Impact of Obesity on Outcomes of Supine Percutaneous Nephrolithotomy

Optimizing Colon Identification by Window Setting Modulation on Noncontrast Computed Tomography Prior to Percutaneous Nephrolithotomy

Background: Preoperative identification of the bowel on imaging is essential in planning renal access during percutaneous nephrolithotomy (PCNL) and avoiding colonic injury. We aimed this study to assess which noncontrast computed tomography (NCCT) window setting provides the optimal colonic identification for PCNL preoperative planning. Methods: Ten urologic surgeons (four seniors, six residents) reviewed 22 images of NCCT scans in both abdomen and lung window settings in a randomized blinded order. Colonic area delineation in each image was performed using a dedicated, commercially available area calculator software. A comparison of the marked colonic area between the abdomen and lung window settings was performed. Results: Overall, the mean marked colonic area was greater in the lung window compared with the abdomen window (8.82 cm2 vs 7.4 cm2, respectively, p < 0.001). Switching the CT window from abdomen to lung increased the identified colonic area in 50 cases (50%). Intraclass correlation showed good agreement between the senior readers and among all readers (0.92 and 0.87, respectively). Similar measurements of the colonic area in both abdomen and lung windows were observed in 26/44 (60%) of the seniors cases and in 7/66 (10%) of the resident cases (p = 0.002). Conclusion: Lung window solely or in combination with abdomen window appears to provide the most accurate colonic identification for preoperative planning of PCNL access and potentially reduce the risk of colonic injury. This pattern is more evident among young urologists, and we propose to introduce it as a standard sequence in PCNL preplanning.

Clinical Considerations for Patients Experiencing Acute Kidney Injury Following Percutaneous Nephrolithotomy

Acute kidney injury (AKI) is a common postoperative outcome in urology patients undergoing surgery for nephrolithiasis. The objective of this study was to determine the prevalence of postoperative AKI and its degrees of severity, identify risk factors, and understand the resultant outcomes of AKI in patients with nephrolithiasis undergoing percutaneous nephrolithotomy (PCNL). A cohort of patients admitted between 2012 and 2019 to a single tertiary-care institution who had undergone PCNL was retrospectively analyzed. Among 417 (n = 326 patients) encounters, 24.9% (n = 104) had AKI. Approximately one-quarter of AKI patients (n = 18) progressed to Stage 2 or higher AKI. Hypertension, peripheral vascular disease, chronic kidney disease, and chronic anemia were significant risk factors of post-PCNL AKI. Corticosteroids and antifungals were associated with increased odds of AKI. Cardiovascular, neurologic complications, sepsis, and prolonged intensive care unit (ICU) stay percentages were higher in AKI patients. Hospital and ICU length of stay was greater in the AKI group. Provided the limited literature regarding postoperative AKI following PCNL, and the detriment that AKI can have on clinical outcomes, it is important to continue studying this topic to better understand how to optimize patient care to address patient- and procedure-specific risk factors.

Predictive factors for success after supine percutaneous nephrolithotomy: an analysis of 961 patients

OBJECTIVE:

The aim of this study was to evaluate the predictive factors for success following percutaneous nephrolithotomy in the supine position.

METHODS:

Patients who underwent percutaneous nephrolithotomy in the supine position from June 2011 to October 2018 were evaluated. Age, sex, body mass index, the American Society of Anesthesiologists physical status classification, hemoglobin level, number of previous surgeries, stone size, and the Guy’s Stone Score were analyzed. Success was considered if no fragments were observed on the computed tomography scan on the first postoperative day. Univariate and multivariate analyses were performed to determine significant parameters.

RESULTS:

We evaluated 961 patients; of them, 483 (50.2%) underwent previous stone-related surgery, and 499 (51.9%) had Guy’s Stone Score 3 or 4. The overall success rate in a single procedure was 40.7%, and complication rate was 13.7%. The univariate analysis showed that the maximum diameter of the stone (25.10±10 mm; p<0.001), previous percutaneous nephrolithotomy (OR 0.52; p<0.001), number of previous percutaneous nephrolithotomy (OR 0.15; p<0.001), the Guy’s Stone Score (OR 0.28; p<0.001), and the number of tracts (OR 0.32; p<0.001) were significant. In the multivariate analysis, the number of previous percutaneous nephrolithotomy (OR 0.54; p<0.001) and the Guy’s Stone Score (OR 0.25; p<0.001) were statically significant.

CONCLUSIONS:

Guy’s Stone Score and the number of previous percutaneous nephrolithotomy are predictors of success with the supine position. Complex cases and with previous percutaneous interventions may require technical improvements to achieve higher stone-free rates.

Effect of Body Mass Index on Outcomes of Percutaneous Nephrolithotomy: A Systematic Review and Meta-Analysis

Objective

The current study aimed to assess the efficacy and safety of percutaneous nephrolithotomy (PCNL) in obese and overweight individuals based on body mass index (BMI).

Methods

We electronically explored the databases of PubMed, CENTRAL, ScienceDirect, Embase, and Google Scholar databases for all types of comparative studies investigating the role of BMI on PCNL outcomes. Only studies defining obesity as >30 kg/m² were included. Efficacy outcomes were stone-free rates and operating time while safety outcomes were complications and length of hospital stay (LOS).

Results

Eighteen studies with 101,363 patients were included. We noted no difference in the stone-free rates after PCNL for morbid obese vs normal BMI patients (OR: 0.78 95% CI, 0.57, 1.08 I²= 7% p = 0.13), overweight vs normal (OR: 1.01 95% CI, 0.89, 1.15 I²= 1% p = 0.83) and obese vs normal patients (OR: 1.00 95% CI, 0.87, 1.16 I²= 0% p = 0.95). PCNL operative time was significantly increased in morbid obese (MD: 9.36 95% CI, 2.85, 15.88 I²= 76% p = 0.005) and obese patients as compared with normal patients (MD: 2.15 95% CI, 1.20, 3.10 I²= 0% p < 0.00001), but not for overweight patients. There was no difference in the odds of complications between morbid obese vs normal (OR: 1.26 95% CI, 0.93, 1.72 I²= 0% p = 0.13), overweight vs normal (OR: 1.11 95% CI, 0.96, 1.28 I²= 0% p = 0.15), and obese vs normal patients (OR: 1.07 95% CI, 0.91, 1.27 I²= 0% p = 0.40). LOS was significantly reduced in obese patients (MD: −0.12 95% CI, −0.20, −0.04 I²= 0% p = 0.004) as compared to normal patients, but not for morbid obese or overweight patients.

Conclusion

PCNL has similar efficacy and safety in morbidly obese, obese, and overweight patients as compared to normal BMI patients with no difference in the stone-free and complication rates. Evidence suggests that operating time is increased in morbidly obese and obese patients and the latter may have shorter LOS.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier: CRD42022313599.