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Correspondence  |   December 2001
A New Technique of Fiberoptic Intubation through a Standard LMATM
Author Notes
  • University of California-San Diego Medical Center, San Diego, California. jbenumof@ucsd.edu
Article Information
Correspondence
Correspondence   |   December 2001
A New Technique of Fiberoptic Intubation through a Standard LMATM
Anesthesiology 12 2001, Vol.95, 1541. doi:
Anesthesiology 12 2001, Vol.95, 1541. doi:
To the Editor:—
The purpose of passing a nasal RAE tracheal tube (NRT) (Mallinkrodt, St. Louis, MO) over a fiberoptic bronchoscope (FOB) to fiberoptically intubate through a standard Laryngeal Mask Airway  ™ (LMA  ™) (Laryngeal Mask Co., Henley on Thames, Oxon, UK) (fig. 1) is to gain a 5- to 6-cm greater depth of tracheal intubation compared with a standard endotracheal tube. 1,2 A standard endotracheal tube, when fully inserted through an appropriately sized standard LMA  ™, enters the trachea by a mere 1–2 cm. 1–3 
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
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Figure 1shows a 7.0-mm-ID NRT inside a No. 5 LMA  ™ (upper left assembly) and a 6.0-mm-ID NRT inside a No. 4 LMA  ™ (lower right assembly). In both assemblies, the distal tip of the NRT is positioned 1 cm proximal to the aperture bars, which then allows one to fiberoptically and sequentially identify the aperture bars, laryngeal structures, and the trachea. The NRT is also positioned within the shaft of the LMA  ™ with the Murphy eye at the 12 o’clock position to facilitate passage of the tip of the NRT through the middle compartment of the aperture bars and then the vocal cords (over the FOB). With this spatial arrangement of the NRT inside the LMA  ™ and assuming a distance from aperture bar to vocal cord of 4.0 cm, 3 fully passing an Olympus BF type P40 FOB (Melville, NY) through a 7.0-mm-ID NRT and passing an Olympus BF type 3C FOB through a 6.0-mm-ID NRT results in the FOB entering the trachea by only 2 and 4 cm, respectively. Indeed, in a few patients (5–10%) with the 7.0-mm-ID NRT, No. 5 LMA  ™, and the larger FOB combination, I have been unable to reach the trachea with the FOB by 0.5–1.0 cm; in these instances, the NRT must be advanced at the same time as the FOB is advanced. However, simultaneous NRT and FOB movement significantly complicates the procedure and disturbs the FOB view. The purpose of this letter to the editor is to point out that by simply cutting off the proximal 2 cm of the NRT, one gains a 2-cm greater depth of tracheal entry by the FOB, while maintaining adequate depth of tracheal intubation by the NRT, i.e.  , satisfactory clinical performance by both the FOB and the NRT.
References
Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. A nesthesiology 1996; 84: 686–99Benumof, JL
Roth DM, Benumof JL: Intubation through a laryngeal mask airway with a nasal RAE tube: Stabilization of the proximal end of the tube (letter). A nesthesiology 1996; 85: 1220Roth, DM Benumof, JL
Asai T, Latto IP, Vaughan RS: The distance between the grill of the laryngeal mask airway and the cords: Is conventional intubation through the laryngeal mask safe? Anaesthesia 1993; 49: 667–9Asai, T Latto, IP Vaughan, RS
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
Fig. 1. Photograph showing the assembly of equipment (fiberoptic bronchoscope, bronchoscopy elbow, nasal RAE tube, and LMA ™) used for fiberoptic intubation of the trachea with a nasal RAE tube passed through an LMA ™. The upper left assembly consists of a 53.5-cm-long, 5.0-mm-OD Olympus BF type P40 fiberoptic bronchoscope; a 37-cm-long, 7.0-mm-ID nasal RAE tube; and a No. 5 LMA ™. The lower right assembly consists of a 54.5-cm-long, 4.0-mm-OD Olympus BF type 3C fiberoptic bronchoscope; a 35-cm-long, 6.0-mm-ID nasal RAE tube; and a No. 4 LMA ™.
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