Anesthesia, SpinalNCT07816003
Machine Learning Prediction of Spinal Anaesthesia Block Duration
An observational study of Anesthesia, Spinal and Nerve Block, run by Specialized Medical Center (SMC).
Trial 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… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Anesthesia, Spinal, Nerve Block, Anesthesia Recovery Period
- How many people
- 255 participants
- Where
- No sites listed yet
- Study dates
- 1 Dec 2026to 1 Sep 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Consecutive adults scheduled for elective surgery under single-shot spinal anaesthesia at Specialized Medical Center, King Fahad campus, Riyadh.
Who may be able to join
- Adults scheduled for elective surgery under single-shot spinal anaesthesia
- ASA physical status I to III
- Written informed consent obtained
Who cannot join
- 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
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Artificial Intelligence-Based Prediction of Sensory and Motor Block Duration Following Spinal Anaesthesia: A Prospective Observational Prediction Model Development Study
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.
Read the detailed description
Background. Spinal anaesthesia produces block of unpredictable duration. Cerebrospinal fluid volume in the lumbosacral region is the dominant determinant of block spread and regression, and correlates inversely with abdominal circumference and directly with vertebral column length. Existing single-variable rules perform poorly, and no validated multivariable model is in routine clinical use. Objectives. The primary objective is to develop and internally validate models predicting the duration of sensory block and the duration of motor block after single-shot spinal anaesthesia. The secondary objective is to compare the predictive performance of machine learning approaches with conventional multivariable linear regression. Design. Single-centre prospective observational cohort study. No study-directed intervention is applied; anaesthetic technique, drug, and dose are determined by the attending anaesthetist according to routine practice and are recorded as candidate predictors. Assessments. Sensory block level is assessed bilaterally by pinprick with a 25-gauge needle along the mid-clavicular line, over dermatomes T4 to S1. Motor block is assessed using the modified Bromage scale (0-3). Assessments are performed at fixed intervals from intrathecal injection until complete regression of sensory and motor block. Candidate predictors. Age, sex, height, weight, body mass index, abdominal circumference, vertebral column length, ASA physical status, local anaesthetic dose and baricity, and adjuvant use. Sample size. A target of 255 participants was derived using the Riley criteria for continuous-outcome prediction models (pmsampsize), assuming 9 candidate predictors, an outcome standard deviation of 40 minutes, anticipated R-squared of 0.35, shrinkage of at least 0.90, and a multiplicative margin of error of 1.10. The four criteria yielded 183, 183, 234, and 246; the largest requirement of 246 was inflated by approximately 4 per cent for attrition. Analysis. Model development will use nested repeated 10-fold cross-validation with bootstrap optimism correction. Performance will be reported as R-squared, root mean squared error, and mean absolute error, with calibration plots. SHAP values will be used to describe predictor contributions. Reporting will follow TRIPOD+AI.
- 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
What is being measured
The primary outcome is the main question the study is designed to answer.
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
Measured: 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)
Measured: Up to 8 hours after intrathecal injection
Secondary outcomes (2)
Predictive performance of machine learning models
R-squared, root mean squared error, mean absolute error, and calibration slope for lasso regression, ridge regression, random forest, extreme gradient boosting, and support vector regression, each compared with multivariable linear regression as the reference model
Measured: Through study completion, an average of 20 months
Time to peak sensory block level
Time from intrathecal injection to the highest dermatomal level of sensory block, assessed by pinprick
Measured: Up to 30 minutes after intrathecal injection
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Sep 2026
- Study start1 Dec 2026 (estimated)
- Primary completion1 Jul 2028 (estimated)
- Study completion1 Sep 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Anesthesia, SpinalStudies 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
- 255 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Specialized Medical Center (SMC)
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, SalahEldin Ahmed Abdelaziz Ahmed, Specialized Medical Center (SMC)
- Investigators
- Salaheldin A abdelaziz Ahmed, Principal investigator, Specialized Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07816003
- Sponsor's protocol ID
- IRBSMC1-2026-0001
- Status last verified
- Sep 2026
- First submitted
- 7 Sep 2026
- Last updated
- 25 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data underlying published results, together with the data dictionary and model code, will be made available to researchers whose proposed use has been approved by an independent review committee. Requests should be directed to the principal investigator. Data will be available from 6 months to 36 months after publication of the primary results.
Study at a glance
From the registry record, last updated by the sponsor on 25 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Artificial Intelligence-Based Prediction of Sensory and Motor Block Duration Following Spinal Anaesthesia: A Prospective Observational Prediction Model Development Study
- ClinicalTrials.gov ID
- NCT07816003
- Acronym / sponsor ID
- IRBSMC1-2026-0001
- 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
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 255 participants (estimated)
- Lead sponsor
- Specialized Medical Center (SMC)University, hospital or other
- Study start
- 1 Dec 2026 (estimated)
- Primary completion
- 1 Jul 2028 (estimated)
- Study completion
- 1 Sep 2028 (estimated)
- First posted
- 11 Sep 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.
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.
Detailed description
Background. Spinal anaesthesia produces block of unpredictable duration. Cerebrospinal fluid volume in the lumbosacral region is the dominant determinant of block spread and regression, and correlates inversely with abdominal circumference and directly with vertebral column length. Existing single-variable rules perform poorly, and no validated multivariable model is in routine clinical use. Objectives. The primary objective is to develop and internally validate models predicting the duration of sensory block and the duration of motor block after single-shot spinal anaesthesia. The secondary objective is to compare the predictive performance of machine learning approaches with conventional multivariable linear regression. Design. Single-centre prospective observational cohort study. No study-directed intervention is applied; anaesthetic technique, drug, and dose are determined by the attending anaesthetist according to routine practice and are recorded as candidate predictors. Assessments. Sensory block level is assessed bilaterally by pinprick with a 25-gauge needle along the mid-clavicular line, over dermatomes T4 to S1. Motor block is assessed using the modified Bromage scale (0-3). Assessments are performed at fixed intervals from intrathecal injection until complete regression of sensory and motor block. Candidate predictors. Age, sex, height, weight, body mass index, abdominal circumference, vertebral column length, ASA physical status, local anaesthetic dose and baricity, and adjuvant use. Sample size. A target of 255 participants was derived using the Riley criteria for continuous-outcome prediction models (pmsampsize), assuming 9 candidate predictors, an outcome standard deviation of 40 minutes, anticipated R-squared of 0.35, shrinkage of at least 0.90, and a multiplicative margin of error of 1.10. The four criteria yielded 183, 183, 234, and 246; the largest requirement of 246 was inflated by approximately 4 per cent for attrition. Analysis. Model development will use nested repeated 10-fold cross-validation with bootstrap optimism correction. Performance will be reported as R-squared, root mean squared error, and mean absolute error, with calibration plots. SHAP values will be used to describe predictor contributions. Reporting will follow TRIPOD+AI.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Consecutive adults scheduled for elective surgery under single-shot spinal anaesthesia at Specialized Medical Center, King Fahad campus, Riyadh.
Key inclusion criteria (3 listed)
- Adults scheduled for elective surgery under single-shot spinal anaesthesia
- ASA physical status I to III
- Written informed consent obtained
Key exclusion criteria (7 listed)
- 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
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
Duration of sensory block
Time frame: Up to 8 hours after intrathecal injection
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
Duration of motor block
Time frame: Up to 8 hours after intrathecal injection
Time from completion of intrathecal injection to return to modified Bromage score 0 (full ability to flex knee and ankle)
2 secondary outcomes
Predictive performance of machine learning models
Time frame: Through study completion, an average of 20 months
Time to peak sensory block level
Time frame: Up to 30 minutes after intrathecal injection
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Sep 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data underlying published results, together with the data dictionary and model code, will be made available to researchers whose proposed use has been approved by an independent review committee. Requests should be directed to the principal investigator. Data will be available from 6 months to 36 months after publication of the primary results.
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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.
Salaheldin A abdelaziz Ahmed principal investigator
Specialized Medical Center
Questions about this trial
What is this clinical trial studying?
An observational study of Anesthesia, Spinal and Nerve Block, run by Specialized Medical Center (SMC).
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 3 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: opening soon, as of the sponsor's last update on 25 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Salaheldin A Abdelaziz Ahmed (+966508818713, saladin28.sa@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Duration of sensory block (time frame: Up to 8 hours after intrathecal injection). The study lists 2 primary outcomes in all. 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 25 Sep 2026.