A study of naloxone effect on urinary retention in the patient receiving morphine patient-controlled analgesia.

PURPOSE: The purpose of the study was to compare urinary retention rates following orthopaedic surgery in patients who received low-dose intravenous naloxone while receiving morphine patient-controlled analgesia with patients who did not receive naloxone. DESIGN: Randomized controlled trial without blinding. SAMPLE: There were 97 participants consenting to the study, 45 were randomly assigned to a control group and 52 assigned to an experimental group. Forty-three patients in the control group and 47 in the experimental group (90 total) completed the study protocol. FINDINGS: Postoperative urinary residuals were lower, patients voided more frequently, and fewer catheterizations were needed when given low-dose naloxone while receiving morphine patient-controlled analgesia. At the same time, naloxone in small doses was found to have negligible effect on overall patient pain control.

Ureteral stents: coil strength and durometer.

OBJECTIVES: To evaluate the coil strength before and after urine exposure and the stiffness of commercially available double-J ureteral stents because both properties may affect stent performance and patient comfort. METHODS: Twelve commercially available 6F ureteral stents were tested for coil strength before and after 30 days of urine exposure. The proximal end of each stent was inserted through a 2-mm hole in bologna, allowed to recoil, and then pulled using a handheld force gauge. Ten different commercially available ureteral stent models were tested for tensile strength using an MTS MicroBionix Testing System and Testworks II software and a 5 N load cell. RESULTS: The Cook Black Silicone and Cook C-Flex stents had the strongest coil strengths before urine exposure at 0.480 +/- 0.0 lb (P < or = 0.0006) and were also the stents that had the greatest decrease in coil strength after urine exposure. After urine exposure, the weakest stent was the Applied Vertex stent at 0.088 +/- 0.008 lb (P < or = 0.02) and the strongest was the Cook Endo-Sof AQ at 0.223 +/- 0.014 lb (P < or = 0.03). Calculating the Young's modulus, E, the Cook C-Flex stent was the stiffest (E = 1472 +/- 196 KPa) and the Cook Black Silicone was the least stiff (E = 122 +/- 18 KPa). The stent models that demonstrated consistent E values across different lot numbers were the Circon Double J stent and Bard InLay. CONCLUSIONS: Ureteral stents can be differentiated according to their coil strength and stiffness. The impact of these properties on stent performance and patient comfort deserve additional evaluation. The significant variability found in stent stiffness among stents from different lot numbers suggests poor quality assurance in biomaterials or stent processing and increases the complexity of cross-stent comparisons.

Ureteroscopic laser lithotripsy for upper urinary tract calculi with active fragment extraction and computerized tomography followup.

PURPOSE: Management of fragments generated by ureteroscopic laser lithotripsy remains controversial. In this study we explored the impact of active fragment extraction after ureteroscopic laser lithotripsy on stone clearance. MATERIALS AND METHODS: A total of 69 patients with 3 or less upper urinary tract calculi (5 to 15 mm) demonstrated on preoperative CT were prospectively evaluated. Stones were translocated to a dependent upper pole calix where laser lithotripsy was performed. An attempt was made to clear all fragments using tipless stone baskets. One month after surgery stone clearance was evaluated exclusively with noncontrast spiral CT. RESULTS: In 58 patients undergoing surgery on protocol, average stone burden was 9.4 +/- 3.4 mm and was significantly smaller in 44 patients with stones in a solitary location (8.5 +/- 2.9 mm) than in 14 patients with stones in multiple locations (12.3 +/- 3.2 mm, p <0.001). Primary stone location was categorized as renal nonlower pole (in 16), renal lower pole (in 19) and proximal ureter (in 23). Average operative time (43.7 +/- 18.4 minutes) was unaffected by stone location or multiplicity after controlling for stone size (p >0.05). Stone clearance rates were not affected by stone location or multiplicity, with overall success rates of 54%, 84% and 95% at fragment thresholds of 0, 2 and 4 mm, respectively (p >0.05). CONCLUSIONS: Ureteroscopic laser lithotripsy with active fragment extraction was time efficient and highly effective. Sensitive postoperative imaging reveals the challenge of achieving a true stone-free state. We were unable to demonstrate an impact of stone location on stone-free rates.