External stent for repair of secondary tracheomalacia

Pulmonary function of children with tracheomalacia and associated clinical factors

OBJECTIVES

Spirometry is easily accessible yet there is limited data in children with tracheomalacia. Availability of such data may inform clinical practice. We aimed to describe spirometry indices of children with tracheomalacia, including Empey index and flow-volume curve pattern, and determine whether these indices relate with bronchoscopic features.

METHODS

From the database of children with tracheomalacia diagnosed during 2016-2019, we reviewed their flexible bronchoscopy and spirometry data in a blinded manner. We specially evaluated several spirometry indices and tracheomalacia features (cross-sectional lumen reduction, malacic length, and presence of bronchomalacia) and determined their association using multivariable regression.

RESULTS

Of 53 children with tracheomalacia, the mean (SD) peak expiratory flow (PEF) was below the normal range [68.9 percent of predicted value (23.08)]. However, all other spirometry parameters were within normal range [Z-score forced expired volume in 1 s (FEV₁ ) = -1.18 (1.39), forced vital capacity (FVC) = -0.61 (1.46), forced expiratory flow between 25% and 75% of vital capacity​​​​​​ (FEF_25%-75% ) = -1.43 (1.10), FEV₁ /FVC = -1.04 (1.08)], Empey Index = 8.21 (1.59). The most common flow-volume curve pattern was the "knee" pattern (n = 39, 73.6%). Multivariable linear regression identified the presence of bronchomalacia was significantly associated with lower flows: FEV₁ [coefficient (95% CI) -0.78 (-1.54, -0.02)], FEF_25%-75% [-0.61 (-1.22, 0)], and PEF [-12.69 (-21.13, -4.25)], all p ≤ 0.05. Other bronchoscopic-defined tracheomalacia features examined (cross-sectional lumen reduction, malacic length) were not significantly associated with spirometry indices.

CONCLUSION

The "knee" pattern in spirometry flow-volume curve is common in children with tracheomalacia but other indices, including Empey index, cannot be used to characterize tracheomalacia. Spirometry indices were not significantly associated with bronchoscopic tracheomalacia features but children with tracheobronchomalacia have significantly lower flow than those with tracheomalacia alone.

Current concepts in tracheobronchomalacia: diagnosis and treatment

Airway collapse from dynamic tracheobronchomalacia (TBM), static compression from vascular compression, and/or tracheobronchial deformation are challenging conditions. Patients are best assessed and managed by a multidisciplinary team in centers specializing in complex pediatric airway disorders. Suspicion is made through clinical history and physical examination, diagnosis of location and severity by dynamic 3-phase bronchoscopy, and surgical treatment planning by MDCT and other studies as necessary to completely understand the problems. The treatment plan should be patient-based with a thorough approach to the underlying pathology, clinical concerns, and combined abnormalities. Patients should undergo maximum medical therapy prior to committing to other interventions. For those children considered candidates for surgical intervention, all other associated conditions, including vascular anomalies, chest wall deformities, mediastinal lesions, or other airway pathologies, should also be considered. Our preference is to correct the airway lesions at the same operation as other comorbidities, if possible, to prevent multiple reoperations with their attendant increased risks. We also strongly advocate for the use of recurrent laryngeal nerve monitoring in all cases of cervical or thoracic surgery to minimize the risks to vocal cord function and laryngeal sensation. Studies that evaluate the effect of these interventions on the patient and caregiver's quality of life are needed to fully grasp the impact of TBM on this challenging patient population.

Experience with bioresorbable splints for treatment of airway collapse in a pediatric population

Objective

To report our experience with novel external tracheal and bronchial placed bioresorbable splints in children with severe symptomatic airway collapse.

Methods

Retrospective review of patients undergoing bioresorbable splint placement.

Results

Between July 2018 and February 2020, 14 patients received 16 external splints (trachea, n = 8; left bronchus, n = 7; and right bronchus, n = 1). Preoperatively, 7 patients had a tracheostomy; 6 of them were receiving mechanical ventilation with ventilator settings so high that they required an inpatient setting, often in an intensive care unit. Median age at implant was 14.5 months (range, 2 months-14 years). Splints were formed from moldable bioresorbable plates (RapidSorb; Synthes, Oberdorf, Switzerland) and were customized intraoperatively around a Hegar dilator. A series of Prolene sutures were placed through into the airway cartilage under simultaneous bronchoscopic and direct visualization and then tied securing the airway within the splint. Concomitant procedures were also performed in the region of the airway splints, consisting of airway reconstruction, cardiovascular procedures, and/or esophageal rotation (related to posterior tracheopexy). Median follow-up was 20 months (interquartile range, 12-21 months). Four patients required no further intervention. Although not necessarily in the splinted region, 7 patients required additional procedures, including posterior tracheobronchopexy (n = 2), temporary tracheal stent placement (n = 1), tracheal resection with end-to-end anastomosis (n = 1), closure tracheostomy (n = 1), and tracheostomy placement (n = 2). One patient required splint replacement and in 1 patient, the splint was removed later. All patients (except 2 deaths from unrelated causes) were discharged home. Three patients required mechanical ventilation at lower settings that allowed home ventilation (1 of those only at night), and 4 patients required tracheostomy collar. Indications for tracheostomy included subglottic stenosis, vocal cord paralysis, pulmonary insufficiency, small airway malacia, and laryngomalacia.

Conclusions

An external bioresorbable splint can provide temporary external support while allowing the age-proportional growth of the airway. We applied readily available bioresorbable plates that were custom-molded based on the location, shape, and length of the collapsing airway in selected patients presenting with severe tracheobronchomalacia from loss of structural support and/or cartilage deformation. Further study that includes long-term outcomes are necessary to define the best role for these external splints as part of comprehensive airway management.

Esophageal Trachea, a Unique Foregut Malformation Requiring Multistage Surgical Reconstruction: Case Report

Abnormal connections between the esophagus and low respiratory tract can result from embryological defects in foregut development. Beyond well-known malformations, including tracheo-esophageal fistula and laryngo-tracheo-esophageal cleft, rarer anomalies have also been reported, including communicating bronchopulmonary foregut malformations and tracheal atresia. Herein, we describe a case of what we have called "esophageal trachea," which, to our knowledge, has yet to be reported. A full-term neonate was born in our institution presenting with a foregut malformation involving both the middle esophagus and the distal trachea, which were found to be longitudinally merged into a common segment, 3 cm in length, located just above the carina and consisted of esophageal tissue without cartilaginous rings. At birth, the esophagus and trachea were surgically separated via right thoracotomy, the common segment kept on the tracheal side only, creating a residual long-gap esophageal atresia. The resulting severe tracheomalacia was treated via simultaneous posterior splinting of such diseased segment using an autologous pericardium patch, as well as by anterior aortopexy. Terminal esophagostomy and gastrostomy were created at that stage due to the long distance between esophageal segments. Between ages 18 and 24 months, the patient underwent native esophageal reconstruction using a multistage traction-and-growth surgical strategy that combined Kimura extra-thoracic esophageal elongations at the upper esophagus and Foker external traction at the distal esophagus. Ten months after esophageal reconstruction, prolonged, refractory, and severe tracheomalacia was further treated via anterior external stenting using a semitubular ringed Gore-Tex® prosthesis, through simultaneous median sternotomy and tracheoscopy. Currently, 2 years after the last surgery, respiratory stabilization, and full oral feeding were stably achieved. Multidisciplinary management was crucial for assuring lifesaving procedures, correctly assessing anatomy, and planning for multiple sequential surgical approaches that aimed to restore long-term respiratory and digestive functions.

3D-printed, externally-implanted, bioresorbable airway splints for severe tracheobronchomalacia

OBJECTIVES/HYPOTHESIS

To report the clinical safety and efficacy of three-dimensional (3D)-printed, patient-specific, bioresorbable airway splints in a cohort of critically ill children with severe tracheobronchomalacia.

STUDY DESIGN

Case series.

METHODS

From 2012 to 2018, 15 subjects received 29 splints on their trachea, right and/or left mainstem bronchi. The median age at implantation was 8 months (range, 3-25 months). Nine children were female. Five subjects had a history of extracorporeal membrane oxygenation (ECMO), and 11 required continuous sedation, six of whom required paralytics to maintain adequate ventilation. Thirteen were chronically hospitalized, unable to be discharged, and seven were hospitalized their entire lives. At the time of splint implantation, one subject required ECMO, one required positive airway pressure, and 13 subjects were tracheostomy and ventilator dependent, requiring a median positive end-expiratory pressure (PEEP) of 14 cm H₂ O (range, 6-20 cm H₂ 0). Outcomes collected included level of respiratory support, disposition, and splint-related complications.

RESULTS

At the time of discharge from our institution, at a median of 28 days postimplantation (range, 10-56 days), the subject on ECMO was weaned from extracorporeal support, and the subjects who were ventilated via tracheostomy had a median change in PEEP (discharge-baseline) of -2.5 cm H₂ O (range, -15 to 2 cm H₂ O, P = .022). At median follow-up of 8.5 months (range, 0.3-77 months), all but one of the 12 surviving subjects lives at home. Of the 11 survivors who were tracheostomy dependent preoperatively, one is decannulated, one uses a speaking valve, six use a ventilator exclusively at night, and three remain ventilator dependent.

CONCLUSIONS

This case series demonstrates the initial clinical efficacy of the 3D-printed bioresorbable airway splint device in a cohort of critically ill children with severe tracheobronchomalacia.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1763-1771, 2019.

Preclinical assessment of resorbable silk splints for the treatment of pediatric tracheomalacia

OBJECTIVE

Tracheomalacia is characterized by weakness of the tracheal wall resulting in dynamic airway collapse during respiration; severe cases often require surgical intervention. Off-label external splinting with degradable implants has been reported in humans; however, there remains a need to develop splints with tunable mechanical properties and degradation profiles for the pediatric population. The objective of this pilot study is to assess the safety and efficacy of silk fibroin-based splints in a clinically relevant preclinical model of tracheomalacia.

METHODS

Silk splints were evaluated in a surgically induced model of severe tracheomalacia in N = 3 New Zealand white rabbits for 17, 24, and 31 days. An image-based assay was developed to quantify the dynamic change in airway area during spontaneous respiration, and histopathology was used to study the surrounding tissue response.

RESULTS

The average change in area in the native trachea was 23% during spontaneous respiration; surgically induced tracheomalacia resulted in a significant increase to 86% (P < 0.001). The average change in airway area after splint placement was reduced at all terminal time points (17, 24, and 31 days postimplantation), indicating a clinical improvement, and was not statistically different than the native trachea. Histopathology showed a localized inflammatory reaction characterized by neutrophils, eosinophils, and mononuclear cells, with early signs suggestive of fibrosis at the splint and tissue interface.

CONCLUSION

This pilot study indicates that silk fibroin splints are well tolerated and efficacious in a rabbit model of severe tracheomalacia, with marked reduction in airway collapse following implantation and good tolerability over the studied time course.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2189-2194, 2019.

Pediatric airway surgery

Pediatric airway surgery is a challenging field in pediatric surgery. Laryngotracheal stenosis has a variety of congenital and acquired conditions that require precise assessment and tailored treatment for each individual patient. About 90% of acquired conditions are represented by subglottic stenosis (SGS) resulting as a complication of tracheal intubation. Congenital tracheal stenosis (CTS) is a rare and life-threatening malformation, usually associated with complete tracheal rings along a variable length of the trachea. Tracheomalacia (TM) is a process characterized by flaccidity of the supporting tracheal cartilage, widening of the posterior membranous wall, and reduced anterior-posterior airway caliber. The clinical presentation can vary from almost asymptomatic patients to near fatal airway obstruction. There is considerable variation in both the morphologic subtypes and the prognosis of pediatric airway. The patients are divided into three clinical groups (mild, moderate, and severe). A further division was proposed according to the presence or absence of associated anomalies. The definitive diagnosis of pediatric airway was made by means of rigid bronchoscope and computed tomography scan with three-dimensional reconstruction (3D-CT). Rigid bronchoscopy and 3D-CT confirmed the diagnosis in all the cases. Other associated anomalies include congenital heart disease, vascular anomalies, and BPFM (maldevelopment of aerodigestive tract). After definitive diagnosis of pediatric airway lesions, surgical intervention should be considered. Surgical strategy was presented on each lesion.

Pediatric tracheomalacia

Tracheomalacia (TM) is defined as an increased collapsibility of the trachea due to structural anomalies of the tracheal cartilage and/or posterior membrane. Tracheomalacia has a wide range of etiologies but is most commonly present in children born with esophageal atresia and tracheal esophageal fistula. Clinical symptoms can range from minor expiratory stridor with typical barking cough to severe respiratory distress episodes to acute life-threatening events (ALTE). Although the majority of children have mild-to-moderate symptoms and will not need surgical intervention, some will need life-changing surgical treatment. This article examines the published pediatric literature on TM, discusses the details of clinical presentation, evaluation, diagnosis, and a variety of treatments.

Dynamic airway evaluation with volume CT: initial experience

PURPOSE

The purpose of the study was to prospectively establish the use of a novel multidetector computed tomography unit (MDCT) with 320 x 0.5 detector rows for the evaluation of tracheomalacia by using a dynamic expiratory low-dose technique.

METHODS

Six adult patients (5 men, 1 woman; mean age, 53.7 years [37-70 years]) referred for a clinical suspicion of tracheomalacia were studied on a 320-row MDCT unit by using the following parameters: 120 kVp, 40-50 mA, 0.5-second gantry rotation, and z-axis coverage of 160 mm sufficient to cover the thoracic trachea to the proximal bronchi. Image acquisition occurred during a forceful exhalation. The image data set was subject to the following analyses: cross-sectional area of airway lumen at 4 predefined locations (thoracic inlet, aortic arch, carina, and bronchus intermedius) and measurement of airway volume.

RESULTS

All 6 patients had evidence of tracheomalacia, the proximal trachea collapsed at a later phase of expiration (3-4 seconds) than the distal trachea (2-3 seconds). The most common region of airway collapse occurred at the level of the aortic arch (5/6 [83%]), Three patients (50%) had diffuse segmental luminal narrowing that involved the tracheobronchial tree. The radiation dose (estimated dose length product, computed tomography console) measured 293.9 mGy in 1 subject and 483.5 mGy in 5 patients.

CONCLUSIONS

Four-dimensional true isophasic and isovolumetric imaging of the central airways by using 320-row MDCT is a viable technique for the diagnosis of tracheomalacia; it provides a comprehensive assessment of airways dynamic.

Tracheobronchomalacia in infants and children: multidetector CT evaluation

Tracheobronchomalacia (TBM) is the most common congenital central airway anomaly, but it frequently goes unrecognized or is misdiagnosed as other respiratory conditions such as asthma. Recent advances in multidetector computed tomography (CT) have enhanced the ability to noninvasively diagnose TBM with the potential to reduce the morbidity and mortality associated with this condition. Precise indications are evolving but may include symptomatic pediatric patients with known risk factors for TBM and patients with otherwise unexplained impaired exercise tolerance; recurrent lower airways infection; and therapy-resistant, irreversible, and/or atypical asthma. With multidetector CT, radiologists can now perform objective and quantitative assessment of TBM with accuracy similar to that of bronchoscopy, the reference standard for diagnosing this condition. Multidetector CT enables a comprehensive evaluation of pediatric patients suspected of having TBM by facilitating accurate diagnosis, determining the extent and degree of disease, identifying predisposing conditions, and providing objective pre- and postoperative assessments. In this article, the authors present a step-by-step primer of multidetector CT imaging for evaluating infants and children with suspected TBM, including clinical indications, patient preparation, multidetector CT techniques and protocols, two- and three-dimensional processing of multidetector CT data, and image interpretation. The major aim of this article is to facilitate the reader's ability to successfully employ multidetector CT imaging protocols for evaluation of TBM in infants and children in daily clinical practice.

Tracheal Ceramic Rings for Tracheomalacia: A Review After 17 Years

BACKGROUND

Despite different support techniques, the surgical management of tracheomalacia is still a challenging problem. Satisfactory results after internal stenting are above 80%, whereas, when performing external stenting using biocompatible ceramic rings, results are reported at over 90%.

OBJECTIVE

The purpose of this study was to examine the efficiency of surgical treatment in patients with segmentary tracheomalacia using external ceramic ring grafts.

METHODS

In this retrospective study, we collected data from 12 patients who underwent surgery during the last 17 years for symptomatic segmentary tracheomalacia by use of biocompatible aluminum-oxide ceramic rings. All except one patient had undergone previous tracheostomy, six had a history of long-term intubation, two had previous trauma, and two patients had previous cancer treatment including radiotherapy. One of the patients still had an existing tracheostoma, which was closed when a ceramic ring was implanted. Tracheal wall collapse with pseudoglottis formation or flattened anterior-posterior tracheal diameter was documented with fiberoscopy at rest, and both pre- and postoperative airway resistance measurements were performed in all 12 patients using a spirometer. After malacic segments were found to be expandable using rigid tracheoscopy while the patient was under general anesthesia, preparation of the trachea was performed using a midline vertical incision in the neck. Subsequently, the malacic trachea was expanded by placing and suturing proper-sized ceramic ring(s) around it.

RESULTS

In all patients, surgical expansion of the malacic segment using ceramic rings was successfully carried out without major complications while inspiratory stridor was resolved. Airway resistance decreased significantly from an average of 0.62 to 0.385 kPascal.

CONCLUSION

Although the results of applying internal tracheal stents are encouraging, complications such as stent migration, granulation tissue and fistula formation, and mucociliary transport arrest are possible. Biocompatible ceramic rings do not cause foreign body reactions, remain stabile, and, with a proper suturing technique, provide a suitable long-term solution.

Tracheoplasty for expiratory collapse of central airways

BACKGROUND

Severe central airway obstruction due to expiratory collapse occurs with malacia of intrathoracic trachea and main bronchi, often with chronic obstructive pulmonary disease. Bronchoscopically observed, it is confirmed by inspiratory-expiratory computerized tomographic chest scans. Prior attempts at surgical stabilization have not given dependable results.

METHODS

Posterior tracheobronchial splinting with polypropylene mesh (Marlex) holds cartilages in more normal configuration, and fixes redundant membranous walls. Fourteen consecutive patients were so treated for severe dyspnea. Prior trials of various autologous and exogenous splints failed.

RESULTS

All felt subjectively improved early, with decreased dyspnea, cough, and secretion retention, and with increased activities. Mean forced expiratory volume in 1 second rose from 51% predicted to 73% (p = 0.009), and peak expiratory flow rate from 49% to 70% (p < 0.00001). One patient was lost to follow-up (1 year), 1 died of unrelated cause (5 years), 1 died of chronic obstructive pulmonary disease (3 years), and 1 had decreased respiratory function over 5 years. Ten patients were available for long-term follow-up: 6 were judged to have an excellent result, 2 were good, and 2 were poor due to collapse of unsplinted main bronchi.

CONCLUSIONS

Complete splinting of all malacic central airways with Marlex restores anatomic configuration and permanently prevents expiratory collapse, with relief of extreme dyspnea, cough, and secretion retention.

Tracheomalacia and Tracheobronchomalacia in Children and Adults

Tracheomalacia and tracheobronchomalacia are disorders that are encountered in both pediatric and adult medicine. Despite increasing recognition of these disease processes, there remains some uncertainty regarding their identification, causes, and treatment. This article is intended to be a comprehensive review of both the adult and pediatric forms of the diseases, and includes sections on the historical aspects of the disorders, and their classification, associated conditions, histopathology, and natural history. We also review the various modalities that are used for diagnosis as well as the state of the art of treatment, including airway stent placement and surgical intervention.

Evaluation of poly-L-lactic acid and polyglycolic acid resorbable stents for repair of tracheomalacia in a porcine model

Poly-L-lactic acid and polyglycolic acid (PLPG) resorbable stents may offer a potential solution to the problem of tracheomalacia. Advantages of this material include its strength, its versatile shaping characteristics, and its resorbability, which would preclude surgical removal and allow for airway growth. The purpose of this pilot study was to examine the usefulness of PLPG stents for temporary external airway stenting of tracheomalacia in a porcine model. A severe tracheomalacia was created in 6 pigs by submucosal resection of segments of tracheal cartilage from 6 consecutive rings. The PLPG stent was then shaped to recreate the tracheal contour and sutured to the underlying airway. Endoscopic photodocumentation during spontaneous ventilation was obtained before and after reconstruction. After creation of the malacic tracheal segment, all animals developed stridor, retractions, and cyanosis during spontaneous ventilation. After repair, all animals were extubated without complication. All animals survived the follow-up period of 9 to 12 weeks without evidence of respiratory distress and with rapid weight gain. Repeat bronchoscopy showed no evidence of airway collapse during spontaneous ventilation. Tracheal measurements revealed growth of the stented segment with a mild narrowing within the repaired region. Histologic examination showed preservation of respiratory epithelium. These preliminary findings suggest that PLPG stents may serve a useful role in the surgical management of tracheomalacia.

Biodegradable external tracheal stents and their use in a rabbit tracheal reconstruction model

OBJECTIVES/HYPOTHESIS

To design and develop an external biodegradable tracheal stent for use in airway reconstructive surgery.

STUDY DESIGN

Experimental model.

METHODS

Biodegradable external tracheal stents were fabricated from polyglycolic acid and poly(D,L-lactide-co-glycolide) (85:15). In vitro studies were performed to analyze the mechanical properties and degradative characteristics of these stents. Then the stents were tested in vivo in an anterior tracheal reconstruction model in New Zealand white rabbits.

RESULTS

The average dry modulus for the external stents was 1,800 kilopascal (kPa). All of the external stents cracked by 4 weeks in buffer solution. Significant mass loss was not appreciated until after 10 weeks in solution, but by 20 weeks the stents were nearly 100% degraded. In the in vivo portion of the study, the attrition rate for the control group was 23.1% versus 50% for the external stent group. The stridor rate was approximately 38% for both groups Of the rabbits that survived the entire 3 months of the study, the stented group, when measured by a balloon catheter method, had more patent airways than the control group, with an average stenosis of 27.8% versus 47.2%, respectively (P < .05). However, more accurate postmortem cast measurements of the internal airways did not confirm this.

CONCLUSIONS

The external biodegradable tracheal stent employed in this study degraded in a predictable fashion and may provide a new method to augment surgical reconstruction of the anterior tracheal wall.

Advances in the management of major airway collapse: the use of airway stents

The management of major airway collapse in the pediatric age group has evolved and continues to evolve over time. Tracheobronchomalacia, either primary or secondary, is still the most frequent cause of major airway collapse. This article reviews tracheobronchomalacia and discusses several treatment options; from traditional aortopexy to the more recent introduction of tracheobronchial stenting. Various types of stents are discussed and the authors' preferences are included.

Bioabsorbable self-reinforced poly-L-lactide, metallic, and silicone stents in the management of experimental tracheal stenosis

The aim of the present study was to compare, in rabbits, the biocompatibility and suitability of a bioabsorbable spiral stent made of self-reinforced poly-L-lactide (SR-PLLA) in the management of experimental tracheal stenosis with stents made of metal and silicone. Tracheobronchial stenosis, and its management, is still problematic because stenoses are not always amenable to surgical resection and reconstruction, especially concerning anastomotic problems and stenosis after lung transplantation. Stenosis can be handled with stenting, although the ideal stent has yet to be developed; all the stents available have their disadvantages. Because stenting of the airways can be only temporary, stents made of bioabsorbable materials, theoretically, offer benefits. Tracheal stenosis was created in rabbits by the extramucosal resection of cartilaginous arches of the cervical trachea. After a few weeks, the animals were operated on again, and those stenoses that had developed were dilated with a balloon. Stents then were implanted in the area of stenosis to keep the dilated trachea open. All the animals in the group with silicone stents had to be killed because of respiratory difficulties: their stents had a tendency to occlude because of internal encrustation, and they developed a hyperplastic polyp at the ends of the stents. The SR-PLLA and metallic stents were tolerated well, and after follow-up ended the animals were put to death. This experimental study showed that silicone stents had a tendency to occlude and that stents made of metal and of SR-PLLA were well tolerated and can be used in the management of airway stenosis.

External stabilization of long-segment tracheobronchomalacia guided by intraoperative bronchoscopy

BACKGROUND

Symptomatic obstruction of long-segment tracheal or bronchial portions either related to congenital instability or secondary to vascular compression are rare malformations, which remain difficult to manage. A method of external tracheal or bronchial stabilization is described.

METHODS

From July 1992 to April 1995, 7 children (age range, 4 months to 4 years; mean age, 19 months) and 1 adult (age, 46 years) were operated on for severe respiratory insufficiency. In 4 cases of congenital tracheal instability, 2 children had associated type IIIb esophageal atresia. Both children with esophageal atresia had previous operations (two and three times, respectively): 1 child had aortopexy and division of a patent ductus arteriosus and another child had distal tracheal resection elsewhere, both without relief of malacia. All children were intubated and ventilated since birth for 11 to 15 months. Secondary tracheobronchomalacia due to vascular compression was seen in 4 patients caused by double aortic arch (n = 2) and persisting ligamentum arteriosum after previous ligation of a patent ductus arteriosus (n = 2), with 1 child ventilated thereafter for 5 months. Operation was performed with the aid of extracorporeal circulation in all patients but 1, and consisted of transection of vascular rings and persistent ligamentum Botalli (n = 5), closure of multiple ventricular septal defects (n = 1) and extensive mobilization of the tracheobronchial tree as well as the great arteries. External stabilization of the severely dysplastic distal trachea (n = 6) or left main bronchus (n = 2) was achieved by suspending the malacic segment within an oversized and longitudinally opened ring-reinforced polytetrafluoroethylene prosthesis. Multiple plegeted sutures were placed extramucosally to the dysplastic tracheal wall and the dyskinetic pars membranacea, as well as to the polytetrafluoroethylene prosthesis in a radial orientation. Guided by simultaneous video-assisted bronchoscopy, reexpansion of the collapsed segments was achieved by gentle traction on the sutures while tying.

RESULTS

Stenosis-free tracheobronchial reexpansion was achieved in all patients, as seen on repeated bronchoscopies during hospitalization and thereafter. All patients were extubated within 1 to 12 days after the operation. There was one late death, unrelated to the procedure, in a 31-month-old child 20 months after the operation. All other patients are free of stridor and in excellent clinical condition 21 to 54 months (mean, 38 months) thereafter.

CONCLUSIONS

The presented method of bronchoscopically guided external tracheobronchial suspension within a ring-reinforced polytetrafluoroethylene prosthesis immediately relieves severe malacia of the trachea or main bronchi in infants as well as adults without necessitating resection. Midterm preliminary data suggest that growth potential of the affected segment exists within the oversized polytetrafluoroethylene prosthesis.

Experimental models of tracheobronchial stenoses: a useful tool for evaluating airway stents

BACKGROUND

Stent implantation is a conservative alternative to open operation for treating benign tracheobronchial strictures. Most of the presently available stents were primarily designed for endovascular use. Their respiratory use entails a risk of iatrogenic complications. From a scientific and from an ethical point of view these risks justify preclinical evaluation of new respiratory stents in experimental models of central airway stenoses. Therefore, an attempt was made to develop such models in piglets and adult minipigs.

METHODS

Tracheal stenoses were obtained by creating first a segmental tracheomalacia through extramucosal resection of cartilaginous arches. The fibrous component of the stenoses was then obtained through bronchoscopic application of a caustic agent causing progressive deep mucosal and submucosal injury. Stenoses of the main bronchi were created by topical application of the caustic agent only.

RESULTS

These models demonstrated the typical features of benign fibromalacic tracheobronchial stenoses with constant recurrence after mechanical dilation. Preliminary experiments showed that short-term problems of tolerance of stent prototypes are easily demonstrable in these models.

CONCLUSIONS

These experimental models, which simulate quite realistically human diseases, offer the opportunity to perfect new tracheobronchial stents specifically designed for respiratory use and to evaluate their long-term tolerance before their use in humans.

Accidental ingestion of a tracheal stent

A 53-year-old man with tracheobronchomalacia had two stents placed in his airways to maintain patency. He ingested one of the tracheal stents that was inadvertently dislodged during a brief coughing episode. The swallowed stent was recovered without complications.

Rib-muscle pedicle flap for the repair of congenital tracheal stenosis

Congenital tracheal stenosis (CTS) is an uncommon congenital anomaly that presents early in life with symptoms of biphasic stridor. Most cases require surgical correction. Techniques have included dilation, resection of the involved segment, and tracheoplasty. Today pericardium and costal cartilage are the most frequently used materials for tracheoplasty, but patients still often encounter problems with the graft, with the procedure, or with late complications. This preliminary study was undertaken to determine the feasibility of a rib-intercostal muscle pedicle flap for the treatment of CTS. Tracheoplasties were performed on seven 3.5- to 5.5-kg piglets with a pedicled segment of the right fourth rib via a lateral thoracotomy incision. The method was found to be technically feasible, and pedicles of greater than 2.5 cm were easily developed. The repair provided good structural support and an airtight seal at high ventilator pressures. Histologic examination after 2 weeks showed the flap to be incorporating into the native trachea and to be without degenerative changes. This "vital" composite flap has several real and theoretic advantages over current methods of repair and may prove to be valuable in the treatment of CTS. The clinical application of this myo-osseous pedicle graft in the treatment of patients with stenoses not amenable to surgical resection and primary anastomosis should be explored.

Nasal continuous positive airway pressure in the treatment of tracheobronchomalacia

The effect of nasal continuous positive airway pressure (CPAP) was assessed in three patients with tracheobronchomalacia (TBM) who failed conventional medical management. Using physiologic measures of airflow and fiberoptic bronchoscopy, we evaluated expiratory airflow and airway collapse during the acute administration of nasal CPAP. FVC increased and dynamic airway collapse [slow vital capacity minus forced vital capacity (SVC--FVC)] decreased with increasing levels of CPAP. Notching associated with airway collapse was observed in the baseline spirograms of all three patients, and it disappeared with the addition of nasal CPAP. Fiberoptic bronchoscopy confirmed the severity of TBM in each patient and documented an acute improvement in expiratory airway collapse with the addition of nasal CPAP. Intermittent nasal CPAP was then added to the patients' treatment regimens, improving the course of their disease. Specific treatment outcomes varied from patient to patient, but they included improved sputum production, atelectasis, exercise tolerance, and patient symptoms plus reduced need for medical care. These findings suggest that the addition of intermittent nasal CPAP to routine medical therapy may be of benefit to patients with severe TBM unresponsive to conventional medical management.

An experimental model for the surgical correction of tracheomalacia

Tracheomalacia may result from large intrathoracic goiters. Due to the chronic compression, particularly within the confines of the thoracic inlet, the tracheal wall weakens, with disintegration of some of the cartilaginous rings. Tracheomalacia can cause acute airway distress, particularly during the post-operative period, and may occasionally result in death. The other major cause of tracheomalacia is related to either prolonged endotracheal intubation or over-inflation of the tracheostomy cuff. While various techniques such as internal stenting, external support devices, tracheostomy, and tracheal resection have been used based on individual circumstances, no one method appears to be perfect. To further study this difficult problem, an experimental model of tracheomalacia was created in eight dogs. Six to seven rings of the tracheal cartilages were dissected submucosally. More than half of the circumference of the tracheal rings was resected. The tracheal walls were reconstructed with polytetrafluoroethylene (PTFE) grafts. The grafts strengthened the tracheal wall without causing luminal constriction. Tracheostomy was not performed on any of the dogs. All dogs tolerated the procedure well and were extubated at the conclusion of the experiment. The dogs were followed for 4 to 6 months and then sacrificed so that the tracheal wall could be examined histologically. There was considerable fibrosis leading to stiff neotrachea. The results of this experimental technique for prosthetic reconstruction to counteract problems simulating tracheomalacia are very encouraging.

Tracheobronchial obstructions in infants and children. Experience with 45 cases

Forty-five infants and children with intrathoracic tracheobronchial obstructions requiring surgical treatment are reported. Segmental stenosis of the trachea is defined as involvement of less than one half the length of the airway, which affected six infants. Elongated stenosis involving more than one half the length of the trachea was seen in 12 infants, and complete annular cartilage rings, along the entire length of the trachea, were present in 11. Severe tracheomalacia occurred in six infants associated with aortic arch anomalies and in nine infants with esophageal atresia. Segmental tracheal resection was performed in 17 cases (two after failure of a rib cartilage graft), and anastomotic stricture developed in three. These three anastomotic strictures were resected, resulting in an excellent airway in two and restricture in one. Rib cartilage grafts were used in five patients: two of three with elongated stenosis with complete tracheal rings required subsequent resection, and one of two infants with tracheomalacia had excellent outcome. Approximately 50% of an infant's trachea can be resected, but rib cartilage grafts should be used for elongated stenosis. Resection of bronchial stenosis in two patients resulted in a widely patent bronchus. From this experience primary segmental tracheobronchial resection and re-resection of recurrent stenosis are highly successful. Anastomotic stricture is due to tension at the suture line and suture material inciting a fibrotic reaction. Rib cartilage grafts amounting to 25% or less of the circumference of the airway readily resurfaces with adjacent epithelium, but when 30% or more of the circumference is rib graft, epithelialization may be impaired.

Pericardial flap aortopexy for tracheomalacia

Tracheomalacia is frequently associated with esophageal atresia and vascular compression of the thoracic viscera. Suture aortopexy, as first described by Gross, has become the most commonly used surgical procedure for alleviating the symptoms of tracheomalacia. External stenting, implantation of cartilage graft, and tracheal resection have been tried in severe cases not amenable to aortopexy. A standard aortopexy was attempted in an infant who had undergone division of the posterior portion of a double aortic arch. Because of very tight posterior attachments of the mediastinal structures, the aortic arch could not be brought up to the sternum without undue tension. A 3 x 2 cm flap of pericardium was formed, based at the aortic root. The free end was then sutured to the undersurface of the sternum, thereby pulling the aorta toward the sternum under gentle, controlled tension. The patient was easily extubated and has remained symptom free. Pericardial flap aortopexy is a relatively simple procedure with minimal risk to the aorta or trachea. It may be the preferred initial procedure in the surgical management of tracheomalacia.

A new intratracheal stent for tracheobronchial reconstruction: experimental and clinical studies

An intraluminal tracheal stent (ITS) was used experimentally in rabbits and piglets, as well as clinically in infants with tracheal stenosis, to facilitate airway reconstruction. The ITSs were constructed of stainless-steel springs covered with silicone rubber. They were implanted in seven piglets (6 to 8 kg), five rabbits (3 to 5 kg) and three infants. No animals developed severe respiratory distress and all appeared to tolerate the ITS. Postmortem examinations 1 to 8 weeks after surgery showed (1) loss of stent fixation (one pig), (2) increased tracheal secretions, (3) pneumonia (one pig, two rabbits), and (4) focal squamous metaplasia of tracheal mucosa. Stents used to treat three infants (2 to 5 months of age) with complex tracheobronchial stenosis were placed at the time of periosteal tracheoplasty in two. Recurrent stenosis necessitated a second tracheoplasty and stenting in one, and a long tracheostomy tube and balloon dilatations in the other. The third child had endoscopic stent insertion to alleviate severe airway collapse after esophageal tracheoplasty. The child died from progressive respiratory failure after stent dislodgment. Although the stents were well tolerated in animals and they enhanced critical ventilation of all pulmonary lobes in infants after tracheal reconstruction, certain modifications such as alternative methods of fixation, accommodation for tracheal growth, and reduction in tissue reactivity are necessary before further use of the ITS can be advocated.

Tracheomalacia: an experimental animal model for a new surgical approach

Tracheomalacia was created by removing the posterior 50% of the circumference of eight cartilage rings (5-6 cm in length) from the intrathoracic trachea in each of 12 piglets while leaving the mucosa intact. In 6 animals an autologous, free tibial periosteal graft was applied over the defect (graft group). The remaining 6 piglets served as the control group. In all animals, a silastic stent was left in the trachea for 2 weeks to prevent immediate tracheal collapse. The presence of tracheomalacia was assessed 6-8 weeks after surgery. At bronchoscopy total tracheal collapse during coughing occurred only in the controls. As the animals went from quiet breathing to coughing, mean intrathoracic pressure increased from 5 to 80 cm H2O in both groups, and average sagittal tracheal diameter decreased by 10% in the graft group and 71% in the controls. During coughing, mean resistance to airflow across the defect increased by 0.005 +/- 0.002 cm H2O/liter/min in the graft group, by 0.083 +/- 0.96 cm H2O/liter/min in the controls (P less than 0.005), and by 0.027 cm H2O/liter/min at the same tracheal level in two normal pigs. At sacrifice 12 weeks postoperatively, bone and collagenized fibrous tissue had been produced by all grafts, without evidence of stricture. This study shows that experimentally induced tracheomalacia can be treated successfully by the application of an autologous periosteal tibial graft, which becomes incorporated into the weakened tracheal wall.

Long-term functional results of prosthetic airway splinting in tracheomalacia and bronchomalacia

The long-term functional results of splinting a collapsing major airway with a silastic Marlex mesh prosthesis were assessed. Six patients in whom follow-up has been longer than 4 years (mean 5.3 years) were studied. The prosthetic semirigid splints had been implanted in five children with tracheomalacia and one with bronchomalacia. Mean age at the time of airway splinting was 4 years (range 6 months to 8 years). At their last clinical evaluation, all six children were leading normal active lives. Three had mild respiratory symptoms not related to the splinting. The only long-term complication was a serous effusion that developed around the splint and compressed the trachea in one child 2 years postoperatively. Tracheal fluoroscopy, barium swallow, and computed tomography scans of the trachea in five patients demonstrated satisfactory tracheal caliber without airway collapse during expiration and coughing. Pulmonary function testing showed a mild increase in airway resistance in one child who had had a tracheostomy. These results demonstrate that the application of composite synthetic graft to a segment of a malacic airway in young patients can provide long-term relief from airway collapse without compromising airway growth.

Reconstructive surgery for obstructing lesions of the intrathoracic trachea in infants and small children

This is a report of ten infants and small children with congenital obstructive lesions of the distal trachea and main bronchi. Four were successfully resected. One with a distal segment stenosis required tracheal resection at age 6 wk, another with stenosis of the distal half of the trachea at age 18 mo, and 2 (1 with distal stenosis and 1 with tracheal hamartoma) at age 4 yr. All 4 are presently free of symptoms and their anastomoses have grown without stricture. A child with coil-spring mucosal stenosis of the left main bronchus developed an excellent airway following bronchoscopic removal of the folds, and a baby with tracheomalacia was successfully treated with a rib splint on a segment of distal tracheomalacia, but she died later of associated cyanotic congenital heart disease. Four babies died with airway obstruction in the newborn period. Two with critical distal stenoses died before tracheal reconstruction could be performed. Two died following emergency resections in which all of the congenital stenosis could not be removed. In both, stenotic trachea remained despite operation. All of these infants had complete cartilage rings the entire length of the trachea. Congenital lesions of the distal trachea may become suddenly life-threatening at birth or during the onset of a respiratory infection. An abrupt or insidious onset of airway symptoms requires an expeditious diagnostic evaluation to define the tracheobronchial anatomy, and the operating team has to be prepared for emergency tracheal reconstruction.