High initial target blood concentration in target-controlled infusion: A randomized controlled trial

Our previously modified propofol intravenous sedation (IVS) method using a target-controlled infusion (TCI) pump with initial target blood concentration (TBC) set at 2.2 μg/ml enables the prediction of the personal optimal intraoperative TBC during induction with a minimal gap. This study aimed to verify whether this method can be useful in case of higher initial TBCs to reduce induction time.

Forty-five patients scheduled to undergo oral surgery under IVS with propofol were randomly divided into three groups (group 1, TCI started with TBC set at 2.2 μg/ml; group 2, TBC was set at 2.6 μg/ml; group 3, TBC was set at 3.0 μg/ml). Immediately after reading the calculated brain concentration when the target sedation was achieved (value A), the initial TBC was manually reset to value A. We manually controlled the intraoperative TBC to maintain moderate sedation, according to the clinical signs and bispectral index values. Of the regulated TBC values, the value farthest from value A was defined as value B. The maximum discrepancy between values B and A and the induction time were compared among the three groups.

The maximum discrepancy (mean ± standard deviation [SD]) was significantly larger in group 3 (1.0 ± 1.3 μg/ml, p = .005) and group 2 (0.8 ± 0.2 μg/ml p = .008) than in group 1 (0.5 ± 0.3 μg/ml). The induction time (mean ± SD) was significantly shorter in group 3 (124 ± 126 min, p = .004) and group 2 (135 ± 33 min, p = .006) than in group 1 (245 ± 1913 min). With the initial TBC set at 2.6 μg/ml, the maximum discrepancy was large at 0.8 μg/ml, but with a small SD (0.2 μg/ml).

Considering this discrepancy, this method with an initial TBC set at 2.6 μg/ml may be acceptable for clinical use for moderate sedation (UMIN 000017197).