Impact of priming the infusion system on the performance of target-controlled infusion of remifentanil

Correction of target-controlled infusion following wrong selection of emulsion concentrations of propofol

Background

We investigated the correction methods following wrong-settings of emulsion concentrations of propofol as a countermeasure against erroneous target-controlled infusions (TCI).

Methods

TCIs were started with targeting 4.0 µg/ml of effect-site concentration (C_eff) of propofol, and the emulsion concentrations were selected for 2.0% instead of 1.0% (FALSE_1-2, n = 24), or 1.0% instead of 2.0% (FALSE_2-1, n = 24). These wrong TCIs were corrected at 3 min after infusion start. During FALSE1-2, the deficit was filled up while injecting after equilibrium (n = 12), or while overriding (n = 12). During FALSE_2-1, the overdose was evacuated while targeting C_eff (n = 12) or targeting plasma concentration (C_p) (n = 12). The gravimetrical measurements of TCI reproduced the C_p and C_eff using simulations. The reproduced C_eff at 3 min (C_eff-3min) and the time to be normalized within ± 5% of target C_eff (T_±5%), were compared between the correction methods.

Results

During the wrong TCI, C_eff-3min was 1.98 ± 0.01 µg/ml in FALSE_1-2, and 7.99 ± 0.05 µg/ml in FALSE_2-1. In FALSE_1-2, T_±5% was significantly shorter when corrected while overriding (3.9 ± 0.25 min), than corrected after equilibrium (6.9 ± 0.05 min) (P < 0.001). In FALSE_2-1, T_±5% was significantly shorter during targeting C_p (3.6 ± 0.04 min) than targeting C_eff (6.7 ± 0.15 min) (P < 0.001).

Conclusions

The correction methods, based on the pharmacokinetic and pharmacodynamic characteristics, could effectively and rapidly normalize the wrong TCI following erroneously selections of the emulsion concentration of propofol.