Percutaneous Nephrolithotomy for Staghorn Stones in Patients with Solitary Kidney in Prone Position or in completely Supine Position : a Single-center Experience

ARTICLE INFO _________________________________________________________ ____________________ IBJU | PCNL FOR STAGHORN STONES IN SOLITARY KIDNEY 789 dergone PCNL for stone disease in our department between March 2004 and October 2011. Eight patients had a previous contralateral nephrectomy (44.4%), 4 patients had an anatomy solitary kidney (23.3%), and 6 patients had nonfunctional contralateral kidneys (33.3%). Non-functional contralateral kidneys were confi rmed by nephro-dynamic imaging. Twelve patients underwent PCNL in prone position. Six patients underwent PCNL in completely supine position. Patient demographic characteristics, including gender, age, body mass index (BMI), history of shock wave lithotripsy (SWL), mean maximum stone diameter, hydronephrosis and previous kidney surgery (open and/or PCNL) were recorded. All surgeries were performed by the same surgeon. The operation style was decided after the common discussion of the surgeon and the patient. Informed consent was obtained from patients before operation. The study protocol was approved by Institutional Review Board of the First Hospital of Jilin University. Preoperatively, widespectrum antibiotics were administered to patients with bacteriuria by experience (Cefuroxime Sodium or Ciprofl oxacin Lactate), or patients were treated according to the antibiogram results. Operation could be done if the results of urinalysis and urine culture follow up testing became negative. Serum creatinine (Cr), systolic blood pressure, diastolic blood pressure, and new onset hypertension were determined preoperatively and postoperatively at 3 months. Equipment and instruments 18-gauge coaxial needle (COOK Inc.), Zebra guide wire(Boston Scientifi c Corporation), fascial dilators(COOK Inc.), X-Force N30 Nephrostomy Balloon Dilation Catheter (BCR Inc.), F9 Olympus ureteroscope (Germany), F20 Storz nephroscope (Germany), Cybersonics Double-catheter system (America), Lumenis 60w holmium lithotripter (USA), Fluoroscopic table (Siemens), Aloka 5 multicolor ultrasound instrument with transducer frequency 3.5 MHz. Technique of PCNL The entire procedure was performed on the fl uoroscopic table with the patient under general anesthesia. Prone position (Group A) After placing the patient in lithotomic position, retrograde ureter catheterization with a 5-French open-ended ureter catheter was performed. All other procedures were completed in the prone position. Under the guide of ultrasound, the coaxial needle was placed in the desired calyx. The working channel was then dilated by using the plastic dilator system or X-Force Nephrostomy Balloon Dilation Catheter to either F18 or F26. And then, the F9 ureteroscope or the F20 nephroscope was placed directly into the kidney through the established tract. The Lumenis 60w lithothiptor or Cybersonics Double-catheter system was used to fragment the renal stone. Completely supine position (Group B) The patients were placed in a completely supine position with the fl ank to be operated raised and slightly rotated by a single underlying 3-liter water bag. The procedure was the same to prone position. Stone clearance was determined by a combination of fl uoroscopy and ultrasound. At the end of the procedure, a double J tube was placed within the ureter. And a clamped 14F or 20F Foley catheter was placed as a nephrostomy tube and it was opened within 24 hours. We rechecked KUB or ultrasound 1 or 2 days post-operation. And the nephrostomy tube was removed if there was no extravasation and larger residual stones at approximately 3 days post-operation. We routinely removed the double J tube about 1 month post-operation in the Outpatient Clinic. Patients were considered stone-free when no stone > 4 mm was visualized. Residual fragments > 5 mm in diameter were treated with extracorporeal shock wave lithotripsy (ESWL) or second phase PCNL. Both of them were performed 1 week postoperatively. Statistical analysis Comparisons between continuous variables were performed using the Student t test while comparisons between categorical variables were performed using a Pearson chi-square test (SPSS 13.0, SPSS Inc, Chicago, IL). P < 0.05 was considered to be statistically signifi cant. IBJU | PCNL FOR STAGHORN STONES IN SOLITARY KIDNEY


INTRODUCTION
Staghorn calculi are branched stones that occupy a large portion of the collecting system, typically fl ling the renal pelvis and branching into several or all of the calices (1).Treatment of staghorn stones in patients with solitary kidney is one of the most challenging problems in urology (2).In this study, we evaluated the safety and efficacy of PCNL in the treatment of staghorn stones both in prone position and in completely supine position in a solitary kidney.To the best of our knowledge, this study is the fi rst series reported in the literature.

Clinical data
We retrospectively reviewed the records of 18 patients with solitary kidneys who had un-dergone PCNL for stone disease in our department between March 2004 and October 2011.Eight patients had a previous contralateral nephrectomy (44.4%), 4 patients had an anatomy solitary kidney (23.3%), and 6 patients had nonfunctional contralateral kidneys (33.3%).Non-functional contralateral kidneys were confi rmed by nephro-dynamic imaging.Twelve patients underwent PCNL in prone position.Six patients underwent PCNL in completely supine position.Patient demographic characteristics, including gender, age, body mass index (BMI), history of shock wave lithotripsy (SWL), mean maximum stone diameter, hydronephrosis and previous kidney surgery (open and/or PCNL) were recorded.All surgeries were performed by the same surgeon.The operation style was decided after the common discussion of the surgeon and the patient.Informed consent was obtained from patients before operation.The study protocol was approved by Institutional Review Board of the First Hospital of Jilin University.
Preoperatively, widespectrum antibiotics were administered to patients with bacteriuria by experience (Cefuroxime Sodium or Ciprofl oxacin Lactate), or patients were treated according to the antibiogram results.Operation could be done if the results of urinalysis and urine culture follow up testing became negative.Serum creatinine (Cr), systolic blood pressure, diastolic blood pressure, and new onset hypertension were determined preoperatively and postoperatively at 3 months.

Technique of PCNL
The entire procedure was performed on the fl uoroscopic table with the patient under general anesthesia.

Prone position (Group A)
After placing the patient in lithotomic position, retrograde ureter catheterization with a 5-French open-ended ureter catheter was performed.All other procedures were completed in the prone position.Under the guide of ultrasound, the coaxial needle was placed in the desired calyx.The working channel was then dilated by using the plastic dilator system or X-Force Nephrostomy Balloon Dilation Catheter to either F18 or F26.And then, the F9 ureteroscope or the F20 nephroscope was placed directly into the kidney through the established tract.The Lumenis 60w lithothiptor or Cybersonics Double-catheter system was used to fragment the renal stone.

Completely supine position (Group B)
The patients were placed in a completely supine position with the fl ank to be operated raised and slightly rotated by a single underlying 3-liter water bag.The procedure was the same to prone position.
Stone clearance was determined by a combination of fl uoroscopy and ultrasound.At the end of the procedure, a double J tube was placed within the ureter.And a clamped 14F or 20F Foley catheter was placed as a nephrostomy tube and it was opened within 24 hours.We rechecked KUB or ultrasound 1 or 2 days post-operation.And the nephrostomy tube was removed if there was no extravasation and larger residual stones at approximately 3 days post-operation.We routinely removed the double J tube about 1 month post-operation in the Outpatient Clinic.
Patients were considered stone-free when no stone > 4 mm was visualized.Residual fragments > 5 mm in diameter were treated with extracorporeal shock wave lithotripsy (ESWL) or second phase PCNL.Both of them were performed 1 week postoperatively.

Statistical analysis
Comparisons between continuous variables were performed using the Student t test while comparisons between categorical variables were performed using a Pearson chi-square test (SPSS 13.0, SPSS Inc, Chicago, IL).P < 0.05 was considered to be statistically signifi cant.There was no new onset hypertension by the end of follow-up in both groups (Table -3).Blood pressure levels in group A were equally matched to those in group B with regard to pre--operation and 3 months after operation.Systolic blood pressure showed a statistically signifi cant improvement in group B (p = 0.034), but a non--statistically signifi cant improvement in group A (p = 0.368) by the end of follow-up period.There were no statistical improvement in both groups about diastolic blood pressure before and 3 months after operation (p = 0.275 and 0.363, respectively).Baseline values of serum creatinine were comparable in the two patients groups (P = 0.92 before operation and P = 0.783 by the end of follow-up).Both groups showed a similar fall in serum creatinine at 3 month follow-up period (p = 0.004 and 0.029, respectively).

DISCUSSION
"Correct position, half operation" is one of the dogmas in surgery.So does in PCNL.The correct position of the patient during PCNL has always been a debated issue, as the precise access to the kidney is facilitated by a careful positioning of the patient and can reduce intraoperative complications (3)(4)(5).
PCNL is traditionally performed in the prone position for a safe approach to the kidney.The prone position has some inherent merits (6)(7)(8).
For example, a wide surgical fi eld for the selection of the puncture site, an adequate nephroscopic manipulation, and a good distention of the collecting system.However, the prone position is often associated with a limitation in respiratory movements and potential anesthesia danger.
Recently, there have been many reports about PCNL in the supine position (9)(10)(11).The potential advantages of supine position in PCNL are as follows.Firstly, the surgeon can work while sitting on chairs during the whole procedures which is more comfortable.Secondly, the supine position has important anesthesiological advantages, such as a low incidence of cardiovascular and respiratory problems.Some authors believe that the incidence of colonic injuries is lower in supine position than that in prone position (11,12).What's more, the supine position allows a simultaneous retrograde approach to the ureter and renal pelvis, with both rigid and fl exible scopes, for contemporaneous treatment of ureteral or complex renal stones.However, every coin has its two sides, so does the supine position.The obviously antero-medial movement of the kidney during dilation makes the procedure more diffi cult.Besides, the superior calyceal puncture is more challenging.A narrow surgical fi eld for the selection of the puncture site is another shortcoming of the supine position.
Valdivia Uria et al. (12) proposed PCNL in a completely supine position with a 3 liter water bag below the ipsilateral fl ank and with the ipsilateral leg totally extended.In their report on 557 patients, the procedure was successful in 93% of the cases, with a low complication rate and no colonic perforation.We adopted this position in our department.
Treatment of staghorn stones in patients with solitary kidney is one of the most diffi culties in PCNL (13).Major complications, although rare, can lead to signifi cant morbidity especially in patients with solitary kidney.This study shows it is safe both in prone position and modifi ed position.No blood transfusions were required and no abdominal or thoracic organ injuries were reported in both groups.The stone free rate of solitary kidney PCNL in group A and group B was 91.7% and 83.3%, res-pectively.The stone free rate was higher in group A than that in group B, but this was not statistically signifi cant (p = 0.596).Four patients(33.3%) in the group A had postoperative fever.This was in contrast to the group B, of which none of the patients had postoperative fever.The probable reason is that the percutaneous tract is horizontal or slightly inclined downward, spontaneous evacuation of stone fragments during the procedure is easier and the pressure inside the pelvis is low in supine position.
Study of blood pressure in patients with solitary kidney and staghron stonesis few.Berkan et al. (14) observed staghorn stones in 16 patients.The number of patients with hypertension before PCNL was fi ve and by the end of follow-up there was no new onset hypertension.The result is similar with us.We also observed that systolic blood pressure showed a statistically signifi cant improvement in group B. The reason why systolic blood pressure improved after 3 months instead of diastolic blood pressure was unclear.
A few studies have investigated the factors that affect renal function in patients with solitary kidney (15)(16)(17)(18)(19).Most of them demonstrated a signifi cant improvement in creatinine or GFR levels from preoperatory levels to about 1-year of follow-up.In this study, we observed that both groups showed a similar fall in serum creatinine at 3 month follow-up period (p = 0.004 and 0.029, respectively).
However, the number of cases in the study was comparatively small, which result in lack of enough confi dence on statistical analysis of the data.The reasons of fewer patients are a short study period and a comparatively lower incidence rate of staghorn stones in patients with solitary kidney.However, we believe that our research will give some inspiration to new studies that should also estimate the preoperative and postoperative GFR and compare them.

CONCLUSIONS
PCNL is safe and has an acceptably high stone free rate in patients with solitary kidneys.At short-term follow-up, systolic blood pressure has improved in PCNL in supine position.

Table 2 -Intraoperative and postoperative parameters.
Major complications included septicemia, hemorrhage requiring blood transfusion, thoracic or abdominal organ injury, acute pancreatitis.