Patient Preparation and Testing Setup
Core concepts
Patient preparation begins before electrodes are applied: verify identity, explain the procedure, obtain consent per policy, and review history, medications, allergies, and recent sleep. Measure the head using landmarks such as nasion, inion, and preauricular points to place electrodes by the 10–20 system. Prepare skin by cleaning with abrasive gel or alcohol until mildly red, then apply conductive paste or collodion according to protocol. Aim for low, stable impedance-commonly ≤5 kΩ. Place EEG, EOG, chin EMG, ECG, leg EMG, airflow, effort, oximetry, snore, and position sensors according to the montage. Confirm the patient is comfortable and that cables allow movement without traction. Follow hand hygiene and infection-control practices, and clean reusable sensors between patients.
Traps
Do not skip identity verification or consent. High impedance causes artifact and poor data; pressing harder is not a substitute for proper skin preparation. Avoid placing electrodes over hair without parting and cleaning the site. Do not ignore safety with oxygen or PAP equipment. A common question trap is confusing “measure from nasion to inion” with “place the electrode at the vertex”-measurement guides placement, but the actual site depends on the montage. Medication and intervention details belong in the record.
Worked example
If F4 impedance is 15 kΩ while other electrodes are 3 kΩ, re-prep the site and reapply. Do not accept a high-impedance electrode just because the channel looks acceptable at the start.
Rule of thumb
Good data start with good contact: clean skin, stable impedance, and a verified, comfortable patient.