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

NCT07446959 | Completed

• 1 other identifier: Bursa City Hospital 15
• Study Type: interventional
• Target: 27
• Locations: 1 country
• Sites: 1

Brief Summary

This study determined the median effective volume (EV50) 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. All patients received bupivacaine at a final concentration of 0.25%, prepared by diluting the commercially available 0.5% preparation 1:1 with 0.9% sodium chloride. Using a sequential up-and-down dose-adjustment method, the volume of local anesthetic was increased or decreased according to the block outcome of the preceding patient. The main outcome of the study was the volume that provided an effective block in 50% of patients. EV50 is not a recommended clinical dose; the results are intended to inform future studies targeting higher effective percentiles.

Conditions

Postoperative Pain Management; Video-assisted Thoracoscopic Surgery (VATS)

Keywords

SPSIP Block; Regional Anesthesia; Dose-Finding Study; Dixon Up-and-Down Method; Thoracic Analgesia

Outcome Measures

Primary Outcomes (1)

• Median Effective Volume (EV50) of 0.25% Bupivacaine for Successful SPSIP Block

  The median effective volume (EV50) of 0.25% bupivacaine required for a successful ultrasound-guided serratus posterior superior intercostal plane block, determined using the Dixon up-and-down sequential allocation method. Bupivacaine 0.25% was prepared by diluting the commercial 0.5% preparation 1:1 with 0.9% sodium chloride; the concentration specified in the ethics committee-approved protocol is 0.25%. Block success was defined by a composite criterion: sensory loss to cold in at least two consecutive dermatomes between T3 and T6, combined with a cumulative fentanyl requirement of less than 2 µg/kg (including the 1 µg/kg induction dose) within the first 60 minutes after induction of general anesthesia. Failure was defined as absence of adequate sensory blockade or a cumulative fentanyl requirement of 2 µg/kg or more.

  Within the first 30 minutes after block performance

Secondary Outcomes (5)

• Postoperative Pain Scores (NRS)

  Up to 24 hours postoperatively

• Postoperative Morphine Consumption via Patient-Controlled Analgesia (PCA)

  First 24 hours after surgery

• Postoperative Adverse Effects

  Up to 24 hours postoperatively

• Quality of Recovery Score (QoR-15)

  24 hours after surgery

• Postoperative Pulmonary Function Parameters

  Preoperative baseline and 24 hours after surgery

Study Arms (1)

Serratus Posterior Superior Intercostal Plane Block (SPSIPB)

EXPERIMENTAL

Participants received an ultrasound-guided serratus posterior superior intercostal plane block (SPSIPB) with 0.25% bupivacaine before video-assisted thoracoscopic surgery (VATS). The solution was prepared by diluting commercially available 0.5% bupivacaine (Buvacin 0.5%, Polifarma, Türkiye) 1:1 with 0.9% sodium chloride, giving a final administered concentration of 0.25%, as specified in the ethics committee-approved protocol. The injected volume was determined using the Dixon up-and-down sequential allocation method, starting from an initial volume of 30 mL and adjusted by 2 mL increments or decrements based on block success or failure in the preceding patient, within a permitted range of 15 to 40 mL. Sensory block was assessed by an outcome assessor blinded to the administered volume, and intraoperative analgesic adequacy was assessed by an anesthesiologist blinded to the administered volume and to the block outcome, according to predefined criteria.

Other: Ultrasound-Guided Serratus Posterior Superior Intercostal Plane Block

Interventions

Ultrasound-Guided Serratus Posterior Superior Intercostal Plane Block OTHER

Ultrasound-guided serratus posterior superior intercostal plane block performed before induction of general anesthesia in patients undergoing video-assisted thoracoscopic surgery (VATS). With the patient seated, a high-frequency linear probe was placed in the sagittal plane over the superior angle of the scapula, and the needle was advanced in-plane until its tip lay between the serratus posterior superior muscle and the third rib. Bupivacaine 0.25%, prepared by 1:1 dilution of the 0.5% commercial preparation with 0.9% sodium chloride, was injected in 5 mL aliquots with intermittent aspiration after hydrodissection with 1 mL of saline. The injected volume was adjusted in 2 mL increments according to the Dixon up-and-down sequential allocation method to determine the median effective volume (EV50). The 0.5% descriptor refers to the commercial preparation only; all participants received bupivacaine at a final concentration of 0.25%.

Serratus Posterior Superior Intercostal Plane Block (SPSIPB)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Bursa City Hospital: lead
• Ulusoy, Emre, M.D.: collaborator

Study Sites (1)

T.C. Sağlık Bakanlığı Bursa Şehir Hastanesi

Nilufer, Bursa, 16110, Turkey (Türkiye)

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Masking Details: The anesthesiologist performing the block was aware of the administered volume. Sensory block assessment, intraoperative assessment of analgesic adequacy, and postoperative data collection were performed by separate anesthesiologists blinded to the administered volume and to the block outcome.
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: prof.

Model Details: Sequential dose-adjustment design using the Dixon up-and-down method, in which local anesthetic volume is increased or decreased in fixed 2 mL steps based on the success or failure of the preceding block.

Study Record Dates

• First Submitted: February 26, 2026
• First Posted: March 3, 2026
• Study Start: March 15, 2026
• Primary Completion: May 11, 2026
• Study Completion: July 15, 2026
• Last Updated: September 24, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)