Does the metabolic syndrome or its components affect the outcome of percutaneous nephrolithotomy?

Analysis of factors affecting intraoperative hemorrhage during percutaneous nephrolithotomy and establishment of nomogram model

Intraoperative hemorrhage is an important factor affecting intraoperative safety and postoperative patient recovery in percutaneous nephrolithotomy (PCNL). This study aimed to identify the factors that influence intraoperative hemorrhage during PCNL and develop a predictive nomogram model based on these factors.A total of 118 patients who underwent PCNL at the Department of Urology, The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University from January 2021 to September 2023 was included in this study. The patients were divided into a hemorrhage group (58 cases) and a control group (60 cases) based on the decrease in hemoglobin levels after surgery. The clinical data of all patients were collected, and both univariate analysis and multivariate logistic regression analysis were conducted to identify the independent risk factors for intraoperative hemorrhage during PCNL. The independent risk factors were used to construct a nomogram model using R software. Additionally, receiver operating characteristic (ROC) curves, calibration curves and decision curve analysis (DCA) were utilized to evaluate the model.Multivariate logistic regression analysis revealed that diabetes, long operation time and low psoas muscle mass index (PMI) were independent risk factors for intraoperative hemorrhage during PCNL (P < 0.05). A nomogram model was developed incorporating these factors, and the areas under the ROC curve (AUCs) in the training set and validation set were 0.740 (95% CI: 0.637-0.843) and 0.742 (95% CI: 0.554-0.931), respectively. The calibration curve and Hosmer-Lemeshow test (P = 0.719) of the model proved that the model was well fitted and calibrated. The results of the DCA showed that the model had high value for clinical application.Diabetes, long operation time and low PMI were found to be independent risk factors for intraoperative hemorrhage during PCNL. The nomogram model based on these factors can be used to predict the risk of intraoperative hemorrhage, which is beneficial for perioperative intervention in high-risk groups to improve the safety of surgery and reduce the incidence of postoperative complications.

Segmental artery angioembolization as an efficient treatment modality for delayed hematuria with normal angiography: two case reports

BACKGROUND

Percutaneous nephrolithotomy is the most commonly used modality for the removal of kidney stones larger than 2 cm in size. Like other stone removal methods, percutaneous nephrolithotomy also has some complications, including bleeding and delayed hematuria. These complications are improved with conservative management and bed rest most of the time. However, it may require more invasive treatments. Angioembolization following an abnormal renal angiography is an efficient treatment modality for delayed hematuria. Furthermore, nephrectomy is suggested in uncontrolled cases of delayed hematuria when renal angiography is normal.

CASE PRESENTATION

We described two cases of uncontrolled delayed hematuria after percutaneous nephrolithotomy and angioembolization were carried out rather than potential nephrectomies. The first case was a 61-year-old Iranian man with left kidney stones, for whom percutaneous nephrolithotomy was planned. The patient was referred to the hospital after discharge with massive hematuria and had normal angiographic findings. An angioembolization was suggested for the patient and was carried out. His hematuria was dramatically improved within 30 minutes, and his hemoglobin level started to increase 2 days later. The second case was a 53-year-old Iranian man with kidney stones who was a candidate for right kidney percutaneous nephrolithotomy. The patient was referred to the hospital 4 days after discharge with a decreased hemoglobin level and massive hematuria. The patient had normal angiographic findings and was planned for angioembolization to control his hemorrhage, which dramatically decreased after the angioembolization within 60 minutes.

CONCLUSION

Embolization of the segmental arteries of the targeted calyx can eliminate hematuria of the patient and prevent further nephrectomy.

Impact of Metabolic Syndrome on Post-Operative Infection in Patients Undergoing Flexible Ureteroscopy Lithotripsy

Background: To investigate retrospectively whether metabolic syndrome (MetS) of flexible ureteroscopy (fURS) lithotripsy can be used to predict post-operative infection. Patients and Methods: After screening, 1,110 patients who received fURS lithotripsy for upper urinary tract stones in our center between January 2015 and December 2022 were analyzed retrospectively. Patients were divided into MetS-positive group and MetS-negative group. Post-operative infection was divided into fever, urosepsis, and septic shock. Relevant data during the peri-operative period were collected. Univariable and multivariable logistic regression analyses were adopted to estimate the impact of metabolic syndrome on post-operative infection in patients undergoing fURS lithotripsy. Results: Among the 1,110 patients, 427 tested positive for MetS, whereas 683 tested negative. Eighty-eight patients suffered from fever (67 patients in the MetS-positive group and 21 in the MetS-negative group). Forty-nine patients had urosepsis (29 patients in the MetS-positive group and 20 in the MetS-negative group), of whom seven patients developed septic shock. No patient developed multiple organ failure or died because of infection. The prevalence of post-operative infections in the MetS-positive group was higher than that in the MetS-negative group (p < 0.001). Multivariable logistic regression analyses showed that diabetes mellitus, MetS-positive, positive urine culture, and longer operation time were positively correlated with post-operative fever. Positive MetS, positive urine culture, and longer operation time were strongly correlated with post-operative urosepsis. Conclusions: Metabolic syndrome was found to be associated with post-operative infection in patients undergoing fURS lithotripsy, suggesting it can serve as a predictive factor.

Risk factors of stone residual after retrograde intrarenal surgery: A prospective cohort study

BACKGROUND

Complete removal of renal stones is crucial for optimal patient outcomes, but recent studies have reported residual stones after retrograde intrarenal surgery (RIRS). This study aimed to identify the associated risk factors to improve patient management and treatment selection.

METHODS

This cohort study was conducted over 18 months at two hospitals and recruited adult patients with renal stones less than 3 cm. Preoperative assessment included medical history, physical examination, laboratory tests, and radiological imaging. Intraoperative and postoperative data collection and follow-up were conducted to evaluate surgical success and potential complications.

RESULTS

A total of 100 patients were included, with a mean age of 45.3 ± 10.7 years and a mean BMI of 26.2 ± 1.4 kg/m2. Approximately 19% of the patients had residual stones after the RIRS procedure. The RUSS score showed good diagnostic performance with an AUC of 0.843, and the optimal cut point was ⩾2.0 with a sensitivity of 52.6% and specificity of 95.1%. Independent predictors of residual stones were multiple sites (OR = 24.98; p = 0.002), multiple stones (OR = 13.62, p = 0.002), stone size of 21-30 mm (OR = 4.91, p = 0.038), lower calyx site (OR = 4.85, p = 0.033), and surgeon experience of fewer than 50 cases (OR = 6.82, p = 0.020).

CONCLUSIONS

This study identifies several factors associated with residual stones after RIRS for renal stones, including stone size, location, number, and surgeon experience. The study suggests that the RUSS score can be used as a reliable tool for predicting the likelihood of residual stones, which can help clinicians in patient selection and treatment planning.

Peri-Operative Factors Affecting Blood Transfusion Requirements During PCNL: A Retrospective Non-Randomized Study

Background

Percutaneous nephrolithotomy (PCNL) is accepted as the gold standard of care for the treatment of large renal calculi. Kidney hemorrhage, which requires blood transfusion, is one of the most common complications after percutaneous kidney stone surgery.

Objective

To evaluate perioperative factors associated with transfusion requirements during PCNL.

Materials and Methods

A total of 226 patients with kidney calculi undergoing PCNL between January 2011 and December 2019 were reviewed retrospectively. We analyzed the impact of perioperative clinical factors on the necessity of blood transfusion during PCNL.

Results

The overall blood transfusion rate was 9.29%. Multiple perioperative determinants were significantly correlated with the application of packed red blood cells (PRCs), including larger stone size (p = 0.006), multiple tract punctures (p = 0.029), presence of staghorn calculi (p = 0.026), and long operative time (OT; p = 0.017). Multivariate analysis demonstrated that only multiple tract punctures independently affected blood transfusion requirements during PCNL (p = 0.038).

Conclusion

In accordance with the present study, only the multiple tract punctures were associated with blood transfusion requirements in PCNL.

Risk factors for hemorrhage requiring embolization after percutaneous nephrolithotomy: a meta-analysis

Background

The aim of this meta-analysis was to systematically review and identify the risk factors for severe hemorrhage after percutaneous nephrolithotomy (PCNL).

Methods

We searched the PubMed and EMBASE database for literature related to the risk factors of severe hemorrhage after PCNL requiring angiography and embolization through to September 2019. The necessary data for each eligible study were extracted by 2 independent reviewers. The Newcastle-Ottawa Scale (NOS) was used for assessing the methodological quality of the included studies. Statistical analyses were conducted using Comprehensive Meta-Analysis version 2 to identify whether there was a statistical association between risk factors and severe hemorrhage post-PCNL.

Results

The results of this meta-analysis showed that urinary tract infection (UTI) (OR =1.98, 95% CI, 1.21–3.26, P=0.007), diabetes mellitus (OR =4.07, 95% CI, 1.83–9.06, P=0.001), staghorn stone (OR =3.49, 95% CI, 1.25–9.76, P=0.017), and multiple tracts (OR =2.09, 95% CI, 1.33–3.28, P=0.001) were independent risk factors for severe hemorrhage post-PCNL, while hypertension (OR =1.18, 95% CI, 0.58–2.42, P=0.65) showed no significant statistical difference.

Conclusions

Urologists should focus on the above identified risk factors for severe hemorrhage post-PCNL, including UTI, diabetes mellitus, staghorn stone, and multiple tracts. More high-quality studies with larger sample sizes are needed to validate these conclusions.

The evolution of percutaneous nephrolithotomy: Analysis of a single institution experience over 25 years

INTRODUCTION

Over time, the incidence of nephrolithiasis has risen significantly, and patient populations have become increasingly complex. Our study aimed to determine the impact of changes in patient demographics on percutaneous nephrolithotomy (PCNL) outcomes.

METHODS

A retrospective analysis of a prospectively collected database was carried out from 1990-2015. Patient demographics, comorbidities, stone and procedure characteristics were analyzed. Multivariate logistic regression was used to evaluate differences in operative duration, complications, stone-free rate, and length of stay.

RESULTS

A total of 2486 patients with a mean age of 54±15 years, body mass index (BMI) of 31±8, and stone surface area of 895±602 mm² were analyzed; 47% of patients had comorbidities, including hypertension (22%), diabetes mellitus (14%), and cardiac disease (13%). Complication rate was 19%, including a 2% rate of major complications (Clavien grade III-V). There was a statistically significant increase in patient age, BMI, and comorbidities over time, which was correlated with an increased complication rate (odds ratio [OR] 1.15; p=0.010). The overall transfusion rate was 1.0% and remained stable (p=0.131). With time, both OR duration (mean Δ 16 minutes; p<0.001) and hospital length of stay (mean Δ 2.4 days; p<0.001) decreased significantly. Stone-free rate of 1873 patients with available three-month followup was 87% and decreased significantly over time (OR 1.09; p<0.001), but was correlated with an increased use of computed tomography (CT) scans for followup imaging.

CONCLUSIONS

Despite an increasingly complex patient population, PCNL remains a safe and effective procedure with a high stone-free rate and low risk of complications.

Number of Metabolic Syndrome Components Is the Central Predictor of the Impact of Metabolic Syndrome on Outcome of Percutaneous Nephrolithotomy in Staghorn Nephrolithiasis

Introduction: How to quantify the impact of metabolic syndrome (MetS) on percutaneous nephrolithotomy (PCNL) is unclear. We aimed to evaluate the quantified effect of the number of MetS components on the outcome of PCNL.

Materials and Methods: In this retrospective cohort study, consecutive 606 patients with idiopathic staghorn renal stones undergoing PCNL were included. The participants were divided into two groups: MetS(+) and MetS(−). The number of MetS components were calculated as 0 to 5. Primary outcomes were stone-free rate (SFR) and overall complication rate.

Results: MetS, obesity, hypertension, increased triglycerides (TG), decreased high-density lipoprotein cholesterol (HDL), and diabetes mellitus were found in 24.1%, 38.1%, 70.0%, 29.9%, 34.5%, and 26.4% of the patients, respectively. SFR values were comparable between groups. MetS resulted in a higher rate of overall complication (p < 0.001, odds ratio [OR] = 2.4, 95% confidence interval [CI] 1.67–3.69), blood transfusion, urosepsis, larger hemoglobin deficiency, and length of hospital stay. Multivariable analysis confirmed that fasting plasma glucose (FPG) (p = 0.033, OR = 1.164, 95% CI 10.22–1.348) and number of MetS components (p = 0.001, OR = 1.496, 95% CI 1.184–1.890) were independent risk factors, whereas HDL (p = 0.014, OR = 0.428, 95% CI 0.217–0.837) played an independent protective role. Compared with 0, having 3, 4, and 5 MetS components was associated with stepwise increase in complication rate (19.5% vs 34.2%, 41.5%, 62.5%, p = 0.027, 0.006, <0.001; OR = 2.1, 2.9, 6.9). Subgroup analysis showed that MetS(+) patients without complications were associated with lower systolic blood pressure, TG, and FPG (p = 0.010, 0.031, 0.002, respectively).

Conclusions: The number of MetS components is the central predictor in assessing both inner severity of MetS and outer risk for PCNL. The number of MetS components is recommended to be calculated on a scale of 0 to 5. Three, four, and five MetS components increase risk for PCNL in a stepwise manner regardless of the presence or absence of obesity. MetS components should be controlled preoperatively.

The Efficacy and Safety of Transcatheter Arterial Embolization to Treat Renal Hemorrhage after Percutaneous Nephrolithotomy

Purpose

The aim of this study was to evaluate the safety and efficacy of transcatheter arterial embolization (TAE) in patients with renal hemorrhage after percutaneous nephrolithotomy (PCNL) and evaluate the risk factors that may result in severe bleeding requiring TAE.

Methods

We retrospectively reviewed 121 patients with post-PCNL renal hemorrhage. Thirty-two patients receiving endovascular embolization were compared with 89 patients only receiving conservative treatment. The demographic and clinical data were recorded and compared between the two groups. The values of estimated glomerular filtration rate (eGFR) and serum creatinine (SCr) were recorded preoperatively, postoperatively, and at last follow-up and analyzed to evaluate the safety and efficiency of TAE.

Results

The successful hemostasis rate of conservative therapy was 73.6% (89/121) and that of TAE was 100% (32/32). SCr and eGFR were not significantly different before PCNL and after the last follow-up of TAE (SCr: 0.95 vs. 0.95 mg/dl, P=0.857; eGFR: 86.77 vs. 86.18 ml/min/1.73m², P=0.715). The univariate analysis demonstrated that advanced age, urinary tract infection, and diabetes mellitus were significantly associated with severe bleeding during PCNL. Multivariate analysis further identified that diabetes mellitus was an independent risk factor for severe bleeding needing TAE [odds ratio (OR): 3.778, 95% confidence interval (CI):1.276-11.190, and P=0.016].

Conclusion

TAE is a safe and effective procedure to treat renal hemorrhage that cannot be resisted by conservative treatment after PCNL. Diabetes mellitus was associated with high risks of severe bleeding needing TAE after PCNL.

Same-day angiography and embolization in delayed hematuria following percutaneous nephrolithotomy: an effective, safe, and time-saving approach

Purpose

To evaluate the results of prompt, same-day selective angiography and transcatheter angioembolization (TAE) on delayed post-percutaneous nephrolithotomy (PCNL) hematuria.

Materials and methods

Between 2011 and 2017, 21 patients with a mean age of 37 years (range, 21–60 years; males, 18) underwent digital subtraction angiography (DSA) and TAE to control delayed gross hematuria following PCNL. Discharged patients who following an uneventful PCNL presented to the emergency room with gross, brisk hematuria were included in the study and taken up for prompt, same-day DSA and same-session TAE with N-butyl-2-cyanoacrylate glue, without resorting to any initial conservative measures. All patient data were retrieved from medical records.

Results

Angiography revealed vascular lesions in all the cases (pseudoaneurysms, 14 cases; arteriovenous fistula, 2; mixed lesions, 5). The mean time of onset of delayed hemorrhage was 10.10±2.67 days. The average time from onset of bleeding to TAE was 4.31±0.64 hours (range 3.5–5.5 hours). Bleeding was controlled in all the cases without any recurrence or the need for further embolization. There were no procedural complications except for transient elevation of serum creatinine in four cases.

Conclusion

Primary DSA and TAE is a safe, effective, and time-saving alternative to conservative management for post-PCNL, delayed, gross hematuria.

Predictive factors of infectious complications in the postoperative of percutaneous nephrolithotomy

OBJECTIVE

Infectious complications (IC) following percutaneous nephrolithotomy surgery (PCNL) can be life-threatening. Our objective was to analyse preoperative predictors of IC in PCNL.

MATERIALS AND METHODS

A total of 203 patients who underwent PCNL were included in a prospective study between January 2013 and February 2016. A postoperative IC was defined as urinary infection/pyelonephritis, systemic inflammatory response syndrome or sepsis. The variables analysed were age, gender, number, size(cm) and side of stone; Hounsfield units,diabetes (insulin dependent or not), preoperative culture, isolated bacteria, multitract, bodymass index and surgical time (min). A multivariate forward stepwise (logistic regression) was performed.

RESULTS

IC occurred in 30 patients (14.8%): 9 (4.4%) had urinary infection, 14 (6.9%) systemic inflammatory response syndrome and 7 (3.5%) sepsis. In addition, 13 (43.3%) had negative preoperative urine culture, 15 (50%) positive and in 2 (6.7%) was not available. On the logistic regression analysis, stone size (cm), insulin dependent diabetes and female sex were independently associated with increased risk of IC (odds ratio [OR] 1.03, 14.6 and 7.8, respectively; P=.0001).

CONCLUSIONS

Patients with large stone burdens, insulin diabetes condition and female gender, should be counselled properly regarding postoperative infection risks and closely followed up to diagnose IC (specially sepsis) soon enough. Negative preoperative urine culture seems not reliable enough to exclude an infectious complication according to our results.

Metabolic Syndrome Increases Risk of Postoperative Myocardial Infarction Following Percutaneous Nephrolithotomy

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for upper tract stone burdens greater than 2 cm. Metabolic syndrome (MetS) is a constellation of conditions (diabetes mellitus, hypertension, dyslipidemia, and obesity) and is a risk factor for nephrolithiasis. Our objective was to investigate adverse cardiovascular outcomes of PCNL in patients with comorbid MetS diagnoses.

MATERIALS AND METHODS

Data from the Healthcare Cost and Utilization Project State Inpatient Database for Florida and California were used to identify PCNL patients (ICD9: 55.03, 55.04) between 2007 and 2011. Patients were categorized having 0, 1-2, or 3-4 components of MetS. Postoperative myocardial infarction (MI) and inhospital mortality rate outcomes were identified. Multivariate logistic regression was used to control for patient characteristics (age, race, and primary insurance provider) and medical comorbidities.

RESULTS

PCNL was performed on 39,868 patients, of whom 17,932 (45.0%) had no MetS conditions, 19,268 (48.3%) had 1-2 MetS conditions, and 2668 (6.7%) had 3-4 MetS conditions. With increasing MetS conditions, patients had increased incidence of postoperative MI (0: 0.6%; 1-2: 1.0%; 3-4: 1.8%, p < 0.001). On multivariate analysis, the presence of 3-4 MetS comorbidities increased the odds of a postoperative MI (1-2: odds ratio [OR] 1.2, 95% confidence interval [CI] 0.94-1.53, p = 0.147; 3-4: OR 2.2, 95% CI 1.54-3.15, p < 0.001).

CONCLUSIONS

MetS patients have an increased risk of MI following PCNL given their pre-existing comorbidities. Routine preoperative cardiac testing may benefit this population before PCNL.

Using the Modified Clavien Grading System to Classify Complications of Percutaneous Nephrolithotomy

Purpose

A modified Clavien classification system has been proposed to grade perioperative complications. We share our experience in grading the complications of percutaneous nephrolithotomy (PNL), according to this new classification.

Methods

A total of 809 PNLs performed between 2010 and 2014 were reviewed retrospectively. The modified Clavien classification system, which classifies the perioperative complications into 5 grades, was applied. Grade wise comparison of complications between the patients with simple and complex calculi was done. We also carried out a univariate analysis of different predictors of complications after surgery.

Results

A total of 253 perioperative complications were observed in 237 (29.29%) patients. Most complications were related to bleeding and urinary leakage. Patients with complex calculi had significantly more number of complications across all Clavien groups. In a univariate analysis, positive preoperative urine culture and multiple access for stone clearance were identified to be the independent predictors of complications.

Conclusion

The modified Clavien system is a simplistic grading system for classification of postoperative complications. However, it suffers from various shortcomings. Therefore, till the proposition of a more comprehensive classification system, the modified Clavien system is useful for reporting the complications and short-term outcomes of PNL.

Risk Factors Related with Retroperitoneal Laparoscopic Converted to Open Nephrectomy for Nonfunctioning Renal Tuberculosis

PURPOSE

The present study was designed to investigate the risk factors affecting the conversion to open surgery in retroperitoneal laparoscopic nephrectomy of nonfunctioning renal tuberculosis (TB).

PATIENTS AND METHODS

The records of 144 patients who underwent a retroperitoneal laparoscopic nephrectomy procedure by a single surgeon were retrospectively reviewed. The following factors, including age, sex, body mass index (BMI), diabetes status, hypertension status, side of kidney, size of kidney, degree of calcification, mild perirenal extravasation, contralateral hydronephrosis, the time of anti-TB, and surgeon experience were analyzed. Univariate and multivariate logistic regression analyses were used for statistical assessment.

RESULTS

Twenty-three patients were converted to open surgery and the conversion rate was 15.97%. In univariate analysis, BMI ≥35 kg/m² (p = 0.023), hypertension (p = 0.011), diabetes (p = 0.003), and kidney size (p = 0.032) were the main factors of conversion to open surgery. Sex, age, side, anti-TB time, calcification, mild extravasation, and surgeon experience were not significantly related. In multivariate regression analysis, BMI ≥35 kg/m², hypertension, diabetes, and enlargement of kidney were the most important factors for conversion to open surgery.

CONCLUSIONS

Depending on the results achieved by a single surgeon, BMI ≥30 kg/m², diabetes, hypertension, and enlargement of kidney significantly increased the conversion risk in retroperitoneal laparoscopic nephrectomy for nonfunctioning renal TB.

The Effect of Metabolic Syndrome on the Success and Complications of Percutaneous Nephrolitotomy

BACKGROUND

The aim of this study was to investigate the effect of Metabolic syndrome (MetS) on the success and complications of percutaneous nephrolithotomy (PNL).

METHODS

Two hundred ten patients who had undergone PNL for kidney stones in our clinic between May 2012 and May 2014 were retrospectively analyzed. The patients were divided into two groups based on whether they had diagnostic criteria for MetS. All patients had lower pole kidney stones between 15 and 20 mm. Complication rates between groups were evaluated using a modified Clavien grading system.

RESULTS

Group1 was a standard PNL group and group 2 consisted of patients with MetS. Mean stone size was 293.25 ± 102.4 mm(2) for group 1 and 301.10 ± 169.5 mm(2) for group 2 (p < 0.05). Mean hospitalization days, fluoroscopy duration, and mean hematocrit loss were significantly higher in group 2. Mean operative time and need for blood transfusions were higher in group 2 but statistically insignificant. One hundred twenty five patients in group 1 (96.1%) and 72 patients in group 2 (90%) obtained stone-free state.

CONCLUSIONS

Our study results reveal an increase in complications and morbidity for patients with MetS during PNL.

Risk factors for sepsis after percutaneous renal stone surgery

Since its introduction into the endourologist's armamentarium almost 40 years ago, percutaneous nephrolithotomy (PCNL) has become the standard of care for patients with large-volume nephrolithiasis. Postoperative infection is one of the most common complications of the procedure, and postoperative sepsis is one of the most detrimental. A number of factors have been found to increase the risk of postoperative sepsis. These include patient characteristics that are known preoperatively, such as urine culture obtained from the bladder or from the renal pelvis if percutaneous access to the renal pelvis is obtained in advance to the procedure. Neurogenic bladder dysfunction secondary to spinal cord injury and anatomical renal abnormalities, such as pelvicalyceal dilatation, have also been associated with increased incidence of fever and sepsis after the procedure. Several intraoperative factors, such as the average renal pressure sustained during PCNL and the operative time, also seem to increase the risk of sepsis. Finally, the contribution of postoperative factors, such as presence of a nephrostomy tube or a urethral catheter, has also been investigated. A short preoperative course of antibiotics has been found to significantly decrease the rate of postoperative fever and sepsis. Novel agents targeted at sepsis prevention and treatment, such as anti-endotoxin antibodies and cholesterol-lowering drugs statins, are currently under investigation.

Parenchymal thickness: does it have an impact on outcomes of percutaneous nephrolithotomy?

OBJECTIVE

To evaluate whether renal parenchymal thickness (RPT) has an effect on the outcomes of percutaneous nephrolithotomy (PNL).

METHODS

We performed a retrospective analysis of 144 patients with lower pole and/or renal pelvic stones who underwent PNL. The relationship between RPT and peri- and postoperative measures was evaluated.

RESULTS

The average age was 45.94 ± 14.47 (15-76) years. The mean BMI was calculated as 27.47 ± 4.73 (16.9-44.9) kg/m(2). The mean stone burden was 293 ± 126 (150-800 mm(2)). The mean RPT was measured as 17.33 ± 5.32 (6-35) mm. No correlation was detected between the RPT and the operation or fluoroscopy times or the duration of hospitalization (p = 0.63, 0.52, 0.08, respectively). The mean drop in hemoglobin level was 1.45 ± 1.25 (0-9) g/dl. A negative correlation was detected between hemoglobin drop and RPT (p = 0.01, r = -0.23). However, the RPT was similar in patients who did or did not require a blood transfusion (p = 0.09). The RPT was found to have no impact on success rate (p = 0.4).

CONCLUSION

The postoperative hemoglobin drop increases in parallel with the increase in RPT. However, no relationship was detected between the RPT and blood transfusion, overall success rate or any other perioperative parameters.

Isolated upper pole access in percutaneous nephrolithotomy: a large-scale analysis from the CROES percutaneous nephrolithotomy global study

PURPOSE

We analyzed the indications for and outcomes of percutaneous nephrolithotomy using upper pole access.

MATERIALS AND METHODS

Between 2007 and 2009 prospective data were collected by the Clinical Research Office of the Endourological Society (CROES) from consecutive patients at 96 centers globally. Data on 4,494 patients were included in this analysis. Patients were divided into upper and lower pole access groups based on the location of percutaneous renal access. Preoperative characteristics and outcomes were compared between the 2 groups by univariate and multivariate tests.

RESULTS

The upper pole access group had more staghorn stones (21.7% vs 15.5%, p <0.001) and a greater stone burden (mean ± SD 476 ± 390.5 vs 442 ± 344.9 mm(2), p = 0.091). Mean operative time was 92.4 ± 46.1 and 75.1 ± 41.3 minutes in the upper and lower pole groups, respectively (p <0.001). The stone-free rate was lower in the upper pole access group (77.1% vs 81.6%, p = 0.030). The overall complication rate was higher in the upper pole group with a higher incidence of hydrothorax (5.8% vs 1.5%) but a lower incidence of pelvic perforation (1.8% vs 3.2%). Mean hospital stay was longer in the upper pole group (p = 0.048). Success and complication rates were similar in upper pole access subgroups, defined as definitive (staghorn and isolated upper calyceal stones) and elective (pelvic, middle calyceal and lower pole stones) indications.

CONCLUSIONS

Isolated upper pole access is indicated in a select group of patients with complex stones. Upper calyceal and staghorn stones are more commonly managed by upper pole access, which is associated with a higher complication rate and longer hospital stay as well as a lower stone-free rate due to procedure complexity.

The impact of metabolic syndrome on long-term outcomes of percutaneous nephrolithotomy (PCNL)

Study Type--Prognosis (cohort) Level of Evidence 2b. What's known on the subject? and What does the study add? The presence of metabolic syndrome is associated with development of kidney stones and an increase in the stone-recurrence rate. However, studies reporting long-term results of percutaneous nephrolithotomy (PCNL) in metabolic syndrome are lacking. The present study showed that metabolic syndrome was associated with worsening renal function at long-term follow-up and the stone-recurrence rate recurrence after PCNL in patients with metabolic syndrome was 3.2-fold higher compared with the control group.

OBJECTIVE

• To investigate the impact of metabolic syndrome on long-term kidney function and stone recurrence rates after percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

• In all, 73 patients with metabolic syndrome who underwent stone analysis and had a minimum follow-up of 12 months after PCNL were reviewed. • In addition, 73 patients without any metabolic syndrome components who had undergone PCNL and were followed-up for at least 12 months were included in the study as the control group. • These control group patients were selected from 226 patients who were matched with the patients with metabolic syndrome using a 1 : 1 ratio. The matching parameters were age, gender and stone size.

RESULTS

• Stone analyses showed that calcium oxalate monohydrate (52.0%) and uric acid (21.9%) were most common among patients with metabolic syndrome, whereas calcium oxalate monohydrate (76.7%) was the most common stone type in the control group. • Stone recurrences occurred with a mean (sd, range) of 36.1 (21.3, 12-109) months follow-up in 26 patients (41.9%) and 12 patients (18.9%) in the metabolic syndrome and control groups, respectively (P = 0.003). • While estimated glomerular filtration rate was decreased from 87.8 to 66.6 mL/min/1.73 m(2) in the metabolic syndrome group, it changed from 96.4 to 91.2 mL/min/1.73 m(2) in control group at long-term follow-up.

CONCLUSIONS

• The most frequent stone type was calcium oxalate monohydrate in patients with or without metabolic syndrome. • In patients with metabolic syndrome who underwent PCNL, the stone recurrence rate was >40%. • Metabolic syndrome is associated with worsening renal function at long-term follow-up.

Correlation of metabolic syndrome with urinary stone composition

OBJECTIVE

To determine the correlation between metabolic syndrome and the distribution of stone components in patients with urolithiasis.

METHODS

Between January 2007 and December 2010, renal or ureteral stones were collected from 712 patients (432 males, 280 females) who underwent surgical intervention at three hospitals in South Korea. Metabolic syndrome was defined according to the latest definition of the International Diabetes Federation, using ethnicity- and sex-specific cut-off values for central obesity. Patients were assessed by factors used in metabolic syndrome. All urinary stones were analyzed using infrared spectrophotometry and categorized according to their main component.

RESULTS

The patients' mean age was 55.9 years (range 19-93 years). Of the 712 patients, 347 (48.7%; 205 males, 142 females) had a diagnosis of metabolic syndrome. Calcium oxalate (71.5%), uric acid (15.3%), carbonate apatite (8.0%) and struvite (4.1%) calculi were found as the main stone components. Overall, the proportion of uric acid calculi was markedly higher in patients with rather than without metabolic syndrome (19.6 vs 11.2%; P=0.002). However, the proportion of calcium oxalate, carbonate apatite and struvite calculi did not differ between the two groups. The multivariable-adjusted odds ratio for uric acid calculi according to the metabolic syndrome components indicated that the presence of metabolic syndrome was associated with a 93% increased odds ratio of uric acid calculi compared with the absence of metabolic syndrome. Impaired fasting glucose and hypertriglyceridemia were independent risk factors for uric acid calculi.

CONCLUSIONS

Metabolic syndrome is associated with a significantly increased risk of uric acid calculi development, especially those with impaired fasting glucose and hypertriglyceridemia.

Risk factors associated with nephrolithiasis: a case-control study in China

Nephrolithiasis is a multifactorial disease. The authors conducted a case-control study in China to explore its associated risk factors. A total of 725 nephrolithiasis patients and 553 controls were asked to complete a questionnaire that asked for information about psychological, behavioral, and dietary factors along with a physical and blood biochemical examination. For men, higher education was negatively associated with nephrolithiasis (odds ratio [OR] = 0.6; 95% confidence interval [CI] = 0.4-1.0), whereas hypso-waist-to-hip ratio (hypso-WHR), defined as WHRs >0.9 for men and >0.8 for women (OR = 2.2; 95% CI = 1.4-3.4); overexercise (OR = 2.1; 95% CI = 1.3-3.5); and having experienced negative life events (OR = 2.2; 95% CI = 1.2-4.1) were positively associated with nephrolithiasis. For women, higher fluid intake was negatively associated with nephrolithiasis (OR = 0.6; 95% CI = 0.3-0.9), and abnormal status of blood pressure (BP) and blood lipids was positively associated with nephrolithiasis. Varied factors were related to differences in nephrolithiasis occurrence between genders. Besides taking enough fluids, maintaining a normal metabolic status, avoiding overexercise, and reducing BP might be beneficial in preventing nephrolithiasis.

Beware the low urine pH--the major cause of the increased prevalence of nephrolithiasis in the patient with type 2 diabetes

There is an increased prevalence of nephrolithiasis and an increase in the incidence of renal colic in patients with diabetes, obesity, hypertension and insulin resistance because of an increased frequency of uric acid crystallization. Uric acid crystallization occurs in the milieu of an acid urine and is not due to hyperuricosuria as with insulin resistance, urinary uric acid levels are generally decreased because of increased renal tubular reabsorption. However, in the presence of insulin resistance, there is decreased renal tubular generation of ammonia and increased sodium absorption leading to acidification of the urine and uric acid crystallization. The presence of a low urine pH should alert the clinician to the increased risk of nephrolithiasis particularly in the obese, diabetic or hypertensive patient. Prevention of nephrolithiasis can be achieved in susceptible individuals either by alkalizing the urine and/or by further decreasing the uric acid content of the urine with a xanthine oxidase inhibitor such as allopurinol.

Impact of percutaneous renal access technique on outcomes of percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

Percutaneous nephrolithotomy (PCNL) is regarded as the gold standard for the treatment of patients with renal stones larger than 2 cm in diameter. Creating a percutaneous renal access is the initial and probably the most important step in performing a PCNL. Two primary methods of obtaining proper percutaneous renal access under fluoroscopic guidance are described: The "triangulation" and the "eye of the needle" techniques. In this article, we compare these two techniques in terms of success and complication rates.

PATIENTS AND METHODS

From October 2010 to May 2011, 80 patients with simple renal stones were prospectively randomized into two groups according to the percutaneous renal access technique used for PCNL. Patients in group 1 (n=40) were assigned to the eye of the needle technique, and patients in group 2 (n=40) were assigned to the triangulation method. Patients needing multiple access points were excluded from the study. The preoperative, operative, and postoperative follow-up findings were thereafter analyzed and compared.

RESULTS

No significant difference between the two groups was detected in terms of patient demographics (mean patient age, body mass index, stone size, or stone location). The operation time, fluoroscopic screening time (FST), and duration of hospitalization were similar in both groups (P=0.52, P=0.32, P=0.26, respectively). Patients in group 1 had a larger drop in hematocrit postoperatively than patients in group 2 (7.6 ± 3.7 vs 4.8 ± 2.1, P=0.001). The blood transfusion rate (7.5%) was similar in both groups, however. Although the complication rate was higher in group 1 than group 2, no significant difference was detected (20% vs 15%, P=0.76).

CONCLUSIONS

The present study demonstrates that PCNL can be performed safely using two different percutaneous access techniques. The two techniques studied in this trial had similar FSTs, operation and hospitalization times, success rates, and complication rates.

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

INTRODUCTION

The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors.

METHODS

The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph's Hospital, London, Canada were reviewed. Information included patients' clinical histories, 24 hour urine collections, blood chemistry and stone analysis.

RESULTS

Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003).

CONCLUSION

The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

Prediction of morbidity and mortality after percutaneous nephrolithotomy by using the Charlson Comorbidity Index

OBJECTIVES

To determine whether the Charlson Comorbidity Index (CCI) predicts postoperative medical complications and death in patients treated with percutaneous nephrolithotomy (PCNL).

METHODS

A total of 1406 PCNL procedures were performed at 4-stone referral centers between September 2004 and March 2011 were reviewed in this multicenter study. Variables included patient and stone characteristics, preoperative comorbidities, intraoperative data, and postoperative complications, including mortality.

RESULTS

The present study included 868 (61.7%) men and 538 (38.3%) women. Mean patient age was 44.1 years (range 1-81). CCI score was calculated as "0" for 993 patients (70.6%, called group I), "1" for 316 patients (22.5%, called group II) and"≥2" for 97 patients (6.9%, called group III). The incidence of comorbidities increased with age (P=.001). The overall postoperative complication rate was 29.3%. Life-threatening medical complications developed in 2.9% of patients in group I, 7.6% of patients in group II, and 21.6% of patients in group III, (P=.001). There were 3 deaths for an overall 0.2% mortality rate. Perioperative bleeding requiring blood transfusion was observed in 9.5% of patients, and we found an increased risk of hemorrhage associated with CCI score (P=.049). High CCI score, patient age, hemorrhage, and operative time were significantly related to higher medical complication rates after PCNL.

CONCLUSIONS

CCI is a quick, simple, and reproducible scoring system that accurately predicts the morbidity and mortality of PCNL.

Can we avoid percutaneous nephrolithotomy in high-risk elderly patients using the Charlson comorbidity index?

OBJECTIVE

To determine whether Charlson comorbidity index (CCI) predicts the postoperative complications after percutaneous nephrolithotomy (PCNL) and could be a plausible option to avoid surgery and its potential risks in elderly patients with significant comorbidites.

METHODS

The data from 283 elderly patients (age ≥ 60 years) who underwent PCNL in 4 large referral hospitals were reviewed in the present multicenter study. For each patient, we evaluated pre-existing comorbidities and calculated the CCI score. The patients were classified to 3 CCI score categories (0, 1, ≥ 2) and compared regarding the stone-free and complications rates.

RESULTS

The mean patient age was 64.7, 65.6, and 67.7 years in the 3 groups. The stone-free rate after primary PCNL was 85.7% in group 1, 86.1% in group 2, and 75.0% in group 3. These rates increased to 90.8%, 95.4%, and 83.9% after a second intervention (P = .049). The overall postoperative complication rate was 38.8%. The most common complication was hemorrhage necessitating blood transfusion in 34 patients (12%), and we found an increased risk of hemorrhage associated with the CCI score (P = .011). Life-threatening medical complications developed in 7.6% of the patients in group 1, 12% of the patients in group 2, and 28.6% of the patients in group 3 (P = .001). A multivariate logistic regression analysis showed that a high CCI score, bleeding, and operative time had significant influence on the postoperative medical complication in this population.

CONCLUSION

Conservative management of asymptomatic large kidney stones appears to be a safe alternative to PCNL in elderly patients with significant comorbidites.

Incidence, prevention, and management of complications following percutaneous nephrolitholapaxy

CONTEXT

Incidence, prevention, and management of complications of percutaneous nephrolitholapaxy (PNL) still lack consensus.

OBJECTIVE

To review the epidemiology of complications and their prevention and management.

EVIDENCE ACQUISITION

A literature review was performed using the PubMed database between 2001 and May 1, 2011, restricted to human species, adults, and the English language. The Medline search used a strategy including medical subject headings (MeSH) and free-text protocols with the keywords percutaneous, nephrolithotomy, PCNL, PNL, urolithiasis, complications, and Clavien, and the MeSH terms nephrostomy, percutaneous/adverse effects, and intraoperative complications or postoperative complications.

EVIDENCE SYNTHESIS

Assessing the epidemiology of complications is difficult because definitions of complications and their management still lack consensus. For a reproducible quality assessment, data should be obtained in a standardized manner, allowing for comparison. An approach is the validated Dindo-modified Clavien system, which was originally reported by seven studies. No deviation from the normal postoperative course (Clavien 0) was observed in 76.7% of PNL procedures. Including deviations from the normal postoperative course without the need for pharmacologic treatment or interventions (Clavien 1) would add up to 88.1%. Clavien 2 complications including blood transfusion and parenteral nutrition occurred in 7%; Clavien 3 complications requiring intervention in 4.1.%; Clavien 4, life-threatening complications, in 0.6%; and Clavien 5, mortality, in 0.04%. High-quality data on complication management of rare but potentially debilitating complications are scarce and consist mainly of case reports.

CONCLUSIONS

Complications after PNL can be kept to a minimum in experienced hands with the development of new techniques and improved technology. A modified procedure-specific Clavien classification should be established that would need to be validated in prospective trials.

Variables that influence operative time during percutaneous nephrolithotomy: an analysis of 1897 cases

BACKGROUND AND PURPOSE

Operative time is an important perioperative factor and is related to postoperative complications and procedural cost-effectiveness. There are few studies, however, investigating factors that affect operative time during percutaneous nephrolithotomy (PCNL). In this study, patient and kidney stone-related factors that influence operative time were analyzed.

MATERIALS AND METHODS

Clinical records from 1897 patients with renal calculi who underwent PCNL were retrospectively reviewed, and these patients were divided into two groups based on their median operative time (group 1: ≤60 min; group 2: >60 min). Multivariate analyses as well as univariate analyses including chi-square, Fisher exact and Mann Whitney U tests were used to investigate the effects of independent variables on operative time, including patient and kidney stone-related factors such as age, sex, body mass index, history of ipsilateral open surgery, shockwave lithotripsy, presence of hydronephrosis, stone burden, stone type and opacity, and surgical experience.

RESULTS

The mean operative time was 64.9±27.6 minutes (range 10-220 min). Univariate analyses determined that a history of open surgery, presence of hydronephrosis, stone type and size, and surgical experience correlated with operative time (P<0.05 for all). Multivariate analyses revealed that presence of hydronephrosis (odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.17-1.78, P=0.002), stone type (OR: 2.12, 95% CI: 1.69-2.70, P<0.0001), stone burden (OR: 2.44, 95% CI: 1.85-3.12, P<0.0001), and surgical experience (OR: 0.56, 95% CI: 0.46-0.70, P<0.0001) were significant independent factors in influencing operative time.

CONCLUSIONS

Presence of hydronephrosis, renal stone size and type significantly affect the operative time during PCNL. The duration of the operation was also observed to decrease with increased surgical experience.

Anaesthetic considerations with the metabolic syndrome

The rising incidence of obesity has led to increased prevalence of a distinct, obesity-related metabolic syndrome. This syndrome is characterized by truncal obesity, insulin resistance, altered lipid levels, and hypertension. Definition of the metabolic syndrome rests on a set of clinical criteria instead of a single diagnostic test. It carries a different risk profile than obesity alone, and poses special challenges for the anaesthesiologist. These include preoperative risk stratification for common comorbidities, identifying reasonable thresholds for implementing preoperative risk reduction, overcoming obesity-related issues in intraoperative management, and delivering safe postoperative care. The metabolic syndrome predisposes to coronary artery disease, congestive heart failure, obstructive sleep apnoea, pulmonary dysfunction, and deep venous thrombosis. Because its different presentations can have different risk profiles, anaesthesiologists should assess the cumulative risk of each component of the metabolic syndrome separately, which significantly complicates preoperative management. Since obesity itself is difficult to treat, preoperative risk reduction can be difficult. Few data exist to inform best practice as to the anaesthetic care of patients with metabolic syndrome. This review evaluates and synthesizes current evidence regarding perioperative care for patients with the metabolic syndrome, including indications for preoperative testing; use of aspirin, β-blockers, statins, heparin, and angiotensin-converting enzyme inhibitors; anaesthetic strategies including regional anaesthesia; and postoperative management including continuous positive pressure ventilation by mask, prevention of pulmonary embolism, and indications for advanced respiratory monitoring.

Factors affecting bleeding during percutaneous nephrolithotomy: single surgeon experience

PURPOSE

To investigate variables that affect bleeding during percutaneous nephrolithotomy (PCNL), focusing on the experience of a single surgeon.

PATIENTS AND METHODS

The records of 649 PCNL procedures that were performed by the same surgeon were reviewed retrospectively. The effect of surgical experience; patient and stone-related factors, including age, sex, hypertension, and diabetes, serum creatinine level, history of ipsilateral renal procedures, stone surface area and type, degree of hydronephrosis, preoperative hemoglobin level; operative factors, such as the calix of puncture, number of accesses, operative time; and intraoperative complications, such as pelvicaliceal system perforation on bleeding (described as decrease in hemoglobin level and need for blood transfusion), were investigated. For statistical assessment, univariate analyses and multivariate stepwise regression analyses were used.

RESULTS

A 92.3% success rate was achieved after one session PCNL. The overall blood transfusion rate was 10.8%. The number of accesses, stone type, diabetes, preoperative hemoglobin level, and operative time were the most important factors for blood transfusion requirement. In the receiver operating characteristic curve, the best cutoff point of operative time was 58 minutes for the blood transfusion requirement. Multivariate stepwise regression analyses showed that there was an association between diabetes, operative time, number of accesses, and stone type with the decrease in hemoglobin levels. No correlation between surgical experience and decrease in hemoglobin level as well as blood transfusion necessity was found.

CONCLUSIONS

Depending on the results achieved by a single surgeon, multiple access tracts, staghorn calculi, presence of diabetes, and prolonged operative time, but not surgical experience, significantly increased blood loss during PCNL.

Tubeless procedure is most important factor in reducing length of hospitalization after percutaneous nephrolithotomy: results of univariable and multivariable models

OBJECTIVES

To evaluate the effects of kidney stones and patient-related parameters on the length of hospitalization (LOH), which is one important factor affecting the cost effectiveness of percutaneous nephrolithotomy (PCNL). Recently, increases in healthcare costs have highlighted the importance of evaluating the cost effectiveness of a treatment as much as its efficacy.

MATERIAL AND METHOD

During an 8-year period, the records of 1669 patients with renal calculi who underwent PCNL were reviewed retrospectively. Eleven patients with urosepsis were excluded from the present study. A total of 1658 patients were categorized into 2 groups (group 1 = ≤2 days; group 2 = >2 days) according to the median LOH (median = 2 days). Multivariate binary logistic regression analysis was used to detect the effects of independent variables, including the patient age, gender, body mass index, history of extracorporeal shock wave lithotripsy or open surgery, stone size and opacity, presence of hydronephrosis, and localization and number of accesses, on the LOH after PNL.

RESULTS

Overall success was achieved in 86.2% of cases after one session of PCNL. The mean length of hospitalization was 2.89 ± 1.66 days (range, 1-21). According to the outcome of the multivariate analysis, diabetes (P = .0001, OR = 1.67), impaired kidney function (P = .03, OR = 1.64), stone size (P = .031, OR = 1.31), number of accesses (P = .001, OR = 1.59), intercostal access (P = .001, OR = 1.79), and tubeless procedure (P = .0001, OR = 0.23) were variables influencing LOH.

CONCLUSIONS

The presence of diabetes, a large stone burden, intercostals access, multiple accesses, and impaired kidney function prolong the LOH after PCNL. The use of the tubeless procedure was able to diminish the LOH.

Obesity, metabolic syndrome, and the surgical patient

Contemporary life, with its sedentary lifestyles, fast foods, processed foodstuff, and desk-bound service employment, is beset by an epidemic of overweight and obese individuals. The World Health Organization reported that worldwide a billion adults are overweight and at least 30% of them are obese. Moreover, increasing numbers of children are obese. In the United States, 2 National Health and Nutrition Examination Surveys of adults aged 20 to 74 years showed that the prevalence of obesity increased from 15% in the 1976 to 1980 survey to 34% in the 2003 to 2004 survey. Obesity and the metabolic syndrome are unfortunately becoming increasingly common perioperative issues. The ultimate aim of caring for such patients is to find ways to minimize the untoward effects of surgery in patients who are obese or have metabolic syndrome.

Obesity, metabolic syndrome, and the surgical patient

Contemporary life, with its sedentary lifestyles, fast foods, processed foodstuff, and desk-bound service employment, is beset by an epidemic of overweight and obese individuals. The World Health Organization reported that worldwide a billion adults are overweight and at least 30% of them are obese. Moreover, increasing numbers of children are obese. In the United States, 2 National Health and Nutrition Examination Surveys of adults aged 20 to 74 years showed that the prevalence of obesity increased from 15% in the 1976 to 1980 survey to 34% in the 2003 to 2004 survey. Obesity and the metabolic syndrome are unfortunately becoming increasingly common perioperative issues. The ultimate aim of caring for such patients is to find ways to minimize the untoward effects of surgery in patients who are obese or have metabolic syndrome.