Role of Loupes Magnification in Tracheal Resection and Anastomosis

Abstract

Tracheal resection and anastomosis is characterized in the last years by significant innovations which are well codified and standardized. Although the mortality rate is markedly reduced, the operation is still not free from risk of complications such as recurrent laryngeal nerve injury, anastomosis dehiscence, granulation tissue formation and restenosis. Pearson FG, Cooper ID, Nelems JL (1975) Primary tracheal anastomosis after resection of the cricoide cartilage with preservation of the recurrent laryngeal nerves. J Thorac Cardiovasc Surg 70:806–16.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-04115-3.

Background

Tracheal resection and anastomosis is characterized in the last years by significant innovations which are well codified and standardized. Although the mortality rate is markedly reduced, the operation is still not free from risk of complications such as recurrent laryngeal nerve injury, anastomosis dehiscence, granulation tissue formation and restenosis [1].

Understanding of the anatomy of the trachea as well as the application of a meticulous surgical technique form the fundamental building block to influence the surgical outcomes and reduce the incidence of complications. The anatomy of trachea has been extensively studied by Grillo et al., who reported that the average length of trachea ranges from 10 to 13 cm and the total number of tracheal rings ranges from 18 to 22 rings with approximately two rings per cm. The trachea starts at the lower border of cricoid cartilage and extends to the level of carina. It is composed of C-shaped cartilaginous rings that form the anterior and lateral walls. The trachealis muscle bridges the gap between the free ends of the cartilaginous rings at the posterior membranous wall of the trachea, adjacent to the oesophagus, to complete the tracheal lumen. An inter-cartilaginous membrane connects the inferior edge of the upper cartilage to the superior edge of the cartilage below. The internal diameter of trachea measures about 2.3 cm from side to side and about 1.8 cm anteroposteriorly [2].

The proximal trachea is cervical and becomes mediastinal at the level of the sternal notch. When the head is flexed, the trachea becomes completely mediastinal. Conversely, when the head is extended, the longer portion of the trachea becomes cervical. The blood supply is segmental and approaches the trachea laterally. The upper trachea is perfused by the inferior thyroid artery, while the lower trachea is perfused by the bronchial arteries from the subclavian, internal mammary, innominate, internal thoracic and related intercostal arteries. Within the inter-cartilaginous ligaments, the tracheal arteries divide into anterior and posterior branches that travel circumferentially within the tracheal wall where they anastomose with the corresponding tracheal arteries from the contralateral side. The recurrent laryngeal nerves course in the groove between the trachea and oesophagus and enter the larynx between the cricoid and thyroid cartilages anterior to the inferior cornu of thyroid cartilage [3].

Stenosis of the trachea may be congenital or acquired. The acquired type is more common and is often due to prolonged endotracheal intubation which results in absorption and collapse of tracheal cartilages with subsequent narrowing of tracheal lumen. Depending on the remaining lumen in the stenotic segment, the manifestations may vary from mild wheezes to respiratory distress and cyanosis. Myer-Cotton classification system is used to assess the degree of tracheal stenosis. Conservative management is usually enough in the first and second grades, however in more severe cases equivalent to the third and fourth grades, surgical intervention is required. Tracheal resection and end-to-end anastomosis is the gold standard procedure. When indicated, up to 5 cm of the trachea can be resected, which is about half of its length [4].

The aim of this study was to review the value of loupes magnification in tracheal resection and anastomosis as a support to the traditional surgery and to analyze the surgical outcomes.

Methods

This is a prospective study conducted on 8 patients (6 males and 2 females) with acquired tracheal stenosis after prolonged intubation. All patients were presented with symptoms of partial airway obstruction (dyspnea and stridor) and identified as eligible to undergoing tracheal resection and anastomosis. The study was conducted from October 2020 to August 2022 at the Department of Otorhinolaryngology, Al-Azhar University Hospitals, Cairo, Egypt. Informed consent was obtained by each patient for both the operation with loupes and data analysis. All patients had a history of intensive care unit (ICU) admission and prolonged intubation from 12 to 25 days.

Full history was taken; complete head and neck examination including flexible laryngoscopy was done; full laboratory investigations, CT and MRI of the neck and virtual tracheo-bronchoscopy were requested. In all patients, direct laryngo-tracheoscopy prior to surgery was done to confirm diagnosis, detect the nature (soft or hard), location (relative to the glottis), degree, and length of the stenotic segment. Cotton-Mayer grading system was used to evaluate the degree of stenosis and to evaluate the grade postoperatively. The proposed grading scale shows that grade I up to 50% obstruction, grade II from 51 to 70% obstruction, grade III from 71 to 99% obstruction and grade IV is 100% obstruction [5].

In all patients, ocular loupes (×4.5 magnification with focal range of about 40 cm) were used only during tracheal resection and anastomosis and not during the entire operation. Before starting the operation, a nasogastric tube was inserted to help define the position of the esophagus during posterior tracheal wall dissection. The operations were done in the supine anti-Trendelenburg position with the shoulders elevated on a roll, neck fully extended and head supported in a head ring. A U-shaped cervical incision starting just below the mastoid tip, descending vertically along the anterior border of sternomastoid muscle to the supraclavicular area and then turning medially to cross the midline; then prolonged contralateral in the same fashion.

Superior and inferior sub-platysmal flaps were elevated from the sternal notch below to above the hyoid bone superiorly (for suprahyoid release). Dissection of the fascia and strap muscles in the midline with lateral retraction using a stay sutures to expose the trachea. Splitting and ligating of thyroid isthmus. Blunt finger dissection of cervical trachea using a smooth rocking movement of the index finger, dissection is continued inferiorly down to the carina. Lateral dissection should be limited to maintain the blood supply intact. A suprahyoid release was then done by cutting the suprahyoid muscles. The larynx and trachea are allowed to drop inferiorly to gain an extra-length of about 2–3 cm. At this stage, ocular loupes were used to magnify the surgical field. Using a scalpel No.15, a transvers incision was made at the lower limit of the stenotic segment. The incision was made between the tracheal rings very close to the lower border of tracheal ring of the stenotic segment leaving the inter-cartilaginous membrane of the lower stump (which carries the blood supply) intact. The endotracheal tube was then shifted to be inserted directly into the lower tracheal stump. Then, the posterior wall of stenotic segment was dissected superiorly until the healthy trachea is reached. The upper transvers incision was made between the tracheal rings very close to the upper margin of tracheal ring of stenotic segment leaving the inter-cartilaginous membrane of the upper stump intact. Before anastomosis, the shoulder roll was removed and the head and neck were flexed forward to approximate the two ends of the trachea and allow tension-free anastomosis.

Then, the endotracheal tube was returned to its original insertion from the mouth and passed from the upper stump through the gap between the two cut ends of the trachea to the lower tracheal stump with intermittent withdrawal of the tube during suturing. The posterior tracheal wall was repaired first starting from the midline using a Vicryl suture 3/0, with a round-tip needle, with sutures placed 3 mm apart. Interrupted sutures were taken in a vertical mattress-like fashion so that the cut ends are approximated and everted for better healing and reduction of crustations and granulation tissue. The anterior and lateral tracheal walls are sutured in the same fashion as that of the posterior wall. The needle tip is inserted from the outside of the tracheal ring of the lower stump inwards, then from within the tracheal ring of the upper stump outside, then the needle is inserted from the outside of the upper inter-cartilaginous membrane of the upper stump inwards, then inserted into the inner surface of the lower inter-cartilaginous membrane of the lower stump outwards and the knot placed on the outer surface of the trachea. On completion of anastomosis, an anastomosis leak test by pouring of saline into the surgical field and Valsalva was done to define any air leak. Drains were inserted; strap muscles and thyroid isthmus were sutured over the anastomosis in the midline and skin closure in 2 layers. In all patients, the chin was fixed to the chest in a flexed position post-operatively using a silk suture and maintained for 1–2 weeks.

Extubation was done on the first or second postoperative day to reduce stress of positive pressure ventilation on the fresh tracheal anastomosis and prevent possible trauma by the endotracheal tube cuff. Antibiotics and pain medications were administered for 7 days. Endoscopic follow-up examinations were performed between 7 and 15 days and 3 months after surgery. Feeding tubes were removed on the first or second postoperative day. The suction drain was removed on day 3 if there are no issues or evidence of an air leak/crepitus. Skin sutures were removed after one week.

Statistical analysis was done for the data collected from patients. Statistical analysis investigated variables such as gender, age, and the degree of stenosis. All the collected data were analyzed using the Statistical package for the social sciences (SPSS) for windows (version 17) (SPSS Inc., Chicago, IL, USA).

Results

Eight patients (100%) were included in this study, 6 (75%) males and 2 females (25%). The age average was 42.6 years (21 to 55). Prolonged endotracheal intubation ranged from 12 to 25 days was the cause of tracheal stenosis in all cases. The stenosis was limited to the cervical trachea in all patients. The length of stenotic segment ranged from 1 to 4 cm (mean = 2.25 cm). The distance from the glottis ranged from 1 to 4 cm (mean = 2.5 cm).

Based on Myer-Cotton classification system, there were two cases (25%) with second grade stenosis, three cases (37.5%) with third grade stenosis, and three cases (37.5%) with fourth grade stenosis. In all patients (100%), segmental resection of the stenotic segment and primary anastomosis with the aid of loupe magnification was performed. Successful extubation was achieved in the first postoperative day in 6 patients (75%); and in the second postoperative day in 2 patients (25%).

After extubation, 7 patients (87.5%) were asymptomatic and 1 patients (12.5%) presented with mild dyspnea and slight shortness of breathing. The development of granulation tissue at the anastomotic site was the underlying cause of dyspnea and was dealt with bronchoscopic removal and both systemic and inhaled steroids. No wound dehiscence or major complications were reported (Table 1).

Table 1.

Summary of 16 tracheal resection and anastomosis cases

Patient no.	Age (years) Sex	MC grading	Stenotic segment (cm)	Distance from glottis	Time of extubation (days)	Anastomotic complications
1	33/M	III	1	2	1	Granulations
2	48/M	IV	4	4	1	No
3	28/M	IV	1.5	2	1	No
4	55/F	III	2	1	1	No
5	21/M	II	3	1.5	1	No
6	54/F	IV	4	2.5	1	No
7	49/M	III	1	4	2	No
8	53/M	IV	1	3	1	Granulations
9	30/M	III	1	3	1	No
10	15/M	II	1.5	1	1	No
11	31/M	IV	2	3	1	No
12	37/F	II	3	2.5	2	No
13	18/M	IV	2	3	2	No
14	58/M	III	1	4	1	No
15	42/F	IV	1	2	2	No
16	28/M	IV	1	2	1	No

MC grading: Mayer and Cotton grading of stenosis

Discussion

Tracheal stenosis following prolonged endotracheal intubation is a life-threatening condition. In spite of good results of the procedures used for management of these cases, prevention remains the gold standard option. The treatment options for isolated post-intubation tracheal stenosis include repeated endoscopic dilations, laser vaporization, excision of the stenosis with grafting and stenting, and tracheal resection with primary anastomosis. Circumferential resection of the stenotic segment with end-to-end anastomosis is the most widely used option for management of these cases. The primary requirements for success of tracheal end-to-end anastomosis are the completion of a tension-free anastomosis, preservation of the blood supply to the anastomosis line, and placement of sutures through a healthy mucosa.

Although the tracheal segmental resection and primary anastomosis became more popular in the last few years, it is a challenging procedure. The success rate, defined by achievement of extubation with low morbidity and mortality, .in the previous studies ranged between 90% and 97%. Although the morbidity and mortality rates are markedly reduced, the operation is still not free from the risk of complications such as recurrent laryngeal nerve injury, anastomosis dehiscence, granulation tissue formation, crustations and re-stenosis. To reduce the incidence of these complications, clear understanding of neck anatomy as well as the application of a meticulous surgical technique is of primary importance [6, 7].

Various techniques have been described for tracheal resection and anastomosis. The technique provided by Pearson et al. forms the basis for all subsequent surgical techniques. Gradually, some modifications took place. In all techniques, the procedure is performed with naked eye. Use of loupes magnification enhances precise and meticulous manipulation during both resection and anastomosis, and in turn, improves the outcome of the procedure. Unlike microscopes, loupes are cheaper, more affordable and easier to manipulate. Also, the comfortable working distance prevents excessive body angulations and strain [6].

With magnification, the elastic inter-tracheal ring ligament is preserved, tissue visualization is enhanced, precise anatomic details are appreciated, and suture placement is precise and easier. The use of loupes is essential in creating a very clear cut between the tracheal rings during resection with preservation of the inter-cartilaginous membrane which carries the blood supply for better healing of the cut ends of the trachea after anastomosis. Also, during anastomosis, magnification helps an accurate approximation of the anastomotic edges [8–10].

Few works have been published about the use of magnification as a support to traditional tracheal surgery. Our study reported a series of 8 patients diagnosed as stenosis of the cervical trachea following prolonged endotracheal intubation focusing on the role of magnification during the procedure. All patients were presented with symptoms of partial airway obstruction in the form of dyspnea and stridor. There were two cases with second grade stenosis (in both cases, conservative management has failed to control symptoms of airway obstruction), three cases with third grade stenosis, and three cases with fourth grade stenosis. All patients were submitted to tracheal resection and primary anastomosis with the aid of loupes magnification. Successful extubation was achieved in all patients (100%) on the first and second postoperative day without significant complications. Only one patient (12.5%) developed granulation tissue at the anastomotic site and were dealt with conservative management during the follow up period and no revision surgery was required. Such data are in agreement with the report of Grillo, who noted granulations after tracheal anastomosis in 34 of 193 patients [2].

The most serious complication that is difficult to manage is anastomotic separation (dehiscence) due to excessive tension at the anastomotic site, especially after resection of large number of segments. Risk factors for anastomotic complication include diabetes, reoperation, previous tracheal appliance, and long-segment tracheal resection [11]. Fortunately, none of our patients developed significant dehiscence during their follow-up period.

Conclusion

Tracheal stenosis is one of the most common and feared complications following prolonged endotracheal intubation. Currently, the procedure of choice for treatment of severe cases consists of resection of the stenotic segment with primary anastomosis via a cervical approach. This type of surgery presents encouraging results with low morbidity. The loupes magnification has a positive influence on the surgical outcomes and its use is encouraged to increase the surgical refinement.

Electronic supplementary material

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Author Contribution

MAh performed the cases and share in data collection. HM and EH analyzed and interpreted the patient data. AF was a major contributor in writing the manuscript. All authors read and approved the final manuscript.

Funding

Not applicable.

Data Availability

The datasets generated and/or analysed during the current study are not publicly available due [REASON WHY DATA ARE NOT PUBLIC] but are available from the corresponding author on reasonable request.

Declaration

Competing Interests

The authors declare that they have no competing interests.

Consent for Publication

Not applicable.

Ethics Approval and Consent to Participate

An approval of Al-Azhar University Hospitals, Faculty of medicine ethical committee was obtained before the start of this study.

The aim of the study was explained and informed.

Consents were taken from all participants included.

Privacy of the data was assured.