[Impact of propofol on the optimal sedative depth in patients undergoing gastroscopy]

To explore the optimal sedative depth and adequate bispectral index (BIS) value in patients undergoing gastroscopy treated with propofol and to explore the maneuverability and practicability of using BIS value as a variable to control the infusion of propofol.

160 patients, 76 males and 84 females, aged 44 +/- 15 voluntarily undergoing painless gastroscopy were randomly divided into 4 equal sex and age-matched groups. Propofol was given intravenously at the speed of 60 ml/min. Encephalographic monitoring was conducted to observe the BIS value. The first administration of propofol was stopped when the BIS value decreased to 80 ~ 75 (Group A), 65 ~ 74 (Group B), 55 ~ 64 (Group C), or < 55 (Group D). The amount of drug administered was recorded. Thirty seconds after the first administration the gastroscope was inserted. If the patients felt uncomforted an additional dose of 30 approximately 50 mg was used. The blood pressure, heart rate, respiratory rate, SpO(2), and BIS value before and during the gastroscopy, times needed for awakening and recovery of orientation were recorded. The patients were asked about if they were conscious during the operation.

The doses of propofol in group A, B, C, and D were (1.15 +/- 0.34) mg/kg, (1.43 +/- 0.27) mg/kg, (1.78 +/- 0.31) mg/kg, and (2.15 +/- 0.27) mg/kg respectively, with a significant difference between each 2 groups (all P < 0.05). The successful rate of gastroscope insertion were 17.5%, 47.5%, 92.5%, and 97.5% in group A, B, C, and D respectively, with a. significant difference between each 2 groups (P < 0.05) except between Groups C and D. The heart rate and mean arterial pressure decreased significantly compared with those before the examination in Group D (both P < 0.05). 17 patients of Group A and 4 cases in Group B remembered that they felt unwell during the operation, and 11 patients in Group B said they heard voices but failed to remember the concrete contents.

It is safe, reliable and feasible to regulate the sedative depth and the dosage of propofol infusion with the BIS monitor. The optimal BIS value in patients undergoing gastroscopy is from 55 to 64.