TENS for the Treatment of Pain and Respiratory Function Following Mastopexy With Augmentation

TENS will be initiated one hour after surgery. A portable device with two channels will be used (Neurodyn Portable TENS, Ibramed, Amparo, São Paulo, Brazil). This device will deliver a biphasic, asymmetrical, balanced current, with a frequency of 100 Hz and pulse duration of 100 μs. Four electrodes (5x5 cm) will be positioned on the left and right sides of the spine according to the indicated instructions. The assessor will increase the intensity to promote a strong tingling sensation, reaching the patient's maximum tolerance level without causing discomfort. Emission will be applied in a single session of one continuous hour and the patients will be informed that the sensation may decrease over time. Every 10 minutes, the assessor will ask the patient if there is habituation to the current and will increase the intensity if necessary. TENS will be administered only once for one hour.

Sham TENS will be performed using equipment identical in appearance to active TENS (Neurodyn Portable TENS, Ibramed, Amparo, São Paulo, Brazil) specifically designed for this study. The device will emit an electrical current gradually increased during the first 30 seconds, followed by a gradual decrease over the subsequent 15 seconds reaching an intensity of 0 mA. The device will remain inactive during the rest of the application, but will have a flashing light, giving the patient the appearance that it is active. The assessor will inform the patient that it is possible to feel the sensation of the current or not depending on individual characteristics. This type of equipment is validated and has been used in other studies to facilitate the blinding of participants. Both systems will be calibrated using a digital oscilloscope (DPO 7000, Tektronix Inc., Beaverton, OR, USA).