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