Clinical and Hemodynamic Correlates of Different Polarities of HD-tDCS in COPD

Participants will receive stimulation through electrode positioning according to the International 10-20 System. The central electrode will be placed over the left diaphragm cortex, accompanied by four return electrodes. The current will be administered using a 3mA protocol for 20 minutes, with a 30-second ramp-up at the beginning and a 30-second ramp-down at the end of the stimulation for active groups. For the placebo group, the setup will remain identical; however, regarding the protocol, the device initially reaches a current of 3 mA and then drops to 0.1 mA within the first 30 seconds, remaining at this current for 20 minutes. A current of 3 mA will be reinstated only in the final 30 seconds, once again accompanied by ramp-up and ramp-down phases.

Participants received sham stimulation using the same electrode positioning as the active conditions (International 10-20 System), with a central electrode over the left diaphragm cortex and four return electrodes. The device initially reached a current of 3 mA and then dropped to 0.1 mA within the first 30 seconds, remaining at this current for 20 minutes. A current of 3 mA was reinstated only in the final 30 seconds, accompanied by ramp-up and ramp-down phases, replicating the initial and final sensations of active stimulation without delivering a sustained therapeutic current.