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

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: Recruiting
• Conditions: Nephrolithiasis; Prone Position; Hemodynamic Stability; Supine Position; Percutaneous Nephrolithotomy (PCNL); Surgical Positioning
• Intervention / Treatment: Procedure: Prone Position Percutaneous Nephrolithotomy; Procedure: Supine Position Percutaneous Nephrolithotomy (Galdakao-modified Valdivia)

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: Interventional
• Enrollment (Estimated): 84
• Phase: Not Applicable

Contacts and Locations

• Study Contact: 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: Arif burak keçebaş, doctor; Phone Number: +90 5412659978; Email: arifkecebas@gmail.com

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Change in Hemodynamic Parameters (Intraoperative)	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	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)	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)	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)	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	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-	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	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	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

Outcome Measure	Measure Description	Time Frame
Operative Time	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	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	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	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	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	The total number of days of hospitalization will be compared between groups.	From hospital admission until discharge (typically 2-10 days).
Nephrostomy Tube Duration	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

• Sponsor: Gaziosmanpasa Research and Education Hospital
• Investigators: Study Director: Burak Arslan, CLINICAL PROFESSOR OF UROLOGY, Gaziosmanpaşa Training and Research Hospital, Urology Department, Istanbul, Türkiye

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2025
• Primary Completion (Estimated): December 30, 2025
• Study Completion (Estimated): December 30, 2025

Study Registration Dates

• First Submitted: August 9, 2025
• First Submitted That Met QC Criteria: August 16, 2025
• First Posted (Actual): August 24, 2025

Study Record Updates

• Last Update Posted (Actual): August 24, 2025
• Last Update Submitted That Met QC Criteria: August 16, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: Prone Position; Hemodynamic stability; Nephrolithiasis; PCNL; Percutaneous Nephrolithotomy; Supine Position
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urolithiasis; Urinary Calculi; Kidney Calculi; Nephrolithiasis
• Other Study ID 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