Minimum Effective Volume of Bupivacaine for Serratus Posterior Superior Intercostal Plane Block in Video-Assisted Thoracoscopic Surgery (SPSIP-EV50)

Determination of the Median Effective Volume (ED50) of Bupivacaine for Serratus Posterior Superior Intercostal Plane Block in Patients Undergoing Video-Assisted Thoracoscopic Surgery Using the Dixon Up-and-Down Method

This study aims to determine the minimum effective volume of bupivacaine required for the serratus posterior superior intercostal plane (SPSIP) block in patients undergoing video-assisted thoracoscopic surgery (VATS). The SPSIP block is an ultrasound-guided regional anesthesia technique used to provide postoperative pain relief after thoracic surgery.

Using a stepwise dose-adjustment method, the volume of local anesthetic will be increased or decreased based on the effectiveness of the block in each patient. The main outcome of the study is to identify the volume that provides effective pain control in 50% of patients. The results may help optimize pain management while minimizing drug exposure.

Study Overview

• Status: Recruiting
• Conditions: Postoperative Pain Management; Video-assisted Thoracoscopic Surgery (VATS)
• Intervention / Treatment: Other: Ultrasound-Guided Serratus Posterior Superior Intercostal Plane Block

Detailed Description

This prospective interventional dose-finding study is designed to determine the median effective volume (ED50) of 0.25% bupivacaine for ultrasound-guided serratus posterior superior intercostal plane (SPSIP) block in patients undergoing video-assisted thoracoscopic surgery (VATS).

The up-and-down sequential allocation method described by Dixon and Massey will be used. The initial volume of bupivacaine will be administered to the first patient, and subsequent volumes will be adjusted in 2 mL increments according to the response of the preceding patient. If the block is successful, the volume for the next patient will be decreased by 2 mL. In case of block failure, the volume will be increased by 2 mL.

Block success will be defined as the presence of sensory loss to cold in at least two consecutive dermatomes between T3 and T6, assessed 20-30 minutes after block performance, combined with a cumulative fentanyl requirement of less than 2 µg/kg within the first 60 minutes after induction of general anesthesia. Failure will be defined as absence of adequate sensory blockade or the need for fentanyl ≥2 µg/kg.

The up-and-down sequence will be continued until nine reversal points are obtained. The ED50 will be calculated as the mean of the midpoint doses of all independent success-failure pairs. Secondary outcomes will include postoperative pain scores and opioid consumption.

This study aims to provide clinically relevant data to optimize the volume of local anesthetic for SPSIP block while maintaining effective analgesia and minimizing potential adverse effects.

• Study Type: Interventional
• Enrollment (Estimated): 27
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: emre ulusoy; Phone Number: +905379492799; Email: emreulusoy36@gmail.com

Study Locations

• Turkey (Türkiye)
  • Bursa, Turkey (Türkiye), 16250
    • Recruiting
    • T.C. Sağlık Bakanlığı Bursa Şehir Hastanesi

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 18 years or older
• Scheduled for elective video-assisted thoracoscopic surgery (VATS)
• American Society of Anesthesiologists (ASA) physical status I-III
• Planned to receive ultrasound-guided serratus posterior superior intercostal plane block for postoperative analgesia
• Ability to provide written informed consent

Exclusion Criteria:

• Refusal to participate in the study
• Known allergy or contraindication to local anesthetics
• Infection at the block injection site
• Coagulation disorders or anticoagulant therapy contraindicating regional anesthesia
• Severe respiratory insufficiency
• Chronic opioid use or chronic pain syndrome
• Pregnancy
• Inability to cooperate or communicate postoperative pain scores

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Serratus Posterior Superior Intercostal Plane Block (SPSIPB); Participants receive an ultrasound-guided serratus posterior superior intercostal plane block (SPSIPB) with 0.5% bupivacaine before video-assisted thoracoscopic surgery (VATS). The injected volume is determined using the Dixon up-and-down sequential allocation method, starting from an initial volume and adjusted by 2 mL increments or decrements based on block success or failure in the preceding patient. Block success is assessed by a blinded outcome assessor according to predefined analgesic criteria.

Other: Ultrasound-Guided Serratus Posterior Superior Intercostal Plane Block; Ultrasound-guided serratus posterior superior intercostal plane block performed prior to general anesthesia in patients undergoing video-assisted thoracoscopic surgery (VATS). A 0.5% bupivacaine solution is injected, and the volume is adjusted in 2 mL increments according to the Dixon up-and-down sequential allocation method to determine the median effective volume (ED50).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Median Effective Volume (ED50) of 0.5% Bupivacaine for Successful SPSIP Block	The median effective volume (ED50) of 0.5% bupivacaine required to achieve successful postoperative analgesia following ultrasound-guided serratus posterior superior intercostal plane block, determined using the Dixon up-and-down sequential allocation method.	Within the first 30 minutes after block performance

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Pain Scores (NRS)	Numerical Rating Scale (NRS) pain scores ranging from 0 to 10, where 0 represents no pain and 10 represents the worst imaginable pain, assessed at rest and during movement at 0, 1, 2, 4, 8, 12, and 24 hours after surgery.	Up to 24 hours postoperatively
Postoperative Morphine Consumption via Patient-Controlled Analgesia (PCA)	Total cumulative morphine dose administered through patient-controlled analgesia (PCA) within the first 24 postoperative hours, measured in milligrams. Higher values indicate increased analgesic requirement.	First 24 hours after surgery
Postoperative Adverse Effects	Incidence of opioid- and block-related adverse effects including nausea, vomiting, pruritus, dizziness, hypotension, respiratory depression, and local complications at the block site.	Up to 24 hours postoperatively
Quality of Recovery Score (QoR-15)	Quality of Recovery assessed using the 15-item Quality of Recovery questionnaire (QoR-15), with scores ranging from 0 to 150, where higher scores indicate better postoperative recovery.	24 hours after surgery
Postoperative Pulmonary Function Parameters	Pulmonary function assessed using spirometric parameters including forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) measured preoperatively and at 24 hours postoperatively.	Preoperative baseline and 24 hours after surgery

Collaborators and Investigators

• Sponsor: Bursa City Hospital
• Collaborators: Ulusoy, Emre, M.D.

Study record dates

Study Major Dates

• Study Start (Actual): March 15, 2026
• Primary Completion (Actual): May 11, 2026
• Study Completion (Estimated): July 15, 2026

Study Registration Dates

• First Submitted: February 26, 2026
• First Submitted That Met QC Criteria: February 26, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 11, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Regional Anesthesia; SPSIP Block; Dose-Finding Study; Dixon Up-and-Down Method; Thoracic Analgesia
• Other Study ID Numbers: Bursa City Hospital 15

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared due to institutional policies and patient confidentiality considerations.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No