Epidural AnesthesiaNCT07697053
Predictors of Epidural Depth in Percutaneous Nephrolithotomy and Model Development
An observational study of Epidural Anesthesia and Percutaneous Nephrolithotomy (PCNL), run by Tongji Hospital at 1 site in China.
Trial summary
Accurate estimation of epidural depth is critical for safe epidural anesthesia during percutaneous nephrolithotomy (PCNL). Although various imaging modalities can predict epidural depth, they increase healthcare burden and are not always feasible in emergency or bedside settings. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Epidural Anesthesia, Percutaneous Nephrolithotomy (PCNL)
- How many people
- 3,278 participants
- Where
- 1 siteChina
- Study dates
- 1 Jan 2014to 31 Aug 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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients who underwent PCNL under continuous epidural anesthesia between January 2014 and December 2025. All patients were treated at a single academic medical center. Data were extracted from electronic medical records and anesthesia records.
Who may be able to join
- Age ≥ 18 years
- Successful epidural puncture and catheter placement using the midline approach
- Clear documentation of puncture level and puncture depth in the anesthesia record
Who cannot join
- Dural puncture during anesthesia (including those who subsequently had a successful repuncture)
- Use of the paramedian approach for epidural puncture
- Uncertain epidural anesthesia effect requiring combined general anesthesia
- Incomplete clinical data
Trial locations and contacts
1 site in 1 country.
China1 site
Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology
Wuhan, Hubei, 430030
About this study
Official title: Analysis of Factors Influencing Epidural Depth in Patients Undergoing Percutaneous Nephrolithotomy and Development of a Predictive Model
Accurate estimation of epidural depth is critical for safe epidural anesthesia during percutaneous nephrolithotomy (PCNL). Although various imaging modalities can predict epidural depth, they increase healthcare burden and are not always feasible in emergency or bedside settings. Identifying simple, easily obtainable clinical parameters-such as sex, age, and body mass index (BMI)-for predicting epidural depth has become a research priority. However, systematic investigations specifically targeting the Chinese population remain scarce. This retrospective study aims to identify independent factors influencing epidural depth in PCNL patients and to develop simple, level-specific predictive models for different puncture sites, thereby providing a practical reference for clinical epidural anesthesia.
Read the detailed description
Percutaneous nephrolithotomy (PCNL) is the standard minimally invasive surgical procedure for removal of kidney stones larger than 2 cm and is established as the gold standard for the management of complex renal calculi. This procedure may be performed under either general anesthesia or regional anesthesia, including epidural or spinal anesthesia. Accumulating meta-analyses have demonstrated that, compared with general anesthesia, regional anesthesia is associated with reduced postoperative pain scores and lower total hospital costs, without compromising the stone-free rate. Furthermore, in awake patients undergoing regional anesthesia, respiratory movements may generate a so-called "respiratory-synchronous stone fragmentation effect," which facilitates the expulsion of stone debris.
Successful epidural anesthesia relies critically on accurate identification of the epidural space and precise control of puncture depth. Insufficient puncture depth may result in improper catheter placement and subsequent block failure, whereas excessive puncture depth increases the risk of dural puncture, leading to cerebrospinal fluid leakage and post-dural puncture headache. In severe cases, inadvertent injection of a large dose of local anesthetics into the subarachnoid space can cause life-threatening cardiovascular and respiratory depression. Therefore, preprocedural estimation of the skin-to-epidural space distance is of considerable clinical importance.
Although racial differences in epidural depth have been reported, systematic investigations specifically targeting the Chinese population remain scarce. Various imaging modalities, including computed tomography, magnetic resonance imaging, and ultrasound, can be used to predict epidural depth. However, these examinations increase healthcare burden and are not always feasible in emergency or bedside settings. Consequently, identifying simple, easily obtainable clinical parameters-such as sex, age, and body mass index (BMI)-for predicting epidural depth has become a research priority.
In this context, the present study aimed to identify factors influencing epidural depth through a retrospective analysis of clinical data from PCNL patients and to develop simple, level-specific predictive models for different puncture sites, thereby providing a practical reference for clinical epidural anesthesia.
- Keywords
- epidural anesthesia, epidural depth, predictive model, body mass index, Percutaneous Nephrolithotomy (PCNL)
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 |
|---|---|---|
| T11-T12 | On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the T11-T12 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. | |
| T12-L1 | On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the T12-L1 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. | |
| L1-L2 | On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the L1-L2 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. | |
| L2-L3 | On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the L2-L3 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Epidural depth
Epidural depth, defined as the vertical distance from the skin surface to the epidural space measured at the time of puncture using the loss-of-resistance technique via the midline approach. Depth was recorded from the needle shaft markings to the nearest 0.1 cm.
Measured: Perioperative/Periprocedural
Secondary outcomes (2)
Adjusted R²
The coefficient of determination adjusted for the number of predictors in the model, reflecting the proportion of variance in epidural depth explained by the predictive model at each puncture level. Higher values indicate better model fit.
Measured: through study completion, an average of 1 month
Root mean square error (RMSE)
The square root of the average squared difference between the model-predicted epidural depth and the actual measured depth, expressed in cm. Lower values indicate better predictive accuracy of the model at each puncture level.
Measured: through study completion, an average of 1 month
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Jul 2026
- Study start1 Jan 2014
- Primary completion31 Dec 2025
- Study completion31 Aug 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Epidural AnesthesiaStudies of the same condition, open and under way.
- More trials run by Tongji HospitalThe sponsor's other registered studies.
- 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
- Other
- Time perspective
- Retrospective
- Enrolment
- 3,278 participants (actual)
Sponsor and investigators
- Lead sponsor
- Tongji Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Hongbo Zheng, Tongji Hospital
- Investigators
- Hongbo Zheng, MM, Principal investigator, Tongji Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07697053
- Sponsor's protocol ID
- EDPN
- Status last verified
- Sep 2026
- First submitted
- 5 Jul 2026
- Last updated
- 29 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data that underlie the results reported in this article, after deidentification (text, tables,figures, and appendices).
Study at a glance
From the registry record, last updated by the sponsor on 29 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Analysis of Factors Influencing Epidural Depth in Patients Undergoing Percutaneous Nephrolithotomy and Development of a Predictive Model
- ClinicalTrials.gov ID
- NCT07697053
- Acronym / sponsor ID
- EDPN
- Keywords
- epidural anesthesia, epidural depth, predictive model, body mass index, Percutaneous Nephrolithotomy (PCNL)
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 3,278 participants (actual)
- Lead sponsor
- Tongji HospitalUniversity, hospital or other
- Study start
- 1 Jan 2014 (actual)
- Primary completion
- 31 Dec 2025 (actual)
- Study completion
- 31 Aug 2026 (actual)
- First posted
- 10 Jul 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.
Accurate estimation of epidural depth is critical for safe epidural anesthesia during percutaneous nephrolithotomy (PCNL). Although various imaging modalities can predict epidural depth, they increase healthcare burden and are not always feasible in emergency or bedside settings. Identifying simple, easily obtainable clinical parameters-such as sex, age, and body mass index (BMI)-for predicting epidural depth has become a research priority. However, systematic investigations specifically targeting the Chinese population remain scarce. This retrospective study aims to identify independent factors influencing epidural depth in PCNL patients and to develop simple, level-specific predictive models for different puncture sites, thereby providing a practical reference for clinical epidural anesthesia.
Detailed description
Percutaneous nephrolithotomy (PCNL) is the standard minimally invasive surgical procedure for removal of kidney stones larger than 2 cm and is established as the gold standard for the management of complex renal calculi. This procedure may be performed under either general anesthesia or regional anesthesia, including epidural or spinal anesthesia. Accumulating meta-analyses have demonstrated that, compared with general anesthesia, regional anesthesia is associated with reduced postoperative pain scores and lower total hospital costs, without compromising the stone-free rate. Furthermore, in awake patients undergoing regional anesthesia, respiratory movements may generate a so-called "respiratory-synchronous stone fragmentation effect," which facilitates the expulsion of stone debris.
Successful epidural anesthesia relies critically on accurate identification of the epidural space and precise control of puncture depth. Insufficient puncture depth may result in improper catheter placement and subsequent block failure, whereas excessive puncture depth increases the risk of dural puncture, leading to cerebrospinal fluid leakage and post-dural puncture headache. In severe cases, inadvertent injection of a large dose of local anesthetics into the subarachnoid space can cause life-threatening cardiovascular and respiratory depression. Therefore, preprocedural estimation of the skin-to-epidural space distance is of considerable clinical importance.
Although racial differences in epidural depth have been reported, systematic investigations specifically targeting the Chinese population remain scarce. Various imaging modalities, including computed tomography, magnetic resonance imaging, and ultrasound, can be used to predict epidural depth. However, these examinations increase healthcare burden and are not always feasible in emergency or bedside settings. Consequently, identifying simple, easily obtainable clinical parameters-such as sex, age, and body mass index (BMI)-for predicting epidural depth has become a research priority.
In this context, the present study aimed to identify factors influencing epidural depth through a retrospective analysis of clinical data from PCNL patients and to develop simple, level-specific predictive models for different puncture sites, thereby providing a practical reference for clinical epidural anesthesia.
Study design
- Observational model
- Other
- Time perspective
- Retrospective
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| T11-T12 | – | –On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the T11-T12 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. |
| T12-L1 | – | –On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the T12-L1 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. |
| L1-L2 | – | –On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the L1-L2 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. |
| L2-L3 | – | –On operating room admission, after providing written informed consent for anesthesia, patients underwent standard monitoring (ECG, NIBP, pulse oximetry). Baseline demographic and anthropometric data, including hospital admission ID, sex, height, and weight, were recorded, and body mass index (BMI) was calculated. After positioning in the lateral decubitus position, the L2-L3 interspace was selected for puncture using a midline approach, and the loss-of-resistance technique confirmed epidural space entry. Puncture depth (skin-to-epidural space) was recorded from needle shaft markings to the nearest 0.1 cm. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients who underwent PCNL under continuous epidural anesthesia between January 2014 and December 2025. All patients were treated at a single academic medical center. Data were extracted from electronic medical records and anesthesia records.
Key inclusion criteria (3 listed)
- Age ≥ 18 years
- Successful epidural puncture and catheter placement using the midline approach
- Clear documentation of puncture level and puncture depth in the anesthesia record
Key exclusion criteria (4 listed)
- Dural puncture during anesthesia (including those who subsequently had a successful repuncture)
- Use of the paramedian approach for epidural puncture
- Uncertain epidural anesthesia effect requiring combined general anesthesia
- Incomplete clinical data
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
Epidural depth
Time frame: Perioperative/Periprocedural
Epidural depth, defined as the vertical distance from the skin surface to the epidural space measured at the time of puncture using the loss-of-resistance technique via the midline approach. Depth was recorded from the needle shaft markings to the nearest 0.1 cm.
2 secondary outcomes
Adjusted R²
Time frame: through study completion, an average of 1 month
Root mean square error (RMSE)
Time frame: through study completion, an average of 1 month
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 29 Sep 2026.
- Individual participant dataSharing planned: Yes. Individual participant data that underlie the results reported in this article, after deidentification (text, tables,figures, and appendices).
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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.
Hongbo Zheng, MM principal investigator
Tongji 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 Epidural Anesthesia and Percutaneous Nephrolithotomy (PCNL), run by Tongji Hospital at 1 site in China.
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 4 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 29 Sep 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 China. 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?
Epidural depth (time frame: Perioperative/Periprocedural). 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 29 Sep 2026.