Vol 13 No 04 July-August 2016 2750 ENDOUROLOGY AND STONE DISEASE Percutaneous Nephrolithotomy Using Split Amplatz Sheath: A Randomized Clinical Trial Ali Tabibi,1 Amir Reza Abedi,2 Mohammad Hadi Radfar,1* Mohammad Reza Kamranmanesh,6 Hormoz Karami,3 Davoud Arab,4 Hamid Pakmanesh5 Purpose: To compare the outcome of percutaneous nephrolithotomy (PCNL) using split or intact Amplatz sheath. Materials and Methods: Seventy two patients who underwent PCNL were randomly divided into two groups; PCNL using intact (group 1) and split (group 2) Amplatz sheath. Preoperative data, operative time, largest extracted stone size, fluoroscopy and lithotripsy time, and serum biochemistry tests before and after PCNL were evaluated. Results: Preoperative features and stone size were not significantly different between the groups. There were no significant differences in complications and postoperative changes in hemoglobin and serum electrolytes. Stone free rate in group 2 (88.1%) was insignificantly higher than group 1 (83.3%) (p = .05), but in staghorn stones and stones larger than 1000 mm2, stone free rate in group 2 was significantly higher than group 1 (82% vs. 72%). The mean extracted stone size in group 2 (150 ± 49mm2) was significantly larger than group 1 (40 ± 16 mm2) (p < .005). The mean operative, lithotripsy and fluoroscopy times were significantly longer in group 1. Conclusion: Using split Amplatz sheath in PCNL facilitates extraction of larger stone fragments which could contribute to shorter fluoroscopy, lithotripsy and operative times. Keywords: Percutaneous nephrolithotomy; Amplatz sheath; Nephrolithiasis. INTRODUCTION Percutaneous nephrolithotomy (PCNL) is the standard procedure for the treatment of stones larger than 2 cm, staghorn calculi, and small stones refractory to shock wave lithotripsy (SWL).(1-3) PCNL has the highest stone- free rate (SFR) among all renal stone treatment options. The SFR after one session of PCNL is more than 80%.(4) Operative time is a key factor correlated with the post- operative and, indirectly with anesthesia-related com- plications.(5,6) A few studies have investigated factors that influence operative time during percutaneous neph- rolithotomy. These studies have shown that a history of open surgery, stone size and surgical experience are correlated with operative time(6,7). In a study by el-Na- has et al. stone size was found to be a predictive fac- tor for both longer operative time and hospital stay.(8) We hypothesized that extraction of stones in larg- er fragments may decrease the need for stone fragmentation and consequently, shorten the op- erative time. Hence, this study was done to com- pare the perioperative and postoperative outcome of PCNL using split and intact Amplatz sheath. MATERIALS AND METHODS Between June and April 2014, 123 patients underwent PCNL in our department. The study was approved by our institutional ethical committee, and informed con- sent was sought from all patients. All patients who were candidate for PCNL were included except patients with The American Society of Anesthesiologists (ASA) risk class III or more, multiple stones and those requiring su- pracostal access. Considering study power of 80%, sam- ple size was calculated to be 36 patients in each group. We randomized patients into two groups; in group one PCNL was performed using intact Amplatz sheath, and in group two longitudinally split Amplatz sheath was used. To have a split Amplatz sheath, a conventional Amplatz sheath was simply cut longitudinally in its total length with a surgical knife. The randomization method was simple randomization using table of random num- bers. Figure 1 shows the CONSORT chart of this study. Preoperative evaluation included laboratory tests (com- plete blood count (CBC), coagulation tests, serum electrolytes, urine analysis and culture) and imaging studies (spiral abdominopelvic computed tomogra- phy (CT) scan and/or intravenous urography (IVU). All patients received prophylactic antibiotics preoper- atively. Data were collected prospectively by one of the authors blinded to the procedure. Participants and care givers were also blinded to group assignment. 1Urology and Nephrology Research Center, Shahid Labbafinejad Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2Urology and Nephrology Research Center, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 3Yazd University of Medical Sciences, Yazd, Iran. 4Semnan University of Medical Sciences, Semnan, Iran. 5Kerman University of Medical Sciences, Kerman, Iran. 6Anesthesiology Research Center, Shahid Labbafinejad Hospital, Shahid Beheshti University of Medical Sciences *Correspondence: Shahid Labbafinejad Hospital, 9th Boostan, Pasdaran Avenue, Tehran, Iran. Tel& Fax: +98 212 258 8016. E-mail: mhadirad@yahoo.com Received April 2016 & Accepted July 2016 PCNL using split Amplatz sheath-Tabibi et al. In the lithotomy position and under spinal anesthesia, cystoscopy was performed to insert a 5F ureteral cath- eter. The position was changed to prone with a support under chest and pelvis. Access to the kidney was ob- tained under fluoroscopic guidance; the tract was di- lated to 30 Fr using Amplatz dilator with single-step dilation technique, and Amplatz sheath (split or intact sheath) was placed. Stone degradation was performed by pneumatic lithotripsy using lithoclast master system (EMS, Switzerland). We did not use flexible nephros- copy for our patients. An 18 Fr nephrostomy tube was inserted at the end of procedure for all patients. All op- erations were supervised by an attending endourologist. CBC and serum electrolytes were checked on the first postoperative day. Abdominal ultrasonography and plain abdomen X-ray were also performed on the first postoperative day. If there was no significant re- sidual stone, nephrostomy tube was removed. Ureter- al catheter was removed when urinary leakage from nephrostomy removal site was less than 100 ml/day. Patients with no residual stone or residual stone < 4 mm were considered stone free. Stone free rate was the primary outcome evaluated in this study. Sec- ondary outcomes included operative time, the larg- est extracted stone size, fluoroscopy and lithotripsy times, blood tests before and after PCNL, ancillary procedures, hospital stay and complications. For sta- tistical analysis, SPSS ver.21 software was used. Quantitative and categorical variables were tested us- ing student’s t-test and chi-square test, respectively. RESULTS Seventy two patients (57 men and 15 women) with mean age of 43.45 ± 13.41 years were included in the study. The preoperative characteristics were not significantly different between the two groups. (Ta- ble 1) The mean body mass index (BMI) was 29.2 ± 5.6 and 28.64 ± 6.1 Kg/m2 in group one and two, re- spectively (p = .68). Table 2 summarizes intra- and Table 1. Stones characteristics. Stone characteristics Intact group Split group Total Stone locationa Upper calyx 1 1 2 Lower calyx 4 3 7 Pelvis 14 13 27 Pelvis + one calyx 10 13 23 Staghorn 6 7 13 Mean stone sizeb (mm2) 950 ± 967 1165 ± 1424 1005.7 ± 23 aStatistically insignificant difference between the groups. (P = .58) b P = .45 Features Intact group Split group P value Operative time (mean ± SD) min 70 ± 22.2 48.33 ± 17.32 .005 Fluoroscopy time (mean ± SD) second 45.8 ± 14.66 25.63 ± 12.8 .005 Extracted stone size (mean ± SD) mm2 40 ± 16 150 ± 49 .005 Preoperative hemoglobin (mean ± SD) g/dl 14.32 ± 1.52 14.1 ± 1.2 .67 Postoperative hemoglobin (mean ± SD) g/dl 11.8 ± 1.56 11.82 ± 2.7 .95 Preoperative Na (mean ± SD) mg/dL 141.7 ± 2.6 141.8 ± 2.6 .14 Postoperative Na (mean ± SD) mg/dL 141.1 ± 2.56 140.08 ± 3.2 .13 Preoperative K (mean ± SD) mg/dL 4.23 ± 0.22 4.34 ± 0.42 .22 Postoperative K (mean ± SD) mg/dL 4.11 ± 0.31 3.95 ± 0.36 .08 Preoperative Cr (mean ± SD) mg/dL 1.11 ± 0.22 1.11 ± 0.27 .9 Postoperative Cr (mean ± SD) mg/dL 1.13 ± 0.27 1.13 ± 0.35 .95 Hospital Stay (mean ± SD) days 3.5 ± 1.5 3.1 ± 1.2 .2 Lithotripsy time (mean ± SD) second 61.9 ± 30.69 38.61±33.58 .003 Access tracts (No. of patients) .005 1 34 33 2 2 3 Table 2. Intra- and postoperative data. Endourology and Stone Diseases 2751 Vol 13 No 04 July-August 2016 2752 postoperative data. The mean operative, fluoroscopy and lithotripsy times in group one (intact sheath) were significantly longer than group two (split sheath). The mean size of extracted stone fragment in group one was significantly smaller than group two. (Figure 2) Hemoglobin change was not significantly different (p = .54) (2.52 ± 1.2 in the split group vs. 2.35 ± 1.07 in intact group). There was no significant difference in mean change of serum sodium (Na), potassium (K), and creatinine between the two groups. (Table 2) Stone free rate was not significantly different between the two groups (83.3% vs. 88.1% in groups 1 and 2, respectively) (P = .5). However, in staghorn stones and stones larger than 1000 mm2, stone free rate in group 1 was significantly lower than group 2 (72% vs. 82%). The need for ancillary procedures was not significantly different between the two groups. SWL was necessary in 6 patients (4 patients in group one and two patients in group two), ureteroscopy in two patients (one pa- tient in each group), and repeat PCNL in two patients (one patient in each group). According to the modified Clavien system, class II complication (blood transfu- sion) was found in 3 patients in group one and 2 pa- tients in group two (P = .56). Class IIIa complication (double-J stent insertion without general anesthesia because of prolonged urine leakage from nephrostomy removal site) occurred in two patients in group 1 and one patient in group 2. There were no perinephric col- lection (evaluated by ultrasonography) or major com- plications (Clavien class IIIb or higher) in our patients. DISCUSSION Since the first report of PCNL in 1976, its instruments and techniques have evolved. PCNL is currently the standard of care for large renal stones (> 2 cm)(9). Al- though PCNL is safe and effective, it is the most costly minimally invasive procedure for renal stone treatment. (10) The cost-effectiveness of PCNL correlates with op- erative time, stone burden, stone free rate, and major complications.(6) Bleeding is one of the most common complications of PCNL, with an incidence rate of 1-55% in different studies.(11) Operative time is an im- portant factor that correlates with perioperative bleed- ing and cost-effectiveness of the procedure.(6) A few studies are available about factors affecting operative time of PCNL. Olbert et al. reported on 109 patients who underwent PCNL and found out that stone size correlates with operative time and hospital stay(12). Ak- man et al. showed that operative time for stones larger than 1000 mm2 was three times longer than for stones less than 1000 mm2. With increasing stone burden, the need for multiple access tracts increases and multiple tracts are correlated with more blood loss and longer hospital stay(6). Bagrodia et al. found that increasing Figure 1. CONSORT chart of the study. Figure 2. A large stone fragment is extracted from the split Am- platz sheath. PCNL using split Amplatz sheath-Tabibi et al. stone size affects treatment related costs. Larger stone burden is associated with longer operative time, longer hospital stay, more salvage procedures, and higher cost. They also showed that average operative time slow- ly decreases with increased experience of surgeon.(10) Some authors have reported that the hydronephro- sis grade could affect operative time. They described that a severely hydronephrotic kidney collapses af- ter percutaneous access and detection of stone frag- ments could be difficult and take longer time.(6,12) Correlation between stone size and operative time could be explained by longer time needed for stone fragmentation and extraction. Since operative time affects complication rate and cost-effectiveness, any attempt to reduce it is of critical importance. Our study compared the outcomes of PCNL using intact and split Amplatz sheath in a randomized clin- ical trial. It showed that using split Amplatz sheath allows for extracting significantly larger stone frag- ments which results in decrease of lithotripsy time and number of stone fragments. As the number of stone fragments is reduced, their detection and extraction could be performed easier, faster, and with less need for fluoroscopy. This could also explain higher stone free rate achieved in group 2, particularly for staghorn calculi and stones larger than 1000 mm2. A technical point of using split sheath was the risk of entrapment of stone fragments in the fascia. To avoid this risk, the fascia should be opened wider. Blood transfusion and mean Hb change was not significantly different be- tween the two groups. There was concern about prob- able fluid leakage through the split sheath and the risk for electrolyte disturbances. Our findings showed that electrolyte changes were not significantly different be- tween the two groups and none of the patients had per- inephric collection on postopearative ultrasonography. CONCLUSION Using split Amplatz sheath during PCNL facilitates ex- traction of larger stone fragments which could contribute to shorter fluoroscopy time, lithotripsy time, and opera- tive time. Operative time is a key factor which correlates with intra- and postoperative complications. It seems that the benefits of using spit Amplatz sheath might be more considerable in large and staghorn stones. This should be confirmed in larger studies with more patients. ACKNOWLEDGEMENTS The authors would like to thank Seyed Muhammed Hussein Mousavinasab for his sincere cooperation in editing this text. REFERENCES 1. Ziemba JB, Matlaga BR. Guideline of guidelines: kidney stones. BJU Int. 2015; 116: 184-9. 2. Skolarikos A, Alivizatos G, de la Rosette JJ. Percutaneous nephrolithotomy and its legacy. Eur Urol. 2005; 47: 22-8. 3. Skolarikos A, de la Rosette JJ. Prevention and treatment of complications following percutaneous nephrolithotomy. Curr Opin Urol. 2008; 18: 229-34. 4. Shin TS, Cho HJ, Hong SH, Lee JY, Kim SW, Hwang TK. Complications of percutaneous nephrolithotomy classified by the modified clavien grading system: a single center's experience over 16 years. Korean J Urol. 2011; 52: 769–75. 5. Falahatkar S, Moghaddam KG, Kazemnezhad E, et al. Factors affecting operative time during percutaneous nephrolithotomy: our experience with the complete supine position. J Endourol. 2011; 25: 1831-6. 6. Akman T, Binbay M, Akcay M, et al. Variables that influence operative time during percutaneous nephrolithotomy: an analysis of 1897 cases. J Endourol. 2011; 25: 1269-73. 7. Tugcu V, Su FE, Kalfazade N, Sahin S, Ozbay B, Tasci AI. Percutaneous nephrolithotomy (PCNL) in patients with previous open stone surgery. Int Urol Nephrol. 2008; 40:881-4. 8. el-Nahas AR, Eraky I, Shokeir AA, et al. Factors affecting stone-free rate and complications of percutaneous nephrolithotomy for treatment of staghorn stone. Urology. 2012; 79:1236-41. 9. Fernstrom I, Johansson B. Percutaneous pyelolithotomy: a new extraction technique. Scand J Urol Nephrol. 1976; 10:257–9. 10. Bagrodia A, Gupta A, Raman JD, Bensalah K, Pearle MS, Lotan Y. Predictors of cost and clinical outcomes of percutaneous nephrostolithotomy. J Urol. 2009; 182: 586- 90. 11. Lee JK, Kim BS, Park YK. Predictive factors for bleeding during percutaneous nephrolithotomy. Korean J Urol. 2013; 54: 448-53. 12. Olbert PJ, Hegele A, Schrader AJ, Scherag A, Hofmann R. Pre- and perioperative predictors of short-term clinical outcomes in patients undergoing percutaneous nephrolitholapaxy. Urol Res. 2007; 35: 225-30. PCNL using split Amplatz sheath-Tabibi et al. Endourology and Stone Diseases 2753