Re-evaluation of appropriate size of the laryngeal mask airway

Abstract

We have assessed 32 males and 31 females in a randomized, crossover study to see if there was any difference in the correct positioning of the laryngeal mask, optimal ventilation (defined as no gas leak around the mask at an airway pressure of 18 cm H2O) and cuff visibility between sizes 4 and 5 masks in males and sizes 3 and 4 in females. The position of the mask in relation to the glottis was assessed using a fibreoptic bronchoscope. There was no significant difference in correct positioning between the two sizes in either sex. Gas leak was significantly less frequent for a larger than a smaller mask (P < 0.01 for both sexes), whereas the cuff was more often seen in the mouth with larger masks (P < 0.02 for males and P < 0.01 for females). Therefore, larger masks (size 4 in females and size 5 in males) provided a better seal than smaller sizes without worsening the relative position of the mask to the glottis; however, the larger mask came up within the mouth more often, which could interfere with tonsillectomy and could increase the risk of sore throat or lingual nerve damage.

Randomized Evaluation of the Single-use SoftSeal™ and the Re-useable LMA Classic™ Laryngeal Mask

“…This study has a number of limitations. Only a size 4 of each type of laryngeal mask was evaluated, this being the recommended size for the RLM in adult females during positive pressure ventilation 3,10 , and that recommended for females of 50 to 70 kg by the manufacturer for the new SULM. Our results may not apply to other sizes of mask or to use in males.…”

Six hours positive pressure ventilation with size 5 laryngeal mask in a 55-kg patient

“…There were no neurovascular or airway complications[12] as described in the literature. LMA cuff was intact after 15 h of continuous use.…”

Comparison of actual and ideal body weight for selection of appropriate size of ProSeal™ laryngeal mask airway in overweight and obese patients: A prospective, randomised study

“…For this reason, it is recommended to replace the larger mask with a mask one size smaller if the cuff of the larger mask is visible through the mouth. [7] They also commented that the use of a smaller mask could increase the incidence of air leak.…”

“…[1011] The inadequate or faulty positioning of the cuff after insertion of the bigger size mask could be a cause of post-operative complications including sore throat. [7] The use of larger masks in obese patients with a smaller upper airway may inflict injury on the soft tissue of the upper airway during device insertion, reflecting the more difficult insertion seen in the ABW group. In our study, no patient required size 5 PLMA in IBW group and hence, despite the comparable duration of surgery in both the groups, there were significantly less post-operative complications in IBW as compared to ABW group.…”