Hemodynamic Effects of Surgical Position in Prone vs. Supine Percutaneous Nephrolithotomy

August 16, 2025 updated by: Arif Burak Keçebaş, Gaziosmanpasa Research and Education Hospital

The Effect of Surgical Position on Hemodynamics in Percutaneous Nephrolithotomy Performed in Prone and Supine Positions

This prospective, randomized controlled study evaluates the hemodynamic effects of prone and supine positions during percutaneous nephrolithotomy (PNL) for large kidney stones. Surgical position may influence intraoperative and postoperative hemodynamic stability. Prone positioning can increase intrathoracic pressure and reduce venous return, whereas supine positioning may provide greater hemodynamic stability. A total of 84 patients will be randomized to undergo PNL in prone or supine positions. Primary outcomes include changes in hemodynamic parameters during surgery. Results may guide surgical position selection, especially in patients with potential hemodynamic risk.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Percutaneous nephrolithotomy (PNL) is a widely used minimally invasive surgical technique for the treatment of large and complex renal calculi. Traditionally, PNL has been performed in the prone position; however, the supine position has gained popularity in recent years due to potential anesthetic and surgical advantages. Surgical positioning can significantly influence cardiovascular and respiratory function, potentially leading to intraoperative and postoperative hemodynamic fluctuations.

Previous literature suggests that the prone position may increase intrathoracic pressure and impair venous return, potentially compromising hemodynamic stability, while the supine position may provide a more stable cardiovascular profile. However, existing data are limited, and results remain inconclusive, particularly in direct comparative studies.

This prospective, randomized controlled clinical trial aims to compare the effects of prone and supine positions during PNL on patients' intraoperative and postoperative hemodynamic parameters. The study will enroll 84 patients aged 18-80 years with American Society of Anesthesiologists (ASA) physical status I-III undergoing elective PNL. Patients will be randomly assigned to either the prone (n=42) or supine (n=42) position.

Inclusion criteria include patients with renal calculi suitable for PNL and meeting the study's eligibility requirements. Exclusion criteria include pregnancy, uncontrolled coagulopathy, previous renal surgery, severe cardiac, pulmonary, or neurological disease, preoperative urinary tract infection, surgery duration outside 60-120 minutes, and multiple access tracts.

Preoperative evaluation will include demographic data, stone characteristics, and relevant laboratory and imaging findings. Intraoperative data will include systolic and diastolic blood pressure, heart rate, arterial blood gas analysis, operative time, anesthesia duration, access details, irrigation volume, and any transfusion or complications. Postoperative parameters will include nephrostomy duration, length of hospital stay, and presence of residual stones as assessed by postoperative CT scan.

Surgical techniques will be standardized for both positions. Prone PNL will involve initial lithotomy positioning for ureteral catheter placement followed by prone positioning for renal access under fluoroscopic guidance. Supine PNL will be performed in the Galdakao-modified Valdivia position with similar access and fragmentation protocols.

The primary outcome is the difference in intraoperative and postoperative hemodynamic stability between positions. Secondary outcomes include complication rates, residual stone rates, and hospital stay duration.

This study aims to provide high-quality evidence to guide surgeons and anesthesiologists in selecting the optimal patient position for PNL, particularly in individuals with higher hemodynamic risk.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
84

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: ARİF BURAK KEÇEBAŞ, UROLOGY CLINIC DOCTOR
  • Phone Number: +90 5412659978
  • Email: arifkecebas@gmail.com

Study Locations

  • Turkey
      • Istanbul, Turkey, 34275
        • Recruiting
        • Gaziosmanpasa Training and Research Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • ASA physical status I-III
  • Presence of renal calculi indicated for PNL

Exclusion Criteria:

  • Pregnancy
  • Uncontrolled coagulopathy
  • Previous renal surgery
  • Severe cardiac, pulmonary, or neurological disease
  • Preoperative urinary tract infection (non-sterile urine culture)
  • Surgery duration <60 minutes or >120 minutes
  • Preoperative blood transfusion
  • Multiple access tracts

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Prone Position
Patients in this group will undergo percutaneous nephrolithotomy (PNL) in the prone position. The procedure begins with ureteral catheter placement in lithotomy position, followed by prone positioning for renal access under C-arm fluoroscopic guidance. Stone fragmentation will be performed using pneumatic or ultrasonic lithotripters, and nephrostomy placement will be completed according to standard protocol.
Procedure: Prone Position Percutaneous Nephrolithotomy
Patients in this arm will undergo percutaneous nephrolithotomy (PNL) in the prone position. The procedure begins with ureteral catheter placement in lithotomy position, followed by prone positioning for renal access under C-arm fluoroscopic guidance. Stone fragmentation will be performed using pneumatic or ultrasonic lithotripters, and nephrostomy placement will be completed according to standard protocol.
Experimental: Supine Position
Patients in this group will undergo percutaneous nephrolithotomy (PNL) in the Galdakao-modified Valdivia supine position. Following general anesthesia, the ipsilateral side will be elevated 20-30°, with the ipsilateral leg extended and the contralateral leg abducted. Ureteral catheter placement will be followed by renal access under C-arm fluoroscopy. Stone fragmentation and removal will be performed using the same standardized lithotripsy and irrigation protocols as in the prone group.
Procedure: Supine Position Percutaneous Nephrolithotomy (Galdakao-modified Valdivia)
Patients in this arm will undergo percutaneous nephrolithotomy (PNL) in the Galdakao-modified Valdivia supine position. Following general anesthesia, the ipsilateral side will be elevated 20-30°, with the ipsilateral leg extended and the contralateral leg abducted. Ureteral catheter placement will be followed by renal access under C-arm fluoroscopy. Stone fragmentation and removal will be performed using the same standardized lithotripsy and irrigation protocols as in the prone group.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Hemodynamic Parameters (Intraoperative)
Time Frame: From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Systolic blood pressure (mmHg) will be recorded at predefined time points (preoperative baseline, intraoperative intervals, and immediate postoperative period) to assess intraoperative hemodynamic stability.
From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Change in Arterial Blood pH
Time Frame: Preoperative, intraoperative, postoperative day 1
Arterial pH will be measured at predefined time points (preoperative, intraoperative, postoperative day 1) to evaluate metabolic changes between prone and supine groups.
Preoperative, intraoperative, postoperative day 1
Change in Diastolic Blood Pressure (Intraoperative)
Time Frame: From induction of anesthesia to the end of surgery (approximately 60-120 minutes
Diastolic blood pressure (mmHg) will be recorded at predefined time points (preoperative baseline, intraoperative intervals, and immediate postoperative period) to assess intraoperative hemodynamic stability.
From induction of anesthesia to the end of surgery (approximately 60-120 minutes
Change in Mean Arterial Pressure (Intraoperative)
Time Frame: From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Mean arterial pressure (mmHg) will be recorded at predefined time points (preoperative baseline, intraoperative intervals, and immediate postoperative period) to assess intraoperative hemodynamic stability.
From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Change in Heart Rate (Intraoperative)
Time Frame: From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Heart rate (beats per minute) will be recorded at predefined time points (preoperative baseline, intraoperative intervals, and immediate postoperative period) to assess intraoperative hemodynamic stability.
From induction of anesthesia to the end of surgery (approximately 60-120 minutes)
Change in Arterial pO₂
Time Frame: Preoperative, intraoperative, postoperative day 1
Arterial oxygen partial pressure (mmHg) will be measured at predefined time points (preoperative, intraoperative, postoperative day 1) to evaluate respiratory function.
Preoperative, intraoperative, postoperative day 1
Change in Arterial HCO₃-
Time Frame: Preoperative, intraoperative, postoperative day 1
Arterial bicarbonate (mmol/L) will be measured at predefined time points (preoperative, intraoperative, postoperative day 1) to evaluate metabolic changes.
Preoperative, intraoperative, postoperative day 1
Change in Oxygen Saturation
Time Frame: Preoperative, intraoperative, postoperative day 1
Arterial oxygen saturation (%) will be measured at predefined time points (preoperative, intraoperative, postoperative day 1) to evaluate respiratory status.
Preoperative, intraoperative, postoperative day 1
Change in Arterial pCO₂
Time Frame: Preoperative, intraoperative, postoperative day 1
Arterial carbon dioxide partial pressure (mmHg) will be measured at predefined time points (preoperative, intraoperative, postoperative day 1) to evaluate respiratory changes.
Preoperative, intraoperative, postoperative day 1

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Operative Time
Time Frame: From initial skin incision until completion of stone removal (approximately 30-180 minutes).
Total time from initial skin incision to completion of stone removal will be recorded for each group.
From initial skin incision until completion of stone removal (approximately 30-180 minutes).
Anesthesia Duration
Time Frame: From induction of anesthesia until termination of anesthesia and awakening of the patient (approximately 60-240 minutes).
Total anesthesia time will be measured to assess any differences related to patient positioning.
From induction of anesthesia until termination of anesthesia and awakening of the patient (approximately 60-240 minutes).
Intraoperative Blood Loss
Time Frame: Intraoperative period (from skin incision to completion of surgery, approximately 30-180 minutes).
Estimated blood loss will be calculated and recorded; intraoperative transfusion requirements will also be noted.
Intraoperative period (from skin incision to completion of surgery, approximately 30-180 minutes).
Complication Rate
Time Frame: From intraoperative period through hospital stay and up to 30 days postoperatively.
Complications will be identified and classified according to the Clavien-Dindo classification system.
From intraoperative period through hospital stay and up to 30 days postoperatively.
Residual Stone Rate
Time Frame: At postoperative 1 month, assessed by CT scan.
Presence of residual stones larger than 4 mm will be recorded; stones ≤4 mm will be considered clinically insignificant.
At postoperative 1 month, assessed by CT scan.
Length of Hospital Stay
Time Frame: From hospital admission until discharge (typically 2-10 days).
The total number of days of hospitalization will be compared between groups.
From hospital admission until discharge (typically 2-10 days).
Nephrostomy Tube Duration
Time Frame: From postoperative day 0 (day of surgery) until nephrostomy tube removal, typically within 7-14 days.
The duration (in days) that the nephrostomy tube remains in place will be recorded for each patient.
From postoperative day 0 (day of surgery) until nephrostomy tube removal, typically within 7-14 days.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Gaziosmanpasa Research and Education Hospital

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Burak Arslan, CLINICAL PROFESSOR OF UROLOGY, Gaziosmanpaşa Training and Research Hospital, Urology Department, Istanbul, Türkiye

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 30, 2025

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 30, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 9, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 16, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 24, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
August 24, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 16, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • AIBU-SBF-ABK-01

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings