Flank-free Modified Supine Position Research Articles

Simplified biplanar (0–90°) versus monoplanar renal puncture technique in flank free modified supine percutaneous nephrolithotomy regarding outcomes and learning curve: Randomized clinical trial

ABSTRACT Objective To evaluate the learning curve and the success rate of the biplanar (0–90°) puncture technique in the flank-free modified supine position in comparison to the monoplanar puncture technique. Methods Randomized controlled study included 68 patients more than 18 years with renal stones more than 2 cm from August 2021 to August 2022 were randomly classified by closed envelope method into group A (34 patients) scheduled for monoplanar renal puncture technique in flank-free modified supine PCN. Meanwhile, group B (34 patients) was scheduled for the 0–90° simplified fluoroscopic puncture technique. Morbid obese patients and patients with contraindications for PNL were omitted from the study. Results There was no significant difference between both groups regarding stone distribution and patients’ demographic data. There was a significant difference between both groups regarding puncture attempts. In 88.2% of patients in group B (Biplanar group), the success of renal puncture occurred from the 1st puncture attempt while in 11.2% of patients in group A (monoplanar group). There was a statistically significant difference between both groups in fluoroscopy time and total operation time (p-value <0.001 & p-value: 0.001), respectively. The stone-free rate was 85.2% vs. 88.2% in both groups, respectively, without significant difference. In this study puncture, attempt trials and puncture time were used as indicators for the easiness and rapid educability of the biplanar (0–90°) fluoroscopic guided renal puncture technique. In the biplanar (0–90°) group after 24 cases, the learning curve had reached the plateau. Conclusion Biplanar (0–90°) puncture technique in flank-free modified supine position allows an easy puncture technique with an easy learning curve without affecting the success rate or complication rate.

Is the Supine Position Suitable for Ultrasound-Guided Percutaneous Nephrolithotomy in Patients with Complex Renal Stones?

Introduction: The aim of the study was to assess the safety and efficacy of ultrasound (US)-guided percutaneous nephrolithotomy (PCNL) for complex renal stones when performed in a modified supine position. Methods: We retrospectively reviewed the charts of patients who underwent PCNL for complex renal stones at our institution between August 2018 and December 2021. During this time, 188 consecutive patients underwent US-guided PCNL in the prone position (P group, n = 129) or in the flank-free modified supine position (S group, n = 59). Patient demographics and intraoperative and postoperative data were analyzed. Results: Successful renal access was achieved in all patients. The baseline demographics were comparable between the two groups. The numbers of renal access were significantly higher (2.1 ± 0.4 vs. 1.2 ± 0.2, p = 0.002), and the operation time was comparable (79.1 ± 14.6 min vs. 96.2 ± 19.6 min, p = 0.06) between the two groups. The postoperative hospital stay was also shorter in the P group (6.2 ± 1.5 d vs. 10.2 ± 1.7 d, p = 0.008). The postoperative hemoglobin loss was similar between the P and S groups (1.7 ± 0.4 g/dL vs. 1.8 ± 0.3 g/dL, p = 0.12). The stone-free rate was significantly lower in the S group (57.5% vs. 82.7%, p < 0.001). There were no embolization or septic complications. Twelve patients (20.3%) in the S group underwent simultaneous or staged retrograde flexible ureteroscopy to remove residual stones. Conclusion: US-guided PCNL in the modified supine position was a safe treatment for complex renal stones. However, the single-session stone clearance rate was not ideal. The supine flank-free position may be unsuitable for US-guided PCNL in patients with complex renal stones according to our preliminary findings.

Ultra-Mini-Percutaneous Nephrolithotomy in Flank-Free Modified Supine Position vs Prone Position in Treatment of Pediatric Renal Pelvic and Lower Caliceal Stones.

Objectives: To report the safety and efficacy of ultra-mini-percutaneous nephrolithotomy (UMPCNL) in flank-free modified supine (FFMS) and prone positions in management of pediatric renal calculi. Patients and Methods: This prospective randomized study included 55 pediatric patients with symptomatic renal stones and suitable for UMPCNL. They were randomized into two groups. Group A included 28 patients who were treated by UMPCNL in FFMS position (with a pad below the ipsilateral shoulder and buttocks, putting ipsilateral upper limb over the chest, and crossing the extended ipsilateral lower limb over the flexed contralateral one) and Group B included 27 patients treated by UMPCNL in the prone position. In both groups dilatation was done to 13F sheath allowing the introduction of 6/7.5F semirigid ureteroscope and fragmentation of stones by Holmium: yttrium-aluminum-garnet laser with a 550-μm fiber laser lithotripter. Results: The operation time in FFMS position UMPCNL group was significantly shorter than prone position UMPCNL group (84.3 ± 9.87 vs 99.3 ± 8.75 minutes) with p = 0.022. There was no significant difference between both groups in terms of stone-free rate (89.3% vs 88.9%), overall complication rate (including transient fever; 21.4% vs 18.5%), postoperative pain (visual analog scale score; 3.4 ± 0.8 vs 3.3 ± 0.9), or hospital stay (3.53 ± 0.8 vs 4.1 ± 1.1 days). Conclusion: Both UMPCNL in FFMs and prone positions are feasible, safe, and effective in treatment of pediatric renal stones with relatively shorter operative time in FFMS position.

A prospective, randomized comparison of standard prone position versus flank-free modified supine position in percutaneous nephrolithotomy: A single-center initial experience.

Background:Percutaneous nephrolithotomy (PCNL) is the first choice for treatment of large renal stone >2 cm. The prone position is the classical position preferred by most surgeons. Aiming to improve patient anesthesia and surgery-related inconveniences of the prone position, Valdivia et al., 1987, described the performance of PCNL with the patient in the supine position. Hence, we aimed to study the safety and efficacy of flank-free modified supine position in PCNL compared to the standard prone position.Patients and Methods:This is a prospective randomized study for 60 patients with large renal stones planned for PCNL operation during the period from November 2017 to May 2019. Patients were divided into two groups (30 patients each group): Group A – patients underwent PCNL in the prone position and Group B – patients underwent PCNL in the modified flank supine position. Patients’ demographics, stone size, Hounsfield unit with intraoperative details as fluoroscopy time, operative time, and complications were recorded. Postoperatively, need for or not to blood transfusions, hospital stay, stone-free status, and postoperative complications were assessed.Results:There was no statistically significant difference between the prone and supine positions regarding stone size (4 cm vs. 4.5 cm, P = 0.16), Hounsfield unit (940 HU vs. 955 HU, P = 0.78), body mass index (31.2 kg/m2 vs. 32.5 kg/m2, P = 0.49), fluoroscopy time (6.9 min vs. 7.3 min, P = 0.5), operative time (89.5 min vs. 90.4 min, P = 0.9), residual stones (10% vs. 20%, P = 0.8), and hospital stay (45.6 h vs. 48.6 h, P = 0.5). Fever occurred in 3.3% of cases in each group and urine leakage observed in one patient with prone position. No blood transfusion was needed in both the groups.Conclusions:PCNL in the modified supine position proved to be a safe and effective choice compared to the prone position for adult patients with large renal calculi.

One-Shot Dilatation vs Metal Dilator During Percutaneous Nephrolithotomy in Flank-Free Supine Position: A Randomized Controlled Study.

Background: The creation and dilatation of the nephrostomy tract is a fundamental step in percutaneous nephrolithotomy (PCNL). In one-shot dilatation (OSD), we used a single Amplatz dilator over a central Alken rod. PCNL in the supine position is as effective and safe as in the prone position. The Barts flank-free modified supine position sums several advantages of the different supine positions. We evaluated the efficacy and safety of OSD compared with metal telescopic dilator (MTD) during PCNL while the patient was in Barts flank-free modified supine position. Materials and Methods: Within 2.5 years, 150 patients with kidney stone candidates for PCNL were randomized into two equal groups according to the dilatation technique. In the OSD group, dilatation was performed using a single Amplatz dilator (30F) and in the MTD group dilatation was performed by sequential MTD (9-30F). All PCNL procedures were done with patients in Barts flank-free modified supine position. Patient characteristics, operative data, and results were collected for statistical analysis. Results: There are no statistically significant differences between both groups regarding patients' characters. The tracts were effectively dilated in all patients. Statistical analyses show a significant difference (p ˂ 0.05) between both groups regarding the time of dilatation (seconds; 68 ± 15 vs 147 ± 18), time of X-ray exposure (seconds; during dilatation; 36 ± 10 vs 61 ± 15 and the total; 157 ± 16 vs 181 ± 20), hemoglobin loss (mg/dL; 0.7 ± 0.2 vs 1.2 ± 0.3), and hospital stay (days; 3 ± 0.6 vs 3.7 ± 0.7) with favorable results to OSD. Complication rates were comparable between the two groups. Conclusions: OSD is efficient as MTD during PCNL while patients are in Barts flank-free modified supine position, with less dilatation time, X-ray exposure, blood loss, and hospital stay than MTD.

Prone Versus Flank-free Modified Supine position Mini Percutaneous Nephrolithotomy in Pediatric Age Group

Background: Children with nephrolithiasis constitute a high-risk patient population with increased risk for stone recurrence during their life- times, so proper evaluation and management is very important. The present study aimed to compare operative time, complications rate, stone free rate in the prone position versus flank-free modified Supine position (FFMSP) Mini-perc percutaneous nephrolithotripsy (M-PCNL) in pediatric age group. Patients and methods: A prospective randomized comparative study was carried out on 20 patients with renal stones scheduled for PCNL at the Urology Department, Faculty of Medicine, Zagazig University in the period from December 2017 till November 2018, they were randomized in two groups; Group A: for Flank-free Modified Supine position Mini Percutaneous Nephrolithotomy position; Group B: for prone mini percutaneous nephrolithotomy position. Results: the current study showed that there was a statistical significant difference between the studied groups regarding to operative time & position time, it was shorter in FFMS than prone with highly significant difference, also there was no statistical significant difference between the two groups in radiation time, access time and laser time, the needed for auxiliary maneuver as ESWL in both position was 5 cases in both group together, there was no significant difference in studied groups. Conclusion: we conclude that the mini- percutaneous nephrolithotripsy in Flank Free Modified Supine position as treatment of pediatric renal stones is, shorter in operation time, less in complication rate but not significant different and has same efficiency as compared to prone mini-percutaneous nephrolithotripsy.

Outcomes of Flank-Free Modified Supine Percutaneous Nephrolithotomy Based on BMI

Objective: To evaluate the impact of body mass index (BMI) on the outcomes of percutaneous nephrolithotomy (PCNL) in the flank-free modified supine position. Patients and Methods: A prospective study was carried out in the urology department during the period from May 2015 to October 2019 on 464 patients admitted for PCNL. The patients were divided into 4 matched groups according to their BMI: group A, normal weight with 18.5 ≤ BMI <25 kg/m²; group B, overweight with 25 ≤ BMI <30 kg/m²; group C, obese with 30 ≤ BMI <40 kg/m²; and group D, morbid obesity with BMI ≥40 kg/m². All operative data as well as postoperative outcomes are recorded and compared to each other. Results: The 4 studied groups were matched regarding age. The comorbidities were slightly higher in groups C and D. The operative time and fluoroscopy time were slightly high in obese and morbid obese groups but with no significant difference. The rate of complications either major or minor was comparable in all groups. No significant difference was seen among all groups regarding hemoglobin loss, stone-free rate, hospital stay, and need for auxiliary procedures. Conclusions: The outcome of PCNL in flank-free modified supine position is not affected by changes in BMI. The procedure can be performed in obese and morbid obese patients safely with results similar to and comparable to nonobese patients.

Radiologic Relation of the Colon to the Trajectory of Percutaneous Nephrolithotomy Access in Prone Versus Flank-free Modified Supine Position: A Prospective Study of Intra and Interindividual Influencing Factors

To compare the distance between the colon and the trajectory of percutaneous nephrolithotomy (PCNL) access both in prone and flank-free modified supine (FFMS) positions as measured on computed tomography and to study the effect of age, gender, BMI, side, and previous renal surgery as influencing factors. In this prospective study, we included 367 patients scheduled for PCNL. All patients underwent low dose abdominal computed tomography both in prone and FFMS positions. Patients <18 years and those with previous colonic surgery or renal congenital anomalies were excluded. The perpendicular distance between the imaginary line of the renal access and the colon was measured. Findings were correlated to different influencing factors. Two hundred nineteen patients were males, and 148 were females. BMI of <30 were reported in 158 patients whereas BMI >30 in 209 patients. Data analysis showed that the mean perpendicular distance between colon and the renal access in FFMS and prone positions were 35.92 ± 0.22 mm and 17.78 ± 0.09 mm, respectively. In prone position only obesity, age, and overall interaction effect were the significant factors on the studied distance. In FFMS position, in addition to the effect of the prior factors, previous renal surgery also significantly reduces this distance. The distance between the colon and assumed PCNL trajectory at a puncture on the posterior axillary line was influenced mainly by patient position. In FFMS position the colon appears to be farther than in prone position. BMI and age significantly influence this distance to a lesser extent.

584 Minimally invasive percutaneous nephrolithotomy versus standard PCNL for management of renal stones in the flank-free modified supine position: Single center experience

584 Minimally invasive percutaneous nephrolithotomy versus standard PCNL for management of renal stones in the flank-free modified supine position: Single center experience

Flank-free Modified Supine Percutaneous Nephrolithotomy in Pediatric Age Group

To evaluate the safety and efficacy of pediatric percutaneous nephrolithotomy (PCNL) in the flank-free modified supine position (FFMSP). PCNL in the supine position is increasingly and successfully used in pediatric age group. Different modifications of supine positions have been described; however, the best supine position is not well established and remains a matter of debate. This prospective study included 22 children presenting with single renal pelvis stone (2-3 cm) in the period between May 2012 and April 2014. Diagnosis was set by plain x-ray and computed tomography in all patients. PCNL was performed with the patients placed in the FFMSP. The operative time and hospital stay were estimated. The outcome and any perioperative complications or conflicts were recorded. The study included 22 children (15 boys and 7 girls) with a solitary renal pelvis stone. Mean ± standard deviation age of the patients was 9.5 ± 3.2 years (range, 3-15.5 years). Stone length, operative time, and hospital stay had mean ± standard deviation of 2.4 ± 0.23 cm, 65.1 ± 18.7 minutes, and 4.4 ± 0.9 days. Stone-free rate was 90.9% after 1 session of PCNL. One patient (4.5%) needed a second-look PCNL. Shock wave lithotripsy was performed for another patient. Postoperative fever occurred in 4 patients (18.2%). One patient received postoperative blood transfusion. Postoperative transient urinoma occurred in 2 patients (9.1%). PCNL in pediatric age group via FFMSP was proved to be safe and effective in management of renal pelvis stones of size 2-3 cm. It provides stone clearance rate comparable with that reported of conventional PCNL in the prone position.

500 The relationship between the colon and the kidney in flank free modified supine position versus prone position on computed tomography

500 The relationship between the colon and the kidney in flank free modified supine position versus prone position on computed tomography

The Barts ‘Flank-Free’ Modified Supine Position for Percutaneous Nephrolithotomy

Background: The last decade has seen the emergence of a variety of supine positions for carrying out percutaneous nephrolithotomy (PCNL). These positions all differ with regard to ease of puncture under image guidance, operative field availability, ability to make and dilate multiple tracts and ease of combining retrograde intrarenal surgery (RIRS). As all of these positions have their limitations regarding the important parameters mentioned above, there is a need for a supine position which addresses some of the difficulties. Methods: We describe and illustrate our flank-free modified supine position, which we believe addresses a number of the issues. Results: Our position allows easy percutaneous access under fluoroscopy (torso only tilted to around 15°), space for placing (flank free of support) and dilating multiple tracts (kidney lies in a fairly neutral position and hence less mobile), a fairly horizontal tract allowing low intrarenal pressures and easy washout of fragments as well as allowing RIRS in a position of relative familiarity. The lesser torso rotation compared with the Valdivia, Galdakao modified and the Barts modified Valdivia positions also means it is more comfortable for patients. Conclusions: Our results are encouraging and easily comparable with published series on prone position, Valdivia, complete supine and the Barts modified Valdivia positions. We would like to highlight the Barts ‘flank-free’ modified supine position as one of the standard positions for carrying out supine PCNL.

Supine percutaneous nephrolithotomy (PCNL): ‘in vogue’ but in which position?

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Supine percutaneous nephrolithotomy (PCNL) has been described for over a decade and has equivalent success rates when compared with the more widely used prone position. The supine position offers a shorter operative duration with better access to the airway for the anaesthetist and also allows for simultaneous retrograde intra-renal surgery (RIRS). Various supine positions have been described but there is little data regarding their differing benefits and disadvantages. The present study looks at the different supine PCNL positions and compares the strengths and weaknesses of each. Each of the previously described supine PCNL positions have some limitations, e.g. ease of puncture under image guidance, the ability and ease of making and dilating multiple tracts, and allowing simultaneous RIRS. The new 'Barts flank-free modified supine position' is described, which seems to offer a good compromise and addresses some of these issues. It is important to highlight that one supine position does not fit all and the endourologist should familiarise themselves with these positions so the appropriate position can be used for the right patient and stone burden. • To discuss the relative merits of the different described supine positions for percutaneous nephrolithotomy (PCNL) and highlight the new 'Barts flank-free modified supine position', as the last decade has seen the emergence of various supine positions for PCNL. • We reviewed English publications on supine PCNL to look at the different positions being used to carry out PCNL and their relative merits. • We describe the new 'Barts flank-free modified supine position', which we think will add significantly to the armamentarium of the endourologist. • Five different supine positions are discussed. • These include the complete supine, the Valdivia, the Galdakao modified Valdivia, the Barts modified Valdivia and the herein described Barts flank-free modified supine position • These positions all differ in regard to ease of puncture under image guidance, operative field availability, ability to make multiple tracts and the ease of combining retrograde intra-renal surgery. • All of the supine positions decrease operative duration, as there is no need for repositioning and allow quick access to the airway for the anaesthetist. • However, one supine position does not fit all and the right one must be chosen for the right patient with the right stone burden. It is important for endourologists of today to familiarise themselves with these positions to be able to make these judgements.

Flank free modified supine position: A new modification for supine percutaneous nephrolithotomy

ObjectivesPercutaneous nephrolithotomy (PCNL) is the standard management for large and/or complex urolithiasis, but the standard patient position for PCNL is undecided. With the patient prone PCNL has several drawbacks, while when supine, as described previously, PCNL has mechanical limitations. We describe a modification that aims to overcome these limitations and provide easy access comparable to that in the prone position. Patients and methodsThis prospective study was carried out at the Urology Department, Zagazig University, Egypt, from October 2008 to March 2011, and included 78 patients (48 men and 30 women). First the patient was placed supine and then in the ‘flank-free modified’ supine position. The distance between the last rib and the iliac crest in the posterior axillary line was measured in both positions. ResultsThe mean age of the patients was 40.8years, the mean (SD) stone diameter was 3.4 (0.7) cm, the number of right/left stones was 34/44, and mean body mass index was 28.8kg/m2. The mean (SD) increase in the distance between the last rib and the iliac crest in the posterior axillary line in the flank free modified supine position vs. the previous supine position was 12 (0.8) mm. ConclusionThe flank-free modified supine position increases the distance between the last rib and the iliac crest, and, together with the absence of a cushion under the flank, provides ample space for puncture, dilatation, multiple tracts and manoeuvrability of the system with the nephroscope.

1029 Biochemical and haemodynamic changes in flank free modified supine position versus prone position during percutaneous nephrolithotomy

1029 Biochemical and haemodynamic changes in flank free modified supine position versus prone position during percutaneous nephrolithotomy