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Predictors of Unilateral Spinal Block Success (UNISS)

6 mei 2026 bijgewerkt door: Derya Arslan Yurtlu, Izmir City Hospital

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.

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.

Studie Overzicht

Toestand

Voltooid

Conditie

Gedetailleerde beschrijving

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.

Studietype

Observationeel

Inschrijving (Werkelijk)

318

Contacten en locaties

In dit gedeelte vindt u de contactgegevens van degenen die het onderzoek uitvoeren en informatie over waar dit onderzoek wordt uitgevoerd.

Studie Locaties

Deelname Criteria

Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.

Geschiktheidscriteria

Leeftijden die in aanmerking komen voor studie

  • Volwassen
  • Oudere volwassene

Accepteert gezonde vrijwilligers

Nee

Bemonsteringsmethode

Niet-waarschijnlijkheidssteekproef

Studie Bevolking

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.

Beschrijving

Inclusion Criteria:

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

Exclusion Criteria:

  • 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

Studie plan

Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.

Hoe is de studie opgezet?

Ontwerpdetails

Cohorten en interventies

Groep / Cohort
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.

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Unilateral Spinal Block Success Rate
Tijdsspanne: 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.
Intraoperative period (within first 30 minutes after spinal anesthesia

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Rate of unilateral spinal anesthesia success by age
Tijdsspanne: Intraoperative period
Proportion (%) of patients achieving unilateral spinal anesthesia success across age groups.
Intraoperative period
Rate of unilateral spinal anesthesia success by BMI
Tijdsspanne: Intraoperative period
Proportion (%) of patients achieving unilateral spinal anesthesia success across age groups.
Intraoperative period
Rate of unilateral spinal anesthesia success by position
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by patient positioning during injection (lateral vs sitting).
Intraoperative period
Rate of unilateral spinal anesthesia success by needle type
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by spinal needle type (Quincke vs pencil-point).
Intraoperative period
Rate of unilateral spinal anesthesia success by needle gauge
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by needle gauge.
Intraoperative period
Rate of unilateral spinal anesthesia success by local aneshtetic dose
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by administered local anesthetic dose (mg).
Intraoperative period
Rate of unilateral spinal anesthesia success by injection speed
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by injection speed category (faster vs ≤1 mL/5 s).
Intraoperative period
Sensory Block Level and Distribution
Tijdsspanne: Intraoperative period
Assessment of sensory block level (dermatomal level) and comparison between operated and non-operated sides.
Intraoperative period
Rate of unilateral spinal anesthesia success by intervertebral level of spinal injection
Tijdsspanne: Intraoperative period
Proportion (%) of unilateral spinal anesthesia success by intervertebral level (L1-2,L2-3,L3-L4 ,L4-L5).
Intraoperative period

Medewerkers en onderzoekers

Hier vindt u mensen en organisaties die betrokken zijn bij dit onderzoek.

Sponsor

Izmir City Hospital

Onderzoekers

  • Hoofdonderzoeker: Derya Arslan Yurtlu, MD, İzmir City Hospital

Studie record data

Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.

Bestudeer belangrijke data

Studie start (Werkelijk)

10 augustus 2025

Primaire voltooiing (Werkelijk)

1 februari 2026

Studie voltooiing (Werkelijk)

1 februari 2026

Studieregistratiedata

Eerst ingediend

9 april 2026

Eerst ingediend dat voldeed aan de QC-criteria

6 mei 2026

Eerst geplaatst (Werkelijk)

12 mei 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

12 mei 2026

Laatste update ingediend die voldeed aan QC-criteria

6 mei 2026

Laatst geverifieerd

1 mei 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Andere studie-ID-nummers

  • UNISS-2025

Plan Individuele Deelnemersgegevens (IPD)

Bent u van plan om gegevens van individuele deelnemers (IPD) te delen?

NEE

Beschrijving IPD-plan

Individual participant data will not be shared due to patient confidentiality and institutional data protection policies

Deze informatie is zonder wijzigingen rechtstreeks van de website clinicaltrials.gov gehaald. Als u verzoeken heeft om uw onderzoeksgegevens te wijzigen, te verwijderen of bij te werken, neem dan contact op met register@clinicaltrials.gov. Zodra er een wijziging wordt doorgevoerd op clinicaltrials.gov, wordt deze ook automatisch bijgewerkt op onze website .

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