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Anesthesiology:
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Use of the Laryngeal Mask for Exchange of Orotracheal Tubes

Asai, Takashi M.D., Ph.D.*

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ENDOTRACHEAL tubes can be exchanged by passing a tube exchanger through an old endotracheal tube into the trachea, removing the old tube, and then passing a new tube over the exchanger into the trachea. 1–5 One major problem associated with this technique is that it often may be difficult to advance an endotracheal tube over an exchanger because the tube's progress may be impeded by the epiglottis, the arytenoids, or the pyriform fossae. 6,7 For example, when a fiberoptic bronchoscope is used as an exchanger, there may be difficulties in tracheal intubation in 50–90% of patients. 6,8 I report the use of the laryngeal mask, which has a potential role in treatment of patients with difficult airways, 9,10 for exchange of endotracheal tubes in a patient in whom tracheal intubation and ventilation through a face mask were difficult.
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Case Report

A 45‐yr‐old man, (height, 172 cm; weight, 68 kg) who attempted suicide by taking diazepam and by stabbing himself in the abdomen, was scheduled for emergency laparotomy. Preoperatively, he was drowsy and responsive to simple verbal command only. Chest radiography showed opacity in the right lower lobe. Analysis of arterial blood gases showed arterial oxygen tension (PaO2) of 70 mmHg, arterial carbon dioxide tension (PaCO2) of 30 mmHg, and pH of 7.45 (fractional inspired oxygen tension [FIO2] = 0.21). A gastric tube was inserted and gastric lavage was performed; the tube was left in place.
There was no difficulty in opening the mouth or in extending or flexing the neck; the jaw was not small, nor was the neck short or “bull‐necked”; the thyromental distance was greater than three‐fingers width. It was not possible to assess other features of his airway after factors caused by insufficient patient cooperation.
In the operating room, routine monitors were attached while the patient was breathing oxygen. Cricoid pressure was applied and anesthesia was induced using thiopental and succinylcholine. Tracheal intubation using a size 4 Macintosh‐type laryngoscope was attempted; however, only the tip of the epiglottis was seen, and it was impossible to insert an 8.0‐mm ID endotracheal tube into the trachea. Ventilation via a face mask was attempted, but it was inadequate. Another two attempts at tracheal intubation, using the same laryngoscope but optimizing the patient's head and neck position and using a gum elastic bougie, failed and oxygen saturation by pulse oximeter (SpO2) decreased to 88%. While a laryngeal mask and a percutaneous transtracheal airway were being prepared, the fourth attempt at tracheal intubation was made, and SpO2 further decreased to 65%. This time, a 7‐mm ID tube was successfully inserted into the trachea and SpO2 rapidly increased to 99%. A suction catheter was passed through the endotracheal tube and a considerable amount of viscous fluid was aspirated. Anesthesia was maintained with fentanyl, nitrous oxide, and sevoflurane in oxygen, and muscle relaxation was produced with vecuronium. Excision of a perforated segment of the small intestine proceeded uneventfully.
After surgery, it was decided to transfer the patient to the intensive care unit before tracheal extubation. Nitrous oxide was discontinued, and 4 mg midazolam, 200 μg fentanyl, and 3 mg vecuronium were injected. Because the pilot balloon of the endotracheal tube was overexpanded, it was planned to adjust the cuff volume. An assistant attempted to remove air from the cuff, but it was difficult. An attempt at adding a small amount of air also was difficult, but suddenly obstruction was relieved and approximately 5 ml air was inadvertently infused. This caused a marked gas leak around the endotracheal tube. It was apparent that the cuff had ruptured, and therefore it became necessary to replace the tube.
Sevoflurane in oxygen was given. The existing endotracheal tube was affixed to the jaw using tape, and a size 5 laryngeal mask was placed without difficulty while the endotracheal tube was still in place. The cuff of the laryngeal mask was inflated with 20 ml air. A fiberoptic bronchoscope (4 mm in diameter) was passed through a 7.0‐mm ID endotracheal tube, and the combination was passed through the laryngeal mask so that the tip was just beyond the grill at the aperture of the laryngeal mask. The old endotracheal tube could be seen passing through the vocal cords. The fiberscope was then passed through the vocal cords into the trachea, alongside the old tube. After the carina was identified, the old tube was removed while the laryngeal mask was held in position. The lungs were ventilated through the new tube, which was in the laryngeal mask. The new tube was then advanced over the fiberscope into the trachea without difficulty, and correct reintubation was confirmed by fiberscopy, capnography, and auscultation. The length of the new endotracheal tube was extended by using a second endotracheal tube, and the laryngeal mask was removed over these tubes. The entire exchange procedure took only a few minutes, and time from removal of the old tube to reintubation took less than 10 s. SpO2 remained 100% throughout the exchange procedure.
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Discussion

The presence of an orotracheal tube does not prevent the placement of the laryngeal mask because the tube passes through the larynx, whereas the distal part of the laryngeal mask is inserted into the hypopharynx. When the endotracheal tube is affixed to the jaw and the laryngeal mask is inserted, using the index finger to slide the mask against the hard palate, it is possible to place the mask while barely touching the endotracheal tube and the tongue. The endotracheal tube can also be removed without dislodging the laryngeal mask. In our previous descriptions of 30 patients, it was always possible to place the laryngeal mask while the endotracheal tube was still in place, to remove the tracheal tube, and to ventilate through the laryngeal mask. 6,11
The laryngeal mask often can be placed successfully in patients in whom tracheal intubation, ventilation through a face mask, or both, has been difficult, 9,10 although there are circumstances in which placement of the laryngeal mask is also difficult. 12 Even if correct placement of the laryngeal mask has failed, a patent airway will not be lost, because an endotracheal tube is still in place. Attempt at placement of the mask may be repeated (possibly using a different size), or the technique of the use of the laryngeal mask may be abandoned.
There are three possibly useful features of the use of the laryngeal mask for tube exchange. First, by connecting the breathing system to a new endotracheal tube that is inserted in the laryngeal mask, it is possible to ventilate the lungs after removal of the old endotracheal tube during insertion of the fiberscope and during reintubation. Even if ventilation through the new endotracheal tube is inadequate during exchange procedure, jet ventilation through the suction port of the fiberscope can be applied. 13 Although not used in this case, by inserting a tube exchanger through the existing tracheal tube before extubation, it is also possible to apply jet ventilation through the exchanger. 14 Second, the laryngeal mask may facilitate location of the vocal cords using a fiberscope. 15 Third, advancement of a new endotracheal tube over the fiberscope into the trachea is less likely to be difficult when the tube is passed through the laryngeal mask than when it is not passed through the laryngeal mask. 6
The limitation of the use of the laryngeal mask for tube exchange is that this method can be used only for the exchange of oral endotracheal tubes: it is not possible to place the laryngeal mask while a nasotracheal tube is in place; nor is it possible to insert a nasotracheal tube while the laryngeal mask is in place. Another limitation is that a 6.0‐mm ID endotracheal tube is the largest that can be passed through the size 3 or size 4 laryngeal mask, although a 7.0‐mm ID tube can be passed through the size 5, as used in this patient.
Possible pitfalls of this technique include dislodgment of the fiberscope, laryngeal mask, or both, during removal of the old endotracheal tube and failure in advancing a new tube into the trachea. To reduce such problems, the old endotracheal tube should be removed gently while the laryngeal mask is stabilized and while confirming that the fiberscope is in the trachea. In addition, the old tube should be removed only after the position of the laryngeal mask is confirmed to be optimal.
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References

1. Millen JE, Glauser FL: A rapid, simple technic for changing endotracheal tubes. Anesth Analg 1978; 57: 735–6

2. Desai SP, Fencl V: A safe technique for changing endotracheal tubes. A NESTHESIOLOGY 1980; 53: 267

3. Loudermilk EP, Hartmanshgruber M, Stoltzfus DP, Langeuin PB: A prospective study of the safety of tracheal extubation using a pediatric airway exchange catheter for patients with a known difficult airway. Chest 1997; 111: 1660–5

4. Cooper RM: Conversion of a nasal to an orotracheal intubation using an endotracheal tube exchanger. A NESTHESIOLOGY 1997; 87: 717–8

5. Hudes ET, Fisher JA, Guslitz B: Difficult endotracheal reintubations: a simple technique. A NESTHESIOLOGY 1986; 64: 515–7

6. Koga K, Asai T, Latto IP, Vaughan RS: Effect of the size of a tracheal tube and the efficacy of the use of the laryngeal mask for fibrescope-aided tracheal intubation. Anaesthesia 1997; 52: 131–5

7. Watson CB: Use of fiberoptic bronchoscope to change endotracheal tube endorsed. A NESTHESIOLOGY 1981; 55: 476–7

8. Schwartz D, Johnson C, Roberts J: A maneuver to facilitate flexible fiberoptic intubation. A NESTHESIOLOGY 1989; 71: 470–1

9. Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. A NESTHESIOLOGY 1996; 84: 686–99

10. Asai T, Morris S: The laryngeal mask airway: Its features, effects and role. Can J Anaesth 1994; 41: 930–60

11. Asai T: Use of the laryngeal mask during emergence from anaesthesia. Eur J Anaesthesiol 1998; 15: 379–80

12. Asai T: Difficulties in insertion of the laryngeal mask, Difficulties in Tracheal Intubation, 2nd edition. Edited by Latto IP, Vaughan RS. London, WB Saunders Company, 1997, pp 197–214

13. Satyanarayana T, Capan L, Ramanathan S, Chalon J, Turndorf H: Bronchoscopic jet ventilation. Anesth Analg 1994; 59: 350–4

14. Benumof JL: Additional safety measures when changing endotracheal tubes. A NESTHESIOLOGY 1991; 75: 921–2

15. Asai T, Latto IP, Vaughan RS: The distance between the grille of the laryngeal mask airway and the vocal cords: Is conventional intubation through the laryngeal mask safe? Anaesthesia 1993; 48: 667–9

Keywords:
Difficult airway; endotracheal intubation; fiberoptic bronchoscope.

© 1999 American Society of Anesthesiologists, Inc.

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