Comparison between effects of ketamine and midazolam as co-induction agents with propofol for prosealTM laryngeal mask insertion

Introduction: Optimal conditions during supraglottic airway placement are important to prevent adverse events associated with inadequate depth of anaesthesia. This study compared propofol co-induction with ketamine or midazolam during ProSeal^TM Laryngeal Mask Airway (PLMA) insertion.

Materials and Methods: A total of 118 ASA I or II patients aged between 18 to 60 years requiring PLMA insertion for surgery were recruited into this prospective, randomised and double blind study. Patients were grouped into propofol (2mg/kg) co-induction with either ketamine (0.5mg/kg) or midazolam (0.03mg/kg). During PLMA insertion, the degree of mouth opening, ease of insertion, swallowing, coughing or gagging, movement and laryngospasm were scored and haemodynamic changes were recorded. Overall insertion conditions were further graded into excellent, good, poor or unacceptable.

Results: The ketamine-propofol group had significantly better mouth opening (p=0.01) and shorter duration of apnoea (p<0.001). Other conditions during PLMA insertion and the overall grading were comparable between groups. Haemodynamic parameters were comparable to baseline within each group. However, the ketamine-propofol group had more stable blood pressure readings and maintained a higher heart rate (p<0.05) compared to the midazolam-propofol group.

Conclusion: Propofol co-induction with either ketamine or midazolam conferred comparable PLMA placement conditions.