Comparison of the Effects of Lma Inflated With Room-Air or N 2o+o2 on the Oropharyngeal Structures

Abstract

In this study, we aimed to evaluate the effects of between different gases for LMA cuff inflation cuff pressure, oropharyngeal lesions and sore throat incidence. Fifty-five ASA I-II patients that underwent general anaesthesia were divited into two groups randomly. The patients were premedicated with midazolam 0.05 mg kg-1 intravenously. Routine monitors were placed, and anaesthesia was induced with intravenous propofol and fentanyl. LMA were inserted after loss of eyelash reflex. LMA cuff inflation was achieved with appropriate volume of 50 % N2O+50 % O2 and room-air respectively in groups I and II. The intracuff pressure was measured at initial, 30th, 60th and 90th minutes during surgery. At the end of the operation, LMA was removed after spontaneous respiration began and oropharyngeal examination was carried out immediately by rigid optic telescope. One hour later, the patients were questioned postoperatively about sore throat. Cuff pressures were significantly lower in group I when compared to group II at 30th, 60th and 90th minutes except for initial cuff pressure. In group II, cuff pressure was gradually and significantly dropped during the course. In group I, there was a negative linear correlation between time and lesion and positive linear correlation between lesion and sore throat. In group II, there was a positive linear correlation between pressure and lesion, pressure and sore throat and lesion and sore throat. Sore throat was significantly more frequent in group II. In conclusion, we suggested that usage of N2O-O2 mixture instead of room-air is suitable for LMA cuff inflation because of decreased sore throat and laryngeal mucous membrane injury.