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Predictors of Epidural Depth in Percutaneous Nephrolithotomy and Model Development

13 juli 2026 bijgewerkt door: Hongbo Zheng, Tongji Hospital

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.

Studie Overzicht

Toestand

Nog niet aan het werven

Conditie

Gedetailleerde beschrijving

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.

Studietype

Observationeel

Inschrijving (Geschat)

3278

Contacten en locaties

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

Studiecontact

Studie Contact Back-up

Studie Locaties

  • China
    • Hubei
      • Wuhan, Hubei, China, 430030
        • Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology
        • Contact:
        • Contact:

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 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.

Beschrijving

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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

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
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.

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Epidural depth
Tijdsspanne: 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.
Perioperative/Periprocedural

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Adjusted R²
Tijdsspanne: through study completion, an average of 1 month
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.
through study completion, an average of 1 month
Root mean square error (RMSE)
Tijdsspanne: through study completion, an average of 1 month
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.
through study completion, an average of 1 month

Medewerkers en onderzoekers

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

Sponsor

Tongji Hospital

Onderzoekers

  • Hoofdonderzoeker: Hongbo Zheng, MM, Tongji 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 (Geschat)

30 juni 2026

Primaire voltooiing (Geschat)

31 augustus 2026

Studie voltooiing (Geschat)

31 augustus 2026

Studieregistratiedata

Eerst ingediend

5 juli 2026

Eerst ingediend dat voldeed aan de QC-criteria

5 juli 2026

Eerst geplaatst (Werkelijk)

10 juli 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

16 juli 2026

Laatste update ingediend die voldeed aan QC-criteria

13 juli 2026

Laatst geverifieerd

1 juli 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Andere studie-ID-nummers

  • EDPN

Plan Individuele Deelnemersgegevens (IPD)

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

JA

Beschrijving IPD-plan

Individual participant data that underlie the results reported in this article, after deidentification (text, tables,figures, and appendices).

IPD-tijdsbestek voor delen

Immediately followingpublication. No end date.

IPD-toegangscriteria voor delen

Anyone who wishes to access the data.

IPD delen Ondersteunend informatietype

  • LEERPROTOCOOL
  • SAP

Informatie over medicijnen en apparaten, studiedocumenten

Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel

Nee

Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct

Nee

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