In patients who will undergo open thoracic surgery, two different types of drugs will be administered to volunteer patients before surgery in order to relieve postoperative pain, facilitate breathing and reduce hospitalization time. The pain intensity, respiratory capacity, the amount of opioid analgesic needed during and after surgery, side effects such as nausea-vomiting, low blood pressure and shortness of breath will be evaluated.

Group Thoracic Epidural Analgesia (TEA): Thoracic Epidural Application: The epidural area will be accessed from the 7th (T7)-8th (T8) level of the thoracic vertebral midline with an 18 gauge (G) epidural needle using the hanging drip technique. After 2 ml of 2% lidocaine is administered and no spinal effect is observed, a mixture of morphine and local anaesthetic 3-4 mg morphine hydrochloride + 5 ml 0.5% bupivacaine + 2 ml 0.9% saline will be administered through the epidural needle at once and the epidural needle will be withdrawn and sterile dressing will be applied.

• The mode of presentation will be face-to-face and individually.
• The intervention will be performed by an anaesthetist with at least 5 years of experience.
• The stages of the intervention will be verbally explained in detail to participants prior to the intervention.
• The patient will be taken to the operating table and electrocardiographic, oxygen saturation with pulse oximetry and non-invasive blood pressure monitoring with automatic manometer will be performed.

The intervention will be administered only once, 3-4 mg of morphine hydrochloride + 5 ml of 0.5 % bupivacaine + 2 ml of 0.9 % saline into the epidural space.

• Immediately before induction of anaesthesia, the patient will be seated and after appropriate sterilisation conditions are provided, the thoracic epidural space will be reached and the analgesic mixture will be given once and the space will be exited.
• Immediately after sterile dressing of the intervention site, the patient will be placed supine and standard general anaesthesia will be applied.
• The intervention will be performed in the thoracic surgery room of our hospital operating theatre.

Grup Erector spinae plane block (ESP): Before induction of anaesthesia, the patient will be placed on the operating table and placed in a forward tilted position. Asepsis and antisepsis conditions will be fulfilled.

The linear ultrasonogram (USG) probe will first be placed in the sagittal plane to visualise the vertebral spinous process. Then the linear probe was moved approximately 2-3 cm lateral to the spinous process T5 - T6 level on the side to be operated on, and the probe will be rotated 90 degrees to the longitudinal plane to visualise the transverse process. The trapezius, rhomboid major and erector spinae muscles will be identified to find the correct probe position. A 22 gauge, 50 mm or 22 gauge 80 mm single shot nerve blocks needle will be inserted through the skin in a cranio-caudal direction. With the needle resting on the transverse process, the plane between the erector spinae muscle and the transverse process will be verified by hydrodissection with 5 ml saline solution. Then, 20 ml of 0.25% bupivacaine will be injected. The ESP block will be considered successful if the local anaesthetic spreads linearly up to the T8 - T9 level. The patient will then be placed in the supine position and general anaesthesia will be administered.

• The mode of presentation will be face-to-face and individually.
• The intervention will be performed by an anaesthetist with at least 5 years of experience.
• The stages of the intervention will be verbally explained in detail to participants prior to the intervention.
• The patient will be taken to the operating table and electrocardiographic, oxygen saturation with pulse oximetry and non-invasive blood pressure monitoring with automatic manometer will be performed.
• The intervention will be performed only once on the side of the surgical incision and 20 ml of 0.25% bupivacaine will be injected once into the relevant area.
• Immediately before induction of anaesthesia, the patient will be seated and after appropriate sterilisation conditions are provided, the fascia of the erector spina muscle will be reached under ultrasound guidance and the analgesic solution will be given to this area only once and the cavity will be exited.
• Immediately after sterile dressing of the intervention site, the patient will be placed supine and standard general anaesthesia will be applied.
• The intervention will be performed in the thoracic surgery room of our hospital operating theatre.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) I-III physical condition
• who were to undergo thoracotomy

Exclusion Criteria:

• patients with acute infection,
• coagulation disorder,
• morbid obesity (Body Mass Index (BMI) > 35),
• drug allergy
• history of chronic pain,
• long-term opioid use,
• history of psychiatric illness,
• emergency surgeries

patients undergoing thoracotomy surgery