Comparison of sufentanil with sufentanil plus magnesium sulphate for sedation in the intensive care unit using bispectral index

In intensive care unit patients we assessed, using bispectral index (BIS) monitoring, whether the addition of magnesium sulphate infusion could decrease the sufentanil infusion required to maintain sedation. A total of 30 adult patients who were expected to require mechanical ventilation for 6 hours in the intensive care unit were randomly assigned to receive either sufentanil infusion or sufentanil plus magnesium infusion. We monitored BIS levels continuously. BIS levels in the range 61-88 are required to maintain a state of sedation, and in both groups BIS levels were kept within this range by increasing or decreasing the sufentanil infusion. Hourly consumption of sufentanil was monitored. Cardiovascular, respiratory and biochemical data were recorded. There was no significant difference between the groups with respect to cardiovascular, respiratory and biochemical parameters. Magnesium infusion, when added to sufentanil infusion, decreased the consumption of sufentanil at all times accept during the first hour (P < 0.001). There was no significant difference in BIS values between the groups (P > 0.05). This is the first clinical study to demonstrate that magnesium sulphate infusion decreases sufentanil requirements. Because of the limited number of patients included and the short period of observation, our findings must be confirmed by larger clinical trials of magnesium infusion titrated to achieve prespecified levels of sedation. Furthermore, randomized clinical studies are needed to determine the effects of magnesium infusion on opioids.