In which scenario are I waves typically absent?

I waves, also known as I-wave activity, are typically absent when patients are under general anesthesia. Under anesthesia, the brain's electrical activity changes significantly, leading to a reduction or absence of certain waveforms, including I waves. These waves are associated with specific neural activities related to motor control and conscious sensory perception.

During awake surgeries, patients are generally monitored using methods that can detect I waves. Similarly, outpatient procedures often do not involve deep anesthesia, allowing the presence of I waves. Non-invasive tests also typically aim to capture a wide range of brain activity, including I waves, depending on the state of the patient. Therefore, the unique condition of being under anesthesia is primarily responsible for the absence of I waves, highlighting changes in brain function and responsiveness.