Evaluation of optimal color for stent identification in a hemorrhagic environment.

INTRODUCTION: The endoscopic deployment and extraction of endoluminal stents, such as ureteral stents, is commonplace in contemporary medical management of many diseases. In a hemorrhagic environment, endoscopic identification of a stent can be challenging. To date, no study has evaluated the optimal color for endoscopic stent identification. METHODS: Eight different colored stents were placed in a simulated bladder model. Each stent color was evaluated in saline and three progressively more concentrated bloody environments. A flexible cystoscope was used to make 15-second video clips of the stents in each environment. Participants viewed the videos in a random sequence. Participants were asked to identify the color of each stent, and rate the identification on a 10-point scale. Logistic regression models were used to model the relationship between identification, stent color, environment, and experience. RESULTS: Forty-seven participants reviewed the videos. In clear and mildly bloody environments, blue stents had the highest identification (p < 0.06, p = 0.001, respectively). In moderately bloody environments, yellow stents had the highest identification (p < 0.01), whereas silver stents had the highest identification in severely bloody settings (p = 0.004). Blue and green stents were identified most commonly and received the highest identification scores in all environments. Level of training and experience with endoscopy were not significantly associated with the correct response rate. CONCLUSIONS: This study demonstrates that the color of a stent plays an important role in endoscopic identification. Our results suggest that blue and green colors offer superior visibility in both clear and hemorrhagic environments.

Erythropoietin-induced optimization of renal function after warm ischemia.

BACKGROUND AND PURPOSE: Recent preclinical data have indicated that erythropoietin (Epo) can protect organs from ischemic damage. We evaluated the ability of Epo to protect the kidney from the effects of ischemia. METHODS: Thirty dogs underwent a laparoscopic nephrectomy and were allowed to recover for 2 weeks. The dogs were then divided into five groups. Animals in groups 1 and 2 underwent 1.5 hours of abdominal insufflation with placebo (saline) injection (group 1) or Epo injection (group 2) before; groups 3 to 5 underwent 1 hour of laparoscopic renal artery clamping after placebo injection (group 3), Epo injection (group 4), or mannitol injection (group 5). Serum evaluations and 24-hour urine collections were performed weekly. After 28 days, the animals were sacrificed. Statistical analysis was performed with the Kruskal-Wallis test. RESULTS: After recovery from the initial nephrectomy, all dogs had similar serum hematocrit and creatinine levels. Hematocrit was not significantly affected by Epo administration at any time point. Immediately after the second surgery, dogs that underwent renal artery clamping (groups 3-5) had significantly lower 24-hour urine creatinine levels than those that were not clamped (groups 1-2). After 4 weeks of recovery, the dogs that had received Epo before ischemia (group 4) had recovered significantly more renal function than the dogs that received placebo or mannitol before ischemia (urine creatinine level = Epo 149.1 mg/dL v placebo 70.7 mg/dL v mannitol 80.7 mg/dL). At sacrifice, microalbuminuria was also significantly less in dogs receiving Epo before ischemia than their mannitol or placebo counterparts. CONCLUSION: The current study demonstrates that administering Epo before warm ischemia can improve the recovery of renal function after ischemia better than placebo or mannitol.

Pilot study evaluating ureteric physiological changes with a novel 'ribbon stent' design using electromyographic and giant magnetoresistive sensors.

OBJECTIVE: To test a novel 'ribbon stent' (RS) design using an extraluminal bipolar electromyographic (EMG) and giant magnetoresistive (GMR) sensor system to characterize ureteric responses. MATERIALS AND METHODS: In all, 11 female domestic pigs were divided into three groups to evaluate ureteric physiology: group 1 (two pigs) with an unstented ureter, group 2 (three) with a standard 6 F ureteric stent, and group 3 (six) with the RS. For all groups EMG/GMR evaluation was performed at baseline, immediately after stenting, and at 3 and 7 days after stenting. All pigs underwent standardized retrograde ureteropyelogram evaluation at these time points, and after the final evaluation the pigs were killed and the urinary tract was harvested for histopathological evaluation. RESULTS: One stent in group 3 could not be deployed due to a problem with ureteric access. For groups 1, 2 and 3 the ureteric peristaltic activity was 109, 63, 72 events/h at baseline (P = 0.49); 61, 70, and 66 events/h immediately after stenting (P = 0.97); 66, 0, 8 events/h at 3 days after stenting (P = 0.002); and 61, 12, 0 events/h at 7 days after stenting, respectively (P = 0.049). CONCLUSION: The RS was deployed easily and safely in the porcine model using a standard technique. As with a standard stent, there was significant ureteric dilation and decrease in peristalsis with the RS.

Evaluation of efficacy of novel optically activated digital endoscope protection system against laser energy damage.

OBJECTIVES: To evaluate the reliability and efficacy of a novel endoscope protection system (EPS) against direct laser energy damage. METHODS: We performed in vitro evaluations of a novel EPS prototype that uses optical feedback from the digital sensor of the DUR-D ureteroscope to terminate the laser energy on retraction of the laser fiber into the ureteroscope. We evaluated various speeds of retraction (0.5, 2.0, and 5.0 cm/s) in normal saline and various concentrations of indigo carmine and human blood. We also evaluated the protrusion distance at which shutdown occurred with the laser fiber cladding cleaved at 0, 3, and 5 mm from the end of the fiber. Twenty trials of each condition were performed. RESULTS: In normal saline and blood dilutions of up to 10 g/L, the EPS worked with 100% efficiency for all trials. For blood dilutions of 10 g/L or greater and indigo carmine concentrations of 0.16 g/L or greater, the reliability of the EPS deteriorated. Lasers stripped of 0, 3, and 5 mm of cladding initiated shutdown at 2.9 +/- 0.13, 5.1 +/- 0.09, and 8.2 +/- 0.15 mm from the ureteroscope distal end, respectively (P <0.01). A single DUR-D ureteroscope was used for all trials and remained completely intact through 120 retractions of the active laser fiber into the channel. CONCLUSIONS: In this evaluation, the novel EPS was highly effective and reliable. When using indigo carmine or high-density blood concentrations, the efficacy of the EPS was compromised. The EPS should be used to complement standard safe laser technique rather than to replace it.