Predictors of Epidural Depth in Percutaneous Nephrolithotomy and Model Development

NCT07697053 | Completed DMC

• 1 other identifier: EDPN
• Study Type: observational
• Target: 3,278
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Epidural Anesthesia; Percutaneous Nephrolithotomy (PCNL)

Keywords

epidural anesthesia; epidural depth; predictive model; body mass index; Percutaneous Nephrolithotomy (PCNL)

Outcome Measures

Primary Outcomes (1)

• 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.

  Perioperative/Periprocedural

Secondary Outcomes (2)

• Adjusted R²

  through study completion, an average of 1 month

• Root mean square error (RMSE)

  through study completion, an average of 1 month

Study Arms (4)

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.

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

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.

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Tongji Hospital: lead

Study Sites (1)

Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology

Wuhan, Hubei, 430030, China

Location

Study Officials

• Hongbo Zheng, MM

  Tongji Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Attending Physician

Study Record Dates

• First Submitted: July 5, 2026
• First Posted: July 10, 2026
• Study Start: January 1, 2014
• Primary Completion: December 31, 2025
• Study Completion: August 31, 2026
• Last Updated: September 29, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Immediately followingpublication. No end date.
• Access Criteria: Anyone who wishes to access the data.

Locations

CN (1)