J m provement in pulmonary function tests after

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1 Efficacy of Tracheal and Bronchial Stent Placement on Respiratory Functional Tests* jean-michel Vergnon, MD; Frederic Castes, MD; Marie Caroline Bayon, MD; and Andre Emonot, MD Stent placement is the only available treatment in patients presenting either a localized external compression or a malacia of the tracheobronchial tree. To assess the functional benefit of prosthesis insertion in these indications, we compared functional respiratory values before, immediately after (48 h), and at sometime after (mean, 10.1 months) operation in 24 patients presenting with a bronchial lesion (B group, n=5) or a lesion of the intrathoracic part (ITT group, n=9) or of the extrathoracic part of the trachea (ETT group, n=10). Before treatment, airflow was severely impaired in most patients without significant differences among the groups. After prosthesis insertion, airflow parameters increased [change in forced expiratory volume in 1 s (D. FEV 1 =440 ml; D. peak expiratory flow (PEF)=0.92 L s -I; D. maximum expiratory flow 25/75 (D.MEF25j75) =0.47 L s-i; and D. forced inspiratory volume in 1 s (D.FIV I =310 ml)] and airway resistances (Raws) decreased (D. Raw= kpa s-l. s-!) without any significant variation in either forced vital capacity (FVC) or total lung capacity. Airflow improvement was more apparent in ITT and ETT groups than in the B group. Moreover, inspiratory flow increase and decrease of FEV t/pef ratio were only observed in the ETT group. This airflow improvement was maintained for a long time after and was associated with a good clinical tolerance. This study supports the clinical and functional benefits of prosthesis placement both in benign and malignant airway compressions for palliative treatment. (Chest 1995; 107:741-46) B group=bronchial group; patients presenting with a mainstem bronchus lesion; ETI=extrathoracic tracheal; ETI group=patients presenting with a lesion localized in the extrathoracic part of the trachea; FEV1=forced expiratory volume in Is; FIV1=forced inspiratory volume in 1 s; FVC=forced vital capacity ITT= intrathoracic tracheal; ITT group=patients presenting with a lesion localized in the intrathoracic part of the trachea; PEF=peak expiratory flow; Raw=airway resistance; TLC=totallung capacity Key words: airflow; palliative treatment; respiratory pulmonary tests; stent; tracheobronchial stenosis J m provement in pulmonary function tests after treatment of an endoluminallesion by either laser or cryotherapy previously has been reported.1-4 However, laser and cryotherapy are indicated to treat exclusively endoluminallesions Conversely, when a main airway external compression occurs, stents are the only palliative treatment to restore tracheal or bronchial lumens.6 Stents are indicated either in external compression due to tumoral mediastinal involvement or in localized tracheobronchomalacia of cicatricial origin. Previous reports presented the technical aspects of prosthesis placement and the different indications and benefits to relieve respiratory symptoms, but only one study 12 has focused on the functional effect of stent placement. The aim of this study therefore was to analyze preoperative and postoperative functional data to assess the specific role of endobronchial prostheses in *From the Department of Chest Diseases and Thoracic Oncology (Vergnon and Emonot), Department of Physiology, GIP Exercice (Costes), and Department of Anesthesiology and Intensive Care Unit (Bayon), Hopital Nord, University Hospital Saint Etienne, St. Etienne, France. Manuscript received January 24, I994; revision accepted July l. Reprint requests: Dr. Vergnon, Service de Pneumologie, CHU de Saint Etienne, Hopital Nord, Saint Etienne Cedex 2, France the improvement of dyspnea. Selection of Patients POPCLATION AND METHODS From July 1988 to Aprill994, we treated I20 patients with I68 tracheal or bronchial stents. Among these patients, we selected only those in whom endobronchial treatment was exclusively a prosthesis placement without endoluminal tumor resection with laser, cryotherapy, or mechanical procedures. So, functional analysis assessed only the mechanical role of the prosthesis to improve respiratory function. The patients in whom more than one stent was placed were excluded in order to obtain a pure functional effect on a tracheobronchial segment. The routine protocol we used in these patients included preoperative and immediate (2 days) postoperative analysis of respiratory function. Methods Prosthesis Placement: The prosthesis was inserted according to Dumon's procedure 6 with the patient under general anesthesia. Briefly, the patients were intubated with a rigid bronchoscope (Dumon-Harrell bronchoscope, EFER, La Ciotat, France) with the aid of video monitoring. The stenotic areas were dilated with the tip of the bronchoscope. The external diameter of the prosthesis was determined by the largest size of the bronchoscope permitted to be inserted in the stenositic areas (the stent diameter generally was 2 mm above that of the tube) and its length, by that of the compression. Two types of prosthesis were used: Endoxane prosthesis (Axion, Aubagne, France) and Nova-Stent (Novadis, Saint Victoret, France). Nova-Stent prostheses were CHEST I 107 I 3 I MARCH,

2 preferred in dyskinetic tracheal lesions, since in this condition we often observed Endoxane prosthesis migration. When Endoxane type was used, the prosthesis was rolled into an introducer tube. After withdrawing the telescope, the introducer tube was passed down the bronchoscope and the stent was pushed blindly into the stenotic segment. With Nova-Stent prostheses, the procedure was slightly different, since the stent was rolled directly into the bronchoscope tube and inserted with a specific forceps with the aid of telescope vision. Whatever the stent, the right position was adjusted with a forceps. All prosthesis procedures were performed in the same institution by the same pulmonologist (J.M. V.). Patients were discharged after chest x-ray film control on the second day after insertion. Functional Data: Functional pulmonary tests were performed 24 h before and 48 h after (immediately postoperative) stent placement for all patients. Spirometry, flow-volume curve, airway resistance (Raw), and thoracic gas volume were measured in a body plethysmograph (Bodyscreen, Jaeger, Wi.irzburg, Germany) according to international procedures. The forced expiratory volume in l s to peak expiratory flow (FEY J/PEF) ratio was calculated as an index of upper tracheal obstruction; a value higher than 10 was considered as evidence of extrathoracic tracheal obstruction Full data are available in all but four patients in whom Raw and thoracic gas volume were not measured. When possible, flow-volume curve was controlled later in some patients (late control). Data are expressed in native values and as a percentage of predicted values. 17 Statistical Analysis: Preoperative and postoperative values were compared by Student's paired t tests using statistical package Statview IV on a Macintosh computer. Within the bronchial group, the values were compared using the Wilcoxon rank test. The level of significance was fixed at probability value of less than Population RESULTS Twenty-four patients, aged 64.3 ± 14 years, were included (21 men and 3 women). Among these patients, five presented with a mainstem bronchial lesion (B group: one post-irradiation scar, four tumoral compression), as shown in Tabie 1. Nineteen presented with a tracheal lesion: ten were located in the extra thoracic part of the trachea (ETT group: five benign post intubation, four post-tracheotomy malacia and one postirradiation) and nine in the intrathoracic part of the trachea (ITT group: one benign postirradiation scar, one benign postsurgical scar, one tracheomalacia, and six tumoral compressions). In benign lesions, surgical procedures had been excluded either for age, poor general condition (cases 15, 16, 21 to 23), or associated disease-like severe cardiac failure (cases 18, 20), evolutive unresectable cancer (cases 4, 17, 18, 23), recurrence of stenosis after surgical resection case 9), or unresectable diffuse malacia (case 14). In tracheobronchial compression due to malignant diseases, the lesions were unresectable, and stents were placed after failure or contraindication of standard treatment including irradiation or chemotherapy. Prosthesis A silicon Endoxane stent was used in 22 patients. Tracheal stents were used in 17 cases: the external diameter was 16 mm (n=ll), 14 mm (n = S), and 13 (n=1). The stent length ranges from 40 to 70 mm. Some aspects of chest x-ray tomodensitometry and endoscopic views are presented in Figures 1 through 3 and Table 1. A bronchial stent was used in five cases (three in the right mainstem bronchus and two in the left one). The external diameter was 12 mm in four cases and 11 mm in the other. The length was 40 or 50 mm. A Nova-Stent was used in two cases in the trachea. The external diameter was 16 mm and the lengths were 40 and 70 mm, respectively. Tolerance and Follow-up Clinical information and endoscopic control studies FIGURE l. Left, Digitalized chest x-ray film after stent placement in patient 11. The silicon prosthesis is not apparent, but the tracheal lumen is well opened. The arrows show the upper and lower tips of the prosthesis. Right, Tomodensitometric view of the same case: the tracheal lumen appears well opened inside the tumoral mass. The prosthesis is slightly visible as a thin white circle. 742 Efficacy of Tracheal and Bronchial Stent Placement on PFTs (Vergnon et alj

3 FrcunE 2. Endoscopic view of an ETT stenosis induced by tracheomalacia secondary to a prolonged intubation (patient 20). Aspect before treatment. Note the absence of exophytic lesion. FrcunE 3. Endoscopic view of patient 20 just after prosthesis insertion (Endoxane, 13-mm diameter, 50-mm length). Table!-Characteristics of the Population, Type of Prosthesis and FolloU>-up Information Follow-up Dataf Survival, Pulmonary Function Patient No. Sex Age, yr Diagnosis Prosthesis Type* months Tests, months B group 1 M 74 Left tumoral compression Endoxane 11 / 40 D, M 45 Left tumoral compression Endoxane 12/ 50 A, M 51 Right tumoral compression Endoxane 12/ 40 D, M 70 Postirradiation malacia Endoxane 12/ 40 A, M 82 Right tumoral compression Endoxane 12/ 40 A, 6 no ITT group 6 M 59 Tumoral compression Endoxane 14/ 70 D, l no 7 M 80 Tumoral compression Endoxane 16/ 50 A, lo M 62 Postirradiation scar Endoxane 16/ 50 A, M 63 Postsurgical scar Endoxane 16/ 50 A, M 61 Tumoral compression Endoxane 16/ 50 D, 0.5 no ll M 44 Tumoral compression Endoxane 16/ 50 D, M 60 Tumoral compression Endoxane 16/ 50 D, 3 no 13 M 48 Tumoral compression Endoxane 16/ 70 D, 3 no 14 M 29 Tracheomalacia Nova-Stent 16/ 70 D, 4.5 ETT group 15 F 81 Posttracheotom y Endoxane 14/ 50 A, M 88 Postintubation Endoxane 16/ 50 A, F 68 Postirradiation scar Endoxane 16/ 50 D, 1.5 no 18 F 75 Posttracheotom y Endoxane 16/ 50 D, 8 no 19 M 65 Postintubation Endoxane 16/ 40 D, M 63 Postintubation Endoxane 13/ 50 A, M 66 Postintubation Endoxane 14/ 50 A, 42 no 22 M 64 Postintubation Endoxane 14/ 50 A, M 84 Posttracheotomy Endoxane 16/ 50 A, 19 no 24 M 62 P~ st t r a che ot o m y Nova-Stent 16/ 40 A, 9 2 *Numbers following type of prosthesis indicate external diameter/ length of prosthesis in millimeters. fsurvival in months and delay of last functional data available; D=dead; A=alive; no=no functional data. CHEST / 107 / 3 / MARCH,

4 FEV1 FIV1 t I r**, **I PEF FVC 0 Pre 11!!11 lmm. post Late control Raw kpa. t 1.s 1 FIGURE 4. Variation of functional parameters preoperatively, immediately postoperatively (lmm. post), and late control after stent placement in the population. Open bars represent mean preoperative values; gray bars, postimmediate values; and solid bars, post-late operative data. Asterisks indicate a significant variation:** p <0.01;* p <0.05. The prosthesis placement induces an improvement in airflow parameters without volume variation. were obtained from our referring chest physicians in each case (Table 1). The follow-up period ranged from 2 weeks to 52 months. During this time, we noted four specific problems: (l) prosthesis infection (Staphylococcus aureus) occurring in patient 15 at the fifth month and justifying the stent change; (2) a slight displacement of a tracheal stent associated with mucus obstruction (patient 16) corrected at 2 months; (3) postintubation tracheal stent migration necessitating the change of the prosthesis at 9 months (patient 9); (4) insertion of a new stent 2.5 or 4 months later, respectively, due to incomplete insertion of a stent and the occurrence of exophytic granulomas (patient 14) or growth of the tumor (patient 11). In the B group, two patients died of neoplastic cachexia without any stent complication or acute dyspnea. In the ITT group, six patients are dead: one of cardiac failure (patient 10) and four of tumor progression and cachexia. Only one patient (patient 14) died of acute asphyxia probably due to obstruction of a very long Dynamic stent (Rusch-Pilling SA, France, 14 em long) with dried secretions. In the ETT group, two patients died of extrapulmonary disease: cardiac failure (patient 15) or intestinal tumor (patient 19) and one (patient 17) died at home of an undetermined acute respiratory failure; the endoscopic control study performed in this patient 2 weeks before was normal. To date, the 13 other patients are alive and do not complain of dyspnea; endoscopic control studies show no reduction of the stent diameter. Functional Results Mean values of functional respiratory tests are detailed in Table 2. Before stent placement, lung function was severely impaired in all the patients, as shown by the decrease in expiratory flows, and the Table 2-Pulmonary Function Test Results in the Three Groups* B Group ITT Group ETT Group Immediate Late Immediate Late Immediate Late Preoperative Postoperative Control Preoperative Postoperative Control Preoperative Postoperative Control (n=5) (n=5)t (n=4)t (n=9) (n =9)t (n =5)t (n=lo) (n=io)t (n=6)t FEV1, L 118± ±0.30! 1.49± ± ± ± ± ± ±0.75 (43±19) (54±21) (48± 11 ) (41 ± 19) (58±16) (64±16) (59± 16) (74±18) (61 ± 19) FVC, L 2.12± ± ± ± ± ± ± ± ±1.02 (61±28) (74± 22) (69±9) (58± 19) (66± 16) (71 ± 19) (80± 19) (78 ± 15) (74±17) PEF, L s ± ± ± ± ± ± ± ± ± (37± 12) (40±12) (40±4) (26± 13) (38± 11 ) (43±10) (33± 13) (50±12) (61 ±20) MEF25/ 75, L s ±0.26 L02±0.31t 1.02± ± ± ±0.50! 1.23± ±0.78! 2.07 ± 1.31 (24±11) (32± 15) (28± 17) (32±18) (45± 16) (49±15) (41 ± 12) (59±23) (61 ±32) FIV1, L 1.24± ±0.42 NM 1.39± ± ± ± ±0.51 NM TLC,L 4.63± ±0.83 NM 5.33 ± ±0.63 NM 4.81 ± ±0.74 NM (76±26) (81 ±23) (82± 13) (84±9) (84± 17) (86±17) Functional residual 3.02± ±0.52 NM 3.64± ± LOO NM 3.00± ±0.39 NM ~ a p a, cl i t y (90±20) (94± 18) (107±31) (97±29) (96±23) (100±26) Raw, kpa L - 1 s ± ±0.40 NM 0.79 ± ± ± ± ± 0.28 NM (274±204) (154± 132) (264 ± 161 ) (146±58) (135±59) (304±158) (126±94) *NM indicates values not measured. Values are mean± SD. Numbers enclosed within parentheses indicate percent of predicted values. timmediate postoperative means 2 d after stent placement; late control means flow-volume curve was controlled later.!probability value less than Probability value less than O.Ol. 744 Efficacy of Tracheal and Bronchial Stent Placement on PFTs (Vergnon et alj

5 flow-volume curve exhibited an obstructive pattern in most of them. Mean FEV 1 was 41 ± 18% of predicted value and forced vital capacity (FVC) was 58± 18%, but total lung capacity (TLC) remained normal (82 ± 13%; PEF also was greatly reduced, and airway resistance increased (26 ± 13% and 264± 160%, respectively). No parameter differed significantly in regard to the site of obstruction. Two days after stent insertion (immediately postoperative), all patients exhibited a dramatic dyspnea decrease. Functional tests, performed at this time, showed a significant improvement in flows without significant volume variations (Fig 4). Expiratory flows increased in 17 of 24 patients (LlFEV 1 =440 ml and LlPEF=0.92 L s-1). Change in inspiratory flow (FIV 1) was only observed in ll of 24 patients with a mean improvement of 306 ml. However, some differences appeared between the patients with regard to the site of obstruction. In the B group, only FEV 1 and MEF25-75 improved (both p<0.05). In the ITT group, FEV1, PEF, and MEF25-75 increased significantly after stent placement (p<0.01, 0.05, and 0.05, respectively). In the ETT group, we found the same improvement of these parameters (p<o.ol, 0.01, and 0.05, respectively). Moreover, Raw decreased (p<0.01) and FIV 1 increased dramatically (p<0.01). The FEV dpef ratio was 11.5 ± 3 in the ETT group, 10.8 ± 3 in the ITT group, and 7.4 ± 3 in the B group. After treatment, this ratio decreased significantly only in the ETT group (p<0.05) and remained higher than 10 in the ITT group. Lung function tests were repeated by the referring chest physicians in 15 of 24 patients with a mean delay of 10.1 months (range, 2 weeks to 49 months, late control). As shown in Table 2 and Figure 4, the flow improvement was maintained at distance without any significant increase in FVC. Between immediately postoperative and late control values, no significant variation was noted. CoMMENT As clinically suspected by the relief of dyspnea experienced by patients, this study shows a good and immediate improvement of flow limitation after stent placement. However, the increase in functional parameters was variable both among the patients and according to the site of the obstruction. Stents restore large and fixed tracheobronchial lumens in external compression or dyskinetic lesions. Since stents do not debulk a complete bronchial obstruction, they are not indicated when a restrictive pattern is caused by bulky tumors. In our series, a severe preoperative restrictive pattern (TLC <70% predicted) was observed in three cases, but it was due to a preexisting restrictive respiratory insufficiency. As expected, we did not observe any improvement in TLC and FVC after prosthesis placement. The largest increase of FVC was observed in the B group, but this FVC change did not reach significance. These results are in accordance with another study12 but contrast with the immediate functional improvement observed after laser or cryotherapy treatments where both flows and volumes increase Flow increase was observed in most patients in each group. This extends the preliminary results reported by Gelb et ap 2 in younger patients. An identical stricture degree induces a less severe flow limitation in a unilateral mainstem bronchus than in the trachea. As a consequence, the same correction of a bronchial stenosis will result in a smaller increment of functional improvement. The variation of most airflow parameters we observed appears to be consistently more significant in tracheal lesions than in unilateral bronchial involvement. The expiratory flow parameters (FEV 1. PEF) increased in a similar range after stent placement both in the ITT and ETT groups. In contrast, we only observed a FIV 1 improvement in the ETT group. Miller and Hyatt 14 have shown that inspiratory flows were more altered in ETT lesions than in ITT lesions, and this supports our results. Although Mohsenifar et ap have reported immediate inspiratory flow improvement after laser treatment of tracheal lesions, to our knowledge, no investigators have analyzed the differential debulking effect of ITT or ETT lesions on inspiratory flow. The FEV dpef ratio has been proposed as an index of the level of a tracheal lesion. We found that this ratio was higher than 10 in all tracheal lesions; this index cannot accurately differentiate between ETT and ITT lesions in our patients. After stent placement, an improvement only was observed in the ETT group. Consequently, we suggest that, as FEV 1. FEV dpef ratio variations indicate the effectiveness of treatment only in the ETT group. Dumon6 and Bolliger et al11 already have pointed out the good clinical tolerance of silicone stents, since we observed only a low complication rate in the long-term follow-up period. We confirmed this point and underlined the functional improvement following prosthesis insertion. We found this benefit to be maintained both in benign and malignant airway compressions. Moreover, we emphasized the persistence of functional improvement as indicated by the late control values obtained 10 months after stent insertion. This result is very encouraging in these patients, since other standard treatments (surgical resection, chemotherapy, or irradiation) had been excluded. In conclusion, our results support the benefits of prosthesis placement on functional parameters measured immediately and a long time afterward, which CHEST I 107 I 3 I MARCH,

6 is associated with an excellent clinical tolerance. This justifies the use of a prosthesis for palliative treatment for those patients who have an external tracheobronchial compression or a localized tracheobronchomalacia. We are of the opinion that intraluminal prostheses offer an adequate palliative treatment for these breathless patients in the absence of any other alternative. REFERENCES 1 Mohsenifar Z, Jasper A, Koerner S. Physiologic assessment of lung function in patients undergoing laser photoresection of tracheobronchial tumors. Chest 1988; 93: Walsh D, Maiwand M, Nath A, eta!. Bronchoscopic cryotherapy for advanced bronchial carcinoma. Thorax 1990; 45: Gelb A, Tashkin D, Epstein J, eta!. Nd-YAG surgery for severe tracheal stenosis physiologically and clinically masked by severe diffuse obstructive pulmonary disease. Chest 1987; 91: Gelb A, Tashkin D, Epstein J, eta!. Physiologic characteristics of malignant unilateral main-stem bronchial obstruction. Am Rev Respir Dis 1988; 138: Cavaliere S, Foccoli P, Farina P. Nd-YAG laser bronchoscopy: a five-year experience with 1,396 applications in 1,000 patients. Chest 1988; 94: Duman JF. A dedicated tracheobronchial stent. Chest 1990; 97: Homasson JP, Renault P, Angebault M, et a!. Bronchoscopic cryotherapy for airway strictures caused by tumors. Chest 1986; 90: Vergnon JM, Schmitt T, Alamartine E, eta!. Initial combined cryotherapy and irradiation for unresectable non-small cell lung cancer. Chest 1992; 102: Orlowski T. Palliative intubation of the tracheobronchial tree. J Thorac Cardiovasc Surg 1987; 94: Nashef S, Dromer C, Velly J, eta!. Expanding wire stents in benign tracheobronchial disease: indications and complications. Ann Thorac Surg 1992; 54: Bolliger C, Probst R, Tschopp K, et a!. Silicone stents in the management of inoperable tracheobronchial stenoses: indications and limitations. Chest 1993; 104: Gelb A, Zamel N, Colchen A, eta!. Physiologic studies of tracheobronchial stents in airway obstruction. Am Rev Respir Dis 1992; 146: Jones J, Renzetti A, Mitchell M. The maximal breathing capacity in extrathoracic airway obstruction. Am Rev Respir Dis 1972; 106: Miller R, Hyatt R. Evaluation of obstructing lesions of the trachea and larynx by flow-volume loops. Am Rev Respir Dis 1973; 108: Rotman H, Liss H, Weg J. Diagnosis of upper airway obstruction by pulmonary function testing. Chest 1975; 68: Kryger M, Bode F, Antic R, et al. Diagnosis of obstruction of the upper and central airways. Am J Med 1976; 61: Quanjer P. Standardization of lung function tests. Bull Eur Physiopath Respir 1983; 19(suppl 5): George P, Pearson M, Edwards D, et al. Bronchography in the assessment of patients with lung collapse for endoscopic laser therapy. Thorax 1990; 45: Efficacy of Tracheal and Bronchial Stent Placement on PFTs (Vergnon et alj