Management of a suspected and unsuspected difficult laryngoscopy with the laryngeal mask airway

Laryngeal mask airway insertion in adults: comparison between fully deflated and partially inflated technique

PURPOSE

The laryngeal mask airway (LMA) is a supraglottic airway device designed to seal around the laryngeal inlet. A controlled study was designed to compare the effectiveness and complications in inserting the LMA when the cuff is fully deflated and partially inflated.

MATERIALS AND METHODS

American Society of Anesthesiologists physical status I or II 172 female patients scheduled for gynecologic procedures were included in this study. Patients were randomly allocated into one of the two groups; fully deflated (n=86) and partially inflated group (n=86). A size #4 LMA was inserted. The number of attempts, time taken for successful insertion, grade of leak, grade of fiberoptic view, and complications were evaluated.

RESULTS

All 172 patients completed the study protocol. The number of attempts, time taken for successful insertion, and grade of leak were not significantly different between the two groups. The grade of fiberoptic view and complications were lower in the fully deflated group.

CONCLUSION

The fully deflated method is more accurate and safe because of better fiberoptic view and lesser complications than the partially inflated group.

Laryngeal mask airway: a more successful method of insertion

STUDY OBJECTIVE

To compare the ease of insertion of the laryngeal mask airway (LMA) by two methods.

DESIGN

Prospective, randomized study.

SETTING

Operating room of a university-affiliated teaching hospital.

PATIENTS

350 ASA I, II, and III patients undergoing general anesthesia, in whom use of the LMA was not contraindicated.

INTERVENTIONS

With all routine monitors in place and after the induction of anesthesia with propofol, we compared the ease of insertion of the LMA in the two groups of 175 patients each. The timing of insertion was made on clinical grounds. In one group, the LMA was inserted with the cuff fully deflated, in the other group, the cuff was partially inflated (i.e., filled with half the recommended air in the cuff). When correct placement of the mask was not successful by one method, the other method was tried and the insertion graded in the same manner.

MEASUREMENTS AND MAIN RESULTS

The ease of insertion of the LMA was graded by the user on a scale of 1-4. Insertion of the LMA with the cuff partially inflated was significantly more successful (97.7%) than when the cuff was fully deflated (92%) (p < 0.05). When correct placement of the mask was not possible with the cuff fully deflated, partial inflation resulted in correct placement.

CONCLUSIONS

Inserting the LMA with the cuff partially inflated is likely to be more successful than with the cuff fully deflated. When it is not possible to insert the LMA with the cuff fully deflated, partial inflation before insertion may result in correct placement.

The laryngeal mask airway: its features, effects and role

The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anaesthetic practice. Numerous articles and letters about the device have been published in the last decade, but few large controlled trials have been performed. Despite widespread use, the definitive role of the laryngeal mask has yet to be established. In some situations, such as after failed tracheal intubation or in anaesthesia for patients undergoing laparoscopic or oral surgery, its use is controversial. There are a number of unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoid pressure prevents placement of the mask. We review the techniques of insertion, details of misplacement, and complications associated with the use of the laryngeal mask. We discuss the features and physiological effects of the device, including the changes in intra-cuff pressure during anaesthesia and effects on blood pressure, heart rate and intra-ocular pressure. We then attempt to clarify the role of the laryngeal mask in airway management during anaesthesia, based on the current knowledge, by discussing the advantages and disadvantages as well as the indications and contraindications of its use. Lastly we describe the use of the laryngeal mask in circumstances other than airway maintenance during anaesthesia: fibreoptic bronchoscopy, tracheal intubation through the mask and its use in cardiopulmonary resuscitation.