Childhood Adenotonsillectomy Trial

6.5.5 Standard Sensors and Placement

Sensors, sampling rates, filter and notch settings, and peak-to-peak ranges will be standardized with respect to the limitations of various recording instruments. In brief, EEG and EOG signals are sampled at a minimum of 200 Hz, ECG and EMG (chin and leg movement) channels at 200 Hz, and respiratory signals at 32 Hz, except for nasal pressure which is collected at 128 Hz. Respiratory belts, airflow and CO2 cannulas are placed using standardized placements. Oximeter sensors are attached to a finger of the non-dominant hand or to a toe. Scalp electrodes are attached according to the International 10-20 system as well as behind the ears at the left (M1) and right (M2) mastoid areas and 3 over the submental muscles. EOG electrodes are applied 1 cm below and 1 cm lateral to the outer canthus of the left and right eye and will be referenced to an electrode at FPz. When possible, electrodes are secured using water soluble pastes, increasing the holding power by using an adhesive enhancer and cleaning agent. Isopropyl alcohol will not be used for any phase of participant preparation or electrode placement. Sensors are placed, calibrated, and signal quality/impedance checked, recording these data on study forms (Appendix A). Sensor positions are modified as needed to improve signal quality, replacing electrodes if impedances > 5 kohms.

Standardized Sensors and Placement

All gold disk scalp electrodes will be placed according to the International 10-20 System