The newly developed supralaryngeal airway Streamlined Liner of the Pharynx Airway (SLIPA™) has been compared successfully to the LMA™, but the haemodynamic response to its insertion has not been evaluated in a randomised study. We compared haemodynamic and Bispectral index (BIS) responses to insertion of the SLIPA™ with classic LMA™ after standardising the anaesthetic technique using BIS to monitor and control the anaesthetic depth. One hundred patients were randomised to receive either a classic LMA™ or SLIPA™ following induction with fentanyl and propofol titrated to a target BIS of 40 and compared heart rate, mean arterial pressure and BIS responses to insertion. There was a significant rise in mean arterial pressure from the pre-stimulus value (73.8 [10.6] mmHg, mean ± SD) at two and three minutes (P <0.05) following insertion of the LMA™ with maximum rise (80.8 [11.5] mmHg) seen at two minutes. There was a significant rise in mean arterial pressure from the pre-stimulus value (73.2 [12.6] mmHg) at one, two, three, four and five minutes (P <0.05) following insertion of the SLIPA™ with maximum rise (86.9 [15.1] mmHg) observed at three minutes. Mean arterial pressure was significantly higher (P <0.05) with SLIPA™ at two, three, four and five minutes. BIS increased significantly (P <0.05) at one, two, three, four and five minutes following insertion of both the devices, but there was no significant difference between the groups. There was a significantly higher (P=0.001) incidence of blood on the device with the SLIPA™ (20/50 vs. 6/50 with LMA™). Thus, insertion of SLIPA™ causes significantly higher blood-pressure response but similar BIS response compared to the LMA™.

A Mallampati class zero per se is not associated with difficult airway unless other airway characteristics contribute to the difficulty. Even though the epiglottis may be large and overhanging, it rarely causes airway difficulty in Mallampati class zero airway.