An animal model for assessment of heat distribution and neural damage around the endo shears coagulation device-applications for laparoscopic nerve-sparing surgery.

BACKGROUND AND PURPOSE: Current urologic laparoscopic procedures include preservation of locoregional nerve fibers. The use of electrical coagulation is limited because of tissue conductance of current and heat production. While ultrasonic coagulation does not use electricity, heat is still produced. We designed an animal model to characterize the heat spread around ultrasonic devices and assess whether it is neurodestructive. MATERIALS AND METHODS: 10 rats were anesthetized; their skin was reflected, exposing the muscles. An ultrasonic probe was introduced into the tissue, and coagulation was performed for 10 seconds. Tissue temperature was measured using four thermocouples, at distances of 4, 8, 12, and 16 mm from the probes and in a circumferential manner. Thermal mapping of the probes was performed with an infrared camera. Further, four rats were anesthetized; the skin above their inner thighs was reflected bilaterally exposing the "nervus ischiadicus." Coagulation was performed in varying distances from the nerve on one side while the other served as control. One week later, the animals were sacrificed, and the nerves were obtained. Silver staining was used to assess the vitality of the axons. RESULTS: In distances of 4 to 8 mm from the device, temperatures as high as 81°C were recorded, and silver staining showed severe axonal damage. CONCLUSIONS: Although ultrasonic coagulation is efficient, local heat production may reach neurodestructive levels with a typical tissue distribution pattern. These features should be addressed during laparoscopic dissection and when considering nerve-sparing procedures.

Clinical and duplex US assessment of effects of sildenafil on cavernosal arteries of the penis: comparison with intracavernosal injection of vasoactive agents--initial experience.

PURPOSE: To prospectively evaluate the clinical response and hemodynamic changes in cavernosal arteries after oral administration of sildenafil without and with audiovisual sexual stimulation and to compare those responses with responses from intracavernosal injections of vasoactive agents. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. Thirteen consecutive patients (age range, 22-77 years; mean, 60.4 years) with erectile dysfunction were evaluated with clinical assessment and cavernosal duplex ultrasonography (US). The patients were examined at two sessions 3 weeks apart. First, each patient received 100 mg of sildenafil citrate orally and was examined 60 minutes later without any sexual stimulation. Each patient then underwent repeat clinical and duplex US assessment after audiovisual sexual stimulation. Three weeks later, the patients underwent identical clinical evaluation and duplex US after intracavernosal injection of a commercially available combination of papaverine, prostaglandin E1, and phentolamine. Clinical and duplex US data (ie, peak systolic velocity [PSV]) were examined by using the Wilcoxon signed rank test for matched pairs. RESULTS: At rest, the overall mean cavernosal artery PSV was 1.08 cm/sec and remained unchanged after intake of sildenafil without any audiovisual stimulation, with no clinical evidence of erection. With the addition of audiovisual sexual stimulation, eight (62%) of 13 patients had penile congestion or erection, and six (46%) had a PSV greater than 25 cm/sec. With intracavernosal injection of the combination of three drugs, all 13 patients achieved congestion or erection, and 10 (77%) had a PSV greater than 25 cm/sec. Both clinical and duplex US responses to intracavernosal injection were significantly greater than they were to sildenafil with audiovisual sexual stimulation (P = .04 and .003, respectively). CONCLUSION: Oral sildenafil with audiovisual sexual stimulation led to a significant clinical response and increment in blood flow in the cavernosal arteries. However, more patients responded to intracavernosal injection of the combination of three drugs than to sildenafil, and the clinical response was significantly better.

Skill assessment of urological laparoscopic surgeons: can criterion levels of surgical performance be determined using the pelvic box trainer?

OBJECTIVES: To correlate between surgeons' experience in urological laparoscopy and their performance of a set of laparoscopic tasks performed on a box trainer in the laparoscopic laboratory. METHODS: 44 urologists participated in this study. A self-administrated questionnaire enquired about their experience in laparoscopy and they were divided to 4 categories: no experience, minimal experience, basic and advanced laparoscopists. Tests consisted of 4 tasks: passage of a ligature, intracorporeal knotting, intracorporeal suturing, and cutting a carton circle out of a square. All tests were supervised and time was recorded for each of the tasks. Histograms were plotted showing the mean time for performance of each task in each experience group. The Kruskal-Wallis analysis of variance was used to assess statistical significance. RESULTS: Seven participants had no previous experience in laparoscopy and 14 had minimal experience. 15 had basic experience and 8 were advanced laparoscopists. No difference in performance was found between the no experience and minimal experience group and they were united and defined as beginners. A significant difference in performance was noted between the beginners, basic and advanced groups, especially when comparing beginners to advanced. Criterion level values of surgical performance drawn from this data were highly discriminative with sensitivity of 71-85% and specificity of 74.2%-88%. CONCLUSIONS: We were able to differentiate between various levels of laparoscopic skills among the participating urologists. Values drawn from such studies could be the basis of criterion level values for technical laparoscopic performance during training programs and before granting laparoscopic privileges to urologists.

Assessment of surgical technique and perioperative morbidity associated with extraperitoneal versus transperitoneal laparoscopic radical prostatectomy.

OBJECTIVES: To compare the perioperative morbidity and surgical technique of the two main variants of laparoscopic radical prostatectomy: the more often used transperitoneal approach with primary dissection of the plane posterior to the seminal vesicles (TP-LRP) and a purely extraperitoneal approach (EP-LRP). METHODS: Our initial 20 consecutive patients who underwent EP-LRP and the last 20 consecutive patients who underwent TP-LRP were included in this retrospective study. The two groups were well matched for age, American Society of Anesthesiologists score, body mass index, prostate-specific antigen level, and Gleason score. The mean time for completion of the individual laparoscopic steps was assessed for both approaches. RESULTS: With EP-LRP, the mean operative time was shorter (169.6 minutes versus 224.2 minutes, P <0.001) and patients resumed a full diet earlier (mean 1.6 days versus 2.6 days, P = 0.002). The mean total dose and duration of morphine administration were higher in the TP-LRP group, but the difference was not statistically significant (6.0 mg versus 12.8 mg and 0.5 day versus 0.9 day, respectively). The catheter time was nearly identical in the two groups (mean 5.3 days with TP-LRP and 4.2 days with EP-LRP). The incidence of positive margins was not affected by the surgical approach. CONCLUSIONS: These preliminary results suggest that the initial posterior dissection associated with TP-LRP is less efficacious than direct access of the prevesical space during EP-LRP. Measures of perioperative morbidity were at least equivalent, if not superior, for the EP-LRP technique. These findings, together with the significant decrease in operative time with EP-LRP, appear sufficiently important to abandon the transperitoneal technique.