Bispectral index variations during tracheal suction in mechanically ventilated critically ill patients: effect of an alfentanil bolus

Objective: To evaluate the impact of an alfentanil dose on bispectral index (BIS) variations during tracheal suction in ICU sedated patients. Design. and setting: A prospective open-label pilot study in a 12-bed surgical ICU in a university-affiliated, tertiary referral hospital. Patients: Eleven sedated (midazolam plus fentanyl) mechanically ventilated patients. Interventions: Continuous monitoring of BIS with arterial pressure and heart rate before, during, and after tracheal suction without (control period) and with an intravenous bolus of alfentanil (15 mug/kg, alfentanil period) before suction. Results: Steady-state BIS value was 61+/-8 for the control period and 59+/-7 for the alfentanil period. Blood pressure and heart rate were similar between baseline periods. One minute after tracheal suction, a significant increase in BIS level was observed in the control period, which remained significantly different from the alfentanil period until 10 min later. Significant higher systolic and diastolic blood pressure and heart rate were observed during the control period than the alfentanil period. However, no difference in Ramsay scores was observed between the two periods. Conclusions: An alfentanil bolus of 15 mug/kg markedly reduced the increase in BIS values, blood pressure, and heart rate observed immediately after tracheal suction. Therefore BIS monitoring in ICU may help to improve analgesia during invasive events.