Original Research
JOURNAL OF ENDOUROLOGY Volume 28, Number 9, September 2014 ª Mary Ann Liebert, Inc. Pp. ---–--DOI: 10.1089/end.2014.0078
Percutaneous Nephrolithotomy in the Oblique Supine Lithotomy Position and Prone Position: A Comparative Study Ahmad Aref Al-Dessoukey, MD,1 Ayman Salah Moussa, MD,1 Ahmed Mahmoud Abdelbary, MD,1 Ahmed Zayed, MD,2 Rabie Abdallah, MD,1 Ahmad A. Elderwy, MD,3 Amr Medhat Massoud, MD,1 and Aly Hussein Aly, MD 4
Abstract
Objectives: To compare the safety, efficacy, and complications of percutaneous nephrolithotomy (PCNL) in the oblique supine lithotomy position vs the prone position in a randomized comparative study. Patients and Methods: The study included 101 and 102 patients in the oblique supine lithotomy position and prone position, respectively. Inclusion criteria were renal and upper ureteral stones. Exclusion criteria were uncorrectable bleeding disorders, active urinary tract infection, and pregnancy. Results: Both the groups were comparable regarding the male/female ratio, stone size, and site. No significant differences were found in terms of the stone-free rate, blood transfusion rate, and complication rates. Significant differences were reported in mean hemoglobin loss ( - 1.03 and - 2.18 g/dL), mean operative time (86.16 and 111.7 minutes), and mean hospital stay (49.88 and 81.2 hours) in the supine and prone positions, respectively, and anesthesiological parameters (the mean blood pressure decreased by 2 and 14.06 mm Hg, the mean heart rate changed by - 0.82 and + 13.28 beat/minute, and the peak air way pressure changed by + 1.08 cm H2O and + 7.56 cm H2O in the supine and prone positions, respectively). Conclusions: PCNL in both positions was equally successful with no significant differences in complications. PCNL in the oblique supine lithotomy position was superior to PCNL in the prone position regarding operative time, hospital stay, and effects on respiratory and cardiovascular status, making it more comfortable for patients and anesthesiologists. Morbidly obese patients, patients with cardiologic disorders, and patients with pulmonary obstructive airway disease need further studies to show if they would benefit from these differences. Additionally, it is more comfortable for the surgeon with little challenges added in the initial puncture. ticularly in obese patients. Abdominal compression decreases respiratory compliance. High airway pressures are required to ensure adequate ventilation. This impairs the venous return, decreasing cardiac output and cardiac index (CI), and increasing systemic venous pressure.3 Other disadvantages include the intraoperative changes of position that requires several nurses and holds risks related to pressure points and possible ocular, spinal, or peripheral nerve injuries and inability to perform PCNL concomitantly with retrograde intrarenal surgery (RIRS). By 1998, Uria and colleagues purposed to perform PCNL in the supine position, reporting promising results regarding its safety and efficacy.4 However, it did not gain much popularity and wide acceptance until the past few years.
Introduction
P
ercutaneous nephrolithotomy (PCNL) approach for stone removal is superior to the open approach in terms of morbidity, convalescence, and cost1; thus, it became the treatment of choice for large renal stones, staghorn calculi, extracorporeal shock wave lithotripsy (SWL)-resistant stones, or stones occurring in kidneys with an abnormal anatomy.2 PCNL in the prone position became the conventional one as it provides wider space for percutaneous access, instrument manipulation, and urologists are familiar with it. However, it is associated with anesthesiological disadvantages, ventilatory and hemodynamic changes occur, par1
Department Department Department 4 Department 2 3
of of of of
Urology, Urology, Urology, Urology,
Faculty of Medicine, Beni Suef University, Beni Suef, Egypt. Theodor Bilharz Research Institute, Cairo, Egypt. Assuit University Hospital, Assuit, Egypt. Cairo University, Cairo, Egypt.
1
2
AL-DESSOUKEY ET AL.
Advantages of the supine position include the absence of cardiovascular and respiratory problems, typical problems in the prone position, particularly in obese patients, and the ability to perform PCNL concomitantly with RIRS.5 Patients and Methods
Between April 2011 and November 2012, and upon getting the approval of the ethics committee, patients presenting to our institute with upper urinary tract stones were enrolled into a prospective, randomized comparative clinical study to compare the safety, efficacy, and complications of PCNL in the oblique supine lithotomy position vs the prone position. Inclusion criteria were single or multiple renal stones >2.5 cm or upper ureteral stones >1 cm. Patients with smaller stones with previously failed SWL were also included. Exclusion criteria were uncorrectable bleeding disorders, active urinary tract infection, and pregnancy. Two hundred three patients completed the follow-up, including 102 patients operated in the prone position and 101 patients in the modified, oblique supine lithotomy position. The randomization scheme was generated using the web site of Randomization.com (www.randomization.com). Informed consents were signed by enrolled patients. Preoperative assessment included history, physical examination, and laboratory investigations (urine analysis, culture and sensitivity, full coagulation profile, complete blood count, serum urea, and creatinine). Imaging included abdominal– pelvic ultrasound (US), kidney, ureter, and bladder (KUB), and either intravenous urography (IVU) or noncontrast computed tomography (NCCT). Operative technique
All patients received general anesthesia. In the prone position PCNL, with the patient in the lithotomy position, cystoscopy is done in the supine position, then a ureteral catheter is fixed and the Foley’s catheter is inserted alongside the ureteral catheter. The patient is then repositioned to the prone position (shoulders, iliac bones, knees, ankles, and feet were padded, supported, and secured). In the oblique supine lithotomy position PCNL, the ipsilateral lower limb is placed on the leg elevator, the hip and knee were flexed and the ipsilateral buttock and shoulder were supported using a roll to make an angle ranging from 20 to 50 according to the ideal position for the track and free movement of the nephroscope. The patient was placed with the stone-bearing side near the operating table edge. The patient’s ipsilateral upper limb was crossed over their chest to provide working space for the surgical team. The contralateral limb is extended (Fig. 1). Cystoscopy is done and a ureteral catheter is fixed. Retrograde pyelography is done, and skin incision is made medial to the posterior axillary line and an 18-gauge nephrostomy needle is passed into the desired calix, then a guide wire is passed antegradely across the renal pelvis and into the ureter, upper or lower calix. When multiple punctures were needed, they were done at this stage of the procedure, and other guide wires were passed. Following this, a second safety guide wire 0.038 is passed into the system. Dilatation is done using a nephrostomy balloon catheter. A 30F Amplatz sheath is passed over the balloon until it resides within the calix. In cases of failed balloon dilation, metal coaxial dilators or malleable dilators (Am-
FIG. 1. (A, B) Showing the supine oblique lithotomy position and (C) urologist working in the relaxed sitting position. platz dilators) were used. A rigid 26F nephroscope was used. Stones £1 cm were directly removed, but larger stones were fragmented using a pneumatic lithotripter or holmium-YAG laser. At the end of the procedure, if irrigant fluid is returning clear, no tube is left and the nephrostomy tract site is closed (tubeless PCNL) with or without the Double-J stent; otherwise, a nephrostomy tube is left in place. If urine was clear on the first day postoperatively, the Foley’s and ureteral catheters were removed and KUB was obtained. The nephrostomy tube was removed the next day in the absence of significant residual stones. If the patient was comfortable, afebrile, and with a dry nephrostomy site, the patient was discharged. Postoperative diclofenac sodium 50 mg injection was given on demand. Operative time (end of anesthesia to placement of nephrostomy), blood loss, blood pressures, mean blood pressure (MBP), heart rate (HR), peak air way pressure (PAP), stone-free rate, analgesics requirements, complications, and
PCNL IN OBLIQUE SUPINE LITHOTOMY AND PRONE POSITION
hospital stay were recorded. Blood loss was calculated as changes in hemoglobin (Hb) and need for blood transfusion. KUB, US, and chest X-ray were performed on day 1 postoperatively. Patients were considered stone free when no stone ‡ 4 mm was visualized. Residual fragments of ‡ 4 mm in diameter were treated with SWL. Sample size calculation and statistical analysis
An a priori power analysis was done for sample size calculation based on the comparison of the operative time between both positions as the primary outcome of our study. The minimum proper sample size was 95 patients in each arm to be able to detect a real difference of 10 to 15 minutes with 95% power at a = 0.05 level using the Student’s t-test for independent samples. Sample size calculation was done using the Stats Direct statistical software version 2.7.2 for MS Windows, Stats Direct Ltd (Cheshire, United Kingdom). The comparison of numerical variables between the study groups was done using the Student’s t-test for independent samples. For comparing categorical data, the chi-square (v2) test was performed. The exact test was used instead when the expected frequency is < 5. Univariate and multivariate analysis models were used to test the preferential effect of the independent variable(s) on the overall occurrence of complications. p-Values < 0.05 were considered statistically significant. Results
The patients in the oblique supine lithotomy position PCNL group were short named as supine, and the patients in the prone position PCNL were short named as prone.
3
Patient’s and stone characteristics of both the groups were comparable (Table 1). A single puncture was needed in 100 (98%) and 96 (95%) patients in the prone and supine groups, respectively ( p = 0.391). PCNL was accomplished in a single session in 97 patients (96%) in the supine group vs 98 patients (96%) in the prone group ( p = 0.82). A tubeless procedure was done in 83 patients (82.2%) in the supine group vs 29 patients (28.4%) in the prone group ( p = 0.001). Double-J stents were inserted in 27 patients (26.7%) in the supine group vs 25 patients (24.5%) in the prone group ( p = 0.185). The stone-free rate was 88.1% (89/101 patients) in the supine group vs 87.3% (89/102 patients) in the prone group ( p = 0.851). Hemodynamic changes showed more significant changes in the prone group (Table 2). The mean operative time was 86.16 minutes (standard deviation [STD] – 33.7) in the supine group and 111.7 minutes (STD – 39.4) in the prone group ( p < 0.001). The mean Hb loss was - 1.03 and - 2.18 g/dL in the supine and prone groups, respectively ( p < 0.001). Blood transfusions were required only in one patient in the supine group vs three patients in the prone group ( p = 0.069). Complication rates showed no significant differences (Table 2). The following are the postoperative analgesics need (limited need: postoperative 12–24 hours; extended need: second postoperative day or more); extended need was reported in 80 patients (78.4%) in the prone group compared with 38 patients (37.6%) in the supine group ( p = 0.034). In tubeless procedures, 21/83 patients (25.3%) in the supine group vs 7/29 patients (24.14%) in the prone group needed extended postoperative analgesic use ( p = 0.31).
Table 1. Sex Distribution, Age of Patients, Stone Size, Stone Site, BMI, and Preoperative (Hb, MBP, and PAP) Variables
Supine
Prone
p-Value
Female n (%) Male n (%) Age (years) Mean (STD)
33 (32.7) 68 (67.3)
34 (33.3) 68 (66.7)
0.920
34.86 (18.967)
37.21 (14.526)
0.08
Stone size (cm) Mean (STD)
3.68 (1.42)
3.93 (1.26)
0.283
Stone site n (%) Upper ureter Pelvic Lower caliceal Pelvic and middle caliceal Pelvic and upper caliceal Pelvic and lower caliceal Stag horn stones
6 40 11 7 11 30 2
(5.9) (39.6) (10.8) (6.9) (10.9) (29.7) (1.98)
2 39 12 6 14 38 2
(2.0) (38.2) (11.7) (5.9) (13.7) (37.2) (1.94)
0.067
BMI (kg/m2) Mean (STD)
27.24 (3.56)
26.87 (3.41)
1.000
Preoperative Hb (mg/dL) Mean (STD)
13.36 (1.444)
13.43 (1.323)
0.697
Preoperative MBP (mm Hg) Mean (STD)
89.36 (6.951)
87.12 (9.401)
0.071
Prepositioning PAP (cm H2O) Mean (STD)
23.32 (2.99)
22.86 (3.45)
0.329
BMI = body–mass index; Hb = hemoglobin; MBP = mean blood pressure; PAP = peak air way pressure; STD = standard deviation.
4
AL-DESSOUKEY ET AL.
Table 2. Hemodynamic and Ventilatory Changes, Postoperative Complications, and Hospital Stay Variables
Supine
Prone
MBP change (mm Hg) Mean - 2.00 - 14.06 STD 1.333 4.772 HR change (Beat/minute) Mean - 0.82 13.28 STD 0.626 6.278 PAP change (cm H2O) Mean 1.08 7.56 STD 0.635 1.540 Postoperative complications n (%) Clavein G II 7 (6.9) 9 (8.8) Clavein G IIIa 3 (3) 5 (4.9) Clavein G IIIb 0 (0) 2 (1.96) Blood transfusion 1 (1) 3 (2.9) Urinary leakage 3 (3) 5 (4.9) Fever 5 (5) 6 (5.9) Colonic injury 0 (0) 2 (1.96) Pleural effusion 1 (1) 0 (0) Overall complications 10 (9.9) 16 (15.7) Hospital stay all patients (hours) Mean 49.88 81.2 STD 19.7 35.1 Hospital stay uncomplicated patients (hours) Mean 43.8 67.2 STD 5.7 11.6
p-Value 0.001a 0.001a 0.001a 0.591 0.479 0.217 0.069 0.479 0.769 0.217 0.314 0.16 0.027a < 0.001a
a Statistically significant. HR = heart rate.
The hospital stay was significantly different between both the groups, in both complicated and uncomplicated patients (Table 2). Multivariate logistic regression was done for the influence of stone size, patient position, and the number of punctures on overall complications (Table 3). Discussion
PCNL was traditionally performed in the prone position for safer approach to the kidney. The prone position may be contraindicated for anesthesiological reasons because of circulatory and ventilatory difficulties, especially in obese patients.6 Moreover, it can be difficult in patients with limb contracture and spine deformities. Supine PCNL positions were suggested to overcome such problems.7 Uria and colleagues pioneered by reporting 557 PCNL done in a completely supine position with a water bag below the ipsilateral flank.4 Many supine positions were developed, including the complete supine, Valdivia, Galdakao-modified
Table 3. Logistic Regression for the Influence of Different Variables on Overall Complications Variables Stone size Position Number of punctures
p-Value 0.058 0.16 0.41
Valdivia, Barts modified, Valdivia, and Barts flank-free modified supine positions; all aiming at improving flank exposure to allow for easy and multiple punctures.8 Supine PCNL positions are nearly similar; putting the patient in the supine position by elevating the flank up to 20 and thus causing the posterior calix to project more laterally often becoming parallel (30) to the fluoroscopy table.9 In this study, we developed the oblique supine lithotomy position, a modification of the traditional lithotomy position. This position needs no special table accessories and is familiar to all urologists. Unlike other supine positions, this position straightens the lumbar lordosis, giving a wider area for puncturing and opening the renal angle, thus allowing for better access to the lower pole and free movement of nephroscope, especially in obese patients. De la Rosette and colleagues reviewed the literature for supine PCNL procedures. There were nine studies conducted until 2008, with a total of 1523 patients; mean operative times ranged from 15 to 300 minutes, stone-free rates ranged from 70% to 95%, the procedure was completed in a single session in 83% to 94%, lower caliceal access was most commonly used, blood transfusion was needed in 0% to 20%, and extravasation occurred in 12% of the patients. Only three patients were converted to open surgery, with no reports of visceral injury, colonic injury, or mortality.10 Hoznek and colleagues prospectively evaluated 47 patients in the Galdakao-modified supine Valdivia position. The mean stone size was 29.6 mm. The average operative time was 123.5 minutes. In the single, multiple, and staghorn stone groups, the immediate success rate after PCNL was 90%, 78%, and 43%, respectively. Complications were acceptable. The mean hospital stay was 3.4 days. In conclusion, the supine PCNL is a safe and reproducible method.11 Only three comparative trials were reported: Shoma and colleagues, a nonrandomized prospective study,12,13 and another two prospective randomized trials comparing supine and prone PCNL by Falahatkar and colleagues and De Sio and colleagues.14,15 Concluding that both positions are equivalent for stone-free rates and complication rates, supine PCNL has a shorter operative time. The small sample size may subject the statistical power of their results into question ( < 40 patients to either arms of the trial). Advantages of supine PCNL included a greater CI, decreased risk of colon injury during lower pole access, decreased radiation exposure to surgeon, improved spontaneous stone drainage through sheath, and a shorter operative time. Disadvantages include increased risk of hepatic and splenic injury during upper pole access and decreased area for percutaneous access.16 Both the groups in the current study (the oblique supine lithotomy PCNL group and the prone PCNL group) were comparable regarding sex distribution, patient’s age, stone size, stone site, body–mass index (BMI), and preoperative Hb, preoperative MBP, and prepositioning PAP. Stone-free rates in this study were comparable to the previously reported rates and showed no statistically significant difference, with a stone-free rate of 88.1% in the supine position compared with 87.3% in the prone position ( p = 0.851). Residual stones were subsequently managed by SWL. MBP significantly decreased ( - 14.06 vs - 2 mm Hg) in the prone position compared with the supine position ( p = 0.001). The HR significantly increased ( + 13.28 vs - 0.82) in the
PCNL IN OBLIQUE SUPINE LITHOTOMY AND PRONE POSITION
prone position compared with the supine position ( p = 0.001). The mean change in PAP was increased (7.56 vs 1.08) in the prone position compared with the supine position ( p = 0.001). These hemodynamic and ventilatory changes are clinically insignificant in patients with American Society of Anesthesia Physical Status (ASA-PS) of 1 to 2, but in patients with ischemic heart disease, heart failure, or obstructive pulmonary diseases, with ASA-PS of 4 (or 3), it may represent more than just a theoretical risk of serious morbidity and needs to be further studied in depth in this particular subset of patients as well as morbid obesity patients with BMI > 40. There was a significant difference in the mean Hb change between pre- and postoperative Hb (-1.03 and - 2.18 g/dL) in the supine and prone positions, respectively ( p < 0.001), but this did not affect the blood transfusion rate ( p = 0.069). However, it may affect intraoperative visibility in the prone position and thus may prolong the operative time. It may be attributed to obstruction of the IVC during PCNL in the prone position and backflow of blood to the renal vein and may explain why bleeding in the prone position is more.9 The mean operative time was significantly different between the supine and prone positions (86.16 and 111.7 minutes, respectively) ( p < 0.001), which was attributed to the lack of repositioning of patients into the prone position and the dependant position of the Amplatz sheath allowing small fragments to pass spontaneously; also, the less bleeding together with the spontaneous clearance of fragments may improve the visibility, and this theoretically may be another factor. The shorter operative time decreases the risk of anesthetic complications, especially in high-risk patients, and will allow regional anesthesia to be sufficient. There were no statistically significant differences between the groups for the overall complication rates nor for the rates of different complications, including postoperative fever, prolonged urinary leakage, visceral injuries, pleural and pulmonary injuries, or bowel injuries. The stone size, site, and number of punctures did not influence the overall complication rates in the whole study group on logistic regression analysis. This may be related to the low incidence of complications of PCNL together with the limited number of the study group. Bowel and colonic injury, in particular, although rarely reported, requires high attention. Colonic injury results in peritonitis, sepsis, abscess, and reno-colonic fistula or colocutaneous fistula. Colonic injuries occur in 0.2% to 0.3% in the prone position PCNL.17–19 On the contrary in 17 published studies reporting on supine PCNL, colonic injury was not reported.20 The retrorenal colon is found on NCCT in 1.9% in the supine position compared with 10% in the prone position (in 4.7% at the lower renal poles).21 Similar findings were reported on human corpses where the colon was more distant from the kidney in the supine position compared with the prone position after performing renal puncture.4 In this study, colonic injuries occurred in two patients (1.96%) in the prone position and none in the supine position and was statistically insignificant. However, the serious morbidity combined with the high-cost management gives it a special clinical importance. Reported complications were graded according to the Clavien classification of surgical complications.22 Statistical analysis showed no statistically significant differences.
5
There was a significantly higher need for extended use of postoperative analgesics in 80 patients in the prone position (78.4%) vs 38 patients in the supine position (37.6%) ( p = 0.034). However, it was mostly related to the presence of a PCN tube as in tubeless procedures, 21/83 patients (25.3%) in the supine position vs 7/29 patients (24.14%) in the prone position needed extended postoperative analgesic use ( p = 0.31). Also in tubed procedures, in most cases, pain was relieved or became tolerable after tube removal. The hospital stay was significantly shorter (49.88 hours) in the supine PCNL group vs 81.2 hours in the prone PCNL group ( p = 0.027). In uncomplicated cases, it was also significantly shorter (43.8 hours) in the supine PCNL group vs 67.2 hours in the prone PCNL group ( p = 0.001). This may be related to less bleeding from the access tract that resulted in the tubeless procedure in 82.2% in the supine position vs 28.4% in the prone position, which allowed for earlier patient discharge. The shorter operative time, less analgesics need, and shorter hospitalization time, which were noted with the supine group, will all probably translate into reduced treatmentrelated costs. Finally, the oblique supine lithotomy position PCNL was more comfortable for the surgery being performed with the surgeon sitting rather than standing and leaning forward while performing PCNL in the prone position, with some technical challenges on performing the caliceal puncture in the first few cases. Conclusions
PCNL in both positions was equally successful with no significant differences in complications. The oblique supine lithotomy position PCNL was superior to the prone position PCNL regarding operative time, hospital stay, blood loss, and effects on respiratory and cardiovascular status, making it more comfortable for the patient and anesthesiologist. Morbidly obese patients and patients with cardiopulmonary disorders need further studies to show if they would benefit from these differences. In addition, it is more comfortable for the surgeon, with little challenges added in the initial puncture. Acknowledgments
To God who guided us, to our fellows and residents for their help and efforts, to our patients for their trust, and to our families for their support. Disclosure Statement
No competing financial interests exist. References
1. Brannen GE, Bush WH, Correa RJ, et al. Kidney stone removal: Percutaneous versus surgical lithotomy. J Urol 1985;133:6–12. 2. Preminger GM, Assimos DG, Lingeman JE, et al. Chapter 1: AUA guideline on management of staghorn calculi: Diagnosis and treatment recommendations. J Urol 2005; 173:1991–2000. 3. Edgcombe H, Carter K, Yarrow S. Anaesthesia in the prone position. Br J Anaesth 2008;100:165–183.
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4. Valdivia Uria JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: Experience with 557 patients in the supine position. J Urol 1998;160:1975–1978. 5. Ibarluzea G, Scoffone CM, Cracco CM, et al. Supine Valdivia and modified lithotomy position for simultaneous anterograde and retrograde endourological access. BJU Int 2007;100:233–236. 6. Peces-Barba G, Rodriguez-Nieto MJ, Verbanck S, et al. Lower pulmonary diffusing capacity in the prone vs. supine posture. J Appl Physiol 2004;96:1937–1942. 7. Manohar T, Jain P, Desai M. Supine percutaneous nephrolithotomy: Effective approach to high risk and morbidly obese patients. J Endourol 2007;21:44–49. 8. Kumar P, Bach C, Kachrilas S, et al. Supine percutaneous nephrolithotomy (PCNL): ‘In vogue’ but in which position? BJU Int 2012;110:1018–1021. 9. Basiri A, Sichani MM. Supine percutaneous nephrolithotomy, is it really effective? A systematic review of literature. Urol J 2009;6:73–77. 10. De la Rosette JJMCH, Tsakiris P, Ferrandino MN, et al. Beyond prone position in percutaneous nephrolithotomy: A comprehensive review. Eur Urol 2008;54:1262–1269. 11. Hoznek A, Rode J, Ouzaid I, et al. Modified supine percutaneous nephrolithotomy for large kidney and ureteral stones: Technique and results. Eur Urol 2012;61:164–170. 12. Shoma AM, Eraky I, El-Kenawy MR, El-Kappany HA. Percutaneous nephrolithotomy in the supine position: Technical aspects and functional outcome compared with the prone technique. Urology 2002;60:388–392. 13. Falahatkar S, Allahkhah AA. Recent developments in percutaneous nephrolithotomy: Benefits of the complete supine position. UroToday Int J 2010;3. 14. Falahatkar S, Moghaddam AA, Salehi M, et al. Complete supine percutaneous nephrolithotripsy comparison with the prone standard technique. J Endourol 2008;22:2513–2517. 15. De Sio M, Autorino R, Quarto G, et al. Modified supine versus prone position in percutaneous nephrolithotomy for renal stones treatable with a single percutaneous access: A prospective randomized trial. Eur Urol 2008;54:196–202. 16. Duty B, Okhunov Z, Smith A, et al. The debate over percutaneous nephrolithotomy positioning: A comprehensive review. J Urol 2011;186:20–25. 17. Reddy PK, Hulbert JC, Lange PH, et al. Percutaneous removal of renal and ureteral calculi: Experience with 400 cases. J Urol 1985;134:662–665.
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18. Segura JW, Patterson DE, LeRoy AJ, et al. Percutaneous removal of kidney stones: Review of 1,000 cases. J Urol 1985;134:1077–1081. 19. Gerspach JM, Bellman GC, Stoller ML, Fugelso P. Conservative management of colon injury following percutaneous renal surgery. Urology 1997;49:831–836. 20. Falahatkar S, Allahkhah A, Soltanipour S. Supine percutaneous nephrolithotomy PRO. Urol J 2011;8:257–264. 21. Hopper KD, Sherman JL, Luethke JM, Ghaed N. The retrorenal colon in the supine and prone patient. Radiology 1987;162:443–446. 22. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004;240:205–213.
Address correspondence to: Ahmad Aref Al-Dessoukey, MD Department of Urology Faculty of Medicine Beni Suef University Beni Suef 62511 Egypt E-mail: [email protected]
Abbreviations Used ASA-PS ¼ American Society of Anesthesia Physical Status BMI ¼ body–mass index CI ¼ cardiac index Hb ¼ hemoglobin HR ¼ heart rate KUB ¼ kidney, ureter, and bladder MBP ¼ mean blood pressure NCCT ¼ noncontrast computed tomography PAP ¼ peak air way pressure PCNL ¼ percutaneous nephrolithotomy RIRS ¼ retrograde intrarenal surgery STD ¼ standard deviation SWL ¼ extracorporeal shock wave lithotripsy US ¼ abdominal–pelvic ultrasound
JOURNAL OF ENDOUROLOGY Volume 28, Number 9, September 2014 ª Mary Ann Liebert, Inc. Pp. ---–--DOI: 10.1089/end.2014.0078
Percutaneous Nephrolithotomy in the Oblique Supine Lithotomy Position and Prone Position: A Comparative Study Ahmad Aref Al-Dessoukey, MD,1 Ayman Salah Moussa, MD,1 Ahmed Mahmoud Abdelbary, MD,1 Ahmed Zayed, MD,2 Rabie Abdallah, MD,1 Ahmad A. Elderwy, MD,3 Amr Medhat Massoud, MD,1 and Aly Hussein Aly, MD 4
Abstract
Objectives: To compare the safety, efficacy, and complications of percutaneous nephrolithotomy (PCNL) in the oblique supine lithotomy position vs the prone position in a randomized comparative study. Patients and Methods: The study included 101 and 102 patients in the oblique supine lithotomy position and prone position, respectively. Inclusion criteria were renal and upper ureteral stones. Exclusion criteria were uncorrectable bleeding disorders, active urinary tract infection, and pregnancy. Results: Both the groups were comparable regarding the male/female ratio, stone size, and site. No significant differences were found in terms of the stone-free rate, blood transfusion rate, and complication rates. Significant differences were reported in mean hemoglobin loss ( - 1.03 and - 2.18 g/dL), mean operative time (86.16 and 111.7 minutes), and mean hospital stay (49.88 and 81.2 hours) in the supine and prone positions, respectively, and anesthesiological parameters (the mean blood pressure decreased by 2 and 14.06 mm Hg, the mean heart rate changed by - 0.82 and + 13.28 beat/minute, and the peak air way pressure changed by + 1.08 cm H2O and + 7.56 cm H2O in the supine and prone positions, respectively). Conclusions: PCNL in both positions was equally successful with no significant differences in complications. PCNL in the oblique supine lithotomy position was superior to PCNL in the prone position regarding operative time, hospital stay, and effects on respiratory and cardiovascular status, making it more comfortable for patients and anesthesiologists. Morbidly obese patients, patients with cardiologic disorders, and patients with pulmonary obstructive airway disease need further studies to show if they would benefit from these differences. Additionally, it is more comfortable for the surgeon with little challenges added in the initial puncture. ticularly in obese patients. Abdominal compression decreases respiratory compliance. High airway pressures are required to ensure adequate ventilation. This impairs the venous return, decreasing cardiac output and cardiac index (CI), and increasing systemic venous pressure.3 Other disadvantages include the intraoperative changes of position that requires several nurses and holds risks related to pressure points and possible ocular, spinal, or peripheral nerve injuries and inability to perform PCNL concomitantly with retrograde intrarenal surgery (RIRS). By 1998, Uria and colleagues purposed to perform PCNL in the supine position, reporting promising results regarding its safety and efficacy.4 However, it did not gain much popularity and wide acceptance until the past few years.
Introduction
P
ercutaneous nephrolithotomy (PCNL) approach for stone removal is superior to the open approach in terms of morbidity, convalescence, and cost1; thus, it became the treatment of choice for large renal stones, staghorn calculi, extracorporeal shock wave lithotripsy (SWL)-resistant stones, or stones occurring in kidneys with an abnormal anatomy.2 PCNL in the prone position became the conventional one as it provides wider space for percutaneous access, instrument manipulation, and urologists are familiar with it. However, it is associated with anesthesiological disadvantages, ventilatory and hemodynamic changes occur, par1
Department Department Department 4 Department 2 3
of of of of
Urology, Urology, Urology, Urology,
Faculty of Medicine, Beni Suef University, Beni Suef, Egypt. Theodor Bilharz Research Institute, Cairo, Egypt. Assuit University Hospital, Assuit, Egypt. Cairo University, Cairo, Egypt.
1
2
AL-DESSOUKEY ET AL.
Advantages of the supine position include the absence of cardiovascular and respiratory problems, typical problems in the prone position, particularly in obese patients, and the ability to perform PCNL concomitantly with RIRS.5 Patients and Methods
Between April 2011 and November 2012, and upon getting the approval of the ethics committee, patients presenting to our institute with upper urinary tract stones were enrolled into a prospective, randomized comparative clinical study to compare the safety, efficacy, and complications of PCNL in the oblique supine lithotomy position vs the prone position. Inclusion criteria were single or multiple renal stones >2.5 cm or upper ureteral stones >1 cm. Patients with smaller stones with previously failed SWL were also included. Exclusion criteria were uncorrectable bleeding disorders, active urinary tract infection, and pregnancy. Two hundred three patients completed the follow-up, including 102 patients operated in the prone position and 101 patients in the modified, oblique supine lithotomy position. The randomization scheme was generated using the web site of Randomization.com (www.randomization.com). Informed consents were signed by enrolled patients. Preoperative assessment included history, physical examination, and laboratory investigations (urine analysis, culture and sensitivity, full coagulation profile, complete blood count, serum urea, and creatinine). Imaging included abdominal– pelvic ultrasound (US), kidney, ureter, and bladder (KUB), and either intravenous urography (IVU) or noncontrast computed tomography (NCCT). Operative technique
All patients received general anesthesia. In the prone position PCNL, with the patient in the lithotomy position, cystoscopy is done in the supine position, then a ureteral catheter is fixed and the Foley’s catheter is inserted alongside the ureteral catheter. The patient is then repositioned to the prone position (shoulders, iliac bones, knees, ankles, and feet were padded, supported, and secured). In the oblique supine lithotomy position PCNL, the ipsilateral lower limb is placed on the leg elevator, the hip and knee were flexed and the ipsilateral buttock and shoulder were supported using a roll to make an angle ranging from 20 to 50 according to the ideal position for the track and free movement of the nephroscope. The patient was placed with the stone-bearing side near the operating table edge. The patient’s ipsilateral upper limb was crossed over their chest to provide working space for the surgical team. The contralateral limb is extended (Fig. 1). Cystoscopy is done and a ureteral catheter is fixed. Retrograde pyelography is done, and skin incision is made medial to the posterior axillary line and an 18-gauge nephrostomy needle is passed into the desired calix, then a guide wire is passed antegradely across the renal pelvis and into the ureter, upper or lower calix. When multiple punctures were needed, they were done at this stage of the procedure, and other guide wires were passed. Following this, a second safety guide wire 0.038 is passed into the system. Dilatation is done using a nephrostomy balloon catheter. A 30F Amplatz sheath is passed over the balloon until it resides within the calix. In cases of failed balloon dilation, metal coaxial dilators or malleable dilators (Am-
FIG. 1. (A, B) Showing the supine oblique lithotomy position and (C) urologist working in the relaxed sitting position. platz dilators) were used. A rigid 26F nephroscope was used. Stones £1 cm were directly removed, but larger stones were fragmented using a pneumatic lithotripter or holmium-YAG laser. At the end of the procedure, if irrigant fluid is returning clear, no tube is left and the nephrostomy tract site is closed (tubeless PCNL) with or without the Double-J stent; otherwise, a nephrostomy tube is left in place. If urine was clear on the first day postoperatively, the Foley’s and ureteral catheters were removed and KUB was obtained. The nephrostomy tube was removed the next day in the absence of significant residual stones. If the patient was comfortable, afebrile, and with a dry nephrostomy site, the patient was discharged. Postoperative diclofenac sodium 50 mg injection was given on demand. Operative time (end of anesthesia to placement of nephrostomy), blood loss, blood pressures, mean blood pressure (MBP), heart rate (HR), peak air way pressure (PAP), stone-free rate, analgesics requirements, complications, and
PCNL IN OBLIQUE SUPINE LITHOTOMY AND PRONE POSITION
hospital stay were recorded. Blood loss was calculated as changes in hemoglobin (Hb) and need for blood transfusion. KUB, US, and chest X-ray were performed on day 1 postoperatively. Patients were considered stone free when no stone ‡ 4 mm was visualized. Residual fragments of ‡ 4 mm in diameter were treated with SWL. Sample size calculation and statistical analysis
An a priori power analysis was done for sample size calculation based on the comparison of the operative time between both positions as the primary outcome of our study. The minimum proper sample size was 95 patients in each arm to be able to detect a real difference of 10 to 15 minutes with 95% power at a = 0.05 level using the Student’s t-test for independent samples. Sample size calculation was done using the Stats Direct statistical software version 2.7.2 for MS Windows, Stats Direct Ltd (Cheshire, United Kingdom). The comparison of numerical variables between the study groups was done using the Student’s t-test for independent samples. For comparing categorical data, the chi-square (v2) test was performed. The exact test was used instead when the expected frequency is < 5. Univariate and multivariate analysis models were used to test the preferential effect of the independent variable(s) on the overall occurrence of complications. p-Values < 0.05 were considered statistically significant. Results
The patients in the oblique supine lithotomy position PCNL group were short named as supine, and the patients in the prone position PCNL were short named as prone.
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Patient’s and stone characteristics of both the groups were comparable (Table 1). A single puncture was needed in 100 (98%) and 96 (95%) patients in the prone and supine groups, respectively ( p = 0.391). PCNL was accomplished in a single session in 97 patients (96%) in the supine group vs 98 patients (96%) in the prone group ( p = 0.82). A tubeless procedure was done in 83 patients (82.2%) in the supine group vs 29 patients (28.4%) in the prone group ( p = 0.001). Double-J stents were inserted in 27 patients (26.7%) in the supine group vs 25 patients (24.5%) in the prone group ( p = 0.185). The stone-free rate was 88.1% (89/101 patients) in the supine group vs 87.3% (89/102 patients) in the prone group ( p = 0.851). Hemodynamic changes showed more significant changes in the prone group (Table 2). The mean operative time was 86.16 minutes (standard deviation [STD] – 33.7) in the supine group and 111.7 minutes (STD – 39.4) in the prone group ( p < 0.001). The mean Hb loss was - 1.03 and - 2.18 g/dL in the supine and prone groups, respectively ( p < 0.001). Blood transfusions were required only in one patient in the supine group vs three patients in the prone group ( p = 0.069). Complication rates showed no significant differences (Table 2). The following are the postoperative analgesics need (limited need: postoperative 12–24 hours; extended need: second postoperative day or more); extended need was reported in 80 patients (78.4%) in the prone group compared with 38 patients (37.6%) in the supine group ( p = 0.034). In tubeless procedures, 21/83 patients (25.3%) in the supine group vs 7/29 patients (24.14%) in the prone group needed extended postoperative analgesic use ( p = 0.31).
Table 1. Sex Distribution, Age of Patients, Stone Size, Stone Site, BMI, and Preoperative (Hb, MBP, and PAP) Variables
Supine
Prone
p-Value
Female n (%) Male n (%) Age (years) Mean (STD)
33 (32.7) 68 (67.3)
34 (33.3) 68 (66.7)
0.920
34.86 (18.967)
37.21 (14.526)
0.08
Stone size (cm) Mean (STD)
3.68 (1.42)
3.93 (1.26)
0.283
Stone site n (%) Upper ureter Pelvic Lower caliceal Pelvic and middle caliceal Pelvic and upper caliceal Pelvic and lower caliceal Stag horn stones
6 40 11 7 11 30 2
(5.9) (39.6) (10.8) (6.9) (10.9) (29.7) (1.98)
2 39 12 6 14 38 2
(2.0) (38.2) (11.7) (5.9) (13.7) (37.2) (1.94)
0.067
BMI (kg/m2) Mean (STD)
27.24 (3.56)
26.87 (3.41)
1.000
Preoperative Hb (mg/dL) Mean (STD)
13.36 (1.444)
13.43 (1.323)
0.697
Preoperative MBP (mm Hg) Mean (STD)
89.36 (6.951)
87.12 (9.401)
0.071
Prepositioning PAP (cm H2O) Mean (STD)
23.32 (2.99)
22.86 (3.45)
0.329
BMI = body–mass index; Hb = hemoglobin; MBP = mean blood pressure; PAP = peak air way pressure; STD = standard deviation.
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AL-DESSOUKEY ET AL.
Table 2. Hemodynamic and Ventilatory Changes, Postoperative Complications, and Hospital Stay Variables
Supine
Prone
MBP change (mm Hg) Mean - 2.00 - 14.06 STD 1.333 4.772 HR change (Beat/minute) Mean - 0.82 13.28 STD 0.626 6.278 PAP change (cm H2O) Mean 1.08 7.56 STD 0.635 1.540 Postoperative complications n (%) Clavein G II 7 (6.9) 9 (8.8) Clavein G IIIa 3 (3) 5 (4.9) Clavein G IIIb 0 (0) 2 (1.96) Blood transfusion 1 (1) 3 (2.9) Urinary leakage 3 (3) 5 (4.9) Fever 5 (5) 6 (5.9) Colonic injury 0 (0) 2 (1.96) Pleural effusion 1 (1) 0 (0) Overall complications 10 (9.9) 16 (15.7) Hospital stay all patients (hours) Mean 49.88 81.2 STD 19.7 35.1 Hospital stay uncomplicated patients (hours) Mean 43.8 67.2 STD 5.7 11.6
p-Value 0.001a 0.001a 0.001a 0.591 0.479 0.217 0.069 0.479 0.769 0.217 0.314 0.16 0.027a < 0.001a
a Statistically significant. HR = heart rate.
The hospital stay was significantly different between both the groups, in both complicated and uncomplicated patients (Table 2). Multivariate logistic regression was done for the influence of stone size, patient position, and the number of punctures on overall complications (Table 3). Discussion
PCNL was traditionally performed in the prone position for safer approach to the kidney. The prone position may be contraindicated for anesthesiological reasons because of circulatory and ventilatory difficulties, especially in obese patients.6 Moreover, it can be difficult in patients with limb contracture and spine deformities. Supine PCNL positions were suggested to overcome such problems.7 Uria and colleagues pioneered by reporting 557 PCNL done in a completely supine position with a water bag below the ipsilateral flank.4 Many supine positions were developed, including the complete supine, Valdivia, Galdakao-modified
Table 3. Logistic Regression for the Influence of Different Variables on Overall Complications Variables Stone size Position Number of punctures
p-Value 0.058 0.16 0.41
Valdivia, Barts modified, Valdivia, and Barts flank-free modified supine positions; all aiming at improving flank exposure to allow for easy and multiple punctures.8 Supine PCNL positions are nearly similar; putting the patient in the supine position by elevating the flank up to 20 and thus causing the posterior calix to project more laterally often becoming parallel (30) to the fluoroscopy table.9 In this study, we developed the oblique supine lithotomy position, a modification of the traditional lithotomy position. This position needs no special table accessories and is familiar to all urologists. Unlike other supine positions, this position straightens the lumbar lordosis, giving a wider area for puncturing and opening the renal angle, thus allowing for better access to the lower pole and free movement of nephroscope, especially in obese patients. De la Rosette and colleagues reviewed the literature for supine PCNL procedures. There were nine studies conducted until 2008, with a total of 1523 patients; mean operative times ranged from 15 to 300 minutes, stone-free rates ranged from 70% to 95%, the procedure was completed in a single session in 83% to 94%, lower caliceal access was most commonly used, blood transfusion was needed in 0% to 20%, and extravasation occurred in 12% of the patients. Only three patients were converted to open surgery, with no reports of visceral injury, colonic injury, or mortality.10 Hoznek and colleagues prospectively evaluated 47 patients in the Galdakao-modified supine Valdivia position. The mean stone size was 29.6 mm. The average operative time was 123.5 minutes. In the single, multiple, and staghorn stone groups, the immediate success rate after PCNL was 90%, 78%, and 43%, respectively. Complications were acceptable. The mean hospital stay was 3.4 days. In conclusion, the supine PCNL is a safe and reproducible method.11 Only three comparative trials were reported: Shoma and colleagues, a nonrandomized prospective study,12,13 and another two prospective randomized trials comparing supine and prone PCNL by Falahatkar and colleagues and De Sio and colleagues.14,15 Concluding that both positions are equivalent for stone-free rates and complication rates, supine PCNL has a shorter operative time. The small sample size may subject the statistical power of their results into question ( < 40 patients to either arms of the trial). Advantages of supine PCNL included a greater CI, decreased risk of colon injury during lower pole access, decreased radiation exposure to surgeon, improved spontaneous stone drainage through sheath, and a shorter operative time. Disadvantages include increased risk of hepatic and splenic injury during upper pole access and decreased area for percutaneous access.16 Both the groups in the current study (the oblique supine lithotomy PCNL group and the prone PCNL group) were comparable regarding sex distribution, patient’s age, stone size, stone site, body–mass index (BMI), and preoperative Hb, preoperative MBP, and prepositioning PAP. Stone-free rates in this study were comparable to the previously reported rates and showed no statistically significant difference, with a stone-free rate of 88.1% in the supine position compared with 87.3% in the prone position ( p = 0.851). Residual stones were subsequently managed by SWL. MBP significantly decreased ( - 14.06 vs - 2 mm Hg) in the prone position compared with the supine position ( p = 0.001). The HR significantly increased ( + 13.28 vs - 0.82) in the
PCNL IN OBLIQUE SUPINE LITHOTOMY AND PRONE POSITION
prone position compared with the supine position ( p = 0.001). The mean change in PAP was increased (7.56 vs 1.08) in the prone position compared with the supine position ( p = 0.001). These hemodynamic and ventilatory changes are clinically insignificant in patients with American Society of Anesthesia Physical Status (ASA-PS) of 1 to 2, but in patients with ischemic heart disease, heart failure, or obstructive pulmonary diseases, with ASA-PS of 4 (or 3), it may represent more than just a theoretical risk of serious morbidity and needs to be further studied in depth in this particular subset of patients as well as morbid obesity patients with BMI > 40. There was a significant difference in the mean Hb change between pre- and postoperative Hb (-1.03 and - 2.18 g/dL) in the supine and prone positions, respectively ( p < 0.001), but this did not affect the blood transfusion rate ( p = 0.069). However, it may affect intraoperative visibility in the prone position and thus may prolong the operative time. It may be attributed to obstruction of the IVC during PCNL in the prone position and backflow of blood to the renal vein and may explain why bleeding in the prone position is more.9 The mean operative time was significantly different between the supine and prone positions (86.16 and 111.7 minutes, respectively) ( p < 0.001), which was attributed to the lack of repositioning of patients into the prone position and the dependant position of the Amplatz sheath allowing small fragments to pass spontaneously; also, the less bleeding together with the spontaneous clearance of fragments may improve the visibility, and this theoretically may be another factor. The shorter operative time decreases the risk of anesthetic complications, especially in high-risk patients, and will allow regional anesthesia to be sufficient. There were no statistically significant differences between the groups for the overall complication rates nor for the rates of different complications, including postoperative fever, prolonged urinary leakage, visceral injuries, pleural and pulmonary injuries, or bowel injuries. The stone size, site, and number of punctures did not influence the overall complication rates in the whole study group on logistic regression analysis. This may be related to the low incidence of complications of PCNL together with the limited number of the study group. Bowel and colonic injury, in particular, although rarely reported, requires high attention. Colonic injury results in peritonitis, sepsis, abscess, and reno-colonic fistula or colocutaneous fistula. Colonic injuries occur in 0.2% to 0.3% in the prone position PCNL.17–19 On the contrary in 17 published studies reporting on supine PCNL, colonic injury was not reported.20 The retrorenal colon is found on NCCT in 1.9% in the supine position compared with 10% in the prone position (in 4.7% at the lower renal poles).21 Similar findings were reported on human corpses where the colon was more distant from the kidney in the supine position compared with the prone position after performing renal puncture.4 In this study, colonic injuries occurred in two patients (1.96%) in the prone position and none in the supine position and was statistically insignificant. However, the serious morbidity combined with the high-cost management gives it a special clinical importance. Reported complications were graded according to the Clavien classification of surgical complications.22 Statistical analysis showed no statistically significant differences.
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There was a significantly higher need for extended use of postoperative analgesics in 80 patients in the prone position (78.4%) vs 38 patients in the supine position (37.6%) ( p = 0.034). However, it was mostly related to the presence of a PCN tube as in tubeless procedures, 21/83 patients (25.3%) in the supine position vs 7/29 patients (24.14%) in the prone position needed extended postoperative analgesic use ( p = 0.31). Also in tubed procedures, in most cases, pain was relieved or became tolerable after tube removal. The hospital stay was significantly shorter (49.88 hours) in the supine PCNL group vs 81.2 hours in the prone PCNL group ( p = 0.027). In uncomplicated cases, it was also significantly shorter (43.8 hours) in the supine PCNL group vs 67.2 hours in the prone PCNL group ( p = 0.001). This may be related to less bleeding from the access tract that resulted in the tubeless procedure in 82.2% in the supine position vs 28.4% in the prone position, which allowed for earlier patient discharge. The shorter operative time, less analgesics need, and shorter hospitalization time, which were noted with the supine group, will all probably translate into reduced treatmentrelated costs. Finally, the oblique supine lithotomy position PCNL was more comfortable for the surgery being performed with the surgeon sitting rather than standing and leaning forward while performing PCNL in the prone position, with some technical challenges on performing the caliceal puncture in the first few cases. Conclusions
PCNL in both positions was equally successful with no significant differences in complications. The oblique supine lithotomy position PCNL was superior to the prone position PCNL regarding operative time, hospital stay, blood loss, and effects on respiratory and cardiovascular status, making it more comfortable for the patient and anesthesiologist. Morbidly obese patients and patients with cardiopulmonary disorders need further studies to show if they would benefit from these differences. In addition, it is more comfortable for the surgeon, with little challenges added in the initial puncture. Acknowledgments
To God who guided us, to our fellows and residents for their help and efforts, to our patients for their trust, and to our families for their support. Disclosure Statement
No competing financial interests exist. References
1. Brannen GE, Bush WH, Correa RJ, et al. Kidney stone removal: Percutaneous versus surgical lithotomy. J Urol 1985;133:6–12. 2. Preminger GM, Assimos DG, Lingeman JE, et al. Chapter 1: AUA guideline on management of staghorn calculi: Diagnosis and treatment recommendations. J Urol 2005; 173:1991–2000. 3. Edgcombe H, Carter K, Yarrow S. Anaesthesia in the prone position. Br J Anaesth 2008;100:165–183.
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4. Valdivia Uria JG, Valle Gerhold J, Lopez Lopez JA, et al. Technique and complications of percutaneous nephroscopy: Experience with 557 patients in the supine position. J Urol 1998;160:1975–1978. 5. Ibarluzea G, Scoffone CM, Cracco CM, et al. Supine Valdivia and modified lithotomy position for simultaneous anterograde and retrograde endourological access. BJU Int 2007;100:233–236. 6. Peces-Barba G, Rodriguez-Nieto MJ, Verbanck S, et al. Lower pulmonary diffusing capacity in the prone vs. supine posture. J Appl Physiol 2004;96:1937–1942. 7. Manohar T, Jain P, Desai M. Supine percutaneous nephrolithotomy: Effective approach to high risk and morbidly obese patients. J Endourol 2007;21:44–49. 8. Kumar P, Bach C, Kachrilas S, et al. Supine percutaneous nephrolithotomy (PCNL): ‘In vogue’ but in which position? BJU Int 2012;110:1018–1021. 9. Basiri A, Sichani MM. Supine percutaneous nephrolithotomy, is it really effective? A systematic review of literature. Urol J 2009;6:73–77. 10. De la Rosette JJMCH, Tsakiris P, Ferrandino MN, et al. Beyond prone position in percutaneous nephrolithotomy: A comprehensive review. Eur Urol 2008;54:1262–1269. 11. Hoznek A, Rode J, Ouzaid I, et al. Modified supine percutaneous nephrolithotomy for large kidney and ureteral stones: Technique and results. Eur Urol 2012;61:164–170. 12. Shoma AM, Eraky I, El-Kenawy MR, El-Kappany HA. Percutaneous nephrolithotomy in the supine position: Technical aspects and functional outcome compared with the prone technique. Urology 2002;60:388–392. 13. Falahatkar S, Allahkhah AA. Recent developments in percutaneous nephrolithotomy: Benefits of the complete supine position. UroToday Int J 2010;3. 14. Falahatkar S, Moghaddam AA, Salehi M, et al. Complete supine percutaneous nephrolithotripsy comparison with the prone standard technique. J Endourol 2008;22:2513–2517. 15. De Sio M, Autorino R, Quarto G, et al. Modified supine versus prone position in percutaneous nephrolithotomy for renal stones treatable with a single percutaneous access: A prospective randomized trial. Eur Urol 2008;54:196–202. 16. Duty B, Okhunov Z, Smith A, et al. The debate over percutaneous nephrolithotomy positioning: A comprehensive review. J Urol 2011;186:20–25. 17. Reddy PK, Hulbert JC, Lange PH, et al. Percutaneous removal of renal and ureteral calculi: Experience with 400 cases. J Urol 1985;134:662–665.
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18. Segura JW, Patterson DE, LeRoy AJ, et al. Percutaneous removal of kidney stones: Review of 1,000 cases. J Urol 1985;134:1077–1081. 19. Gerspach JM, Bellman GC, Stoller ML, Fugelso P. Conservative management of colon injury following percutaneous renal surgery. Urology 1997;49:831–836. 20. Falahatkar S, Allahkhah A, Soltanipour S. Supine percutaneous nephrolithotomy PRO. Urol J 2011;8:257–264. 21. Hopper KD, Sherman JL, Luethke JM, Ghaed N. The retrorenal colon in the supine and prone patient. Radiology 1987;162:443–446. 22. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004;240:205–213.
Address correspondence to: Ahmad Aref Al-Dessoukey, MD Department of Urology Faculty of Medicine Beni Suef University Beni Suef 62511 Egypt E-mail: [email protected]
Abbreviations Used ASA-PS ¼ American Society of Anesthesia Physical Status BMI ¼ body–mass index CI ¼ cardiac index Hb ¼ hemoglobin HR ¼ heart rate KUB ¼ kidney, ureter, and bladder MBP ¼ mean blood pressure NCCT ¼ noncontrast computed tomography PAP ¼ peak air way pressure PCNL ¼ percutaneous nephrolithotomy RIRS ¼ retrograde intrarenal surgery STD ¼ standard deviation SWL ¼ extracorporeal shock wave lithotripsy US ¼ abdominal–pelvic ultrasound
