Canadian Journal of Anaesthesia

, Volume 41, Issue 7, pp 589–593

Laryngeal mask airway cuff pressure and position during anaesthesia lasting one to two hours

  • J. Brimacombe
  • A. Berry
Reports of Investigation


The cuff of the laryngeal mask airway (LMA) is highly permeable to nitrous oxide (N2O), and cuff pressure increases during N2O/O2 anaesthesia. The extent of these changes and their effect on LMA position have previously only been investigated for short procedures. The current study was designed to investigate the effects of nitrous oxide-oxygen (N2O/O2) anaesthesia lasting one to two hours on cuff pressure, LMA positioning and pharyngeal morbidity. Twenty-four male patients underwent spontaneous ventilation anaesthesia with 66% N2O in oxygen and isoflurane. Following insertion and inflation of a #4 LMA with 30 ml air, mean (SD) cuff pressures immediately increased from 107 (9) to 145 (12) mmHg and then at a decreasing rate for 90 min to peak at 215 (12) mmHg. There was a correlation between N2O concentration and final cuff volume (P < 0.001). There was no displacement of the LMA cuff in any patient. Three of 19 patients had a mild sore throat. This study demonstrates that the increase in LMA cuff pressure is self limiting over a one-to-two-hour period and does not cause displacement of the LMA. There is no evidence that cuff pressure monitoring and pressure limitation is necessary during LMA anaesthesia.

Key words

anaesthetics, gases: nitrous oxide equipment: laryngeal mask airway 


Le coussinet du masque laryngé (ML) est hautement perméable au protoxyde d’azote (N2O), et sa pression augmente pendant l’anesthésie au N2O/O2. L’importance de ces changements et leur effet sur la position du ML n’ont été investigués précédemment que pour de courtes interventions. Cette étude propose d’investiguer les effets du mélange de protoxyde d’azote et d’oxygène (N2O/O2) sur la pression du coussinet au cours d’une anesthésie d’une à deux heures, ainsi que sur la position du ML et ses répercussions sur le pharynx. Vingt-quatre patients masculins sont soumis à une anesthésie en ventilation spontanée avec 66% de N2O dans l’oxygène et de l’isoflurane. Après l’insertion et l’inflation d’un ML #4 avec 30 ml d’air, les pressions moyennes (DS) du coussinet augmentent immédiatement de 107 (9) à 145 (12) mm de Hg et ensuite atteignent un pic de 215 (12) mm de Hg après une augmentation décroissante de 90 min. Il y a une corrélation entre la concentration de N2O et le volume final du coussinet (P < 0,001). Il n’y a eu de déplacement du coussinet du ML chez aucun patient. Trois des 19 patients ont eu une douleur modérée de la gorge. Cette étude démontre que l’augmentation de la pression du coussinet du ML se limite d’elle même après une période d’une à deux heures et ne provoque pas de déplacement du ML. Il n’y a pas d’argument indiquant que le monitorage de la pression du coussinet et sa limitation soient nécessaires au cours d’une anesthésie au ML.


  1. 1.
    Lumb AB, Wrigley MW. The effect of nitrous oxide on laryngeal mask cuff pressure.In vitro andin vivo studies. Anaesthesia 1992; 47: 320–3.PubMedCrossRefGoogle Scholar
  2. 2.
    Marjot R. Pressure exerted by the laryngeal mask airway cuff upon the pharyngeal mucosa. Br J Anaesth 1993; 70: 25–9.PubMedCrossRefGoogle Scholar
  3. 3.
    Thomson SJ, Healy M, Littlejohn IH. Nitrous oxide and laryngeal mask cuff pressure (Letter). Anaesthesia 1992; 47: 815.PubMedCrossRefGoogle Scholar
  4. 4.
    Brain AIJ. The Intavent laryngeal mask — instruction manual. London: Intavent, 1991.Google Scholar
  5. 5.
    Brimacombe J, Berry A. A proposed fibre-optic scoring system to standardize the assessment of laryngeal mask airway position (Letter). Anesth Analg 1993; 76: 457.PubMedGoogle Scholar
  6. 6.
    Revenäs B, Lindhold C. Pressure and volume changes in trachéal tube cuffs during anaesthesia. Acta Anaesthesiol Scand 1976; 20: 321–6.PubMedGoogle Scholar
  7. 7.
    Seegobin RD, van Hasselt GL. Endotracheal cuff pressure and tracheal mucosal blood flow: endoscopic study of effects of four large volume cuffs. BMJ 1984; 288: 965–8.PubMedGoogle Scholar
  8. 8.
    Joh SJ, Matsura H, Kotani Y, et al. Change in tracheal blood flow during endotracheal intubation. Acta Anaesthesiol Scand 1987; 31: 300–4.PubMedGoogle Scholar
  9. 9.
    Marjot R. Trauma to the posterior pharyngeal wall caused by a laryngeal mask airway (Letter). Anaesthesia 1991; 46: 589–90.PubMedCrossRefGoogle Scholar
  10. 10.
    Harris TM, Johnston DF, Collins SRC, Heath ML. A new general anaesthetic technique for use in singers: the Brain laryngeal mask airway versus endotracheal intubation. Journal of Voice 1990; 4: 81–5.CrossRefGoogle Scholar
  11. 11.
    Lee SK, Hong KH, Choe H, Song HS. Comparison of the effects of the laryngeal mask airway and endotracheal intubation on vocal function. Br J Anaesth 1993; 71: 648–50.PubMedCrossRefGoogle Scholar
  12. 12.
    McCrirrick A, Ramage DTO, Pracilio JA, Hickman JA. Experience with the laryngeal mask airway in two hundred patients. Anaesth Intensive Care 1991; 19: 256–60.PubMedGoogle Scholar
  13. 13.
    Alexander CA, Leach AB. Incidence of sore throats with the laryngeal mask (Letter). Anaesthesia 1989; 44: 791.PubMedCrossRefGoogle Scholar
  14. 14.
    Reddy SVG, Win N. Brain laryngeal mask — study in 50 spontaneously breathing patients. Singapore Med J 1990; 31: 338: 40.Google Scholar
  15. 15.
    Latto IP. The cuff.In: Latto IP, Rosen M (Eds.). Difficulties in Tracheal Intubation. London: Bailliere Tindal, 1984; 48–74.Google Scholar
  16. 16.
    Brimacombe J, Berry A. Insertion of the laryngeal mask airway — a prospective study of four techniques. Anaesth Intensive Care 1993; 21: 89–92.PubMedGoogle Scholar
  17. 17.
    Maltby JR, Loken RG, Watson NC. The laryngeal mask airway: clinical appraisal in 250 patients. Can J Anaesth 1990; 37: 509–13.PubMedGoogle Scholar
  18. 18.
    Brimacombe JR. Laryngeal mask anaesthesia and recurrent swallowing. Anaesth Intensive Care 1991; 19: 275–6.PubMedGoogle Scholar
  19. 19.
    Brimacombe J, Shorney N. The laryngeal mask airway and prolonged balanced regional anaesthesia. Can J Anaesth 1993; 40: 360–4.PubMedCrossRefGoogle Scholar
  20. 20.
    Brain AIJ, McGhee TD, McAteer EJ, Thomas A, Abu-Saad MAW, Bushman JA. The laryngeal mask airway. Development and preliminary trials of a new type of airway. Anaesthesia 1985; 40: 356–61.PubMedCrossRefGoogle Scholar
  21. 21.
    Miranda AF, Reddy SVG. Controlled ventilation with Brain laryngeal mask. Med J Malaysia 1991; 45: 65–9.Google Scholar
  22. 22.
    Brain AIJ. 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; 4: 5–17.Google Scholar
  23. 23.
    Brimacombe J, Berry A. The flexible, reinforced tube LMA — initial experience (Letter). Anaesth Intensive Care 1993; 21: 379.PubMedGoogle Scholar
  24. 24.
    Johnston DF, Wrigley SR, Robb PJ, Jones HE. The laryngeal mask airway in paediatric anaesthesia. Anaesthesia 1990; 45: 924–7.PubMedCrossRefGoogle Scholar
  25. 25.
    Welsh BE, Martin DW. Will we ever learn? (Letter). Anaesthesia 1990; 45: 892.PubMedCrossRefGoogle Scholar

Copyright information

© Canadian Anesthesiologists 1994

Authors and Affiliations

  • J. Brimacombe
    • 1
  • A. Berry
    • 1
    • 2
  1. 1.Department of Anaesthesia and Intensive CareCairns Base HospitalCairnsAustralia
  2. 2.Department of AnaesthesiaRoyal Berkshire HospitalReadingUK

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