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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Prone Position | Experimental | 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. |
|
| Supine Position | Experimental | 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. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Prone Position Percutaneous Nephrolithotomy | Procedure | 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. |
| 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) |
| 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 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| ARİF BURAK KEÇEBAŞ, UROLOGY CLINIC DOCTOR | Contact | +90 5412659978 | arifkecebas@gmail.com |
| Name | Affiliation | Role |
|---|---|---|
| Burak Arslan, CLINICAL PROFESSOR OF UROLOGY | Gaziosmanpaşa Training and Research Hospital, Urology Department, Istanbul, Türkiye | Study Director |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Gaziosmanpaşa Training and Research Hospital | Recruiting | Istanbul | 34275 | Turkey (Türkiye) |
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| Supine Position Percutaneous Nephrolithotomy (Galdakao-modified Valdivia) | Procedure | 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. |
|
| 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 |
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. |
| ID | Term |
|---|---|
| D008192 | Deception |
| D053040 | Nephrolithiasis |
| ID | Term |
|---|---|
| D012919 | Social Behavior |
| D001519 | Behavior |
| D007674 | Kidney Diseases |
| D014570 | Urologic Diseases |
| D052776 | Female Urogenital Diseases |
| D005261 | Female Urogenital Diseases and Pregnancy Complications |
| D000091642 | Urogenital Diseases |
| D052878 | Urolithiasis |
| D052801 | Male Urogenital Diseases |
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