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.

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.

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.