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The anaesthetic management of a case of severe upper airways obstruction due to an enlarging subglottic benign polyp

Vadodaria, B.1; Cooper, C. M. S.2

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European Journal of Anaesthesiology: November 2001 - Volume 18 - Issue 11 - p 766-769

Abstract

Presentation

A 76-year-old woman presented to the Ear, Nose and Throat (ENT) department with a 3-day history of increasing inspiratory and expiratory stridor. She had lost her voice, had worsening shortness of breath and was dysphagic for solid food. She was severely orthopnoeic, being unable to move from the sitting position and developed respiratory obstruction whenever her neck was slightly extended. An ENT consultant had performed an indirect laryngoscopy: he found a large subglottic polyp rising up through the vocal cords such that the glottic inlet was virtually occluded. At that time it was thought that the polyp did not extend more than 1 cm below the vocal cords and that endotracheal access might be achieved most easily posterolaterally. Anaesthetic assessment was requested to permit an emergency microlaryngoscopy to remove the polyp and to allow diagnostic upper airway panendoscopy. The patient had no family or past medical history of any problems. She had not undergone anaesthesia before.

The patient was conscious, well oriented and extremely anxious. She had a pulse rate of 110 beats min–1 and blood pressure 120/60 mmHg. She was very dyspnoeic with a respiratory rate of 36–40 bpm and any attempt to extend her neck produced airway obstruction. Signs of upper airway obstruction were present: dilated alae nasi, use of accessory muscles of respiration, suprasternal, intercostal and subcostal retraction plus tracheal tug. However, the patient was not cyanosed, and her jugular venous pressure was normal. She had a Mallampati score of grade I, thyromental distance of 6.5 cm, good mouth opening and neck extension. Auscultation of the chest was normal apart from conducted obstructive sounds from the upper airways. SPO2 was 93% during air breathing. The following investigations were performed and all were within normal limits: full blood count, coagulation profile, plasma urea and electrolyte determinations, and chest radiography. Immediate control of her airway was indicated.

The patient was brought into the operating theatre in a semi-sitting position. Pure oxygen was administered before induction of anaesthesia. An 18-gauge intravenous (i.v.) cannula was already in situ. Electrocardiography, SPO2 and on-invasive arterial pressure monitoring were established. The special difficult intubation trolley was checked and the ENT surgeon was requested to stand by in case an immediate surgical tracheostomy became necessary. A cricothyroid needle and Sander’s jet injector were prepared ready for subglottic jet ventilation. The tissues anterior to the trachea were infiltrated with a mixture of lidocaine 1% and epinephrine 1:200 000 in anticipation of any urgent need to insert a surgical airway. We were also prepared to insert an intercostal drain if the need arose.

The patient was preoxygenated breathing 100% oxygen for 5 min and glycopyrrolate 0.2 mg i.v. was given. Anaesthesia was induced with alfentanil 3 mg and propofol 40 mg, followed by succinylcholine 100 mg. Direct laryngoscopy, with a Macintosh size three blade, revealed a Cormack and Lehane Grade I view of the glottic inlet [2] and a large polyp which completely obstructed the airway was seen (Figure 1). An elective decision had already been made to use the Hunsaker tube should this situation arise. It proved possible to pass this tube (3-mm OD) posterolateral to the polyp as had been suggested by the ENT surgeon. The Hunsaker tube was then connected to a Sander’s jet injector.

Figure 1.
Figure 1.:
Laryngoscopic view of the subglottic polyp almost totally obstructing the glottic opening.

Ventilation of the lungs was controlled at a rate of 8–10 bpm by gradually increasing the pressure administered through the jet injector, while monitoring bilateral air entry and observing chest expansion. An air leak around the tube was confirmed to permit expiration. Moreover, sufficient time was allowed for expiration to occur lest air trapping developed because of the narrow glottic opening. The anaesthetic was maintained using a combination of two repetitive boluses each of alfentanil (1 mg) and propofol (50 mg). Dexamethasone 8 mg was given to reduce tissue oedema. The subglottic polyp was completely excised with minimal blood loss. A 5.0-mm microlaryngeal tube was then inserted to replace the Hunsaker tube and the anaesthetic maintained by manual ventilation of the lungs with isoflurane in a mixture of nitrous oxide and oxygen. Oesophagoscopy was performed uneventfully.

At the end of the procedure, the patient was given naloxone 2 mg i.v. and paracetamol 1.5 g and diclofenac 100 mg suppositories for postoperative analgesia. Tracheal extubation was uneventful. The patient was admitted to the high-dependency unit overnight should airway complications develop. Fortunately, there were none and the patient made a full recovery. Histology showed the polyp to be benign.

Discussion

The options we considered for the safe induction and maintenance of anaesthesia are stated in Table 1. Options I and II were not chosen because we judged the patient to be unable to maintain adequate lung ventilation during either technique, and the additional problem of completely occluding her airway with the latter. A surgical tracheostomy would have been difficult to perform in the sitting position. Option III was thus kept in reserve should the other options fail. It is important to have the surgeon standing by in case of failure to intubate and difficulty in oxygenating the patient.

Table 1
Table 1:
Options considered for safe induction and maintenance of anaesthesia

Option IVa was not a method of choice as there was a high risk of accidentally damaging the polyp and causing haemorrhage. Option IVb, i.e. endotracheal intubation with a microlaryngoscopy tube after i.v. induction with or without a muscle relaxant was not a technique of choice as we suspected it would be difficult to introduce a size 5.0 cuffed tube through the laryngeal opening. Moreover, it might have avulsed the polyp and pushed it more distally raising the risk of a ball valve effect lower in the airway and causing bleeding. Option IVc was rejected as it could distend the stomach and could lead to pulmonary aspiration. Moreover, it could be ineffective because of the narrowed laryngeal opening. Option IVd was an impractical solution considering the size of the glottis. Also there is the risk of hypercapnia and associated problems, e.g. hypertension, dysrhythmias and increased bleeding.

After our risk benefit analysis, it was decided to use plan IVe. We chose to use a rapid sequence i.v. induction followed by total intravenous anaesthesia (TIVA) for maintenance during surgery. Another option for maintenance of anaesthesia might have been TIVA with continuous propofol and remifentanil infusions. However, we had no facilities for this. Because we had the benefit of the information obtained by previous indirect laryngoscopy together with our airway assessment, we were confident we would achieve immediate access to the glottis at direct laryngoscopy using this technique. We had electively decided that once we could see the glottis we would then select either the correct sized endotracheal tube or else the Hunsaker Monjet tube. If that had proved impossible an immediate tracheostomy would be needed. Because there was no difficulty anticipated in viewing the glottis, this was considered to be a more feasible approach to gaining access to the airway than opting for a tracheostomy at the outset.

Hunsaker specifically designed this tube to be used in cases of suspension laryngoscopy where there is no airway obstruction, as there is a risk of tension pneumothorax resulting from its use in the presence of airway obstruction. Although we used this tube in a patient with airway obstruction we always kept in mind the possibility of a tension pneumothorax developing and so we took every precaution to avoid – as well as diagnose and treat it – should it occur. Ideally, it would have been safer to use a device that allows better control of the rise in intrathoracic pressure than is possible with a Sanders’ injector. An example of this is the Monjet III (VBM Medizintechnik GmbH, Sulz a.N., Germany), which is a high-pressure injector and includes a reducing valve and manometer to vary the driving pressure. After surgical excision of the polyp enough space had been created for the introduction of a size 5.0 microlaryngeal tube for better control of the airway.

The Hunsaker Monjet tube (Figure 2) has several advantages. It is made from a flexible, non-kinkable, combustion-resistant polymer that conforms to the patient’s airway and has an external diameter of 2.9 mm (Figure 3). It has an integral monitor line, which minimizes the space needed for monitoring end-tidal CO2. It allows maximal visualization and surgical access with minimal vocal fold motion during ventilation of the lungs. In addition, it is laser compatible, where indicated.

Figure 2.
Figure 2.:
The Hunsaker Monjet tube.
Figure 3.
Figure 3.:
Dimensions of the Hunsaker Monjet tube.

Ideally, the patient should have had some kind of imaging (e.g. by computerized tomography or magnetic resonance) performed before surgery to identify the exact anatomical extension of the polyp in the trachea. However, in view of the urgency for securing the airway this was not performed because the surgeons were sure of the lower limit of this polyp from their previous findings at indirect laryngoscopy. The ideal anaesthetic technique for short laryngeal operations should not only provide immobility of the vocal cords and obtund pressor reflexes, but also ensure rapid recovery of airway reflexes at the end of the anaesthetic and airway protection from bleeding. By giving large doses of a short-acting opioid during surgery with the addition of succinylcholine, we achieved a deeply anaesthetized, immobile, relaxed patient with good cardiovascular stability. We chose to ‘reverse’ the anaesthetic with the opioid antagonist naloxone because postoperative discomfort was to be controlled with non-steroidal anti-inflammatory drugs.

We successfully managed this patient with a severely compromised upper airway by the combined means of new and traditional techniques. The availability of this innovation made it possible to avoid alternatives with the significant risks associated with them. It allowed the procedure to be successfully carried out with good intraoperative stability and rapid recovery without sequelae.

In conclusion, we must stress that this tube is not routinely recommended for an obstructed airway, but its use should be encouraged and practised more often in routine microlaryngeal surgery. This would permit confidence in its use in unusual cases.

References

1 Hunsaker DH. Anesthesia for microlaryngeal surgery: the case for subglottic jet ventilation. Laryngoscope 1994; 104 (Suppl. 65): 1–30.
    2 Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984; 39: 1105–1111.
    Keywords:

    RESPIRATORY INSUFFICIENCY, airway obstruction

    © 2001 European Academy of Anaesthesiology