Effect of Different Dosages of Intravenous Midazolam Premedication on Patients Undergoing Head and Neck Surgeries- A Double Blinded Randomized Controlled Study

Abstract

Introduction: Benzodiazepines primarily acts on the central nervous system. Most patients are extremely anxious in the pre-operative period. Excessive anxiety adversely influences anaesthetic induction and often leads to functional impairment and poor recovery after surgery. Aim: To determine whether amnesia, anxiety, sedation and cardio respiratory symptoms are affected while administering two different doses of intravenous midazolam (0.02 mg/kg & 0.06 mg/kg). Materials and Methods: Two forty patients posted for head and neck surgeries were involved in this double blinded prospective randomised controlled trial. The patients were randomized into two main groups, Group 1 receiving 0.02 mg/ kg and Group 2 receiving 0.06 mg/kg midazolam intravenously as premedication. Visual recognition and recall were tested using eight laminated A4 size posters pre-operatively and four further images were shown at the postoperative interview. Anxiety was evaluated by a Visual Analogue Scale (VAS) and sedation depth was determined by the Observer’s Assessment of Alertness/Sedation Scale (OAAS) scale. Vital signs including heart rate, respiratory rate, mean blood pressure and arterial oxygen saturation (SpO2 ) were monitored. Statistical analysis was done using paired Student's t-test and Chi-square test. Results: VAS scores were lower in Group 2 (0.06 mg/kg) than in Group 1 (0.02 mg/kg) at T15 (15 minutes after the injection of midazolam). Comparison of OAAS scores among Group 1 and Group 2 showed that more patients in Group 1 were alert at T15 compared to Group 2. Recall of events was significantly lower in Group 2 compared to Group 1. There was no significant statistical variation in haemodynamic parameters between the groups except for decreased diastolic blood pressure and room air saturation in Group 2. Conclusion: A higher dosage of midazolam improves the quality of anxiolysis and sedation with lesser rates of intraoperative recall and maintains haemodynamic stability.

Keywords

• benzodiazepines
• observer’s assessment of alertness/sedation scale
• visual analogue scale