What is the proper usage of CPT 97150 and what are the documentation requirements for that?
See page 299 in the Common Procedure Code chapter of the 2017 DeskBook (5.2).
Here is some general information for you (below). As far as documentation requirements...you must document to support medical necessity, type(s) of therapy, and all other specific therapy related details for each participating individual.
97150 - Therapeutic procedure(s), group (2 or more individuals)
(Report 97150 for each member of group)
(Group therapy procedures involve constant attendance of the physician or other qualified health care professional [ie, therapist], but by definition do not require one-on-one patient contact by the same physician or other qualified health care professional)
Therapeutic procedures performed in a group of 2 or more individuals can include aquatic therapy, conditioning therapies, or exercise therapy with a physician or licensed therapist in constant attendance but not in one-on-one contact with the individual patient. The purpose of the therapeutic procedure(s) should be to improve, develop, or restore body function(s) that may be impaired due to injury, illness, or surgery. The individuals in the group may perform identical or different activities but there should be a common, unifying element. The physician or licensed therapist provides introductory instructions to each individual or to the whole group and then continues to observe and give clinical expertise and feedback during the session, making modifications or progressions to the program as necessary. Code 97150 is applied to an untimed period of observation and assistance. If it is used with additional therapeutic procedure code(s), there must be clear documentation to support that the group and the individual therapeutic procedures were performed during separate periods of activity.