Are electrocardiogram electrodes acceptable for electroencephalogram bispectral index monitoring?

The monitoring of electroencephalogram bispectral index (EEG-BIS) during anaesthesia reduces anaesthetic use and improves recovery. However, it also increases the direct costs of anaesthesia due to the need for special EEG electrodes. In the present study we tested the feasibility of less expensive electrocardiogram (ECG) electrodes for EEG-BIS monitoring.

In the first part of the study we compared skin-electrode impedances when EEG electrodes were used after alcohol swab pretreatment of skin to impedances when ECG electrodes were used after alcohol swab pretreatment with or without skin abrasion paste. In the second part of the study we evaluated the difference in parallel BIS values collected with two BIS monitors, using either ECG electrodes or EEG electrodes. In the third part of the study we compared parallel BIS values collected with two sets of EEG electrodes.

Skin pretreatment with abrasion paste led to lower impedances with ECG electrodes than did alcohol swab pretreatment of skin with EEG electrodes. When the skin was pretreated with alcohol swab, higher impedances were measured with ECG electrodes than with EEG electrodes. In most patients, BIS values collected with ECG electrodes were also higher than those collected with adhesive EEG electrodes. The difference between parallel BIS values collected with two sets of adhesive EEG electrodes was smaller than the difference between BIS values collected with ECG and EEG electrode sets.

Low skin-electrode impedances indicating reliable skin-electrode contact can be ensured with inexpensive pregelled ECG electrodes only if the skin is carefully prepared with both abrasion paste and alcohol. When only alcohol pretreatment of skin is used, the BIS values collected with EEG electrodes and ECG electrodes are not equal. EEG-BIS monitoring with pregelled ECG electrodes is recommended only if skin is prepared with abrasion paste before attaching the electrodes.