The 2nd character defines the particular body system or general physiological system or anatomical region involved.
In extracorporeal therapy, equipment outside the body is used for a therapeutic purpose that does not involve the assistance or performance of a physiological function. Extracorporeal therapy procedure codes have a first character value of “6”. The second character value for body system is physiological systems. There are ten root operations in the extracorporeal therapy section, as defined below.
The 4th character specifies the body system on which the extracorporeal therapy is performed (e.g., skin, circulatory). The fifth character specifies the duration of the procedure (e.g., single or intermittent). The sixth character is not specified for extracorporeal therapies, and always has the value No Qualifier. The seventh character qualifier is used in the root operation Pheresis to specify the blood component on which pheresis is performed.