New Jersey Subscriber
Answer: The descriptor for electroencephalogram (EEG) code 95819 specifies "including recording awake and asleep." Because you indicate the patient is awake and drowsy (rather than asleep), the more appropriate choice is 95816 (Electroencephalogram [EEG]; including recording awake and drowsy). These codes also include hyperventilation and/or photic stimulation when appropriate, and reporting times of 20-40 minutes, according to CPT.
Because you are reading the results only, you should append modifier -26 (Professional component) to 95816. This allows you to recoup payment for your work, but allows the hospital to bill separately for the procedure's technical component.