Assessing a novel second generation laryngeal mask airway using the 'ADEPT' approach: results from the LMA® Protector™ observational study

To address the problem of lack of clinical evidence for airway devices introduced to the market, the Difficult Airway Society (UK) developed an approach (termed ADEPT; Airway Device Evaluation Project Team) to standardise the model for device evaluation. Under this framework we assessed the LMA Protector, a second generation laryngeal mask airway. A total of 111 sequential adult patients were recruited and the LMA Protector inserted after induction of general anaesthesia. Effective insertion was confirmed by resistance to further distal movement, manual ventilation, and listening for gas leakage at the mouth. The breathing circuit was connected to the airway channel and airway patency confirmed with manual test ventilation at 20 cm H20 (water) pressure for 3 s. Data was collected in relation to the time for placement, intraoperative performance and postoperative performance of the airway device. Additionally, investigators rated the ease of insertion and adequacy of lung ventilation on a 5-point scale. The median (interquartile range [range]) time taken to insertion of the device was 31 (26-40[14-780]) s with the ability to ventilate after device insertion 100 (95% CI 96.7- 100)%. Secondary endpoints included one or more manoeuvres 60.3 (95% CI 50.6-69.5)% cases requiring to assist insertion; a median ease of insertion score of 4 (2-5[3-5]), and a median adequacy of ventilation score of 5 (5-5[4-5]). However, the first time insertion rate failure was 9.9% (95% CI 5.1-17.0%). There were no episodes of patient harm recorded, particularly desaturation. The LMA Protector appears suitable for clinical use, but an accompanying article discusses our reflections on the ADEPT approach to studying airway devices from a strategic perspective.

Clinical Performance Comparison of LMA Protector™ Cuff Pilot™ and LMA Supreme™ When Used in Anesthetized, Non-paralyzed Patients

Introduction

The advancement of supraglottic airways (SGAs) has eased airway management, especially for anesthetists. There were functional improvements implemented to the newer SGA. We aim to assess the clinical performance of laryngeal mask airway (LMA) Protector™ Cuff Pilot™ (Teleflex Inc., Wayne, Pennsylvania, USA) against LMA Supreme™ (Teleflex Inc., Wayne, Pennsylvania, USA), in terms of oropharyngeal leak pressure (OLP), successful insertion attempts, mean insertion time, ease of gastric tube insertion, laryngeal view, and incidence of sore throat among anesthetized, non-paralyzed patients undergoing general anesthesia.

Methods

In this prospective single-blinded study, 60 patients were randomized to use either LMA Protector™ Cuff Pilot™ or LMA Supreme™. Both groups received standard monitoring and induction regimes. Post-insertion, a bronchoscope was used to verify its position. A gastric tube was inserted and OLP was measured. Patients were assessed during the post-operative period for sore throats.

Results

LMA Protector™ Cuff Pilot™ was comparable to LMA Supreme™ in terms of mean OLP (30.72±8.60 vs 27.23±8.09 cmH₂O, P = 0.114), first successful attempt (P = 0.312), mean insertion time (27.72±9.45 vs 24.37±6.46 seconds, P = 0.116), and grade 1 laryngeal view (51.7% vs 36.7%, P = 0.244). At first attempt, LMA Protector™ Cuff Pilot™ had a lower success rate of gastric tube insertion than LMA Supreme™ (55.17% vs 96.67%, P <0.001). The incidence of the blood-stained device and sore throat post-operatively were comparable between the two groups.

Conclusion

LMA Protector™ Cuff Pilot™ was comparable to LMA Supreme™ in terms of overall clinical performance, except for the first successful gastric tube insertion. Improvements should be made to the gastric channel for easier gastric tube insertion in the LMA Protector™ Cuff Pilot™.

Comparison of Intracuff Pressure and Postoperative Sore Throat Following Use of Laryngeal Mask Airway Protector With or Without Nitrous Oxide Anesthesia

PURPOSE

In general anesthesia, the laryngeal mask airway (LMA) is a frequently used effective option. The effect of nitrous oxide on intracuff pressure of the LMA and postoperative sore throat is well known; however, there are no studies related to the second-generation LMA Protector. The purpose of this study was to determine the differences in intracuff pressure and postoperative sore throat, depending on the use of nitrous oxide during general anesthesia using the LMA Protector.

DESIGN

This randomized double-blind prospective study was conducted among 88 patients aged 20 to 70 years.

METHODS

The cuff pressure started with a baseline of 40 cm H₂O and was measured using a digital cuff pressure manometer for 30 minutes. Postoperative sore throat, dysphonia, dysphagia, and numeric rating scale scores were also recorded.

FINDINGS

Over time, the intracuff pressure of the nitrous oxide group increased significantly compared with that of the air group. Furthermore, postoperative sore throat and pharyngolaryngeal complications were not significantly different between the two groups.

CONCLUSIONS

Intracuff pressure of the LMA Protector increased during anesthesia using nitrous oxide. When the anesthesia time was less than 2 hours, however, there was no difference in postoperative sore throat.

A prospective, randomized comparison of the LMA-protector™ and i-gel™ in paralyzed, anesthetized patients

Background

In the present study, we compare the LMA-Protector™ and the i-gel™ in terms of adequacy of the airway seal, insertion time, ease and accuracy of insertion, and the incidence of postoperative sore throat.

Methods

In 110 anesthetized and paralyzed adult patients, the i-gel™ (n = 55) or the LMA-Protector™ (n = 55) was inserted. The primary outcome was airway leak pressure. The secondary outcomes included the first-attempt success rate, insertion time, ease and accuracy of the device insertion, ease of gastric tube placement, blood staining on the device after removal, and incidence and severity of postoperative sore throat.

Results

The airway leak pressure was higher with the LMA-Protector™ than with the i-gel™ (31 [7] cmH₂O vs. 27 [6] cmH₂O, respectively; P = 0.016). Insertion time was longer with the LMA-Protector™ than with the i-gel™ (27 [16] sec vs. 19 [16] sec, respectively, P < 0.001), but ease of insertion and the first-attempt success rate were not different between the two groups. The LMA-Protector™ provided a worse fiberoptic view of the vocal cords and more difficult gastric tube insertion than the i-gel™ (both P < 0.001). Blood staining on the device was more frequent with the LMA-Protector™ than with the i-gel™ (P = 0.033). The incidence and severity of postoperative sore throat were not different between the two groups.

Conclusion

The LMA-Protector™ provided a better airway sealing effect than the i-gel™. However, it required a longer insertion time, provided a worse fiberoptic view of the vocal cords, and caused more mucosal injury compared to the i-gel™.

Trial registration

ClinicalTrials.gov (NCT03078517). Registered prior to patient enrollment, Date of registration: Mar 13, 2017.