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Is there a need for the epiglottic bars in the laryngeal mask airway?

Kent UK

To the Editor:

The laryngeal mask airway (LMA-Classic) has been used widely in clinical practice including as a conduit for fibreoptic-aided intubation.¹ Fibreoptic-aided intubation is preferred to blind intubation due to the lower risk of soft tissue trauma and the ability to confirm correct positioning of the tracheal tube. Bars at the junction of the mask and the tube were designed to prevent the epiglottis from occluding the airway,² but may obstruct the passage of the tracheal tube.³

After approval of Ethics Committee, we evaluated the effect of the absence of the bars on the positioning of the LMA-Classic and its effect on the clinical management of the airway in adults. The manufacturer’s instructions regarding the size of the LMA were followed. One hundred and sixty patients were divided into two groups; LMAs with and without bars. Anesthesia was induced using fentanyl and propofol and supplemented with oxygen, nitrous oxide and sevoflurane, with rocuronium when surgically indicated. The LMA was inserted one minute after completion of induction and following the loss of lash reflex and the relaxation of the jaw. The anesthesiologist who inserted the LMAs (B.A.-S.), blinded to the type of the LMA, used the standard technique of insertion⁴ applying standardized clinical tests to evaluate the correct placement of the LMA.⁵ Using a fibrescope with its tip located at the inner aperture of the LMA, another anesthesiologist (D.P.) who was not present during the placement of the LMA, assessed the position of the epiglottis using a standardized four-point scale.⁵ The incidence of laryngeal spasm, both endoscopically and clinically, was documented. Statistical analysis was with Chi-squared test. LMAs with no bars were used in a further 300 patients undergoing gynecological and orthopedic procedures.

No patient was excluded from the study. All 160 patients, in both groups, had a patent and clinically acceptable airway from the first attempt of the LMA insertion. There was no significant difference between the two groups in the incidence of correct and suboptimal positioning of the LMAs as shown in the Table. The LMAs were inserted and placed successfully from the first attempt in all 300 patients. None of the 460 patients had laryngeal spasm during the insertion of the LMA.

References

1 Benumof JL. Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 1996; 84: 686–99.[Medline]

2 Brain AI. The development of the Laryngeal Mask – a brief history of the invention, early clinical studies and experimental work from which the Laryngeal Mask evolved. Eur J Anaesthesiol 1991; Suppl 4: 5–17.

3 McNeillis NJ, Timberlake C, Avidan MS, Sarsang K, Choyce A, Radcliffe JJ. Fibreoptic view through the laryngeal mask and the intubating laryngeal mask. Eur J Anaesthesiol 2001; 18: 471–5.[Medline]

4 Brain AIJ. The Intavent Laryngeal Mask Instruction Manual, 4^th edition. Intavent; 1999.

5 Joshi S, Sciacca RR, Solanki DR, Young WL, Mathru MM. A prospective evaluation of clinical tests for placement of laryngeal mask airways. Anesthesiology 1998; 89: 1141–6.[Medline]

This Article Full Text (PDF) Submit a scholarly reply Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Al-Shaikh, B. Articles by Pilcher, D. Search for Related Content PubMed PubMed Citation Articles by Al-Shaikh, B. Articles by Pilcher, D.