Position of bite block in size 1 laryngeal mask airway ProSeal™ and stability during insertion.

Sir,

One of the important contributors to the stability of the laryngeal mask airway (LMA) ProSeal[1] during insertion is its integral bite block, particularly when used without introducer blade. The LMA ProSeal introducer blade has been provided in order to avoid putting the operator's hands in the patient's mouth during insertion of the device. However, in our experience, the digital insertion method is more commonly used. The integral bite block constitutes more than one third of the shaft of all sizes of LMA ProSeal except size 1. Over last 3 years, residents and consultants in our institution, encountered difficulty in insertion of the size 1 LMA ProSeal[1] by digital insertion method (neonates/infants up to 5 kg). All described it as more ‘’flimsy’’/’’unstable’’ compared with other pediatric sizes. This is probably because the integral bite block is only 1/6 of shaft length of LMA ProSeal 1 [Figure 1]. Often, we observed that the bite block of size 1 LMA ProSeal stays outside the mouth in neonate and infant. There are limited studies and case reports available in relation to size 1 LMA ProSeal. The initial reports described instability during insertion of the size 1 ProSeal was without a bite block[12] but later a bite block was incorporated by the manufacturer with integral bite block only 1/6 of shaft length [Figure 1]. Long integral bite block (as in other size of LMA ProSeal) helps in providing good vertical stability and axial strength during insertion. It also provides stability to withstand the load of angle connector and ventilator circuit particularly in neonate and children.

Figure 1

Integral bite block in size 1 and 2 the laryngeal mask airway ProSeal™

This report highlights that the length of the bite block is not sufficient enough for stability during insertion and there is a need for improvement in the design of the size 1 LMA ProSeal, viz integral bite block should be at least one third of the shaft length as that of other sizes.