Clinical practice guidelines are
"documents designed to support decisions regarding the diagnosis, care, and treatment of a particular disease or condition".
Leng, G.C., & Connell, C., (2010) 'Clinical Guidelines'. In E. Haxby, D. Hunter & S. Jaggar, An introduction to clinical governance an patient safety. Oxford University Press.
Clinical practice guidelines are produced by governing bodies and can generally be found on these bodies' websites. See the Health page in this guide for some suggestions. Some databases, such as PubMed, will allow you to filter your results to Clinical practice guidelines.
Another approach to finding Clinical Practice Guidelines is to use the Hand Searching technique.