Intra-ocular pressure changes during rapid sequence induction of anaesthesia. A comparison between thiopentone and suxamethonium and thiopentone and atracurium.

The changes in intra-ocular pressure associated with two different anaesthetic induction and tracheal intubation techniques were compared (n = 30). After pre-oxygenation, Group A received thiopentone (5 mg/kg) followed by suxamethonium (1.5 mg/kg), both within 25 seconds, and Group B atracurium (0.5 mg/kg) followed by thiopentone (5 mg/kg) again both within 25 seconds. Tracheal intubation occurred after one minute in Group A and 2 minutes in Group B to allow for full paralysis. In Group A intra-ocular pressure did not alter significantly from baseline and the maximum increase was only 0.93 mmHg. The statistical type II error risk was consistently below 55% and all 95% confidence limits included negative values. Intra-ocular pressure in Group B was consistently lower than baseline (p less than 0.05) but with a longer induction-intubation interval. These results therefore provide valuable information about the 'balance of risks' when choosing a muscle relaxant for an inadequately starved patient with a penetrating eye injury.