REMIFENTANIL REQUIREMENT FOR CLASSIC™, FASTRACH™ AND I-GEL™ LARYNGEAL MASK AIRWAY INSERTION WITH TARGET-CONTROLLED PROPOFOL INFUSION

Aim: To determine the 50% effect-site concentration (EC50) of remifentanil in order to provide clinically acceptable insertion conditions for classic laryngeal mask airways (c-LMA), fastrach LMA (f-LMA), and 1-gel LMA at a 4 ng mL(-1) target controlled infusion (TCI) of propofol. Material and method: This prospective randomized study enrolled 102 patients. Patients were randomly divided into three groups to provide the airway with c-LAIA (n=38), f-LMA (n=33), or with I-gel LMA (n=31). After premedication with 0.04 mg kg(-1) midazolam. retnifentanil with effect site 4 ng mL(-1) TCI was given to the first patient in each group. After achieving target effect-site concentration of remifentanil, TCI propofol 4 ng niL4 effect-site concentration was started in all patients. The dose of rentifentand used for subsequent patients in each group was determined by the response in the previously tested patient by using Dixon 's modified up-and-down method with 0.2 ng niL.' step size. Heart rate (HR), mean arterial pressure (MAP), bispectral index (BIS) value, insertion time, number of attempts, and mask ventilation were also recorded. Results: From Dixon 's modified up-and-down method, EC50 of retnifentand was determined to be 1.56 ng mL(-1) for c- LMA, 2.41 ng mL(-1) for f-LMA, and 1.78 ng mL(-1) for 1-gel LMA. The probit analysis determined that the EC50 was 0.648ng nil, for c-LMA, 0.767 ng mL(-1) for f-LMA, and 0.754 ng mL(-1) for I-gel LMA. The EC50 values obtained with a probit analysis did not differ significantly from those calculated from the up-and-down method (p>0.05). HR and MAP values significantly decreased from baseline values when compared with before insertion or 1 min after insertion in all groups (p<0.05). Mean insertion times were 25.2 +/- 3.2 sec for c-LMA, 27.3 +/- 4.8 sec for f-LMA, and 16.9 +/- 1.3 sec for 1-gel LMA. The insertion time for I-gel was significantly shorter than for c-LMA or f-LMA (p<0.05). Conclusion: Fastrach LMA required the highest dose of remifentanil (2.41 ng mL(-1)), the second highest dose for I-gel, and the lowest dose for classic LMA (1.78 ng 1.56 tig mL(-1), respectively) in healthy adults.