Discovery of a rare aberrant artery overlying trachea during open tracheostomy

Abstract

Tracheostomy is a common surgical procedure for securing a patent airway. Anatomical variations of major vessels overlying the trachea may pose significant bleeding risk during the procedure. Hence, thorough preoperative assessment of the neck and surgeon’s intraoperative vigilance are essential. Open tracheostomy is a safer option than percutaneous dilatational tracheostomy. Extra caution with stoma wound care and change of tracheostomy tube are necessary postoperatively if any major vessel is detected in close proximity with the tracheal stoma.

Background

Tracheostomy is performed on the anterior surface of trachea in order to gain access to the airway. It could be done either open or close as percutaneous dilatational tracheostomy (PDT). Recognition of variations in vascular anatomy around the trachea is essential to avoid serious and potentially life-threatening bleeding complications in front-of-neck airway access.

Case presentation

A woman in her 90s was admitted for respiratory failure due to chest infection. She required intubation and mechanical ventilator support but later became ventilator dependent. An open tracheostomy was then arranged by the ear, nose and throat (ENT) surgeon for her prolonged intubation. During preoperative anaesthetic assessment, the patient was noticed to have short neck. Otherwise, no other abnormality was detected during the neck examination.

The operation was performed inside the operating theatre with general anaesthesia. The patient was positioned with shoulder support and neck extension. The ENT surgeon made a transverse incision mid-way between cricoid and suprasternal notch. Strap muscles were separated and thyroid isthmus was retracted superiorly. At this moment, a large pulsatile artery was discovered overlying trachea above the sternal notch (figure 1, video 1) with mild deviation of trachea to the right side.

Figure 1.

Intraoperative photo showing aberrant artery overlying fourth tracheal ring.

Video 1. Intraoprtative video showing aberrant artery overlying fourth tracheal ring.

bcr-2022-251123supp000.mp4 ^{(668.9KB, mp4)}

DOI: 10.1136/bcr-2022-251123.video01

The ENT surgeon decided to proceed with the operation and the incision was made further upwards. A tracheostomy was made at the second tracheal ring and a size 7.0mm cuffed Portex tracheostomy tube was inserted. The patient was not reversed and transferred back to ward.

Outcome and follow-up

Postoperatively, there was mild oozing around the tracheostomy site for a few days. Apart from that, there was no other complication related to the tracheostomy. First change of tracheostomy tube was done on postoperative day 40 by ENT surgeon, which was smooth and uneventful. There was no further bleeding from the tracheostomy site up to a 3-month follow-up period.

Discussion

A literature search was done. The discovery of a major vessel overlying trachea intraoperatively during open tracheostomy is rare. There was one case report describing the finding of an aberrant right subclavian artery (ARSA).¹ Tracheostomy was then done at the second and third rings uneventfully. The patient made good recovery progress, which led to decannulation 16 days later. Therefore, awareness of anatomical variations of branches from aortic arch around trachea is important to avoid damage to the major vessels if front-of-neck airway access is attempted. Injury to the great vessels can potentially lead to devastating consequences, including massive haemorrhage, stroke, air embolism or even death. There was also a case report illustrating development of central nervous system toxicity due to direct injection of local anaesthetic into an aberrant carotid artery overlying the trachea before PDT.²

In order to reduce risks of major vessels injury, detailed history with thorough neck examination is necessary during preoperative anaesthetic assessment for tracheostomy. Beware of patients with congenital heart disease, previous neck or upper mediastinal surgery. Previous surgery in the neck (eg, thyroidectomy or carotid surgery) may cause scarring and retraction of vessels out of their normal position, making them vulnerable to be damaged during procedures.³ Moreover, on physical examination, look for any neck lesion, upper chest deformity or abnormal pulsation over trachea.

Furthermore, ultrasound examination of the neck in extension may be performed as a routine or in suspicious cases, augmented by Doppler studies or other imaging studies to identify any anomalous vessels overlying trachea.

Intraoperatively, the risks could be further minimised by surgeon’s vigilance and knowledge of the neck and tracheal anatomy in establishment of a tracheostomy. The need to palpate the area overlying the trachea even before giving local anaesthetic infiltration is particularly emphasised.²

With regard to the tracheal anatomy, in contrast to what is commonly stated in textbooks, the midline of trachea cannot be considered to be cleared of major vessels.⁴ Moreover, the prevalence of major vessels anterior to the trachea might be more common than previously anticipated. According to a study involving screening of 500 thoracic CT scans in adult patients, 53% of the scans demonstrated the presence of part of a major vessel in the suprasternal notch.⁵ At 10, 20 and 30 mm above the suprasternal notch, the prevalence was 25%, 9% and 1%, respectively. As none of the CT scan showed a major vessel anterior to cricothyroid membrane, cricothyroidotomy could be regarded as having minimal chance of injuring major vessels compared with tracheostomy in emergency management of unanticipated difficult airway. In addition, as surgical tracheostomy tubes are typically placed in the region of the second to fourth tracheal rings,⁶ the higher the level of insertion of the tubes, the less likely is the chance of damage to a major artery.

There are also several arteries that are of particular importance due to their close anatomical relation with the trachea. The most common vascular aberrations are actually tortuous versions of normally positioned vessels.⁷ Advanced age and atherosclerosis can lead to dramatic tortuousness of major arteries of the central low neck. Specifically, the innominate artery, the right and left common carotid arteries and the right subclavian artery are prone to being displaced in elderly patients. The aberrant innominate artery could be highly located crossing the fourth and fifth tracheal ring as observed during a cadaveric neck dissection.⁸

Moreover, in around 8% of individuals, a thyroidea ima artery may arise from the brachiocephalic artery, right common carotid artery, aortic arch or internal thoracic artery.⁹ It travels on anterior surface of trachea in the midline and superiorly to the thyroid gland and may be vulnerable to be injured during tracheostomy.

Another important vascular anomalies of the great vessels of the neck is the ARSA. It is the most common embryological abnormality of the aortic arch, also known as arteria lusoria.¹⁰ In up to 2% of the population, it arises as the fourth major branch from the aortic arch. The ARSA usually runs behind the oesophagus but rarely, it also passes anteriorly over trachea.

On the other hand, although PDT has the advantages of simplicity, cost-effectiveness and could be done as a bedside procedure, it is still a semiblind technique that relies on surface anatomy. There had been fatal cases of acute severe haemorrhage due to major vascular damage during PDT in the intensive care unit.^{11 12} Open tracheostomy is definitely a safer option than PDT if operating theatre resources and manpower allowed, especially in patients with high risks of anatomical variations.

Besides, there was another case report about a patient with aberrant brachiocephalic artery discovered before tracheostomy. It was suggested that the potential late risk of erosion into the major vessel by a rigid plastic tube in a mobile neck area was too high so the procedure was abandoned.¹³ However, our case demonstrated that a tracheostomy could still be done at a higher tracheal level with long-term safety. Moreover, special surgical technique had been described to protect a high riding artery from erosion of tracheostomy tube.¹⁴ Nevertheless, extra caution with stoma wound care and change of tracheostomy tube is recommended postoperatively.¹⁵

Learning points.

• Awareness of anatomical variations of vessels anterior to trachea is important to avoid bleeding complications when tracheostomy is performed.

• Detailed history with thorough neck examination is essential during preoperative assessment to identify high-risk patients.

• Open tracheostomy is a safer option than percutaneous dilatational tracheostomy when resources allowed.

• Extra caution with stoma wound care and change of tracheostomy tube are required postoperatively if any major vessel is detected in close proximity with the tracheal stoma.

Ethics statements

Patient consent for publication

Consent obtained from next of kin.