Spinal AneshtesiaUNISSNCT07581561
Predictors of Unilateral Spinal Block Success
An observational study of Spinal Aneshtesia and Unilateral Spinal Anesthesia, run by Izmir City Hospital at 1 site in Turkey (Türkiye).
Trial summary
This prospective observational study aims to determine the factors affecting the success of unilateral spinal anesthesia in patients undergoing orthopedic lower extremity surgery. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Spinal Aneshtesia, Unilateral Spinal Anesthesia, Regional Anaesthesia
- How many people
- 318 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 10 Aug 2025to 1 Feb 2026
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
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.
Who may be able to join
- Patients aged 18-65 years
- ASA physical status I-III
- Undergoing elective unilateral lower extremity surgery under spinal anesthesia
- Provided written informed consent
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Determination of Factors Affecting Success in Unilateral Spinal Anesthesia: A Prospective Observational Study
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.
Read more
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.
Read the detailed description
This prospective observational study is designed to investigate the factors influencing the success of unilateral spinal anesthesia in patients undergoing lower extremity orthopedic surgery.
Spinal anesthesia is widely used in lower extremity procedures; however, it may be associated with hemodynamic instability such as hypotension. Unilateral spinal anesthesia has been proposed as a technique to limit sympathetic blockade and maintain more stable hemodynamic conditions. Despite its advantages, the determinants of successful unilateral block remain unclear.
Patients aged between 18 and 65 years with American Society of Anesthesiologists (ASA) physical status I-III who are scheduled for elective lower extremity surgery will be included in the study after providing written informed consent. This study will be conducted in a single tertiary care center.
No intervention will be performed by the investigator. All anesthesia procedures will be carried out according to routine clinical practice. The investigator will record patient demographics, including age, sex, height, weight, and body mass index.
Procedure-related variables such as patient positioning, spinal needle type, needle orientation, injection speed, level of injection, local anesthetic type and dose will be recorded.
Block characteristics will be assessed intraoperatively, including sensory and motor block distribution. The primary outcome is defined as successful unilateral spinal anesthesia, characterized by the absence of contralateral sensory block. Secondary outcomes include factors associated with block success and variability in block characteristics.
Data will be collected using standardized case report forms and analyzed to identify factors influencing the success of unilateral spinal anesthesia. The results of this study are expected to contribute to optimizing anesthesia techniques and improving patient safety.
- Keywords
- unilateral spinal anesthesia, spinal block success, regional anesthesia, anesthesia technique, block distribution, lower extremity surgery
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| 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. |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Intraoperative period (within first 30 minutes after spinal anesthesia
Secondary outcomes (9)
Rate of unilateral spinal anesthesia success by age
Proportion (%) of patients achieving unilateral spinal anesthesia success across age groups.
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by BMI
Proportion (%) of patients achieving unilateral spinal anesthesia success across age groups.
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by position
Proportion (%) of unilateral spinal anesthesia success by patient positioning during injection (lateral vs sitting).
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by needle type
Proportion (%) of unilateral spinal anesthesia success by spinal needle type (Quincke vs pencil-point).
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by needle gauge
Proportion (%) of unilateral spinal anesthesia success by needle gauge.
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by local aneshtetic dose
Proportion (%) of unilateral spinal anesthesia success by administered local anesthetic dose (mg).
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by injection speed
Proportion (%) of unilateral spinal anesthesia success by injection speed category (faster vs ≤1 mL/5 s).
Measured: Intraoperative period
Sensory Block Level and Distribution
Assessment of sensory block level (dermatomal level) and comparison between operated and non-operated sides.
Measured: Intraoperative period
Rate of unilateral spinal anesthesia success by intervertebral level of spinal injection
Proportion (%) of unilateral spinal anesthesia success by intervertebral level (L1-2,L2-3,L3-L4 ,L4-L5).
Measured: Intraoperative period
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 May 2026
- Study start10 Aug 2025
- Primary completion1 Feb 2026
- Study completion1 Feb 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Spinal AneshtesiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 318 participants (actual)
Sponsor and investigators
- Lead sponsor
- Izmir City Hospital
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Derya Arslan Yurtlu, Izmir City Hospital
- Investigators
- Derya Arslan Yurtlu, MD, Principal investigator, Izmir City Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07581561
- Sponsor's protocol ID
- UNISS-2025
- Acronym
- UNISS
- Status last verified
- May 2026
- First submitted
- 9 Apr 2026
- Last updated
- 12 May 2026
- Results posted
- No
- Data monitoring committee
- No
- Individual data sharing
- No: Individual participant data will not be shared due to patient confidentiality and institutional data protection policies
Study at a glance
From the registry record, last updated by the sponsor on 12 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Determination of Factors Affecting Success in Unilateral Spinal Anesthesia: A Prospective Observational Study
- ClinicalTrials.gov ID
- NCT07581561
- Acronym / sponsor ID
- UNISS / UNISS-2025
- Keywords
- unilateral spinal anesthesia, spinal block success, regional anesthesia, anesthesia technique, block distribution, lower extremity surgery
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 318 participants (actual)
- Lead sponsor
- Izmir City HospitalOther government
- Study start
- 10 Aug 2025 (actual)
- Primary completion
- 1 Feb 2026 (actual)
- Study completion
- 1 Feb 2026 (actual)
- First posted
- 12 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
This prospective observational study is designed to investigate the factors influencing the success of unilateral spinal anesthesia in patients undergoing lower extremity orthopedic surgery.
Spinal anesthesia is widely used in lower extremity procedures; however, it may be associated with hemodynamic instability such as hypotension. Unilateral spinal anesthesia has been proposed as a technique to limit sympathetic blockade and maintain more stable hemodynamic conditions. Despite its advantages, the determinants of successful unilateral block remain unclear.
Patients aged between 18 and 65 years with American Society of Anesthesiologists (ASA) physical status I-III who are scheduled for elective lower extremity surgery will be included in the study after providing written informed consent. This study will be conducted in a single tertiary care center.
No intervention will be performed by the investigator. All anesthesia procedures will be carried out according to routine clinical practice. The investigator will record patient demographics, including age, sex, height, weight, and body mass index.
Procedure-related variables such as patient positioning, spinal needle type, needle orientation, injection speed, level of injection, local anesthetic type and dose will be recorded.
Block characteristics will be assessed intraoperatively, including sensory and motor block distribution. The primary outcome is defined as successful unilateral spinal anesthesia, characterized by the absence of contralateral sensory block. Secondary outcomes include factors associated with block success and variability in block characteristics.
Data will be collected using standardized case report forms and analyzed to identify factors influencing the success of unilateral spinal anesthesia. The results of this study are expected to contribute to optimizing anesthesia techniques and improving patient safety.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| 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. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- 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.
Key inclusion criteria (4 listed)
- Patients aged 18-65 years
- ASA physical status I-III
- Undergoing elective unilateral lower extremity surgery under spinal anesthesia
- Provided written informed consent
Key exclusion criteria (7 listed)
- 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)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Unilateral Spinal Block Success Rate
Time frame: Intraoperative period (within first 30 minutes after spinal anesthesia
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.
9 secondary outcomes
Rate of unilateral spinal anesthesia success by age
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by BMI
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by position
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by needle type
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by needle gauge
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by local aneshtetic dose
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by injection speed
Time frame: Intraoperative period
Sensory Block Level and Distribution
Time frame: Intraoperative period
Rate of unilateral spinal anesthesia success by intervertebral level of spinal injection
Time frame: Intraoperative period
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 May 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be shared due to patient confidentiality and institutional data protection policies
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Derya Arslan Yurtlu, MD principal investigator
Izmir City Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Spinal Aneshtesia and Unilateral Spinal Anesthesia, run by Izmir City Hospital at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 12 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Unilateral Spinal Block Success Rate (time frame: Intraoperative period (within first 30 minutes after spinal anesthesia). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 May 2026.