The study was conducted in 98 ASA grade I and II patients between age 20-50 years undergoing lower abdominal, perineal and lower limb surgeries under age as well as unwanted effects of overdosage. combined spinal epidural block upto T10 level.
Patients were randomly allocated to one of the following two groups:
Group I- (n=50) Midazolam 0.1% infusion starting with 0.5 mg.kg−1.h−1 till BIS level reached 75 and then dose reduced and titrated to maintain a BIS of 65-85.
Group II- (n=48) Propofol 1% infusion starting with 6mg.kg−1.h−1 till BIS level reached 75 and then dose was reduced and titrated to maintain a BIS of 65-85.
A written informed consent was taken from all patients. They were fasted for a minimum of 6 hours before surgery. No preoperative opioids or prophylactic antiemetics were given. No other preoperative medication was allowed. Patients suffering from heart disease, hypertension, diabetes, spinal deformity, neurological problem or any bleeding disorder were excluded from the study. All patients were monitored with an electrocardiograph, noninvasive blood pressure, pulse oximeter and BIS monitor. Baseline readings were recorded. Preloading was done with 15ml.kg−1 of Ringer lactate prior to block. Combined spinal and epidural block was given. Epidural catheter was put at L3-4 or L2-3 level, 3 ml of 0.5% bupivacaine was given into the subarachnoid space and the epidural catheter was maintained for providing postoperative analgesia. 1 % propofol or 0.1% midazolam infusion was started with the help of a manually controlled variable rate infusion pump.
Propofol infusion was given at a rate of 6mg.kg−1.hr−1 and midazolam at 0.5 mg.kg−1.hr−1 and after reaching a BIS value of 75, the rate of infusion was reduced to half and then with subsequent observations, the anaesthetics were titrated to keep a BIS level between 65 and 85.
Blood pressure, heart rate, oxygen saturation, and BIS level were assessed every 2 min till maintenance dose was reached ie a BIS level of 65-85 and then every 10 min till 105 min or till the end of surgery which- ever was earlier and every 15 min (if duration of surgery extended beyond that).
O2 inhalation by ventimask was given when SpO2 came down below 90% and vasopressor was given if MAP decreased beyond 20% of baseline.
Following observations were made:
- Time to reach required level of sedation.
- Duration of surgery
- Duration of infusion
- HR, Mean Arterial pressure, arterial saturation of oxygen were recorded every 2 minutes till required sedation level was reached and then every 10 min till 105 min or end of the surgery whichever was earlier and then every 15 minutes.
- Time taken for recovery (for comparison, BIS>90 was taken as a recovery parameter )
- Side effects
- Nausea & Vomiting
- Pain in arm
- Dose to reach required level of sedation.
- Dose to maintain required level of sedation
Statistical analysis was done with independent t test for age, weight, duration of surgery and end infusion, time for recovery, heart rate, mean arterial pressure, and SpO2 at various intervals. Chi square test was applied for sex distribution and for adverse effects as respiratory obstruction, apnea, laryngospasm, nausea & vomiting, awareness, hypotension, and oxygen supplementation. Paired t test was applied for intra-group variation in heart rate and mean arterial pressure. Fischer's exact test was used for incidence of complications.