Intraocular pressure changes in patients undergoing cataract extraction and lens implantation : laryngeal mask airway versus endotracheal tube

Abstract

OBJECTIVES: To investigate the influence on intraocular pressure (IOP) of airway management with a laryngeal mask airway (LMA) or tracheal tube (ETT), and secondly to compare the devices with regard to their impact on IOP. DESIGN: Prospective, randomized observational study over a four-month period (August - November 2002) SETTING: University-affiliated tertiary level hospital in Pretoria, South Africa. SUBJECTS: Forty ASA I and II adult patients undergoing unilateral cataract extraction and lens implantation under general anaesthesia. OUTCOME MEASURES: Changes in intraocular pressure after placement of airway device. METHODS: Following a standard anaesthestic induction with propofol and atracurium, airway management was randomized to LMA or ETT. IOP was measured pre-induction, 3 min post induction but before airway manipulation, 20 sec post LMA or ETT insertion and finally 2 min post airway instrumentation. RESULTS: There was a small increase in mean IOP in the LMA group, which was statistically insignificant. However there was a significant rise in mean IOP in the ETT group (p = 0.0001) which returned to almost pre-insertion levels at 2 minutes. CONCLUSIONS: The LMA causes minimal changes in intraocular pressure when used to secure the airway during cataract surgery. The rise in IOP following tracheal intubation is significant, yet transient and probably clinically insignificant.