Effects of the Transcranial Direct Current Stimulation on Prevention of Cognitive Dysfunction in Elderly Patients Submitted to Cardiac Surgeries: Prospective, Randomized and Double-blind Study

SUMMARY Postoperative cognitive dysfunction (POCD) is a contrary event observed between 20 to 83%, especially on elderly, patients submitted to cardiac surgery. Besides the difficult diagnosis, the limitations of prevention and rehabilitation on cases of POCD may compromise the quality of life and increase the mortality in surgical patients. The neuromodulator effect of the noninvasive cerebral stimulation, also known as transcranial stimulation, with a low intensity electric current (tDCS) has been studied to be used in the treatment of brain injuries and depression, and also in the cognitive rehabilitation. The hypothesis is that the use of the tDCS technique in sessions can decrease the occurrence of POCD and cognitively rehabilitate patients submitted to cardiac surgeries. The objective of this study is to evaluate the effect of the tDCS over the occurrence of POCD on patient submitted to cardiac surgeries with cardiopulmonary bypass (CPB)

After the approval by the constitutional ethics commission, will be included in the study 138 adult patients submitted to a cardiac surgery. After the subscription of the consent form by the responsible the patients will be randomly allocated in two groups:

tDCS GROUP: These patients will be submitted to 2 daily sessions of cerebral stimulation, starting from the first day after the surgery, for 4 consecutive days, with each session having 20 minutes, and a minimum break of 8 hours between them. Will be applied a direct current stimulus of 2 milliampere (mA) in the right anode and in the left cathode on the prefrontal right region.

CONTROL GROUP: In these patients will be applied, with the same equipment used in tDCS, a simulated stimulus similar to the active one. They will also be submitted to some psychological test to evaluate theirs mnemonics, attentional, executive and global functions. The volunteers will be evaluated in a model with the intention to treat (ITT) of recovering the cognitive functions evaluated by scores on the test based on normative tables, this is the primary outcome. The secondary outcome will be improvements on the response of these cognitive tests, the admission of these patients will last 15 days in the intensive treatment unity and in the hospital. There will also be evaluated data relative to the surgery, the cognitive evolution and the quality of life in postoperative period.

Will also be applied neuropsychological tests to evaluate memory, attention, and executive functions as well as another tests to assess specifics contents useful to describe the sample and research' results.