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Introduction: Laryngeal mask airway (LMA) cuff pressure has been implicated as a prime reason for post-operative sore throat.LMA cuff pressure increases when the air is used for the cuff inflation during oxygen: Nitrous oxide (O2: N2O) anesthesia, whichresults in post-operative pharyngolaryngeal adverse events. We conducted this study to compare the effect of LMA supremecuff inflation with air, air: Oxygen, and oxygen: Nitrous oxide mixture in adults.Aim: The aim of the study was to compare the changes in cuff pressure intraoperatively with different gas composition (air,air: Oxygen mixture, and oxygen: Nitrous oxide mixture) used to inflate the LMA supreme by a manometer and post-operativepharyngolaryngeal morbidity.Design: It was a potential randomized double-blind study which was conducted on 120 patients admitted for elective surgeryunder general anesthesia.Materials and Methods: A total of 120 patients were randomly allocated into three groups of 40 each according to thecomposition of gases used to inflate the supreme LMA cuff to achieve 40 cm H2O cuff pressure, air was used as cuff inflationmedium in Group A, air: Oxygen mixture in Group AO, and oxygen: Nitrous oxide mixture in Group ON.Statistical Analysis: The cuff pressure, ventilatory parameters, and post-operative pharyngolaryngeal complications werenoted. The analysis was done by Student’s t-test and Chi-square test. P < 0.05 was considered statistically significant.Results: In Group A and Group OA cuff pressure significantly increased from initial cuff pressure of 40 cm H2O until the end ofthe surgery to 74.35 ± 7.41 cm H2O and 56.35 ± 3.63 cm H2O, respectively. An initial decrease in cuff pressure was observedat 15 min to a mean of 32.85 ± 1.42 cm H2O in Group ON which again gradually increased to near initial pressures to a meanof 40.10 ± 2.31 cm H2O toward the end of surgery. Cuff volume increased in Group A and Group AO; however, it decreased inGroup ON (23.18 ± 4.45 ml, 18.73 ± 2.61 ml, and 11.50 ± 1.93 ml, respectively) from initial values. Ventilatory and hemodynamicparameters were comparable in all the three groups. A significant difference in pharyngolaryngeal morbidity was observedbetween Group A and Group ON.Conclusion: Cuff inflation with 50% O 2: N2O mixture provided more stable cuff pressure in comparison to air and O2: Air mixtureduring O2: N2O anesthesia. Ventilatory parameters and hemodynamic parameters did not change with variation in SLMA cuffpressure. Post-operative pharyngolaryngeal morbidity had a strong correlation with cuff pressure and was more in Group Aand least in Group ON.
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Backgroud: The purpose of this study was to assess the effect of inflating a laryngeal mask airway ProSeal(TM) (PLMA(TM)) cuff, prior to insertion, on the degree of difficulty of inserting a PLMA(TM) by the inexperienced, and the incidence of postoperative sore throat. METHODS: Before induction, we measured the thyromental and sternomental distance. PLMA(TM) insertions were conducted by those with experience of less than 15 previous insertions. One hundred and five consecutive patients undergoing general anesthesia were randomized into 3 groups: In group 1, the PLMA(TM) was inserted with the cuff fully deflated, in group 2, the cuff was partially inflated (i.e., filled with half the recommended air), in group 3, the cuff was fully inflated. Successful insertion was judged primarily by the clinical function of the airway. The number of insertion attempts to achieve a satisfactory airway were recorded. Each patient was asked whether he had a sore throat, dysphonia, or dysphagia just before leaving the postanesthesia care unit (PACU) and again 24 hr after surgery. RESULTS: The number of insertion attempts required to achieve a satisfactory airway and the failure rate of insertion were not significantly different in the 3 groups. However, the 3 groups were significantly different in terms of the incidence of postoperative sore throat in the PACU. This was highest in group 3 (P<0.05). The incidences of other variables of laryngopharygeal morbidity in the PACU and 24 hrs after surgery were not significantly different in the 3 groups. CONCLUSIONS: Inflation of the cuff prior to insertion did not affect the success rate of inserting a PLMA(TM) by the inexperienced, and PLMA(TM) insertion after partial inflation was associated with higher incidence of postoperative sore throat in the PACU. Thus, in general anesthesia, it is desirable that the inexperienced insert the PLMA(TM) with the cuff fully deflated.