| Background and Objective: Fiber-optic bronchoscopy-assisted tracheal intubation during slow induction is the safer method to handle difficult airway. Midazolam has sedative-,anxiolytic-, amnesia, ventilation-sparing effects. Midazolam combined with opioids has been used without the optimal dosage for sedation during difficult airway for a long time.Propofol acts immediately, metabolizes fast, the sedative dosage barely affects respiration,which has been used widely in clinic, ICU and during local anesthesia, but without the consistent effect-set concentration during tracheal intubation in slow induction.Methods: Two hundred and fifteen American Society of Anesthesiologists (ASA) grade I,II patients undergoing general anesthesia for oral cancer surgery aged (18?65) years,with body mass index of (18?30) kg/m~2,were randomly assigned into midazolam group (group M, n=72) or propofol group (group P, n=65) or dexmedetomedine (group D, n=78). All patients received fentanyl 1.5 ?g/kg after entering the operating room. Patients in group M were injected midazolam 0.02 mg/kg, the dose was increased according to bispectral index(BIS). Patients in group P were infused propofol TCI (target controlled infusion, TCI) with an initial plasma concentration (Cp) of 1.2 ?g/ml, the propofol Cp was adjusted according to BIS. Patients in group D received propofol TCI with the initial Cp of 1.0 ?g/ml,accepted dexmedetomidine (0.5 ?g/kg, 10 min) at the same time, propofol Cp was adjusted according to BIS, too. 1% tetracaine 2.5 ml was injected into tracheal through cricothyroid membrane, naso-pharyngeal membrane was infiltrated with 1 % tetracaine 2 ml for topical anesthesia in all groups until BIS value fell to 85. FOB was loaded as soon as BIS value was between 80 and 70. Tracheal tube was placed once FOB passed the glottis, patients in all groups were administrated propofol 1 mg/kg at the same time. General anesthesia was commenced after the nasotracheal tube was secured. Intraoperative and postoperative events were recorded. Propofol Ce at the time of cricothyroid membrane puncture and FOB placed were recorded, respectively. Results ?There were no significant differences between three groups in tracheal intubation time, difficult intubation, the incidence of cough or aspiration. ?Compared with group M, airway obstruction and sore throat were significantly decreased in group P (P < 0.05, respectively), patient comfort was significantly increased in group P (P < 0.05); pain recall and patient comfort were significantly increased in group D (P < 0.05, respectively). Compared with group P, airway obstruction, patient comfort, pain recall and sore throat were significantly increased in group D (P < 0.05, respectively).?The dose of midazolam in group M was (0.03?0.04)mg/kg,the mean propofol Ce were (0.7 ± 0.2) ?g/ml in group P and group D for cricothyroid membrane puncture respectively. For FOB insertion the cumulative dosage was (0.05?0.06) mg/kg in group M; compared with group P,the propofol Ce in group D was significantly decreased (1.1 ± 0.3 vs 1.0 ± 0.2,P < 0.05). Conclusion ?The dose of midazolam is (0.03?0.04) mg/kg,the mean propofol Ce is (0.7 ? 0.2) ?g/ml for cricothyroid membrane puncture. The cumulative dosage of midazolam was (0.05?0.06)mg/kg, the propofol Ce is (1.1 ± 0.3) ?g/ml for FOB insertion. ?Propofol TCI is superior to midazolam for sedation during difficult tracheal intubation. ?Infusion dexmedetomidine (0.5 ?g/kg, 10 min) used to supplement topical anesthesia for FOB-assisted nasotracheal intubation decreases propofol Ce for sedation, makes patient more comfortable, but complications such as airway obstruction, pain recall and sore throat need to be considered. |
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