Thyroid tumour
Communication with the patient and surgical team is of paramount importance in the emergency situation where the patient has a threatened airway. The anaesthetist should also be experienced in the technique of AFOI before attempting a difficult airway in an unusual position. This case demonstrates how one must then adapt to a particular situation.
1 Make an initial assessment of the acutely compromised airway.
2 Formulate a plan for emergency management of the difficult airway.
2A01
A 71-year-old female presented with increasing shortness of breath over 3 weeks. She now has severe dyspnoea and a choking sensation which is relieved by lying prone. Her only past medical history is that of hypothyroidism. On examination, she is lying prone, propped up on her elbows. She is maintaining her own airway, is able to talk in short sentences, and has an inspiratory stridor. She has an obvious large neck mass, originating on the left and causing a tracheal deviation to the right. She is referred for an urgent tracheostomy.
The airway is in a critical condition. Supplemental oxygen should be given. IV dexamethasone and nebulized adrenaline (1 mg in 5 mL of saline) will help to reduce any associated mucosal oedema and buy some time for the preparation of equipment, drugs, and staff.
Initial nasendoscopy by an ENT surgeon showed a normal larynx and normal vocal cords. Therefore, the entire obstructive lesion was below the cords. Further investigation was necessary to determine the extent of the lesion, prior to definitive treatment. The patient underwent emergency radiological investigations, comprising ultrasound and CT scans (performed whilst the patient remained prone). These demonstrated a large solid mass arising from the thyroid, deviating and compressing the trachea to approximately 5 mm, but with no retrosternal component. The carotid artery was also displaced. Upper airway assessment was unremarkable, with good mouth opening, full dentition, and a Mallampati class 2. The surgical plan is for a tracheostomy and biopsy of the lesion. For this, the patient will need to be turned supine.
The airway is in a critical condition and at risk of sudden total obstruction. The patient is now becoming exhausted, both by the work of breathing and that of keeping herself propped up on her elbows. The trachea is severely deviated, possibly kinked, and is significantly compressed. Whether this compression is fixed or not is unknown.
The tumour is potentially causing venous congestion, further hazarding the airway and increasing the bleeding risk on both airway manipulation and surgery. The patient can only maintain her airway in the knee–elbow prone position. This partially relieves the compression on the trachea, due to the weight of the tumour. Any airway manipulation will need to be done in this position.
1 Is it possible to do a tracheostomy under local anaesthesia?
No. It is not technically possible to perform this in the prone position. It is also likely to be an extremely difficult procedure, due to the large tumour in the way, the potential bleeding, and the extent of the tracheal deviation and compression.
2 Is it possible to intubate under general anaesthesia?
No. It is not possible to do this prone, as the patient’s position will collapse. Supine, there is an unsurmountable risk of a CICV and ‘can’t achieve front of neck access’ situation.
Therefore, the plan is to intubate her awake, whilst she remains self-supporting.
A topical ‘spray-as-you-go’ technique is required, as superior laryngeal nerve blocks and a cricothyroid puncture are obviously not possible. There is a risk of causing bleeding and laryngospasm, or the patient might panic, causing a sudden loss of airway.
Sedation is contraindicated, as the patient’s airway is dependent on her being fully awake and self-supporting. The unusual position creates additional complications. Although experienced in fibreoptic intubation, this operator had never performed the procedure in that position before.
It is very important to build up a rapport with the patient and gain her confidence. An explanation of the plan and the fact that it is the only safe option available is essential. All members of the theatre team must remain calm. Your plan must be communicated and discussed with the rest of the team.
Routine monitoring, IV access, and supplemental oxygen are applied. An antisialogogue, such as glycopyrrolate, is necessary, given as early as possible. All equipment should be prepared and checked.
The patient will be positioned prone on the operating table, supporting herself on her elbows, as far up the table as possible, allowing easy access to her head for the operator to sit on the floor beneath her.
Topical anaesthesia, using 4% lidocaine, can be carefully applied to the upper airway, using whatever method the operator is experienced in. This can be supplemented by further instillations via the working channel of the fibrescope.
A small-diameter, atraumatic ETT is preferred such as a size 6.0. This will minimize the gap between the fibrescope and the ETT, with less chance of encountering resistance passing through the cords and traumatizing the compressed trachea. If available, a bullet-tipped reinforced ETT, e.g. Fastrach™, will also have the advantage of resisting compression by the tumour on turning the patient supine.
The only adult ETT available with a smaller diameter would be a microlaryngoscopy tube, sizes 5 and 5.5. Their compatibility would need to be checked with the particular make/size of the fibreoptic scope used.
In this case, there is really not any other option, and an emergency cricothyroidotomy will not be possible. However, an experienced consultant ENT surgeon was present and scrubbed, with surgical instruments immediately to hand.
The procedure was well tolerated and straightforward. Below the cords, the trachea was ‘slit-like’, but the fibreoptic scope passed through, and a 6.0 Portex™ Ivory ETT was gently railroaded with ease.
Once the airway was secured, the patient was anaesthetized and turned supine. She underwent an uneventful surgical tracheostomy, using a size 8.0 adjustable flange tracheostomy tube, positioned laterally due to the tumour.
Subsequent pathology results of the biopsy were returned as a high-grade lymphoma. The patient received chemotherapy but unfortunately died within a month.
Summary
If conscious, patients with acute airway compromise will automatically adopt the easiest position in which to breathe. In this case, the patient’s position (equivalent to that of the quadrupedal animal) creates an airway alignment with an atlanto-occipital extension, opening the airway up, along with gravity displacing the soft tissues. Securing the airway with the patient awake and self-supporting is the only safe option.