Chest pain is one of the most difficult problems to solve after thoracic surgery. Its correct control is often quite difficult, which can cause complications due to an ineffective cough and superficial respiratory movements. It could provoke secretion retention, lung atelectasis, and even pneumonia. In addition, insufficient treatment of postoperative pain also causes a slower recovery of mobility, delaying the incorporation to daily life activities.

Transcutaneous electrical stimulation (TENS) is a technique that attempts to establish pain control by applying electrical current through superficial electrodes Is transcutaneous electrical nerve stimulation effective for the pain rehabilitation approach after thoracic surgery? Are there spirometry changes related to pulmonary function after the application of transcutaneous electrical nerve stimulation in postoperative rehabilitation of thoracic surgical patients?

All patients likely to be part of the study will have an exhaustive medical history. Said clinical history will have, as a basis, the following aspects:

• Filiation data.
• Personal history.
• Type of intervention carried out.
• Incisions made.
• Chronology, location and characteristics of pain. Once intervened, the data corresponding to the surgical intervention performed will be collected. Once the period of 7 days after the intervention has passed and in the absence of complications and pleural drainage, the period of respiratory physiotherapy will begin.

Assessment of quality of life The SF-36 (Short Form Health Survey) health questionnaire will be carried out. This questionnaire is used in medical and mental health research and, in general, in health-related research. It offers an overview of the health status of the person, with the advantage that it is quick and easy to fill out, while also being easy to assess. In the same way, by allowing the numerical assessment of different aspects of the health of the person, it becomes an excellent tool for any research related to health. It contains 36 questions that address different aspects related to the daily life of the person who fills in the questionnaire. These questions are grouped and measured in 8 sections that are evaluated independently and give rise to 8 dimensions that the questionnaire measures.

The eight dimensions are:

1. Physical functioning.
2. Limitation due to physical problems.
3. Body pain.
4. Functioning or social role.
5. Mental health.
6. Limitation due to emotional problems.
7. Vitality, energy or fatigue.
8. General perception of health. In 1991, the project known as "International Quality of Life Assessment" (International Quality of Life Assessment Project, IQOLA) was started, which basically consists of adapting and testing the intercultural applicability of a generic instrument called the SF-Health Survey. (Short Form 36 Health Survey).

The Spanish version of the SF-36 is one of the most widely used generic instruments in the national territory, both in descriptive studies that measure the impact on HRQL in different patient populations and for the evaluation of therapeutic interventions.

Pain assessment

The necessary tools to make a correct pain assessment. In this sense, two ways of measuring it will be established:

1. Self-reports, where the visual analog scale (VAS) will be the basic measurement tool. The pain will be marked with a scale from 0 (absence of pain) to 10 (maximum possible pain).
2. The standardized tests, as an objective of the study, are also proposed to analyze sensitive, affective and behavioral aspects of pain in these patients, it is for this reason that the Mc Gill test will be the tool to take into account.

Assessment of respiratory function The different respiratory parameters will be measured by spirometry (Siebel spirometer): Forced Vital Capacity (FVC); Forced expiratory volume of the first second (FEV1); FEV1 / FVC (Tiffeneau Index).

Inclusion Criteria:

• Signed the informed consent.
• Affected by pulmonary or mediastinal pathology.
• Who have required thoracic surgery.

Exclusion Criteria:

• Patients with pacemakers.
• Diseases with chronic need for analgesic drug.
• History of drug addiction.
• Patients who do not require hospital readmission after surgery.

The principal investigator and the patient do not know which technique will be applied. The principal investigator and the patients do not know which group they are in, intervention, placebo or control.