Machine Learning Prediction of Spinal Anaesthesia Block Duration

NCT07816003 | Not Yet Recruiting

• 1 other identifier: IRBSMC1-2026-0001
• Study Type: observational
• Target: 255
• Locations: 0 countries
• Sites: N/A

Brief Summary

The duration of sensory and motor block after spinal anaesthesia varies widely between patients given the same dose of local anaesthetic. Much of this variability is explained by differences in lumbosacral cerebrospinal fluid volume, which cannot be measured routinely in clinical practice but is related to simple body measurements such as abdominal circumference and vertebral column length. This prospective observational study will develop and internally validate prediction models for the duration of sensory and motor block following spinal anaesthesia in adults undergoing elective surgery. Preoperative clinical and anthropometric variables will be recorded, and block regression will be assessed serially after intrathecal injection. Machine learning methods (lasso regression, ridge regression, random forest, extreme gradient boosting, and support vector regression) will be developed and compared against multivariable linear regression as the reference model. The aim is a practical tool that helps anaesthetists anticipate how long a spinal block will last in an individual patient, supporting decisions about case scheduling, supplementation, and discharge planning.

Conditions

Anesthesia, Spinal; Nerve Block; Anesthesia Recovery Period

Keywords

spinal anaesthesia; sensory block duration; motor block duration; abdominal circumference; vertebral column length; machine learning; prediction model; TRIPOD+AI

Outcome Measures

Primary Outcomes (2)

• Duration of sensory block

  Time from completion of intrathecal injection to regression of sensory block to the S1 dermatome, assessed bilaterally by pinprick with a 25-gauge needle along the mid-clavicular line

  Up to 8 hours after intrathecal injection

• Duration of motor block

  Time from completion of intrathecal injection to return to modified Bromage score 0 (full ability to flex knee and ankle)

  Up to 8 hours after intrathecal injection

Secondary Outcomes (2)

• Predictive performance of machine learning models

  Through study completion, an average of 20 months

• Time to peak sensory block level

  Up to 30 minutes after intrathecal injection

Eligibility Criteria

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

Study Population

Consecutive adults scheduled for elective surgery under single-shot spinal anaesthesia at Specialized Medical Center, King Fahad campus, Riyadh.

You may qualify if:

• Adults scheduled for elective surgery under single-shot spinal anaesthesia
• ASA physical status I to III
• Written informed consent obtained

You may not qualify if:

• Contraindication to neuraxial anaesthesia (coagulopathy, local or systemic infection, raised intracranial pressure, patient refusal)
• Failed or incomplete block requiring conversion to general anaesthesia
• Repeated or top-up intrathecal injection
• Pregnancy
• Known spinal deformity or previous spine surgery
• Pre-existing neurological or neuromuscular disease affecting sensory or motor assessment
• Inability to cooperate with sensory and motor assessment

Sponsors & Collaborators

• Specialized Medical Center (SMC): lead

Study Officials

• Salaheldin A abdelaziz Ahmed

  Specialized Medical Center

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Salaheldin A Abdelaziz Ahmed

CONTACT

+966508818713; saladin28.sa@gmail.com

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Anesthesia registrar

Study Record Dates

• First Submitted: September 7, 2026
• First Posted: September 11, 2026
• Study Start (Estimated): December 1, 2026
• Primary Completion (Estimated): July 1, 2028
• Study Completion (Estimated): September 1, 2028
• Last Updated: September 25, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE
• Time Frame: Data will become available 6 months after publication of the primary results and will remain available for 36 months
• Access Criteria: Requests should be directed to the principal investigator. Proposals will be reviewed by the principal investigator and the Specialized Medical Center Institutional Review Board. Requesters must provide a methodologically sound proposal and sign a data access agreement.