“Comparison of Cuff Pressure Changes Between Air with Oxygen or Nitrous Oxide with Oxygen During General Anaesthesia Using Proseal LMA for Laproscopic Surgery”

Background: LMA exerts pressure on the pharyngeal mucosa which may lead to throat discomfort.Nitrous oxide is known to diffuse into air containing cavity.Nitrous oxide use causes increase in proseal LMA(PLMA)cuff pressure was proved, but whether the resulting increased cuff pressure leading to laryngopharyngeal morbidity which is clinically important remains unclear.We therefore, tested the hypothesis.Methods:Eighty patients are randomly divided into group A(O 2 +Air) and group N(O 2+ N 2 O) each containing 40 Patients using computer generated randomization list.Patients monitored during surgical procedure regarding intraoperative hemodynamic changes , increase in PLMA cuff pressure , number of deflations required and laryngopharyngeal morbidity during intra and postoperatively upto 24 hrs.PLMA cuff pressure was monitored using cuff pressure monitor[VBM Aneroid meter].Results:There were no significant intraoperative differences between two groups air andnitrous oxide with respect to hemodynamic parameters, but statistically significant ( p valve < 0.001) cuff pressure changeswith nitrous oxide use which was exceeding > 60 cms of H2O and upto six deflations to maintain pressure in PLMA were required .There was no statistically significant difference for laryngopharyngeal morbidity, probably because we have limited cuff pressure upto 60 cms of H2O in nitrous oxide group as well in laproscopic surgeries > 3 hrs.Conclusions:Our study concludes that use of cuff pressure monitoring in PLMA to maintain cuff pressure as recommended by the manufacturer probablyreduces the incidence of postoperative pharyngo-laryngeal morbidity.Cuff pressures are increased with nitrous oxide use and repeated deflation of cuff is required .Butpharyngo-laryngeal morbidity can be limited by deflation and monitoring of cuff pressure for nitrous oxide.Nitrous oxide can be safely used forlaproscopic surgeries with PLMA for surgeries lasting less than three hours .