To the Editor:—
We read with interest the study by van Zundert et al.1
regarding performance characteristics of three disposable extraglottic airways. van Zundert found that the CobraPLA (Engineered Medical Systems, Indianapolis, IN) was more difficult to insert and caused more mucosal trauma than either the LMA-Unique
™ (LMA North America Inc., San Diego, CA) or the Soft Seal laryngeal mask (Portex Ltd., Hythe, United Kingdom), noting that this finding is in contrast to previous studies conducted by Gaitini et al.2
and Akca et al.3
He attributes this difference, in part, to the fact that the patients in Akca's study were paralyzed. However, Akca's patients were not relaxed before insertion of the devices studied. As an alternative, we suggest that van Zundert's more precisely defined ease of insertion (3/2/1/0 vs.
difficult/not difficult), along with a greater number of patients studied (105 patients vs.
40 patients studied each by Gaitini and Akca)2,3
might have allowed a statistical difference to emerge. Although the CobraPLA has a flexible tip to aid insertion at the back of the throat, we believe that CobraPLA's straight breathing tube might have contributed to the insertion difficulty (fig. 1A
As a result of our own experience using the CobraPLA in several hundred patients and at our suggestion, the manufacturer (Engineered Medical Systems) has modified the basic design of the device to incorporate a distal bend in the breathing tube on both the standard CobraPLA and the newly introduced CobraPLUS (figs. 1B and C
) while leaving the other features of the airway (e.g.
, flexible tip, circumferential cuff) unchanged. The decision to accomplish this design change was driven in part by discussions with Dr. van Zundert while his study was in progress (although actual results were not known) regarding how the device might logically be improved to aid insertion. As a result of this modification, the specific product studied by van Zundert is no longer being manufactured. We believe the curved distal end greatly facilitates insertion and minimizes trauma because it now conforms to the shape of the anatomy it must traverse, and initial reports with its use have been encouraging (Xavier Marquez, M.D., Instituto Urologico, Caracas, Venezuela, personal communication, April 2006).
The fact that the basic design of the CobraPLA studied by van Zundert is no longer being manufactured in no way diminishes the importance of his study. Rather, we believe it validates how respected researchers can help to drive product design for improved patient safety. The improved performance characteristics of the newly changed CobraPLA, require validation by additional research. We have sent the newly designed CobraPLA to Dr. van Zundert and would be interested to learn his initial impressions.
David Alfery, M.D.
Peter Szmuk, M.D.*
*University of Texas Southwestern Medical School and Anesthesiologists for Children at Children's Medical Center Dallas, Dallas, Texas, and Outcomes Research Institute, Louisville, Kentucky. firstname.lastname@example.org
1. van Zundert A, Al-Shaikh B, Brimacombe J, Koster J, Konig D, Mortier E: Comparison of three disposable extraglottic airway devices in spontaneously breathing adults: The LMA-Unique™, the Soft Seal laryngeal mask, and the Cobra peripharyngeal airway. Anesthesiology 2006; 104:1165–9
2. Gaitini L, Yanovski B, Somri M, Vaida S, Riad T, Alfery D: A comparison between the PLA Cobra and the Laryngeal Mask Airway Unique during spontaneous ventilation: A randomized prospective study. Anesth Analg 2006; 102:631–6
3. Akca O, Wadwha A, Sengupta P, Durrani J, Hanni K, Wenke M, Yucel Y, Lenhardt R, Doufas A, Sessler D: The new perilaryngeal airway (CobraPLA) is as efficient as the laryngeal mask airway (LMA) but provides better airway sealing pressure. Anesth Analg 2004; 99:272–8
© 2007 American Society of Anesthesiologists, Inc.