Intraocular pressure and haemodynamic responses to insertion of the i-gel, laryngeal mask airway or endotracheal tube.

CONTEXT: We hypothesised that the effects of insertion of an i-gel supraglottic airway management device on intraocular pressure (IOP) and haemodynamic variables would be milder than those associated with insertion of a laryngeal mask airway (LMA) or an endotracheal tube.

OBJECTIVES: This study evaluated IOP and haemodynamic responses following insertion of an i-gel airway, LMA or endotracheal tube.

DESIGN AND SETTING: This was a randomised controlled study in a tertiary care centre in which 60 adults scheduled for elective non-ophthalmic procedures under general anaesthesia were allocated to one of three groups. Patients with pre-existing glaucoma, cardiovascular, pulmonary or metabolic diseases or anticipated difficult intubation were excluded.

INTERVENTIONS: Following induction of general anaesthesia, an endotracheal tube, LMA or i-gel device was inserted.

MAIN OUTCOME MEASURES: IOP, SBP, DBP, heart rate (HR) and perfusion index were measured before induction of anaesthesia and before and after insertion of the airway device.

RESULTS: Insertion of the i-gel did not increase IOP. Insertion of an endotracheal tube increased IOP from 11.6 ± 1.6 to 16.5 ± 1.7 mmHg (P < 0.001). The post-insertion IOP exceeded the pre-induction value (P < 0.05). Insertion of the LMA increased IOP from 13.0 ± 1.5 to 14.7 ± 1.8 mmHg (P < 0.01), but this did not exceed the pre-induction value. Tracheal intubation significantly increased HR, SBP and DBP. Insertion of the LMA significantly increased HR and SBP. These increases were significantly higher than those which followed insertion of the i-gel device. Insertion of the endotracheal tube or LMA resulted in a significant decrease in perfusion index which was maintained for 5 min following tracheal intubation and for 2 min after insertion of the LMA. Insertion of the i-gel device did not change perfusion index significantly.

CONCLUSION: Insertion of the i-gel device provides better stability of IOP and the haemodynamic system compared with insertion of an endotracheal tube or LMA in patients undergoing elective non-ophthalmic surgery.