SUDS is short for Subjective Unit of Discomfort Scale.
This is a zero-to-100 scale used to rate a patient's discomfort at a given moment.
This scale is subjective. There's no way to know exactly how distressing a patient's 100 feels relative to another patient's 100.
SUDS is useful for identifying trends and tracking habituation, and for making the patient aware of their own distress levels.
However, this is not a reliable or objective measurement, so decreasing SUDS should never be a goal of treatment, and you should be careful not to insinuate to the patient that lower SUDS ratings are a goal.
Part of introducing SUDS is calibrating the patient's scale.
Get anchor points for zero, 50, and 100.
To get an anchor point for zero, ask the patient when he was the most relaxed he's ever been.
To get an anchor point for 100, ask the patient what the most stressful moment of his life was.
To get an anchor point for 50, ask the patient what would be halfway between zero and 100.
Optionally, you can get anchor points for 25 and 75.
Where possible, these anchor points should be unrelated to the trauma, because the patient's response to trauma reminders will likely change as treatment progresses. It's normal and completely acceptable, though, for patients' 100-SUDS anchor to be the worst part of their trauma.