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Correspondence  |   July 1997
Usable versus Overall Tracheal Tube Length  : The Difference May Be Critical
Author Notes
  • Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, 171 Ashley Avenue, Charleston, South Carolina 29425–2207.
Article Information
Correspondence
Correspondence   |   July 1997
Usable versus Overall Tracheal Tube Length  : The Difference May Be Critical
Anesthesiology 7 1997, Vol.87, 173. doi:
Anesthesiology 7 1997, Vol.87, 173. doi:
To the Editor:-Asai recently suggested that tracheal intubation through the laryngeal mask airway (LMA) may best be accomplished using the 6.0-mm reinforced tracheal tube (Mallinckrodt, Althone, Ireland) when sufficient tracheal tube length is a consideration. [1 ] The possibility of intralaryngeal or supraglottic tracheal tube cuff positioning after intubation with a standard 6.0-mm tracheal tube passed through the LMA has been previously described, [2 ] and suggested solutions have included the use of tubes with additional length such as the extra-long 5.0-mm microlaryngeal tracheal tube (Mallinckrodt, St. Louis, MO), [2 ] the nasal RAE[registered sign](Mallinckrodt), [3 ] or “splicing” two tubes together. [4 ]
We agree with Asai that the reinforced tube may be preferable because of its greater flexibility and increased diameter compared with the 5.0-mm microlaryngeal tube, however, he incorrectly states that the length of the 6.0-mm reinforced tube is 33 cm. By the manufacturer's specifications and our own measurements, the length of the 6.0-mm reinforced tracheal tube measured from its distal tip to the proximal polyvinyl chloride end of the tube is 29 cm. Possibly, Asai included the connector length when measuring the tube and reported its overall length, which is 33 cm. Because the connector does not pass into the LMA and is extremely difficult to remove from this tube, by design, it should not be included when calculating usable tube length. We considered the possibility that the reinforced tube manufactured outside the United States may be of a different length, although the manufacturer confirms that the dimensions are universally consistent. In actuality, the reinforced tracheal tube is identical in length to a standard tracheal tube, therefore, it offers no advantage when additional tracheal tube length is necessary for reliable tracheal tube cuff positioning during intubation through the LMA.
Susan C. Harvey, M.D.
Melinda K. Bailey, M.D.
James E. Cooke, M.D.
Department of Anesthesia and Perioperative Medicine; Medical University of South Carolina; 171 Ashley Avenue; Charleston, South Carolina 29425–2207
(Accepted for publication March 27, 1997.)
References 
References 
Asai T: Tracheal intubation through the laryngeal mask airway. Anesthesiology 1996; 85:439.
Benumof JL: Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 1996; 84:689-99.
Alfery DD: Laryngeal mask airway and the ASA difficult airway algorithm: I. Anesthesiology 1996; 85:685.
Ullman DA: Laryngeal mask airway and the ASA difficult airway algorithm: III. Anesthesiology 1996; 85:686.