This study evaluates the difference of deep and superficial serratus anterior plane block on intraoperative opioid consumption, emergence time and hemodynamic stability in patients undergoing video-assisted thoracic surgery.

Thoracotomy is known as one of the most painful surgery. Thus, there is a development to reduce surgical stress in terms of operation technique, which is video-assisted thoracoscopic surgery. Although it has reduced postoperative pain and complications compared with thoracotomy, VATS is still quite painful operation. Serratus plane block is a novel technique which provide analgesic effect for lateral chest wall by blocking lateral branch of intercostal nerve. Two methods were proposed to target the top and bottom of the serratus anterior muscle. However, the difference of deep and superficial serratus anterior plane block during intraoperative period has not yet been studied.

In this study, therefore, the investigators decided to assess the difference of deep and superficial serratus anterior plane block on intraoperative opioid consumption, emergence time and hemodynamic stability in patients undergoing video-assisted thoracic surgery.

Inclusion Criteria:

• a) American Society of Anesthesiologists (ASA) physical status 1 or 2
• b) age 20-75 years
• c) elective three port Video-assisted thoracoscopic surgery (VATS) lobectomy.

Exclusion Criteria:

• a) a history of drug allergy for opioids or local anesthetics
• b) local infection at the injection site and systemic infection
• c) coagulopathy
• d) difficulty in understanding the study protocol
• e) refusal to participate