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If you wish to respond to a paper or other item already published in the BJA, please go to the abstract/full text version of that item and click on the link "E-Letters: Submit a response to the article".

Electronic Letters to:

Short Communications:
C. Keller, J. R. Brimacombe, K. Keller, and R. Morris
Comparison of four methods for assessing airway sealing pressure with the laryngeal mask airway in adult patients
Br. J. Anaesth. 1999; 82: 286-287 [Abstract] [PDF]
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[Read E-letter] Risk of airway seal test
jan paul j Mulier   (3 July 2007)

Risk of airway seal test 3 July 2007
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jan paul j Mulier
AZ sint Jan av Brugge

Send letter to journal:
Re: Risk of airway seal test

Dear C Keller,

I noticed that your proposal to use the airway seal test might have risks for patients. In a recent publication from Cheng W Li this test was used and might have caused volutrauma. If I understand your test correctly, the APL valve is set at 40 cmH20 and the fresh gas flow at 3 L/min in the breathing bag mode without manual compression. When a stable airway pressure is reached, the locations are determined and then the ventilation is re undertaken manually or mechanically. What size and compliance of manual breathing bag was used during these experiments? How long were the patients without ventilation? What were the peak and plateau airway pressures during normal ventilation? What airway pressure was reached during these tests? In normal healthy ASA I patients peak airway pressures are below 20 cmH20. At 3 L/min fresh gas flow airway resistance is not important in contributing to pressures up to 40 cmH20. These pressures will hyperinflate the lungs and might cause volutrauma, certainly in the most compliant parts of the lungs. In the US, breathing bags should be compliant to keep airway pressures under 35 cmH20 according to an old rule of 1984 to prevent barotrauma. In the modern view on volutrauma these values are still a risk and should be kept as low as possible or at least under the airway pressure that inflate the lungs above its normal volume. Would it not be safe to warn every anesthetist for the volutrauma risk when using this test. You could also lower the APL setting to below 20 cmH20 or shorten at least the time the lung is inflated above 20 cmH20. ref: 1. Cheng W Li et all Cricoid pressure impedes insertion of, and ventilation through, the proseal laryngeal mask airway in anesthetized, pralyzed patients. Anesth Analg 2007, 104:1995-8

Jan Paul J Mulier MD PhD chairman anesthesiology az sint jan av Brugge Ruddershove 10 8000 Brugge Belgium jan.mulier@azbrugge.be

Conflict of Interest:

None declared