MOV); 2. regular deflation of the balloon; 3. the use of new tracheal catheters: such as double-bladder single-lumen tracheal catheter, pharyngeal closure of the tracheal catheter, etc. are in the animal test stage, through comparison with the ordinary single-bladder tracheal catheter found that every 2 hours alternate double-bladder single-lumen tracheal catheter Inflation and deflation of the two air sacs significantly reduced the damaging effect on the tracheal mucosa compared with the normal single-cyst tracheal catheter [4]. In 2008, Li Yaqiang et al [5] reported 248 cases (64.25%) of bronchial tuberculosis among 386 cases of benign central airway stenosis, 58 cases (15.03%) after long-term tracheal intubation and tracheostomy, and the second highest tuberculous stenosis in this group of patients, considering that it may be related to the current controlled incidence of tuberculosis in China and the early diagnosis and treatment of the disease. This is probably related to the control of the incidence of tuberculosis in China and the early diagnosis and treatment of the disease.
Among the benign central airway stenosis cases in this group, 120 patients (94.5%) were cured by bronchoscopic interventions, indicating that most patients with benign airway stenosis can be cured satisfactorily by noninvasive bronchoscopic interventions. There are many methods of tracheoscopic treatment, and how to choose the appropriate treatment method is a question we have been exploring for a long time. The etiologic typing of benign central airway stenosis is diverse, and there is no clear guidance for the selection of treatment methods. Through the analysis of this group of cases, benign central airway stenosis was divided into four types, and the treatment methods, efficacy and prognosis of various stenosis types are significantly different.