We would like to report six cases of spontaneous cuff deflation that occurred during a clinical trial of a new disposable extraglottic airway device, the CobraPLA® (Engineered Medical Systems, Inc., Indianapolis, IN).1The cuff pressure decreased to almost zero during maintenance of anesthesia. These events were detected by continuous cuff pressure monitoring using a transducer attached to a monitor (S/5 AM; Datex-Ohmeda, Helsinki, Finland) during the maintenance phase of anesthesia and did not influence the clinical performance of the device, primarily because the patients were breathing spontaneously. The patients were not moved during surgery, with the transducer positioned on the patient's shoulder throughout the duration of the procedure. The devices' cuffs were checked for leaks before use as recommended by the manufacturers. When checked after removal of the device, the cuff itself did not show any defect, but submersion in water revealed tiny bubbles of air escaping from the pilot balloon valve, showing a continuous leak at the cuff deflator valves with their surroundings (fig. 1).

Fig. 1.  Arrow indicates where leak exists between cuff valve deflator and surroundings of the pilot balloon cuff of the CobraPLA®. 

Fig. 1.  Arrow indicates where leak exists between cuff valve deflator and surroundings of the pilot balloon cuff of the CobraPLA®. 

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A similar problem has been reported with another new extraglottic airway mask, the Marshall Laryngeal Airway Device (Marshall Products Ltd., Bath, United Kingdom). In the United Kingdom, the Medical Devices Regulatory Agency issued a Medical Device Alert †in 2003 regarding cuff failure due to a small number of pilot balloon valves leaking. This led to the manufacturer's recall of the product.

Cuff deflation is undesirable because it can lead to a loss of seal with the respiratory/gastrointestinal tracts and put the patient at risk of ventilatory failure, aspiration, and gastric insufflation.2 

We urge the manufacturers of new extraglottic devices to ensure better quality control of their products, including the cuff deflator valves. However, because one cannot guarantee 100% quality control at all times, we also urge clinicians to incorporate cuff pressure monitoring into their routine practice.

* Catharina Hospital-Brabant Medical School, Eindhoven, The Netherlands. zundert@iae.nl

Akca O, Wadhwa A, Sengupta P, Durrani J, Hanni K, Wenke M, Yucel Y, Lenhardt R, Doufas AG, Sessler DI: The new perilaryngeal airway (CobraPLA) is as efficient as the laryngeal mask airway (LMA) but provides better airway sealing pressures. Anesth Analg 2004; 99:272–8
Brimacombe J: Problems, Laryngeal Mask Anesthesia: Principles and Practice, 2nd edition. London, WB Saunders, 2004, pp 551–76
WB Saunders