Predictors of Unilateral Spinal Block Success

NCT07581561 | Completed

• 1 other identifier: UNISS-2025
• Study Type: observational
• Target: 318
• Locations: 1 country
• Sites: 1

Brief Summary

This prospective observational study aims to determine the factors affecting the success of unilateral spinal anesthesia in patients undergoing orthopedic lower extremity surgery. Unilateral spinal anesthesia is preferred to minimize unwanted effects such as hypotension and to provide more stable hemodynamic conditions, especially in vulnerable patient populations. Unilateral spinal anesthesia is defined as achieving sensory and motor block predominantly on the operated side without significant contralateral spread. However, the factors influencing the success of this technique have not been fully clarified. This study will evaluate various patient-related and procedure-related factors, including age, sex, body mass index, patient positioning, needle type and orientation, injection technique and local anesthetic dose. The primary outcome is the success of unilateral spinal anesthesia, defined as the absence of contralateral block. The results of this study are expected to contribute to improving clinical practice by identifying major and minor factors affecting block success and optimizing anesthesia techniques.

Conditions

Spinal Aneshtesia; Unilateral Spinal Anesthesia; Regional Anaesthesia

Keywords

unilateral spinal anesthesia; spinal block success; regional anesthesia; anesthesia technique; block distribution; lower extremity surgery

Outcome Measures

Primary Outcomes (1)

• Unilateral Spinal Block Success Rate

  Successful unilateral spinal anesthesia defined as the absence of contralateral sensory block, assessed by pinprick test and bromage scale within the first 20 minutes after spinal anesthesia.

  Intraoperative period (within first 30 minutes after spinal anesthesia

Secondary Outcomes (9)

• Rate of unilateral spinal anesthesia success by age

  Intraoperative period

• Rate of unilateral spinal anesthesia success by BMI

  Intraoperative period

• Rate of unilateral spinal anesthesia success by position

  Intraoperative period

• Rate of unilateral spinal anesthesia success by needle type

  Intraoperative period

• Rate of unilateral spinal anesthesia success by needle gauge

  Intraoperative period

Study Arms (1)

patients undergoing unilateral spinal anesthesia

Patients aged 18-65 years with ASA physical status I-III undergoing elective unilateral lower extremity surgery under spinal anesthesia.

Eligibility Criteria

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

Study Population

Adult patients aged 18-65 years with ASA physical status I-III undergoing elective unilateral lower extremity surgery under spinal anesthesia in a single tertiary care center.

You may qualify if:

• Patients aged 18-65 years
• ASA physical status I-III
• Undergoing elective unilateral lower extremity surgery under spinal anesthesia
• Provided written informed consent

You may not qualify if:

• ASA IV patients
• Known allergy to local anesthetics
• Contraindications to spinal anesthesia
• Decompensated congestive heart failure
• Hemodynamic instability (including sepsis, septic shock, or need for inotropic support)
• Pregnancy
• Patients with vertebral anomalies (e.g., scoliosis, vertebral fractures) preventing proper positioning

Sponsors & Collaborators

• Izmir City Hospital: lead

Study Sites (1)

İzmir City Hospital

Izmir, Turkey (Türkiye)

Location

Study Officials

• Derya Arslan Yurtlu, MD

  Izmir City Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor of Anesthesiology

Study Record Dates

• First Submitted: April 9, 2026
• First Posted: May 12, 2026
• Study Start: August 10, 2025
• Primary Completion: February 1, 2026
• Study Completion: February 1, 2026
• Last Updated: May 12, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)