Interesting question. I would have thought cardiothoracics pertains to a general terms for anything to do with cardio thoracic region of the body.

Cardiopulmonary physio to me seems more specific to the actual relationship of the heart and lungs. This might be more relevent to say cardiac rehab.

Cardiorespiratory Physiotherapy would appear more of a specialist field of practice. This could include cardiac rehab but would also include things like cystic fibrosis, atelectasis, transplant, emphysema, bronchiectasis etc.

What are your thoughts? 8o