Method: Quasi-experimental and repeated-measures study designs were used in this study. Twenty-six adults with normal hearing (17 females, 9 males) participated. ABRs were acquired from the study participants at 3 intensity levels (80, 60, and 40 dB nHL), 3 frequencies (500, 1000, and 2000 Hz), 2 electrode montages (ipsilateral and vertical), and 2 stimuli (NB LS CE-Chirp and tone-burst) using 2 stopping criteria (fixed averages at 4,000 sweeps and F test at multiple points = 3.1).
Results: Wave V amplitudes were only 19%-26% larger for the vertical recordings than the ipsilateral recordings in both the ABRs obtained from the NB LS CE-Chirp and tone-burst stimuli. The mean differences in the F test at multiple points values and the residual noise levels between the ABRs obtained from the vertical and ipsilateral montages were statistically not significant. In addition, the ABR elicited from the NB LS CE-Chirp was significantly larger (up to 69%) than those from the tone-burst, except at the lower intensity level.
Conclusion: Both the ipsilateral and vertical montages can be used to record ABR to the NB LS CE-Chirp because of the small enhancement in the wave V amplitude provided by the vertical montage.
MATERIAL AND METHODS: A total of 80 adult patients who were scheduled for elective surgery under general anaesthesia were randomised to two groups: Group BM: Baska mask (n = 40) and Group IG: i-gel (n = 40). The assessment focused on ease of insertion, number of attempts, insertion time, number of corrective manoeuvres, oropharyngeal leak pressure, tidal volume, peak airway pressure (PAP) and post-insertion complications.
RESULTS: Group IG showed a significantly shorter median insertion time (13.3 [interquartile range, IQR 7.8] vs. 17.0 [IQR 9.6] s; P < 0.001), a higher percentage in the 'very easy' ease of insertion category (62.5% vs. 10.0%; P < 0.001), a higher percentage in the no corrective manoeuvre category (92.5% vs. 72.5%; P = 0.003) and a higher percentage in the no post-operative throat pain category (67.5% vs. 32.5%; P = 0.011) than Group BM. However, Group BM showed a significantly higher generated PAP than Group IG (12.7 [1.8] and 11.5 [2.2] cm H2O, respectively; P = 0.010). There were no significant differences in other parameters.
CONCLUSIONS: The i-gel was better than the Baska mask in terms of ease of insertion, speed of insertion, fewer corrective manoeuvres and less post-operative throat pain. However, the Baska mask had a better cuff seal, as shown by a higher generated PAP.