Performance of first and second generation supraglottic airway devices in patients with simulated difficult airway: a randomised controlled trial

Background
Guidelines for management of unanticipated difficult intubation recommend the use of supraglottic airway devices (SADs) in cases of failed intubation. How­ever, there is a lack of comparative studies for different type of devices. In this randomised controlled trial, the performance of 1st and 2nd generation supraglottic airway devices was compared in patients with a simulated difficult airway.

Material and methods
We enrolled 90 patients, scheduled for elective surgery and suitable for supraglottic airway device insertion. Laryngeal mask airway (LMA)-classic (LMAC), LMA-proseal (LMAP) and LMA-flexible (LMAF) were evaluated. The modified Mallampati test was used for the preoperative airway assessment. Maximal mouth opening, body mass index, thyromental and sternomental distances, and neck circumference were measured, and patients with predicted difficulty were excluded. Insertion time, ease of insertion, oropharyngeal leak pressure, and Brimacombe and Berry Bronchoscopy Scores were evaluated. Peak airway pressure was measured at 1, 15 and 60 min following the insertion of SADs. Complications were recorded.

Results
Oropharyngeal leak pressures were 35.2 ± 8.1, 31.7 ± 7.7 and 31.3 ± 6.0 mm Hg for LMAP, LMAC and LMAF respectively (P = 0.079). First min peak airway pressure values were 14.0 ± 4.2, 15.0 ± 3.9, 14.9 ± 4.4 mm Hg respectively (P = 0.403). There was a significant positive correlation between oropharyngeal leak pressure and first min peak airway pressure (r = 0.264, P = 0.013). Mean number of attempts was 1.1 ± 0.3 times (P = 0.840). Insertion time was 20.0 ± 10.4, 17.0 ± 5.7 and 16.4 ± 10.2 s respectively (P = 0.440). Ease of insertion score was 2.0 ± 0.9, 2.1 ± 0.9 and 2.1 ± 1.3 respectively (P = 0.837). There was no significant difference for optimization manoeuvre requirement or fibreoptic scope grades (P = 0.265, P = 0.651, respectively).

Conclusions
First and second generation of supraglottic airway devices provided similar clinical performance for patients with difficult airway and trauma due to limited cervical motion.