Dural Sac Area-Guided Spinal Anesthesia Dosing for TURP

NCT07794852 | Enrolling By Invitation

• 1 other identifier: E-24687260-604.01-1701514
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

This randomized controlled study will evaluate whether individualizing the dose of spinal anesthesia according to the ultrasound-derived dural sac cross-sectional area (DSCSA) can improve hemodynamic stability in patients undergoing transurethral resection of the prostate (TURP). Participants aged 40 years or older will be randomly assigned to one of two groups. In the individualized-dose group, the anteroposterior diameter of the dural sac will be measured by ultrasound at the L3-L4 level, and DSCSA will be calculated from this measurement. The dose of intrathecal bupivacaine will then be individualized according to the calculated DSCSA. In the control group, participants will receive a fixed dose of intrathecal bupivacaine. Both groups will also receive intrathecal fentanyl. The main outcome is the incidence of intraoperative hypotension. The study will also evaluate the number of hypotensive episodes, minimum mean arterial pressure, vasopressor and atropine requirements, sensory and motor block characteristics, respiratory monitoring parameters, cerebral oxygenation, and adverse events. The study aims to determine whether a DSCSA-guided dosing strategy can reduce excessive spinal block and improve hemodynamic stability while maintaining effective spinal anesthesia.

Conditions

Intraoperative Hypotension; Spinal Aneshtesia; TURP(Transurethral Resection of Prostate)

Keywords

Dural sac cross-sectional area; Spinal anesthesia; Individualized spinal anesthesia; Ultrasound; Intraoperative hypotension; Hemodynamic stability; Transurethral resection of the prostate

Outcome Measures

Primary Outcomes (1)

• Incidence of Intraoperative Hypotension

  Intraoperative hypotension is defined as a decrease in mean arterial pressure (MAP) of ≥20% from baseline or an MAP \<65 mmHg. Participants meeting either criterion at least once during surgery will be classified as having intraoperative hypotension. The outcome will be reported as the percentage of participants with intraoperative hypotension.

  During surgery (from completion of spinal anesthesia until the end of surgery)

Secondary Outcomes (13)

• Number of Intraoperative Hypotension Episodes

  During surgery (from completion of spinal anesthesia until the end of surgery)

• Minimum Intraoperative Mean Arterial Pressure

  During surgery (from completion of spinal anesthesia until the end of surgery)

• Percentage of Participants With a ≥30% Decrease in Mean Arterial Pressure

  During surgery (from completion of spinal anesthesia until the end of surgery)

• Percentage of Participants Requiring Ephedrine

  During surgery (from completion of spinal anesthesia until the end of surgery)

• Total Ephedrine Dose

  During surgery (from completion of spinal anesthesia until the end of surgery)

Other Outcomes (3)

• Mean Left Regional Cerebral Oxygen Saturation During the First 60 Minutes

  During the first 60 minutes after spinal anesthesia

• Minimum Regional Cerebral Oxygen Saturation

  During the first 60 minutes after spinal anesthesia

• Maximum Relative Decrease in Regional Cerebral Oxygen Saturation

  During the first 60 minutes after spinal anesthesia

Study Arms (2)

DSCSA-Guided Individualized Dose

EXPERIMENTAL

The dural sac cross-sectional area (DSCSA) will be estimated from the ultrasound-measured anteroposterior dural sac diameter at the L3-L4 level. The intrathecal bupivacaine dose will be individualized according to the DSCSA, using 150 mm² as the reference area corresponding to 10 mg bupivacaine. The calculated bupivacaine dose will be limited to 6-12.5 mg. Fentanyl 25 micrograms will also be administered intrathecally.

Procedure: DSCSA-Guided Individualized Spinal Anesthesia Dosing; Drug: Bupivacaine; Drug: Fentanyl (FEN)

Fixed Dose

ACTIVE COMPARATOR

Participants will receive a fixed intrathecal dose of 10 mg (2 mL of 0.5%) bupivacaine together with fentanyl 25 micrograms.

Drug: Bupivacaine; Drug: Fentanyl (FEN)

Interventions

DSCSA-Guided Individualized Spinal Anesthesia Dosing PROCEDURE

The dural sac cross-sectional area (DSCSA) is calculated from the ultrasound-measured anteroposterior dural sac diameter at the L3-L4 level. The intrathecal bupivacaine dose is individualized according to DSCSA.

DSCSA-Guided Individualized Dose

Bupivacaine DRUG

Hyperbaric bupivacaine is administered intrathecally in both study groups. In the DSCSA-guided group, the dose is individualized according to DSCSA, using 150 mm² as the reference corresponding to 10 mg, with a permitted dose range of 6 to 12.5 mg. In the fixed-dose group, 10 mg (2 mL of 0.5% bupivacaine) is administered.

DSCSA-Guided Individualized Dose; Fixed Dose

Fentanyl (FEN) DRUG

Fentanyl 25 micrograms is administered intrathecally together with bupivacaine in both study groups.

DSCSA-Guided Individualized Dose; Fixed Dose

Eligibility Criteria

• Age: 40 Years+
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male participants aged 40 years or older
• American Society of Anesthesiologists (ASA) physical status I-III
• Scheduled to undergo transurethral resection of the prostate (TURP) for prostate cancer

You may not qualify if:

• Refusal of spinal anesthesia
• Local infection or wound at the planned puncture site
• Current anticoagulant therapy
• Neurological disease, including multiple sclerosis, myelopathy, or peripheral neuropathy
• Known allergy to any of the study medications
• Inability to maintain the required position during ultrasound measurement or spinal puncture

Sponsors & Collaborators

• Istanbul University: lead

Study Sites (1)

Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine

Istanbul, 34360, Turkey (Türkiye)

Location

MeSH Terms

Interventions

Bupivacaine; Fentanyl

Intervention Hierarchy (Ancestors)

Anilides; Amides; Organic Chemicals; Aniline Compounds; Amines; Piperidines; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Study Officials

• Ezgi Budak Özyalçın, MD

  Istanbul University - Cerrahpasa

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: Participants and outcome assessors will be blinded to group allocation. The clinician performing spinal anesthesia will follow the assigned dosing protocol and therefore will not be blinded to the intervention.
• Purpose: SUPPORTIVE CARE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Specialist in Anesthesiology and Reanimation

Model Details: Participants are randomly assigned in parallel to either dural sac cross-sectional area-guided individualized spinal anesthesia dosing or fixed-dose spinal anesthesia.

Study Record Dates

• First Submitted: August 23, 2026
• First Posted: August 31, 2026
• Study Start: August 27, 2026
• Primary Completion (Estimated): November 24, 2026
• Study Completion (Estimated): December 10, 2026
• Last Updated: October 1, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)