Dear Eunyarko,
Well, as far as I understand postural drainage is a simple treatment technique to learn, but quite a demanding clinical practice.
I am sure my practicing colleagues will agree with me that to obtain optimum efficacy of PD treatment mere positioning the patient in the right direction will not suffice.
It involves a constellation of factors like proper auscultation, scrutiny of the chest x-ray, pathophysiology of the disease condition, the state of the patient so on and so so forth.
For a general outlook and for a quick refresher on postural drainage I have attached a note on PD. It does highlight about positioning as well, so I am sure it will be of help to you, Eunyarko.
Cheers,
Thomas