The simultaneous use of three ventilatory techniques to maintain oxygenation in a patient undergoing tracheal laser resection of tumour

Summary

Patients undergoing subglottic airway surgery present a challenge to both anaesthetist and surgeon, and often a balance between surgical access and method of ventilation has to be struck. We report a case in which a 38‐year‐old female with a large mediastinal mass causing distal tracheal obstruction underwent tracheal laser resection. In order to maintain oxygenation throughout she required simultaneous transnasal humidified rapid‐insufflation ventilatory exchange, supraglottic high‐frequency jet ventilation and suprastomal manual jet ventilation through her tracheostomy stoma. Where the use of one technique alone failed, the simultaneous use of all three maintained oxygenation and facilitated surgical access for the duration of the procedure.

Introduction

Tubeless anaesthesia is a common requirement for laryngeal and tracheal surgery, and was first published as a technique by Sanders in 1967 1, with others adopting it later 2. Although it allows an unimpeded view of the larynx and trachea to benefit the surgeon, ventilation can often be challenging, and novel techniques have had to be developed. Before the recent development of transnasal humidified rapid‐insufflation ventilatory exchange (THRIVE) 3, the mainstay of ventilation was by jet ventilation, both supraglottic and subglottic (often using a Hunsaker Mon‐Jet catheter). High‐frequency jet ventilation (HFJV) and THRIVE can be effective modes of ventilation but there are certain patients in which these techniques fail, resulting in the requirement of a tracheal tube, interruption of surgery and a significantly reduced surgical field.

Here, we report the simultaneous use of THRIVE, supraglottic HFJV and suprastomal manual jet ventilation (MJV) to successfully maintain oxygenation in a patient undergoing laser resection of a mediastinal mass eroding into the trachea. We believe this to be the first report of the simultaneous use of all three techniques (Fig. 1).

Figure 1.

Transnasal humidified rapid‐insufflation ventilatory exchange, supraglottic high‐frequency jet ventilation and suprastomal manual jet ventilation being used simultaneously.

Report

A 38‐year‐old, 98‐kg female was scheduled for an urgent tracheal stenting following transfer from another hospital. Three months earlier she had been diagnosed with an aggressive mediastinal non‐germ cell choriocarcinoma of lung origin. This initially presented as difficulty in breathing with airway compromise, which was managed by emergency tracheal intubation and subsequent tracheostomy. Following this initial event, choriocarcinoma was diagnosed and chemotherapy was commenced. She responded well to treatment initially, but subsequent computerised tomography (CT) scans showed progression of the disease with tracheal and right main bronchus invasion and obstruction.

On the morning of surgery, she was spontaneously ventilating via an adjustable‐flange size eight tracheostomy with the cuff deflated. She was short of breath at rest, her exercise tolerance was less than 5 m and she could not lie flat. An echocardiogram showed there was no significant cardiac involvement. She had no other significant co‐morbidities.

In the operating theatre, she was positioned on the operating table in a head‐up position and pre‐oxygenated with an F_IO₂ of 1.0 both with THRIVE (delivered using OptiFlow™, Fisher & Paykel Healthcare Limited, Maidenhead, UK) at a flow of 70 l.min⁻¹ and via the anaesthetic circuit attached to the tracheostomy with the cuff deflated. Anaesthesia was induced with a total intravenous technique using a target‐controlled infusion of propofol (Marsh model) and remifentanil (Minto model). Ventilation through the tracheostomy tube was verified, and paralysis was induced using 0.6 mg.kg⁻¹ of rocuronium. She then underwent a microlaryngoscopy, at which point supraglottic HFJV was started using a Monsoon III Jet Ventilator (Acutronic Medical, Hirzel, Switzerland) in addition to THRIVE. At this point the tracheostomy tube was removed and the stoma covered. Microlaryngoscopy revealed no laryngeal pathology, and a flexible bronchoscopy was undertaken. Upon visualisation, it was noted that the tumour had invaded the lower trachea (> 80% obstruction) and right main bronchus (50% obstruction). Tumour debulking using cryo‐extraction and laser coagulation was commenced.

Despite the combined use of two oxygenation techniques (THRIVE and supraglottic HFJV), the patient began to desaturate after 12 min, so we added a third technique: suprastomal low‐frequency MJV through tracheostomy stoma using a Manujet III (VBM‐Medical, Sulz, Germany). The addition of this technique increased her oxygen saturation to 99%, and all three methods of ventilation were continued throughout the operation, with brief pauses in each to allow for safe laser resection. It was noted during these apnoeic spells that if all three techniques had not been used in the preceding period, the time to desaturation reduced from around 10 min to 3 min, therefore all three were required for optimum oxygenation.

Postoperatively, a tracheostomy tube was re‐inserted and the anaesthetic was discontinued. Upon waking she was transferred to the high dependency unit for ongoing monitoring. She was successfully decannulated the next day and discharged home for ongoing oncological care.

Discussion

Airway surgery can be complex and high risk, and there have been various techniques described in the past for oxygenating and ventilating patients while also allowing an unobstructed surgical field 4. On occasion one technique alone is not enough and combinations are used, but despite this, oxygen desaturation does occasionally occur. This may necessitate intubation and intermittent positive pressure ventilation to rerecruit atelectatic lung segments, resulting in a reduced surgical field and/or pauses in the operation before removing the tracheal tube and continuing with surgery.

Jet ventilation is achieved when jetstreams originating from high‐pressure sources are cut by pneumatic or electronic flow interruption devices, generating a tidal volume that is supplemented by entrainment of gases at the jet needle. Expiration is passive and dependent on lung and chest wall recoil. The degree of ventilation and oxygenation is often a result of two variables: the tidal volumes delivered and the composition of the jet gas. High‐frequency jet ventilation tidal volumes are usually less than the dead space but the high frequency results in movement of gasses by a combination of bulk transfer, Taylor‐type dispersion and Pendelluft ventilation 5. The tidal volumes themselves are not set, but are influenced by driving pressure, frequency, inspiratory time and the degree of entrainment, which itself is affected by the driving pressure and the location of the jetting needle. Modern jet ventilators allow one to set the desired F_IO₂, but due to entrainment of air, the delivered F_IO₂ is often much lower 2. The combined use of THRIVE and supraglottic HFJV increases the F_IO₂ delivered by a process of entrainment of the oxygen delivered by THRIVE.

In this situation, there were two key factors that affected our decision to add a third, simultaneous, method of ventilation in the form of suprastomal MJV. Firstly, the laser resection of the tumour was causing significant airway bleeding and we were concerned that pausing the procedure could result in further blood loss and that the introduction of positive pressure ventilation could force clots further into the bronchial tree. Secondly, we were in the fortunate position of the patient having an alternate route into her airway via the well‐established tracheostomy stoma.

It was interesting to note that THRIVE combined with supraglottic HFJV insufficient to maintain oxygenation, possibly due to the dissipation of the driving pressure between the ventilator and the jetting needle, the needle and the trachea, and malalignment/obstruction of the jet stream by the flexible bronchoscope. The suprastomal MJV had a much shorter attachment, and was closer to the airway, theoretically resulting in a greater preservation of driving pressure, and consequently greater chest wall excursion was observed. Despite increased chest wall movement, oxygen saturations continued to fall when this technique was used in isolation, leading us to conclude that MJV alone was not sufficient to maintain oxygenation. A possible explanation for this is that the delivered F_IO₂ was too low as a result of the entrainment of air. It was the combination of supraglottic HFJV and THRIVE to deliver a higher F_IO₂, and suprastomal MJV to deliver a suitable driving pressure that provided sufficiently stable conditions to continue with the operation.

In this case we did not witness any complications from the oxygenation techniques, but with any form of jet ventilation (particularly MJV), there is a risk of barotrauma and volutrauma 6, 7. It stands to reason that using multiple forms of jet ventilation concurrently increases this risk. We adopted standard jet ventilation safety measures to minimise risk; the patient's chest was uncovered so we could directly see and feel the degree of chest wall movement, allowing us to alter the frequency and duration of MJV as appropriate. The presence of the tracheostomy stoma meant that there was an unobstructed path for gas egress, minimising the risk of the accumulation of pressure and volume and, therefore, the risk of injury.

Although this technique will not be possible, nor indeed required, for most patients, it allowed a technically difficult operation to be completed with minimal interruption. We would recommend that in similar situations clinicians should consider the addition of suprastomal MJV if oxygenation is not optimal.