Manikin study of fibreoptic-guided intubation through the classic laryngeal mask airway with the Aintree intubating catheter vs the intubating laryngeal mask airway in the simulated difficult airway.

In this randomised crossover manikin study of simulated difficult intubation, 26 anaesthetists attempted to intubate the trachea using two fibreoptic-guided techniques: via a classic laryngeal mask airway using an Aintree intubating catheter and via an intubating laryngeal mask airway using its tracheal tube. Successful intubation was the primary endpoint, which was completed successfully in all 26 cases using the former technique, and in 5 of 26 cases using the latter (p < 0.0001). The former technique also proved quicker to reach the vocal cords with the fibrescope (median (IQR [range])) time 18 (14-20 [8-44]) s vs 110 (70-114 [30-118]) s, respectively; p = 0.008); and to first ventilation (93 (74-109 [52-135]) s vs 135 (79-158 [70-160]) s, respectively; p = 0.0038)]. We conclude that in simulated difficult intubation, fibreoptic intubation appears easier to achieve using a classic laryngeal mask airway and an Aintree intubating catheter than through an intubating laryngeal mask airway.

The use of mandibular nerve block to predict safe anaesthetic induction in patients with acute trismus.

Acute trismus can be caused by pain, muscle spasm, swelling or mechanical obstruction. Unfortunately, the cause is not always obvious during pre-operative airway assessment. In this pilot study, we prospectively evaluated mandibular nerve block as a pre-operative tool to identify patients with reversible causes of trismus, namely pain or spasm, in order to allow safe anaesthetic induction. Six patients with unilateral fractured mandibles and trismus received a mandibular nerve block before induction of general anaesthesia. There was an increase in maximal inter-incisor gap after the blocks (median (range) distance: pre-block 16.5 (14-30) and post-block 34 (32-35) mm; p = 0.027), and no further improvement after induction of general anaesthesia (post-induction 37 (30-40) mm; p = 0.276 compared with post-block). There was an improvement in pain scores (p = 0.027), and no side-effects were detected. Pre-operative mandibular nerve blockade appears to reverse trismus caused by pain and muscle spasm, allowing the anaesthetist to decide whether awake intubation is genuinely indicated.