The present study was conducted to compare the effects of different gas mixtures used for anaesthesia and for Proseal LMA cuff insufflation on the intra cuff pressure and postoperative upper airway morbidity.

After approval by the Hospital Ethics Committee, the present study was conducted in Ninety ASA grade I, II or III adult patients of either sex in the age group of 18 to 80 years admitted at Batra Hospital & Medical Research Centre, New Delhi who underwent elective laparoscopic surgery under general anaesthesia using PLMA. They were randomly divided into three groups (NN) (AN) and (AA) depending on the gas used for insufflating their cuffs and for maintenance of anaesthesia during the surgical procedure. In all the patients, cuff pressure monitoring was done both at the beginning and at the end of procedure with the help of a manometer and the rise in cuff pressure if any noted at the end of the surgery. The incidence of post operative respiratory complications was assessed in the PACU and 24 hours post operative.

There was no statistically significant difference in the demographic data between the three groups. All the three groups were comparable in terms of age, weight, height, sex, ASA grade, duration of surgery, PLMA used, number of attempts and the volume of air/ O2+N2O

mixture injected into the cuff at the time of insertion of PLMA. We found that-

The mean cuff pressure in all the three groups at the beginning of surgery was comparable and did not differ significantly ( P > 0.05)

At the end of surgery, the rise in cuff pressure was significantly higher in the (AN)

group where air was used to insufflate the PLMA cuff and O2+N2O was used as a part

of balanced anaesthesia where as there was no rise in the cuff pressure of the group where only air was used both to insufflate as well as to maintain anaesthesia i.e (AA) as measured by the manometer. In the third group, i.e.(NN) group, where O2+N2O mixture was used to both insufflate the cuff as well as for maintenance, the

rise in cuff pressure was quite less than the (AN) group. The difference in the rise of cuff pressure over time between these three groups was found to be statistically significant (P< 0.001).

The incidence of sore throat was significantly high in the (AN) group than (NN) or (AA) group both in the PACU (P < 0.007) and also after 24 hours (P < 0.001). The incidence of cough and hoarseness amongst the three groups was comparable and statistically insignificant (P > 0.05).