Review patient positioning requirements for the examination and determine patient’s ability to maintain proper positioning for all portions of the exam:

• Sitting or supine position with head supported or stabilized for transtemporal, orbital and sub-mandibular approach
• Turned to side with neck flexed/chin toward chest to optimize access to foramen magnum for sub-occipital (transforamenal) approach
• Alternatively, the sub-occipital exam can be performed with patient in sitting position, arms crossed and supported by stretcher or bedside table, head resting on arms so that neck is supported and relaxed
• Patient should be kept awake throughout the exam due to changes in CO2 during sleep which may affect velocities and result in misdiagnosis
• The TCD examiner should be positioned at the patient’s head with arms supported