There have been many studies to find the optimum anaesthetics to provide excellent conditions for laryngeal mask insertion. We compared the effects of dexmedetomidine administered before propofol, on laryngeal mask insertion with fentanyl combined with propofol.
In all, 52 patients, ASA I-II, scheduled to have minor urological procedures were randomized into two groups. Group F received 1 microg kg(-1) fentanyl (in 10 mL normal saline) and Group D received 1 microg kg(-1) dexmedetomidine (in 10 mL normal saline). We used 1.5 mg kg(-1) propofol for induction and 50% N2O and 1.5% sevoflurane in oxygen for maintenance. We observed jaw mobility (1: fully relaxed; 2: mild resistance; 3: tight but opens; 4: closed), coughing or movement (1: none; 2: one or two coughs; 3: three or more coughs; 4: bucking/movement) and other events such as spontaneous ventilation, breath holding, expiratory stridor and lacrimation. In each category, scores <2 were acceptable for laryngeal mask insertion.
More patients developed apnoea and their apnoea times were longer in Group F than Group D (P < 0.001). Respiratory rates increased in Group D (P < 0.001). Adverse events during laryngeal mask insertion were similar. The reductions in systolic and mean blood pressures were greater in Group F (systolic: P < 0.05, mean: P < 0.01). Emergence times were shorter in Group F than in Group D (P < 0.001).
Dexmedetomidine, when used before propofol induction provides successful laryngeal mask insertion comparable to fentanyl, while preserving respiratory functions more than fentanyl.