Positive pressure ventilation during fibreoptic intubation: comparison of the laryngeal mask airway, intubating laryngeal mask and endoscopy mask techniques

Background

The efficacy of delivery of mechanical ventilation through different airway devices during fibreoptic intubation is not known.

Methods

We compared the laryngeal mask airway (LMA^†), intubating laryngeal mask (ILM) and endoscopy mask for positive pressure ventilation (PPV) during fibreoptic intubation. In 80 adult paralysed patients, fibreoptic intubation was performed during PPV using a combination of a size 3 or 4 LMA with a 6.0 mm nasal RAE tracheal tube (LMA3/4 group; n=22), a size 5 LMA with a 7.0 mm nasal RAE tube (LMA5 group; n=18), an ILM with an 8.0 mm special reinforced tracheal tube (ILM group; n=20) or an endoscopy mask (Patil mask) with a 7.5 mm standard tracheal tube (Patil group; n=20). The inspiratory and expiratory tidal volumes (Vi and Ve) with a ventilation pressure of 20 cm H₂O were measured using a pneumotachograph.

Results

Mean Ve values during fibreoptic intubation in the LMA5 [5.3 (sd 1.5) ml kg⁻¹] and ILM [7.1 (2.3) ml kg⁻¹] groups were greater than in the LMA3/4 group [2.6 (1.0) ml kg⁻¹, P<0.0001]. The mean Ve was greater in the Patil group [20.6 (4.9) ml kg⁻¹] than in the other three groups (P<0.0001). Gastric insufflation during intubation was more frequent in the Patil group (30%) than in the other three groups (4.5–5.6%) (P<0.05).

Conclusions

PPV is possible with the LMA, ILM or endoscopy mask during fibreoptic intubation. With an airway pressure of 20 cm H₂O, ventilation during intubation using a size 3 or 4 LMA was almost insufficient, while ventilation using a size 5 LMA or an ILM was almost acceptable. Ventilation during intubation with the endoscopy mask was greater than that with the LMA or ILM, but gastric insufflation was more frequent.