Department of Anaesthesia, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK*Corresponding author
LMA® is the property of Intavent Limited.
Accepted for publication: July 13, 2001
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Abstract |
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Br J Anaesth 2001; 87: 78790
Keywords: equipment, Montgomery T-tube; anaesthetic management
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Introduction |
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During the management of general anaesthesia for patients undergoing laryngotracheal surgery, anaesthetists may have to deal with patients who need insertion of a Montgomery tube, or deal with cases that have such a tube in situ. As these cases are rare, they may present difficulties for anaesthetists who are not familiar with the tube.
We describe two cases involving the Montgomery tube, and discuss their anaesthetic management.
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Case 1: insertion of Montgomery T-tube following tracheoplasty |
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He received pre-medication with 10 mg of oral temazepam and was given 0.2 mg of glycopyrrolate i.v. before induction of anaesthesia. After pre-oxygenation and institution of non-invasive monitoring, inhalation induction of anaesthesia was carried out using sevoflurane in 100% oxygen through the tracheostomy tube. Atracurium 40 mg was used for muscle relaxation and to facilitate controlled ventilation of the lungs. In order to facilitate surgery, a size 6 mm cuffed microlaryngeal tube (Mallinckrodt Medical, Athlone, Ireland) was inserted easily into the trachea through the tracheostomy stoma after the removal of the tracheostomy tube. General anaesthesia was maintained with sevoflurane, nitrous oxide, and oxygen, and supplemented with i.v. fentanyl as required. During surgery, the patient was monitored using pulse oximetry, end-tidal carbon dioxide concentration, arterial pressure, and electrocardiogram. After an uneventful tracheoplasty, a size 4 laryngeal mask airway (LMA) was inserted in the usual manner and secured in place. The upper end of the LMA was blocked off and controlled ventilation continued using 100% oxygen through the microlaryngeal tube until the surgeon replaced it with a size 12 Montgomery tube in order to stent the tracheoplasty. Once in place, the extratracheal part of the Montgomery tube was occluded with a spigot. The anaesthetic breathing system was connected to the LMA using a standard catheter mount, and ventilation continued thereafter using the LMA. The safe and appropriate position of the upper intratracheal part of the Montgomery tube was then confirmed with a fibreoptic laryngoscope inserted through the LMA. The procedure was uneventful with satisfactory ventilation maintained throughout the operation.
At the end of the procedure, residual neuromuscular block was antagonized with neostigmine (2.5 mg) and glycopyrrolate (0.5 mg). The spigot was removed from the extratracheal portion of the Montgomery tube, and the LMA removed with the patient awake. The patient could thus breathe through both parts of the Montgomery tube.
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Case 2: anaesthesia for laser application to the trachea in a patient with a Montgomery tube in situ |
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Due to a compromised upper airway, an inhalation technique for induction of general anaesthesia using sevoflurane in 100% oxygen was chosen. A modified breathing system was used to anaesthetize the patient (Fig. 2). It consisted of a lightweight Bains circuit carrying fresh gas and volatile agent to a Y-piece connection. One end of the Y-piece was connected to a facemask, the other end of the Y connection was attached to the extratracheal part of the Montgomery tube via a long catheter mount, using a suitable tracheal tube connector. A high fresh gas flow was used to compensate for the altered breathing system and to aid carbon dioxide elimination.
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Discussion |
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There are a few reports about the anaesthetic management of patients who need Montgomery tube insertion.25 However, there are no reports regarding the management of patients who present for anaesthesia with a Montgomery tube in situ.
Insertion of the Montgomery tube and airway control
The standard method of inserting the tube is to grasp it with curved haemostatic forceps and place the long intratracheal portion through the tracheostomy. The extratracheal lumen is then tugged anteriorly to straighten the tube in the trachea, and thus position the upper intratracheal limb. However, during this time the airway is not fully under control until the tube is secured in position. During insertion the tube can become misplaced or kinked below the junction of the extratracheal portion with the intratracheal part, leading to complete airway obstruction. In such cases, the Montgomery tube should be removed and reinserted appropriately. Previous descriptions of methods to overcome these problems are either too complicated or do not ensure correct placement of the Montgomery tube.
Cooper and others3 used a rigid bronchoscope after the tracheal stoma had been created. A tape was threaded through the T-tube, and visualized through the bronchoscope after being passed through the tracheal stoma. A long forceps was then used to pull the tape superiorly and railroad the T-tube over it. This method is complicated and does not ensure adequate ventilation during the procedure.
Chonchubhair and colleagues4 used a technique in which neuromuscular block was antagonized at the end of operation thus establishing spontaneous respiration. A gum elastic bougie was inserted through the tracheal tube. The bougie was then visualized and delivered through the tracheal stoma to the exterior. The T-tube was then railroaded into the trachea over the bougie. Once in place, the tracheal tube was advanced through the Montgomery tube, recommencing anaesthesia through the tracheal tube. This method suffers from several drawbacks. Although there is a continued presence of a tracheal tube during the insertion of the T-tube, ventilation is discontinued. There is a further risk of dislodging the T-tube and injuring reconstructed tissue during the process of advancing the tracheal tube through it and indeed, during extubation. Sichel and colleagues5 have described a variation of this technique, using a nasogastric tube to railroad the T-tube.
Hypoventilation and air dilution of anaesthetic gases, because of the open intratracheal upper end of the Montgomery tube, were recognized by Montgomery.1 He suggested passing a Fogarty embolectomy catheter through the extratracheal lumen up to the upper stem of the T-tube and occluding the open upper end by inflating the balloon of the catheter. A suitably sized tracheal tube could then be placed in the extratracheal lumen of the T-tube adjacent to the catheter, and ventilation continued.
In order to deal with the above problems during insertion of the tube, continuous i.v. anaesthesia and insufflation of oxygen into the lungs using a fine catheter can be used. The technique we described above offers safety and avoids the cumbersome use of catheters and railroading devices. As an LMA is inserted prior to the Montgomery tubes insertion, the airway is always under the control of the anaesthetist. Furthermore, our management of the airway does not interfere with the surgical reconstruction. Therefore, even if technical difficulties or a delay in the insertion of the Montgomery tube is encountered, the patients safety is not put at risk. Uchiyama and Yoshino6 have used a technique similar to the one we describe, with an important difference. They occlude the top end of the LMA, thus employing it as a means of upper airway occlusion, while ventilation continues via the extratracheal portion of the Montgomery tube. Our method not only provides a means to ventilate the patients lungs, but also allows us to use a fibreoptic laryngoscope placed via the LMA to visually confirm the correct position of the Montgomery tube.
Anaesthesia with an in situ Montgomery tube
The main problem with a patient with an in situ Montgomery T-tube is the uncertainty regarding the volume of air passing across the tracheal stoma and that passing via the upper laryngeal end of the tube and through the larynx. Administration of a neuromuscular blocking agent at induction of anaesthesia and attempts to control ventilation under these circumstances would, therefore, be hazardous until and unless the airway is secured.
Inhalation induction of anaesthesia remains the method of choice in such patients. However, it is also necessary to supply the patient with the same composition of fresh gas flow and a volatile anaesthetic agent at both the extratracheal and laryngeal ends to prevent air dilution. We have found no description of the anaesthetic management of such patients in the literature.
We prefer to anaesthetize such patients by using a modified breathing system. A Bains breathing system is used, and a Y-connector placed at the end of the circuit splits the fresh gas flow into two streams: one to the Montgomery tube, and the other to a standard anaesthetic face mask (Figure 2). A fresh gas flow at a rate of 50 ml kg1 min1 is added empirically to the standard fresh gas flow requirements for the Bains system to make allowances for our alteration. The addition of the facemask to deliver anaesthetic gases compensates for any leak around the laryngeal port of the Montgomery tube. Once the patient is anaesthetized, the Montgomery tube can be removed with gentle traction, and an appropriate laser protected tracheal tube is inserted through the tracheal stoma. If the Montgomery tube needs to be reinserted at the end of the operation, our earlier method of using an LMA is followed.
We have used these techniques for several years with good results and no adverse effects. As these patients are unlikely to present frequently, an anaesthetist who is not familiar with the Montgomery tube may be faced with difficulties. We hope that the management of these patients, which we have described above will improve safety. We also strongly suggest detailed discussions with the surgical team to avoid potential problems when dealing with a shared airway.
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Acknowledgements |
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References |
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3 Cooper JD, Todd TRJ, Ilves R, et al. Use of the silicone tracheal T-tube for the management of complex tracheal injuries. J Thorac Cardiovasc Surg 1981; 82: 55968[Abstract]
4 Chonchubhair AN, OConnor T, OHagan C. A novel approach to insertion of the Montgomery T-tube. Anaesthesia 1994; 49: 6057[ISI][Medline]
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6 Uchiyama M, Yoshino A. Insertion of the Montgomery T-tube. Anaesthesia 1995; 50: 4767