These  are a few articles that may help

1. Intensive Care Med Exp. 2015 Dec; 3(Suppl 1): A942.doi: 10.1186/2197-425X-3-S1-A942, A comparison in tracheostomy weaning and complications rate between neuro critical care patients and general critical care patients, M Colomo,corresponding author T Chamroo, N Muchoki, J Darroch, and G De la Cerda/

2. The indication of tracheotomy conditions the predictors of time to decannulation in critical patients G. Hernández, R. Ortiz, A. Pedrosa, R. Cuenad, C. Vaquero Collado, P. González Arenas, S. García Plaza, A. Canabal Berlanga, R. Fernández.Med Intensiva 2012;36:531-9 - Vol. 36 Num.8 DOI: 10.1016/j.medine.2012.10.013

3.Tracheostomy procedures in the intensive care unit: an international survey

Maria Vargas, Yuda Sutherasan, Massimo Antonelli, Iole Brunetti, Antonio Corcione, John G. Laffey, Christian Putensen, Giuseppe Servillo and Paolo Pelos Critical Care201519:291, DOI: 10.1186/s13054-015-1013-7

Established and validated protocol probably is rare. One study on the background of the need for a protocol in the decision to remove the tracheal tube has shown six criteria for tracheal decannulation: level of consciousness, respiration, tracheal secretion, phonation, swallowing, and coughing. Probably we can adapt this, prepare protocol and validate it. You can go through the study http://dx.doi.org/10.1055/s-0033-1363467

One article suggested a system for Decision making in the process of decannulation  probably this can also help us developing in protocol.

http://article.sapub.org/10.5923.j.otolaryn.20150401.01.html