A retrospective evaluation of the efficacy of midazolam and ketamine as premedication for paediatric patients undergoing elective surgery

Abstract

Background: Preoperative anxiety is common in paediatric patients and is associated with negative postoperative outcomes. Sedative premedication may alleviate some of this anxiety. A new sedation protocol using midazolam and ketamine in combination was instituted at our tertiary hospital. We aimed to evaluate the efficacy and the side effect profile of this regimen.

Methods: We conducted a retrospective review of paediatric surgical patients who received oral midazolam (0.25 mg/kg) together with ketamine (3 mg/kg) as premedication, prior to induction of anaesthesia for elective surgery. The Watcha scale was used to assess preoperative and postoperative behaviour. Premedication efficacy was assessed using the Wilson sedation scale together with the 4-point anxiety scale. We further compared the incidence of significant preoperative anxiety with the incidence from a previous study.

Results: We included 146 patients in our study. There was optimal sedation (Wilson sedation score = 1/2) in 47.9% of the patients (CI 39.9–56.1) with failed sedation (Wilson sedation score = 0) in 34.9% (CI 27.6–43.1) and over-sedation (Wilson sedation score = 3/4) in 17.1% (CI 11.8–24.2) of the patients. Optimal anxiolysis (4-point anxiety scale = 1) was achieved in 76.0% of the patients (CI 68.4–82.3). Failed anxiolysis (4-point anxiety scale = 2/3/4) occurred in 23.3% of the patients (CI 17.7–31.6). The majority of patients had no side effects (79.5%; CI 72.1–85.3). For those who experienced side effects, the most common was hypersalivation (12.3%; CI 7.9–18.8). The incidence of postoperative delirium was 3.4% (CI 1.4–8.0) and there was significantly less anxiety compared to our previous regimen (5.5%; CI 2.7–10.6 versus 13.5%; p = 0.007).

Conclusion: The combination of midazolam and ketamine appears effective in providing safe sedation and reducing preoperative anxiety. Side effects occurred in up to a fifth of patients; predominantly hypersalivation. The combination of midazolam and ketamine for premedication should be considered for ASA I–II patients without contraindications undergoing elective surgery.