Letters to the Editor: Letters & Announcements
To the Editor:
Drs. von Urgern-Sternberg and Erb reported a case of airway obstruction during the use of a size 2 laryngeal mask airway due to an unnoticed detachment of the cuff weld near the device tip (1). There have already been several reports of the same problem (2–4).
The authors were surprised to hear that the manufacturer claimed the incident was “user’s fault,” because such a deformity may occur during sterilization if air or moisture is in the cuff (1). If 1–2 mL of air is remaining in the cuff, air may expand by 20 times (up to 40 mL) during sterilization (5). This volume should be no problem for a size 3 or larger (6), but could in theory decrease the integrity of the cuff of a size 2 or smaller. Water in the cuff evaporates and expands its volume considerably more than air does and can deform or even rupture the cuff (5). Therefore, the manufacturer’s claim is reasonable. It is prudent to deflate the cuff as much as possible immediately before sterilization, since the cuff refills spontaneously with time.
The authors stated that “it may be difficult to notice the detachment of the weld as long as the cuff of the LMA is deflated,” and recommend to check any deformity by inflating the cuff before its use (1). However, deformity of the cuff may not be apparent when the cuff is inflated with a usual volume of air (5) but may become apparent when the cuff is inflated with a volume of air 50% larger than the recommended maximum volume (e.g., 15 mL for the size 2) (5,6). Therefore, it is important to check the device before each use, by inflating the cuff with this higher volume, as recommended by the manufacturer. With these additional precautions, the reusable laryngeal mask can be used more safely.
Takashi Asai, MD, PhD
Department of Anesthesiology; Kansai Medical University; Osaka, Japan; firstname.lastname@example.org
Dr. von Urgern-Sternberg does not wish to respond.
1. von Ungern-Sternberg BS, Erb TO. Partial airway obstruction by a pediatric laryngeal mask airway. Anesth Analg 2004;99:951.
2. Newman PTF. Discarding used laryngeal mask airways-can there still be life after 40? Anaesthesia 1994;49:81.
3. Boge E, Brandis K. Testing the laryngeal mask. Anaesh Intensive Care 1995;23:751–2.
4. Handsworth JL. Faulty laryngeal mask. Anaesth Intensive Care 1996;24:728–9.
5. Asai T, Koga K, Morris S. Damage to the laryngeal mask by residual fluid in the cuff. Anaesthesia 1997;52:977–81.
6. Brimacombe J. Laryngeal mask residual volume and damage during sterilization. Anesth Analg 1994;79:391.