Tracheal reconstruction under tension: an experimental study in sheep

Tracheal Anastomosis Leaks Across Suture Techniques and Tensions: A Biomechanical Ex Vivo Study

BACKGROUND

Anastomotic leak after tracheal resection may occur while coughing in the early postoperative period. We investigated the varying effects of suturing technique, stretch, and tension on anastomotic leaks during simulated coughs.

METHODS

End-to-end anastomoses were performed using continuous or interrupted sutures on excised porcine larynges. Tracheas were secured to a pressurized system simulating cough forces, submerged in a water bath, and stretched to 1, 2, and 3 cm above baseline. Peak pressure, incomplete cough generation, and observed leakages were recorded. Parameters were analyzed using Analysis of Variance (ANOVA), multiple linear regression, and logistic regression modeling.

RESULTS

Peak tension (B = -0.660, p < 0.001) and stretch lengths (B = -0.329, p = 0.006) were associated with variance in peak pressure (R2 = 0.77, F(3,294) = 8.182, p < 0.001). Incomplete coughs increased with higher peak tension (odds ratio [OR] = 15.627, p < 0.001) and stretching to 3 cm above baseline (OR = 4.335, p < 0.007). Similarly, leak occurrences, primarily from the posterior tracheal wall, increased with higher peak tension (OR = 1.787, p < 0.001) and stretching to 3 cm (OR = 2.613, p = 0.017). No significance was identified with suturing technique.

CONCLUSION

Interrupted and continuous suture techniques do not differ in anastomotic strength during simulated coughs. Increased peak tracheal tension is associated with a weaker anastomosis, and tracheal stretch to 3 cm was associated with a weaker anastomosis. Our study supports the commonly held clinical belief that, to create a stronger anastomosis, tension should be minimized, and particular attention should be placed at the posterior tracheal wall during closure.

LEVEL OF EVIDENCE

N/A, Benchtop study Laryngoscope, 2024.

Temporary Stenting for Anastomotic Stenosis after Tracheal Resection of Adenoid Cystic Carcinoma: A Case Report

A 51-year-old man who noticed discomfort in the pharynx was found to have a tracheal tumor on physical examination. He was diagnosed as having adenoid cystic carcinoma by a transbronchial biopsy and underwent tracheal segmental resection via a collar incision. He was additionally treated with radiation therapy owing to a positive surgical margin, and he subsequently developed anastomotic tracheal stenosis. Silicon stent placement to open the airway was performed for the tracheal stenosis. One year after stent placement, the trachea was dilated, so the stent was removed, and he is still under follow-up without recurrence free 1.5 years after stent replacement.

[Assessment of tracheal elasticity and tracheal anastomosis tension in cicatricial stenosis]

OBJECTIVE

To assess the tracheal elasticity and tracheal anastomosis tension for prevention of anastomosis-related complications and estimation of the maximum length of resection.

MATERIAL AND METHODS

At the first stage, 20 patients with cicatricial tracheal stenosis underwent tracheoscopy in usual position, under maximum flexion and extension of the head for the period from September 2017 to December 2019. We measured the total length of trachea and length of stenotic segment. Tracheal extensibility was assessed considering the difference in measurements. At the second stage, anastomosis tension was intraoperatively measured using a dynamometer in normal head position, as well as at maximum flexion in 22 patients who underwent tracheal resection. Unlike multiple other studies, we studied tissue tension intraoperatively.

RESULTS

Mean length of trachea was 12.8 cm, extensibility - 1.3 cm. Tracheal elasticity was greater in patients with a longer trachea and in patients under 40 years old. Mean length of resection was 3.9 cm (30% of mean length of trachea), anastomosis tension - 2.7 H or 270 g. Head flexion was followed by tension decrease by 0.7 H (26.9%), i.e. 70 g. This approach is less effective in case of resection of more than 30% of trachea length in a particular patient.

CONCLUSION

Further experience in measurement of tracheal extensibility and anastomosis tension will make it possible to establish clinical significance of these indicators for prevention of complications.

Tracheal Squamous Cell Carcinoma Treated with Tracheal Resection and Anastomosis in a Cat

A 10-year-old male castrated domestic shorthair cat presented for a suspected tracheal mass. Radiographs confirmed an intraluminal tracheal mass. Tracheal resection and anastomosis of 5 tracheal rings was performed with minimal, mild intraoperative complications and no postoperative complications. Histopathology of the tracheal mass revealed a diagnosis of squamous cell carcinoma (SCC) with incomplete margins both cranially and caudally. Further treatment, including surgical revision, radiation therapy, or chemotherapy, was recommended. At the time of publication, no further treatment has been initiated, and a scheduled consultation with the oncologist has been canceled. The cat is doing well at home with no reported signs of recurrence 120 days postoperatively. This is the first report of a cat with a tracheal SCC to be treated with a tracheal resection and anastomosis and only the third feline tracheal SCC to be treated in the veterinary literature.

Successful tracheoscopy-assisted reconstruction of traumatic tracheal avulsion in a cat

OBJECTIVE

To outline the clinical findings, surgical management, complications, and outcomes in a case of intrathoracic, traumatic, tracheal avulsion.

CASE SUMMARY

A 2-year-old domestic shorthair cat presented with respiratory distress 18 days after a motor vehicle accident. A tracheal avulsion was diagnosed and treated by surgical anastomosis. The initial anastomosis failed. The subsequent tracheoscopic-assisted tracheal anastomosis was successful. The cat had no further episodes of respiratory distress following the second surgery in a 9-month follow-up period.

UNIQUE INFORMATION PROVIDED

This communication describes a complication of intrathoracic, traumatic, tracheal avulsion repair that has not previously been described and the use of tracheoscopy during the subsequent surgical procedure to ensure accurate suture placement.

Despite the Effects of Tension and Intraluminal Pressure, Which Suture Technique Is the Most Appropriate for Prevention of Air Leakage or Anastomotic Dehiscence in Tracheal Anastomoses in the Short Term? An Experimental Research on Ex Vivo Model

Purpose: We performed an experimental study comparing different suture techniques in trachea anastomoses using the ex vivo sheep model, which deals with the parameters that suture tension, air leakage, intraluminal pressure, and tension at which the anastomosis will rupture. We aimed to find an answer to “Which suture technique should be used in tracheal anastomoses?”

Methods: In all, 45 sheep tracheas were randomly divided into three groups (each n = 15) differing in suture technique for anastomoses: single stitches, mixed, and continuous suture. The anastomoses were evaluated for air leakage under normal (25 mbar) and high (70 mbar) intraluminal pressures without tension. Then, air leakage was followed under high intraluminal pressure with tensile stress. Tension levels of dehiscence were also recorded. Data were statistically evaluated.

Results: No air leakage was observed at 25 mbar intraluminal pressure. At 70 mbar pressure without tension, no statistically significant difference was found among the groups (p >0.05). However, single-stitch technique was the best in terms of air leakage tension and rupture tension levels (p <0.05).

Conclusion: The most reliable and advantageous is single-stitch technique for a tracheal anastomosis in short-term results. Further studies are needed to analyze longer ventilation periods in terms of other serious complications as ischemic dehiscence and stenosis.

Reconstruction of Ovine Trachea with a Biomimetic Composite Biomaterial

The aim of this study was to evaluate a novel composite material for tracheal reconstruction in an ovine model. A polymer containing various forms of carbon fibers (roving, woven, and nonwoven fabric) impregnated with polysulfone (PSU) was used to create cylindrical tracheal implants, 3 cm in length and 2.5 cm in diameter. Each implant, reinforced with five rings made of PSU-impregnated carbon-fiber roving, had three external layers made of carbon-fiber woven fabric and the inner layer formed of carbon-fiber nonwoven fabric. The inner surface of five implants was additionally coated with polyurethane (PU), to promote migration of respiratory epithelium. The implants were used to repair tracheal defects (involving four tracheal rings) in 10 sheep (9-12 months of age; 40-50 kg body weight). Macroscopic and microscopic characteristics of the implants and tracheal anastomoses were examined 4 and 24 weeks after implantation. At the end of the follow-up period, outer surfaces of the implants were covered with the tissue which to various degree resembled histological structure of normal tracheal wall. In turn, inner surfaces of the prostheses were covered only with vascularized connective tissue. Inner polyurethane coating did not improve the outcomes of tracheal reconstruction and promoted excessive granulation, which contributed to moderate to severe stenosis at the tracheal anastomoses. The hereby presented preliminary findings constitute a valuable source of data for future research on a tracheal implant being optimally adjusted for medical needs.

Initial Load Stability of Different Trachea Suture Techniques: Tests on an Ex Vivo Model

Objective Tracheal anastomosis can be performed with different suture techniques. In this experimental work, the resilience of anastomotic techniques to pressure and tensile stress was studied. Study Design Ex vivo pig model. Setting Experimental. Subjects and Methods The trachea with the 2 main bronchi in freshly slaughtered pigs was isolated and intubated (CH 8.0). Both main bronchi were closed distally by a stapler. After resection of the trachea, an anastomosis (n = 15 per group) was created: group 1, single interrupted sutures; group 2, continuous running suture; group 3, mixed technique. A continuous tensile stress of 0, 500, 1000, or 1500 g was applied to the preparations. Mechanical ventilation with a maximum pressure of 70 mbar was initiated. The airtightness of the anastomosis was verified by submerging the entire preparation under water. Results At tensile loads of 0.5 and 1.0 kg, all anastomoses created in the single-stitch technique were airtight; at 1.5 kg, 93.3% were without leaks. In the continuous suture technique, the airtightness of anastomoses decreased with increasing tensile load: from 93.3% at 500 g to 73.3% at 1 kg and 66.6% at 1.5 kg ( P = .02 at 1.5 kg). Anastomoses in the mixed technique were airtight in 80% at 500 g, 66.6% at 1 kg, and 46.6% at 1.5 kg ( P = .01 in comparison with single stitches). Conclusion Anastomoses created with single interrupted sutures showed the highest resilience against combined pressure and tensile stress.

Initial Resistance of Carina Anastomoses with Increasing Tensile Stress: An ex vivo Model Comparing Different Suture Techniques

BACKGROUND

After resection of the carina with a length of more than 4 cm, anastomoses often need to be performed under tension despite maximum mobilization. If the patient cannot be extubated, the anastomosis remains under continued stress. Anastomoses of the carina can be constructed using various suture techniques, including single interrupted sutures, back wall running but front wall single interrupted sutures, and complete running suture. This experimental study was designed to determine the most tensile stress-resistant anastomotic suture technique.

MATERIALS AND METHODS

Isolated preparations of tracheobronchial trees were recovered from freshly slaughtered pigs. Resection of the carina was carried out in preparation of the experiments. After blind randomization, anastomoses (n = 15 per group) between the distal trachea and the proximal left main bronchus were performed with PDS 4-0 employing three different suture techniques: (1) single interrupted sutures, (2) back wall running but front wall single interrupted sutures (= mixed technique), and (3) complete running suture. The anastomotic specimen was fixed onto a specially constructed device. The tracheal end was intubated with a tube (CH 8.0) and connected to a respirator. Different weights were attached to the distal end of the preparation via a clamp and guide rollers. Airtightness was investigated at the following tensile loads: 0, 500, 1,000 and 1,500 g. Intrabronchial pressure was increased in 5-mbar steps. In an underwater trial, we analyzed whether anastomoses were airtight at a maximum intrabronchial ventilation pressure of 70 mbar.

RESULTS

At an intrabronchial pressure of 25 mbar without tensile stress, all anastomoses were initially airtight. In tensionless anastomoses at 70 mbar, 100% of single interrupted and continuous sutures were airtight, as compared to 80% of sutures in mixed technique. At 70 mbar and tensile loads of 1,500 g, 80% of single interrupted sutures, 60% of sutures in mixed technique and 53% of the running sutures remained competent.

CONCLUSION

If tracheal anastomoses can be performed without tension, the suture technique is not important. With increased tension, anastomoses performed in single interrupted suture technique were clearly superior. Thus, in situations, where high tensile stress is to be expected, single interrupted sutures should be preferred.

Treatment of large tracheal defects after resection: Laryngotracheal release and tracheal replacement

OBJECTIVE

Resection with direct tracheal or laryngotracheal anastomosis is the standard procedure employed for treatment of benign stenosis or occasionally primary or secondary tracheal malignancy.

DATA SOURCES

Literature review.

RESULTS

A tracheal anastomosis usually heals without complications provided that the ends being joined are adequately supplied with blood, an atraumatic suturing technique is used, and the anastomosis does not become infected. It is especially important that the anastomosis is not subjected to tension.

CONCLUSION

Various techniques of laryngeal and tracheal release serve to reduce the tension on the anastomosis by mobilizing and reducing the distance between the two segments to be approximated. These techniques can be used in different combinations depending on situation encountered during surgery. In cases where more than 50% of the tracheal length must be excised, prosthetic replacements, autologous tissue transfer and allografts are required. All present various problems. The use of tissue-engineering techniques utilizing autologous stem cells has opened new perspectives for tracheal replacement. Such procedures are still in an experimental state.

Microscopic examination of iatrogenic subglottic tracheal stenosis: observations that may elucidate its histopathologic origin

OBJECTIVES

The histopathologic origin of iatrogenic subglottic tracheal stenosis (ISTS) remains unclear. The purpose of this study was to use detailed operative microscopy to systematically examine the operative en bloc specimens of patients with ISTS and to observe the histologic and morphological changes in the hopes that these observations will provide insight into the histopathologic origin of these devastating injuries.

METHODS

The operative specimens of 18 patients who underwent open tracheal or laryngotracheal resection for ISTS were examined. Precise morphological characteristics were investigated for each tissue layer, including the adventitia, the outer surface of the perichondrium, the cartilage, the inner surface of the perichondrium, the submucosa, and the mucosa. Each tissue layer was evaluated independently and in relationship to the other layers. The cartilaginous airway was further evaluated relative to the pars membranacea.

RESULTS

The most common morphological finding in the epithelium was squamous metaplasia with occasional intense inflammation visible in the underlying mucosa, including cicatrization. The underlying cartilage demonstrated ossific metaplasia with sequestration in many cases. By far the most pronounced changes were found in the outer perichondrium and overlying adventitia and included diffuse paucicellular or hyperplastic fibrosis with intense hyperplastic scar formation or hyaline cicatrization. In the pars membranacea, severe scar formation and hyperplastic fibrosis were predominant. Ossific metaplasia was particularly severe in the lateral or outer parts of the tracheal ring, particularly in the vicinity of the adventitia and outer perichondrium. These changes were much more pronounced than the relatively minor changes observed in the submucosa and mucosa.

CONCLUSIONS

The most severe pathologic observations occurred in the lateral tissue layers, ie, the outer perichondrium and adventia. Given that an injury occurs from the tracheal lumen, these tissue layers have the greatest distance from the site of injury. As only minor changes occurred in the inner tissue layers, we hypothesize that these tissues have a greater regenerative capacity than the outer layers. This study supports the theory that the depth of the airway injury is more critical to the development of ISTS than is the extent or length of the injury.

Sutures enriched with adipose-derived stem cells decrease the local acute inflammation after tracheal anastomosis in a murine model

OBJECTIVES

Local inflammatory reaction and tension are the main causes of postoperative complications after tracheal surgery. Adipose-derived stem cells (ASCs) are known to have immunomodulatory activity. The exact mechanism of this activity is not known, although it is possible that they modulate the function of different cells involved in the immune response. Little is known of their impact on acute inflammation, especially in the problematic tracheal area. We aimed to study the effect of ASCs applied locally in an animal model of tracheal resection and anastomosis.

METHODS

ASCs from the subcutaneous fat of BDIX rats were infected for expression of the enhanced green fluorescent protein (eGFP) and were cultured with Polyglactin 910 sutures to obtain biosutures (ASC-coated sutures). After tracheal resection, 90 BDIX rats (syngeneic, autologous model) underwent anastomosis with biosutures (1.5 10(6) cells/biosuture [Group 1] or 0.5 10(6) cells/biosuture [Group 2]) or conventional sutures (Group 3). The animals were killed after 1, 4, 10, 30 or 60 days and histological and immunofluorescence studies were performed on the anastomotic areas. Inflammatory cell densities were graded semiquantitatively by the pathologist in a blinded fashion.

RESULTS

In the early period (1 and 4 days), the biosuture groups presented an atypical pattern of acute inflammation, characterized by the almost complete absence of neutrophils, and the presence of abundant lymphocytes and plasma cells, compared with the control group (P < 0.05). Moreover, abundant macrophages/monocytes were immunolocated around blood vessels near the biosutures and between biosuture threads 1 day after anastomosis, whereas the presence of macrophages/monocytes in animals treated with conventional sutures was discrete (P < 0.05). No differences were observed in the later period. No side effects in the biosuture groups were found.

CONCLUSIONS

Biosutures are a comfortable way of stem cell delivery to the surgical field without modification of the operative protocol. ASCs suppress the local acute inflammatory reaction (increased macrophage migration and decreased neutrophil infiltration) in the tracheal anastomosis and cause an early switch from acute to chronic inflammation.

The fate of homograft tracheal transplants in sheep

OBJECTIVE

An established method of tracheal substitution is not yet available, but homograft tracheal transplantation might provide a realistic tracheal replacement. With the objective of sequentially examining the healing of tracheal homografts, we have established a suitable large-animal model.

METHODS

Five sheep received orthotopic tracheal transplantation of a 4-cm cervical tracheal homograft. The trachea was supported for 6 weeks with a self-expanding polyester stent. The plan was to euthanize the animals after 2, 4, 8, 12 and 16 weeks, or whenever complications occurred.

RESULTS

The implantation itself was performed without complications. After 2 weeks the homograft was firmly encapsulated by connective tissue, without signs of necrosis or abscess. The original mucous membrane no longer existed; the cartilage rings were exposed. In all animals that were euthanized at the later dates, the homografts were completely absorbed and replaced by inflammatory scar tissue. This, in turn, was covered with a shiny cellular surface layer.

CONCLUSIONS

The results from this animal experiment reveal-contrary to data published to date-that tracheal homografts are not incorporated but absorbed. They are replaced by scar/granulation tissue that cannot secure the stability of the trachea. Therefore, further experiments with respect to the biocompatability of homografts appear to be necessary.

Pullout Strength for Three Suture Patterns Used for Canine Tracheal Anastomosis

OBJECTIVE

To compare pullout strength of 3 suture patterns used for canine tracheal anastomosis.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Cadaveric canine tracheae (n = 20).

METHOD

Tracheal segments were anastomosed with 1 of 3 suture patterns: simple continuous, simple interrupted, and simple interrupted reinforced with horizontal mattress, each encircling annular cartilage rings adjacent to the transection site. Horizontal mattress sutures encircled the annular rings proximal and distal to the rings closest to the anastomosis. Each construct was distracted (0.5 mm/s) in a materials testing machine to failure. Load-displacement curves were generated and failure load (pullout strength) determined and mode of failure recorded.

RESULTS

Tracheal anastomosis with a simple interrupted pattern was significantly weaker (mean+/-SD pullout strength, 102.55+/-30.14 N) than simple continuous (135.53+/-15.47 N) or simple interrupted plus horizontal mattress (132.39+/-21.46 N), which were not different from each other. Mode of failure was consistently by suture tear out.

CONCLUSIONS

Both simple continuous and simple interrupted reinforced with horizontal mattress suture patterns have significant biomechanical advantage over a simple interrupted pattern alone in canine cadaveric tracheal anastomosis. The simple continuous pattern had the least variability in pullout strength.

CLINICAL RELEVANCE

A simple continuous technique should be considered when selecting a tension-relieving pattern for canine tracheal anastomosis. It offers the same biomechanical advantage as a simple interrupted pattern reinforced with a horizontal mattress pattern and its strength appears to be reliably maintained when tested in canine cadaver tracheae.

Does successful segmental tracheal resection require releasing maneuvers?

OBJECTIVES

Tracheal resection is a well-established option for the management of airway stenosis. Releasing maneuvers have been described to reduce anastomotic tension. The aim of this study is to report on a series of tracheal resections performed without the use of these maneuvers.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary hospital.

METHODS

All patients undergoing tracheal resection by the first author over a 6-year period were reviewed.

RESULTS

Patients (n = 17; 7 men and 10 women, ages 23-76) were managed with tracheal resection and anastomosis without stenting or postoperative tracheotomy. 16/17 (94%) patients had successful treatment of their stenosis. 1/17 (6%) failed and 1/17 (6%) required dilation. There was no postoperative swallowing dysfunction.

CONCLUSIONS

Segmental tracheal resection without releasing maneuvers was successful in 16/17 (94%) patients.

SIGNIFICANCE

Though extrapolation from this series may be limited, future practitioners may consider forgoing additional releasing maneuvers for tracheal resection in many cases.

Tracheal release maneuvers

Careful preoperative trachea "mapping" with accurate measurements should make an unexpected shortfall in remaining tracheal length and mobility uncommon. Bronchoscopy is the most accurate means of "mapping" the pathologic tracheal anatomy. Rigid bronchoscopy using the ventilating bronchoscope is preferred over flexible bronchoscopy because it provides the most accurate means of measuring the length of stenotic trachea (especially when used in conjunction with rigid fiberoptic telescopes), it can be used to dilate a tracheal stenosis before operative repair, and it establishes a safe airway under direct vision. When the anatomy of the tracheal pathology is accurately defined, specific plans for tracheal resection can be established to accomplish a well-vascularized, low-tension tracheal anastomosis.

Survival analysis of rats implanted with porous titanium tracheal prosthesis

BACKGROUND

Surgical treatment of a malignancy in the trachea may lead to a long resection that has to be reconstructed with an artificial prosthesis. However, most of the available prostheses encounter inflammatory rejection and mechanical constraint problems. To improve tracheal rehabilitation a porous titanium prosthesis was developed. The aim of this study was to test the biocompatibility of this novel material.

METHODS

Seventeen rats had a partial tracheal prosthesis made of porous titanium inserted in the cervical trachea. The histologic analysis of the tissue surrounding the prosthesis was performed in 11 surviving animals after a period of 15 to 41 days.

RESULTS

Fibroblast colonization of titanium pores and a ciliary cylindrical epithelial layer developed on the endoluminal side of the prosthesis and the inflammatory reaction was minimal.

CONCLUSIONS

The results of this short-term study validate, from surgical and histologic standpoints, the usefulness of a porous titanium tracheal prosthesis.

The mechanical stability under load of tracheal anastomoses after various phases in vivo

OBJECTIVE

The objective of our study was to postoperatively examine the mechanical stability under load of tracheal anastomoses over different periods in time and to compare these with native tracheae.

STUDY DESIGN

A randomized experimental study on animals.

METHOD

We performed tracheal anastomoses on sheep with three different suturing techniques and different resection lengths (3, 6, and 9 cm): These anastomoses were subjected to a breaking test at different intervals in vivo (1, 2, 4, 8, and 24 wk) and compared with the tracheae of healthy sheep.

RESULTS

After 1 week in vivo, the anastomosis itself tore off from the remaining trachea under tension, regardless of the suturing technique used and the length of resection. With all animals that survived for a longer period, the trachea broke a greater distance away from the anastomosis. The necessary breaking forces were only minimally lower than those required for breaking healthy tracheae and the difference is statistically insignificant. When all operated tracheae are combined and the forces compared with native tracheae, this reveals that the operated tracheae are significantly more stable (P =.015) and present a lower longitudinal elasticity (P =.004).

CONCLUSION

During the first postoperative days, the stability under load of tracheal anastomoses is slightly lower than that of healthy trachea. This difference is, however, far from those values that can be measured intraoperatively on tracheal anastomoses. Thus, supplementary measures for the mechanical protection against suture line separation do not seem necessary.