Effect of pneumoperitoneum on renal tissue oxygenation and blood flow in a rat model.

OBJECTIVES: To determine the correlation between the renal blood flow (RBF) and tissue oxygenation (PO(2)) at varying intra-abdominal pressures (IAPs) and to compare the effects on renal blood flow from carbon dioxide-induced pneumoperitoneum. METHODS: Carbon dioxide pneumoperitoneum was established in Sprague-Dawley rats (n = 6). Licox oxygen/temperature tissue probes were laparoscopically inserted into the renal parenchyma, with the renal PO(2) and RBF recorded every 30 seconds while the IAP was gradually increased. Microprobes measuring the RBF, mean arterial pressures and serum pH were placed into the parenchyma to compare the effects of carbon dioxide pneumoperitoneum (n = 7) with that of open surgery (n = 6) and medical air pneumoperitoneum (n = 6). RESULTS: Renal PO(2) was inversely related to the IAP (P < .001). Despite the reduction in IAP, the renal PO(2) in the recovery phase was lower than at baseline (P = .045). The renal PO(2) and RBF changed in a virtually identical pattern at varying levels of IAP (P > .05). The RBF significantly declined with a pneumoperitoneal pressure of 15 and 20 mm Hg (P = .022), regardless of the gas used to create the pneumoperitoneum. A partial reversal of the RBF occurred with a decrease of the IAP. The RBF in the open surgical arm remained unchanged. Although both the serum pH and the mean arterial pressure were inversely proportional to the IAP (P < .001), the mean arterial pressure was depressed to the greatest extent in the medical air group (P = .02). CONCLUSIONS: These results have demonstrated that elevated IAP secondary to pneumoperitoneum causes significant renal hypoxia and decreased RBF. Additionally, this experiment has demonstrated the use of the Licox probes in monitoring the renal PO(2) and established a novel method for evaluating the effects of IAP on the kidney.

Impact of arterial and arteriovenous renal clamping with and without intrarenal cooling on renal oxygenation and temperature in a porcine model.

BACKGROUND: As laparoscopic partial nephrectomy increases in prominence, more needs to be understood about the combined effect of the pneumoperitoneum and renal ischemia during tumor resection. The purpose of this study is to investigate the effect of combined renal hilar clamping (arterial only versus arteriovenous) and retrograde intrarenal cooling on renal temperature and oxygenation in a porcine laparoscopic partial nephrectomy model. MATERIALS AND METHODS: Under general anesthesia, laparoscopic access with intra-abdominal pressure of 15 mm Hg to the left renal hilum was obtained. Licox tissue oxygenation and temperature probes were placed into the kidney transcutaneously; measurements were taken every 30 seconds. After establishing baseline readings, either the artery alone (n=18) or the artery and vein (n=18) were clamped for 30, 60 or 90 minutes (n=12 each). During vascular clamping, retrograde, intrarenal cooling was performed with ice cold saline infused via a percutaneously placed ureteric catheter in 18 pigs. Changes in renal pO2 and temperature were analyzed with repeated measures ANCOVA in SPSS 16. RESULTS: Retrograde cooling decreased renal parenchyma to 75.8% of baseline temperature (27.9 degrees C) within 15 minutes. There were no differences in cooling whether arterial or arteriovenous clamping was used (p=0.79). In uncooled animals, there was no significant difference in the decrease in renal pO2 during the clamp phase (p=0.18) or during the recovery phase (p=0.52). During the recovery phase, renal pO2 in uncooled animals was significantly higher than in those who received cooling (p=0.01). Animals who underwent hilar clamping for extended periods (60 and 90 min) had a slower recovery of renal pO2 to baseline than those with hilar clamping for 30 minutes (p=0.04) CONCLUSION: Retrograde intrarenal cooling can reliably cool the porcine kidney to 28 degrees C, regardless of whether arterial or arteriovenous clamping is used. Renal pO2 is not significantly different between animals that undergo artery only versus en bloc hilar clamping. Pigs that were provided with retrograde cooling had a slower return of pO2 to baseline following release of hilar clamps, possibly due to hypothermic vasospasm. Clamp durations greater than 60 minutes were also associated with slower return of renal oxygenation to baseline.

Stone attenuation and skin-to-stone distance on computed tomography predicts for stone fragmentation by shock wave lithotripsy.

OBJECTIVES: To determine whether stone attenuation and the skin-to-stone distance (SSD) can predict for stone fragmentation by SWL independently. Identifying the factors predictive of shock wave lithotripsy (SWL) outcome would help streamline the care of patients with stones. METHODS: A retrospective review was performed of 111 patients undergoing initial SWL for a solitary, 5-20 mm, renal calculus. Stone size, location, attenuation value, and SSD were determined on pretreatment noncontrast computed tomography. The outcome was categorized as stone free, complete fragmentation <5 mm, and incomplete fragmentation >or=5 mm or unchanged at 2 weeks on kidney/ureter/bladder radiography. RESULTS: After SWL, 44 (40%) were stone free, 27 (24%) had complete fragmentation, and 40 (36%) of 111 patients had incomplete fragmentation. The stone attenuation of the successfully treated patients (stone free and complete fragmentation groups) was 837 +/- 277 Hounsfield units (HU) vs 1092 +/- 254 HU for those with treatment failure (incomplete fragmentation; P < .01). The mean SSD also differed: 9.6 cm +/- 2.0 vs 11.1 cm +/- 2.5 for the successful treatment group vs the treatment failure group, respectively (P = .01). On multivariate analysis, the factors that independently predicted the outcome were stone attenuation, SSD, and stone composition. When patients were stratified into 4 risk groups (stone <900 HU and SSD <9.0 cm, stone <900 HU and SSD >or=9.0 cm, stone >or=900 HU and SSD <9.0 cm, and stone >or=900 HU and SSD >or=9.0 cm), the SWL success rate was 91%, 79%, 58%, and 41%, respectively (odds ratio 7.1, 95% confidence interval 1.6-32 for <900 HU and SSD <9.0 cm group vs other 3 risk groups; P = .01). CONCLUSIONS: The results of our study have shown that a stone attenuation of <900 HU, SSD of <9 cm, and stone composition predict for SWL success, independent of stone size, location, and body mass index. These factors will be considered important in the prospective design of a SWL treatment nomogram at our center.

Prospective determination of ureteral orifice location: a guide for fluoroscopic ureteral stent insertion.

PURPOSE: Ureteral stents are commonly inserted under fluoroscopic guidance. Our objective was to determine the intravesical landmarks for stent insertion by mapping the fluoroscopic location of the ureteral orifices (UOs) and bladder neck (BN) in relation to the pubic symphysis (PS). METHODS: In patients undergoing ureteroscopy, the UO to BN distance was measured during cystoscopy with a 5F ureteral catheter. Radiographic distance between the UO, BN, and superior border of the PS was determined by mapping their locations on digital fluoroscopic images. Measurements were performed with a full (to 50 cm H2O) and empty bladder. RESULTS: With an empty bladder, the mean cystoscopic BN to UO distance was 1.8 cm (+/- 0.4) for men (n = 10) and 2.0 cm (+/- 0.4) for women (n = 11). With a full bladder, it was 2.8 cm (+/- 0.5) for men and 2.9 cm (+/- 0.6) for women. Although the intravesical distance lengthened during cystoscopy (by 50%), there was no difference when viewed fluoroscopically; the BN to UO distance lengthened by only 15%. In men, the UOs were located superior to PS in the majority (83% and 95%, empty and full bladder, respectively). In women, however, the UOs resided behind the PS (73% and 50%, empty and full bladder, respectively). The BN in men was also cephalad to that in women (P = 0.01); superior to the PS in 50%; and behind the upper two thirds of the PS in 50%. In women, the BN was behind the lower two thirds of the PS in the majority (81%). CONCLUSIONS: During fluoroscopic ureteral stent insertion, the radiopaque marker of the stent positioner is situated at the superior border of the PS in men and behind the lower one third of the PS in women, permitting formation of an intravesical distal coil. One way to remember this is that men are on top and women are on the bottom of the PS.

Ureteral access sheath use and stenting in ureteroscopy: effect on unplanned emergency room visits and cost.

PURPOSE: We studied the impact of stented and unstented ureteroscopy on unplanned emergency room (ER) return visits, medical costs, and whether use of a ureteral access sheath precluded uncomplicated ureteroscopy. PATIENT AND METHODS: A series of 161 consecutive patients undergoing ureteroscopy for renal or ureteral stones was evaluated retrospectively. We examined sex, age, stone size, stone location, use of a ureteral access sheath, use of a ureteral stent, unplanned ER visits, unplanned imaging, and interventions. Medical costs were calculated according to British Columbia Medical Services Plan rates. RESULTS: In the 107 stented and 54 unstented patients, the mean stone sizes were 9 and 7 mm, respectively (P = 0.01), and ureteral access sheaths were used in 55% and 35% (P = 0.002). Stent use did not differ by patient age or sex or stone location. The ER return rates were 17% v 22% for the stented and unstented patients, respectively (P = 0.40), with emergency CT scans being performed in 28% v 75% of the returning patients (P = 0.02), hospital readmission in 22% v 58% (P = 0.05), and urgent decompression in 0 v 25% (P = 0.04). Among patients who were not stented, 37% of those treated using ureteral access sheaths v 14% treated without access sheaths returned to the ER (P = 0.04). The median costs were CDN dollars 1212 for stented and CDN dollars1071 for unstented patients (P < 0.0001). CONCLUSIONS: The unplanned ER return rate is similar whether patients are stented or unstented after ureteroscopy. The median cost saving for unstented patients is approximately CDN dollars140. Use of a ureteral access sheath precludes uncomplicated ureteroscopy, and a ureteral stent should be placed in these cases.

Shock wave lithotripsy correlates with stone density on preoperative computerized tomography.

PURPOSE: We reviewed our experience with the Dornier Doli S lithotriptor to address 2 questions. 1) What is the stone-free rate? 2) Can a stone-free outcome be predicted by preoperative computerized tomography? MATERIALS AND METHODS: The records of 76 consecutive patients undergoing shock wave lithotripsy for solitary urinary calculi 5 to 20 mm in diameter were studied retrospectively. Pretreatment noncontrast computerized tomography was reviewed to determine Hounsfield density. The shock wave lithotripsy outcome was determined at 12 weeks on imaging and categorized as 1) stone free, 2) any residual fragments or 3) stone unchanged. RESULTS: Of the patients 28 (37%) were stone free, 11 (14%) had residual fragments and 37 (49%) had stones that remained unchanged on computerized tomography after a single treatment with shock wave lithotripsy using a Dornier Doli S. Stones of patients rendered stone free had a lower median density compared to stones in patients with residual fragments and unchanged stones (684 vs 1,034 and 920 HU, respectively, p = 0.04). The stone-free rate for stones less than 1,000 HU was 46% vs 17% for stones 1,000 HU or greater (p = 0.01). CONCLUSIONS: The combined stone-free and fragmentation rate was 51%, lower than in other published reports. In patients with calculi greater than 1,000 HU shock wave lithotripsy achieved a stone-free rate of only 17%. Patients should be informed of the likelihood of treatment failure or need for auxiliary procedures if the Doli S lithotriptor is used, particularly for stones greater than 1,000 HU.

Interstitial cystitis and female sexual dysfunction.

OBJECTIVES: To use the Female Sexual Function Index (FSFI) to compare female sexual dysfunction in patients with interstitial cystitis/painful bladder syndrome (IC) with that in controls. METHODS: Consecutive patients with IC and asymptomatic controls were tested for voiding diary voided volumes, Pelvic Pain and Urgency/Frequency Questionnaire scores, and FSFI scores. RESULTS: Of the 97 subjects, 75 had IC and 22 were controls. The mean age was 38 and 43 years (P = 0.09), the voided volume was 165 mL and 294 mL (P <0.0001), and the Pelvic Pain and Urgency/Frequency Questionnaire score was 18 versus 3 (P <0.0001) for the IC and control groups, respectively. The total adjusted FSFI scores differed between patients with IC and the controls (20.2 +/- 9.6 versus 29.0 +/- 6.8, respectively, P <0.001). Using 26.55 as the cutpoint, 51 patients with IC (68%) had an abnormal FSFI score versus 3 controls (14%; P <0.001). Patients with IC scored worse on all domains of female sexual dysfunction than did the controls (P <0.01). CONCLUSIONS: The results of our study have shown that female patients with IC have sexual dysfunction, including pain, more commonly than do controls.