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NCT Number: NCT07794852

Dural Sac Area-Guided Spinal Anesthesia Dosing for TURP

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.

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Key information

Conditions

Intraoperative Hypotension Spinal Aneshtesia TURP(Transurethral Resection of Prostate)

Age range

40 year and older

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Istanbul University-Cerrahpasa, Cerrahpasa Faculty of Medicine

Istanbul, 34360, Turkey (Türkiye)

Location contact

Münevver Kayhan, MD

CONTACT

[email protected]

+905057983044

About this study

This prospective, randomized controlled study compares two routinely used approaches to determining the intrathecal bupivacaine dose for spinal anesthesia in patients undergoing transurethral resection of the prostate (TURP). No new drug, new indication, or experimental treatment will be introduced. Both dosing approaches are currently used in routine clinical practice; the study will prospectively and randomly compare their clinical effects.

Participants will be randomly assigned to either a dural sac cross-sectional area (DSCSA)-guided individualized dosing group or a fixed-dose control group.

Before spinal anesthesia, the anteroposterior diameter of the dural sac will be measured by ultrasound at the L3-L4 intervertebral level. DSCSA will be calculated using the formula A = π × (D/2)².

In the individualized-dose group, a DSCSA of 150 mm² will be used as the reference value corresponding to 10 mg of intrathecal bupivacaine. The bupivacaine dose will be adjusted proportionally according to the participant's calculated DSCSA and limited to a minimum of 6 mg and a maximum of 12.5 mg. Fentanyl 25 micrograms will be added intrathecally.

In the fixed-dose group, participants will receive 10 mg (2 mL of 0.5%) intrathecal bupivacaine together with fentanyl 25 micrograms.

Spinal anesthesia will be performed at the L3-L4 intervertebral space using a 27-gauge Quincke needle. Standard intraoperative monitoring will be performed according to the study protocol. Sensory and motor block characteristics and hemodynamic variables will be recorded prospectively for comparison between the two dosing strategies.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

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.

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.

Fentanyl (FEN)

Drug

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

Primary outcomes

  1. Incidence of Intraoperative Hypotension

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

    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.

Secondary outcomes

  1. Number of Intraoperative Hypotension Episodes

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

    Number of intraoperative hypotension episodes recorded for each participant. Hypotension is defined as a decrease in mean arterial pressure (MAP) of ≥20% from baseline or an MAP <65 mmHg.

  2. Minimum Intraoperative Mean Arterial Pressure

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

    Lowest mean arterial pressure (MAP), measured in mmHg, recorded during the intraoperative period.

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

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

    Percentage of participants experiencing at least one decrease in mean arterial pressure (MAP) of ≥30% from baseline during surgery.

  4. Percentage of Participants Requiring Ephedrine

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

    Percentage of participants receiving at least one intravenous dose of ephedrine for treatment of intraoperative hypotension.

  5. Total Ephedrine Dose

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

    Total intravenous ephedrine dose, measured in milligrams (mg), administered to each participant during surgery.

  6. Percentage of Participants Requiring Atropine

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

    Percentage of participants receiving intravenous atropine for treatment of intraoperative bradycardia.

  7. Total Atropine Dose

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

    Total intravenous atropine dose, measured in milligrams (mg), administered to each participant during surgery.

  8. Maximum Sensory Block Level

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

    Highest cephalad sensory block level achieved after spinal anesthesia, assessed by the pin-prick test and recorded as the corresponding dermatomal level.

  9. Time to Achieve T10 Sensory Block

    Time frame: Up to 30 minutes after spinal anesthesia

    Time, measured in minutes, from completion of intrathecal injection to achievement of a T10 sensory block, assessed using the pin-prick test.

  10. Time to Two-Dermatome Sensory Regression

    Time frame: From maximum sensory block until two-dermatome regression, assessed up to 3 hours after spinal anesthesia

    Time, measured in minutes, from the maximum sensory block level to regression of the sensory block by two dermatomes, assessed using the pin-prick test.

  11. Time to Recovery to Modified Bromage Score 0

    Time frame: From completion of spinal anesthesia until recovery to Modified Bromage score 0, assessed up to 3 hours after spinal anesthesia

    Time, measured in minutes, from completion of intrathecal injection until recovery to a Modified Bromage score of 0, indicating complete recovery of lower-extremity motor function.

  12. Number of Integrated Pulmonary Index ≤4 Episodes

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

    Number of episodes in which the Integrated Pulmonary Index (IPI) is ≤4. The IPI is a composite score ranging from 1 to 10 based on end-tidal carbon dioxide, respiratory rate, oxygen saturation, and pulse rate; lower scores indicate greater respiratory compromise.

  13. Incidence of Adverse Events

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

    Percentage of participants experiencing at least one adverse event recorded during the intraoperative study period.

Other outcomes

  1. Mean Left Regional Cerebral Oxygen Saturation During the First 60 Minutes

    Time frame: During the first 60 minutes after spinal anesthesia

    Mean left regional cerebral oxygen saturation (rSO₂), measured continuously by frontal near-infrared spectroscopy (NIRS) during the first 60 minutes after spinal anesthesia. The outcome will be reported as the mean rSO₂ value.

  2. Minimum Regional Cerebral Oxygen Saturation

    Time frame: During the first 60 minutes after spinal anesthesia

    Lowest regional cerebral oxygen saturation (rSO₂) value recorded by frontal near-infrared spectroscopy (NIRS) during the first 60 minutes after spinal anesthesia.

  3. Maximum Relative Decrease in Regional Cerebral Oxygen Saturation

    Time frame: During the first 60 minutes after spinal anesthesia

    Maximum relative decrease in regional cerebral oxygen saturation (ΔrSO₂max) from the baseline value during the first 60 minutes after spinal anesthesia, measured by frontal near-infrared spectroscopy (NIRS).

Study contacts

Contact information is provided by the study sponsor or research team.

Ezgi Budak Ozyalcin, MD

CONTACT

[email protected]

+905056043177

Sponsors and collaborators

Lead sponsor

Istanbul University

Other

Registry information

Official study title

Clinical Effects of Individualized Spinal Anesthesia Dosing Based on Ultrasound-Measured Dural Sac Cross-Sectional Area in Patients Undergoing Transurethral Resection of the Prostate: A Prospective, Randomized Controlled Trial

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Aug 31, 2026
Registry last updated
Aug 31, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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