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Hypopharyngeal seal pressure during projectile vomiting with the ProSeal^TM laryngeal mask airway: a case report and laboratory study

Joseph Brimacombe^* and Christian Keller, md

^* James Cook University, Cairns Base Hospital, Cairns, Australia
Leopold-Franzens University, Innsbruck, Austria, E-mail: jbrimaco{at}bigpond.net.au

To the Editor:

A principal advantage of the ProSeal^TM laryngeal mask airway (PLMA; Laryngeal Mask Company, Henleyon-Thames, UK) over the Classic^TM laryngeal mask airway is better protection against gastric aspiration.¹ A critical factor contributing to airway protection is the efficacy of the seal with the hypopharynx. We found this to be as high as 73 cm H₂O,² however, there are no data from anesthetized patients. We present a case of projectile vomiting via the drain tube of the PLMA that allowed us to perform a laboratory study to estimate the hypopharyngeal seal based on the distance the fluid traveled.

A 46-yr-old, 88-kg healthy male was scheduled for knee surgery. Induction was achieved with midazolam 3 mg iv, alfentanil 1 mg iv and propofol 220 mg iv. The airway was managed with a size 5 PLMA, inserted using a laryngoscope-guided, bougie-guided technique.³ The cuff was inflated with 30 mL air. A gastric tube was not inserted. Sevoflurane 2–3% and N₂O 66% and O₂ provided maintenance anesthesia. Intracuff pressure was 60 cm H₂O. Anesthesia was uneventful, but during emergence, the patient retched once and expelled across the bed approximately 20 mL of slightly bile-stained fluid from the drain tube. A gastric tube was immediately inserted, and a further 60 mL of fluid was removed from the stomach. The PLMA was removed five minutes later when the patient opened his mouth to command. Inspection of the PLMA bowl and airway tube revealed no bile-stained fluid. The inner cuff and airway tube was swabbed with litmus paper and was negative for acid. There were no other sequelae. The maximum distance between the drain tube and the point where the fluid landed on the sheet was 1.2 m. The PLMA drain tube was approximately 45° to the horizontal and the sheet was at a similar height to the proximal aperture of the drain tube.

We simulated the clinical event to more accurately determine the esophageal pressure required to eject fluid 1.2 m. A size 5 PLMA was placed on a flat surface so that the proximal aperture of the drain tube was at an angle of 45° to the horizontal. The distal aperture was attached to a calibrated vertical glass column 1.5 m in height with an internal diameter of 3.5 cm. The height of the column was assumed to be the pressure at the distal cuff of the PLMA. The PLMA was curved slightly to mimic the caudal curve in the patient. A clip was applied to the distal portion of the drain tube and a dry drape was placed in the trajectory line. The column was therefore filled with saline (which has similar properties to slightly bile-stained fluid) to a height of 80–140 cm in 10 cm increments. At each increment the clip was released and the maximum distance to the point of initial impact recorded on ten consecutive occasions (Table). The mean ± SD (range) height of the column for an endpoint of 1.2 m was 105 ± 10 (95–140) cm using Dixon’s up-and-down method.

Footnotes

Accepted for publication November 25, 2005.

References

1 Brain AI, Verghese C, Strube PJ. The LMA ‘ProSeal’ - a laryngeal mask with an oesophageal vent. Br J Anaesth 2000; 84: 650–4.[Abstract/Free Full Text]

2 Brimacombe J, Keller C. The laryngeal mask airway in fresh cadavers versus paralysed anaesthetized patients: ease of insertion, airway sealing pressure, intracuff pressures and anatomic position. Eur J Anaesthesiol 1999; 16: 699–701.[Medline]

3 Brimacombe J, Keller C, Judd DV. Gum elastic bougie-guided insertion of the ProSeal^TM laryngeal mask airway is superior to the digital and introducer tool techniques. Anesthesiology 2004; 100: 25–9.[Medline]

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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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Brimacombe, J. Articles by Keller, C. Search for Related Content PubMed PubMed Citation Articles by Brimacombe, J. Articles by Keller, C.