When we do preop cardiac evaluation we frequently use METs for quantification of physical activity: pt is able to sustain 4, 6 METs etc.

However I never found any way to assign METs to specific type of surgery- is 4 METs enough to tolerate complex spinal fusion/ bilateral hip replacement? What are METs of 4 hrs shoulder arthroscopy? robotic prostatectomy? it is very helpful concept of applied physiology as long as it can be xtrapolated onto what it is being evaluated for.