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

Abstract

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. 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). 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. 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. A higher dosage of midazolam improves the quality of anxiolysis and sedation with lesser rates of intraoperative recall and maintains haemodynamic stability.