Monitoring: Equipment and Computers
Background: We tested the effects of ketamine (KET) and rocuronium (ROC) on an ANFIS transformation algorithm of the electroencephalogram (EEG), as calculated by the qCON® monitor (Quantium Medical S.L., Barcelona, Spain). We reanalyzed raw EEG obtained from a prior study1.
Methods: After ethics’ committee approval, 41 patients were allocated to four groups. Baseline measurements were performed after implementing calculated steady-state anaesthesia with propofol and remifentanil. No additional drugs were given in the CONTROL group. The KET group received a bolus of ketamine (0.4mg/kg) followed by 1 mg/kg/h. The ROC group received rocuronium (0.9 mg/kg). The ROC+KET group received both. All data was stored during 14 minutes after baseline (Figure 1). qCON was extracted posthoc from raw EEG obtained on the mastoid position by the A-line® AEP monitor (Danmeter, Odense, Denmark). Mean qCON changes from baseline were tested within each group (ř-test+Dunnett) and compared with CONTROL.
Results: In CONTROL, one patient was excluded due to artifacts not properly filtered out by the qCON artifact rejection algorithm. Compared to baseline, qCON increases in KET (p< 0.05 at min 9, mean (SD): 41(9) versus 46 (9)), decreases in ROC (p< 0.05 from min 2 to min 14, mean (SD): 41(8) versus 36(4) at lowest point) and increases in ROC+KET (p< 0.05 from min 9 to min 14, mean (SD): 37(6) versus 43(6) at highest point). In the intergroup comparison, only the changes in ROC and ROC+KET remained significantly different compared to the CONTROL group.
Conclusion: Rocuronium decreases qCON when calculated from EEG on a mastoid channel. The increase in qCON evoked by ketamine is more pronounced when electromyographic activity is inhibited by rocuronium. Our conclusions must be confirmed by frontal derived EEG. Results may be affected by the applied artifact rejection algorithm, which is not developed for mastoid electrode position.
1. Vereecke HE, et al. Anesthesiology 2006; 105: 1122-34