The aim of this study is to assess the effectiveness of analgesia of US guided MTP block in pediatrics undergoing thoracotomy.

Pain following surgery is a universal phenomenon which up to now is often underestimated and undertreated especially in pediatrics. Any postoperative analgesic technique should meet three criteria, which are effectiveness, universal applicability and safety.

Thoracotomy is widely known to cause severe acute pain. This pain can be very distressing for both children and their parents. If not treated properly, it may acutely cause ventilation-perfusion disorder and hypoxemia, together with a change in lung mechanics. It may lead to a delay in recovery, with some long-term sequelae. As a part of multimodal analgesia, many regional blocks have been described.

Regional anesthesia techniques are increasingly used in all surgical settings. Even in the context of thoracic surgery, new peripheral regional anesthesia techniques are being tested as alternatives to those already used. This proliferation of new techniques is explained, on the one hand, by the evolution of surgical techniques, which are becoming less and less invasive, and on the other hand, by the frequency and severity of the complications induced by thoracic epidural anesthesia and paravertebral block - currently the gold standards in context of pediatric setting.

Paravertebral block (PVB) has gained more popularity than other regional analgesic techniques including epidural for perioperative analgesia in pediatric surgery. Thoracic PVB provides adequate postoperative analgesia with favorable adverse effects. The use of thoracic PVB is associated with decreased pain severity and opioid consumption in both adults and children.

Many clinicians hesitate to apply the PVB technique due to the risk of serious complications such as pneumothorax. Therefore, the safest and most effective methods are being tried by clinicians. In a study conducted on cadavers claimed that mid-transverse process to pleura (MTP) block (an injection point midway between the pleura and posterior border of the transverse process) provides a paravertebral block due to the paravertebral spread of the local anesthetic agent through fenestrations and septations in the superior costotransverse ligament. They thought that MTP block may be as effective as PVB in postoperative pain management with less risk of possible complications.

Inclusion Criteria:

• The study will include 50 pediatric patients of both sexes aged from 5 to 15 years old with American Society of Anesthesiologists physical status I& II undergoing elective open thoracotomy.

Exclusion Criteria:

• Refusal of parents.
• Repeated thoracotomy.
• Emergency surgery.
• Mechanically ventilated patients.
• Bleeding disorders.
• Allergy to study drugs.
• Infection at the site of the needle puncture.