The aim of this study is to compare serratus anterior plane block and erector spinae plane block for postoperative analgesia after VATS as measured by the duration till 1st requirement of analgesia.

Video-assisted thoracoscopic surgery has become the standard surgical procedure for both minor and major oncological lung surgery, as it is considered less invasive and equally effective compared with thoracotomy . However, it is a fact that pain following VATS can be severe and long-lasting. According to Homma et al., 18.8% of patients who undergo VATS present with persistent pain 2 months after surgery.

Serratus anterior plane block is a type of interfascial plane block that was defined by Blanco and his colleagues in 2013 .Ultrasound-guided SAPB has recently gained the interest of the anesthesiologists and pain physicians due to its efficacy, relative ease, single-injection method with limited side-effect profile.

The SAPB targets the lateral cutaneous branches of the thoracic intercostal nerves, which arise from the anterior rami of the thoracic spinal nerves and run in a neurovascular bundle immediately inferior to each rib. At the midaxillary line, the lateral cutaneous branches of the thoracic intercostal nerve traverse through the internal intercostal, external intercostal, and serratus anterior muscles innervating the musculature of the lateral thorax.These branches of the intercostal nerves, therefore, travel through the two potential spaces described above. Local anesthetic inserted into these planes will spread throughout the lateral chest wall, resulting in paresthesia of the T2 through T9 dermatomes of the anterolateral thorax.

Erector spinae plane block is an interfascial plane block that was defined by Forero and colleagues in 2016. Erector spinae plane block has a wide indication range for pain management of the thoracic, abdominal , lumbar, hip, and even shoulder areas . Erector spinae plane block is a paraspinal block that targets the dorsal and ventral rami so that it can provide analgesia in the anterolateral and posterior chest wall .

Erector spinae plane block emerged in recent years to be effective in reducing postoperative pain at 24 h, i.e. preoperative ESPB plus intravenous opioid reduced pain scores and opioid consumption after VATS when compared with intravenous fentanyl only .

Inclusion criteria

• Patients with American Society of Anesthesiologists (ASA) physical status 1-3 --
• scheduled for VATS .

Exclusion Criteria:

1. ≤20 or ≥80 years old.
2. Refusing to participate in the study .
3. History of allergy to the medications used in the study.
4. Contraindication to regional anesthesia (including coagulopathy and local infection).
5. Severe hepatic impairement (serum protein < 3g/dl and serum bilirubin > 3mg/dl) .
6. Renal dysfunction (as determined by creatinine levels greater than 2mg/dl or predicted creatinine clearance (CLcr)<50ml/min).
7. Psychiatric disorder.
8. Pregnancy.
9. Body mass index (BMI) ≥40 or ≤18 kg/m2.