Are multiple cryoprobes additive or synergistic in renal cryotherapy?

OBJECTIVE: To investigate the relationship between multiple cryoprobes was investigated to determine whether they work in an additive or synergistic fashion in an in vivo animal model because 1.47 mm (17-gauge) cryoprobes have been introduced to the armamentarium for renal cryotherapy. METHODS: Laparoscopic-guided percutaneous cryoablation was performed in both renal poles of 3 pigs using 3 IceRod cryoprobes. These 12 cryolesions were compared with 12 cryolesions using a single IceRod cryoprobe. Each cycle consisted of two 10-minute freeze cycles separated by a 5-minute thaw. The iceball volume was measured using intraoperative ultrasonography. The kidneys were harvested, and cryolesion surface area was calculated. The lesions were fixed and excised to obtain a volume measurement. Statistical analysis was used to compare the single probe results multiplied by 3 to the multiple probe group for iceball volume, cryolesion surface area, and cryolesion volume. RESULTS: The iceball volume for the first freeze cycle for the single cryoprobe multiplied by 3 was 8.55 cm3 compared with 9.79 cm3 for the multiple cryoprobe group (P=.44) and 10.01 cm3 versus 16.58 cm3 for the second freeze (P=.03). The cryolesion volume for the single cryoprobe multiplied by 3 was 11.29 cm3 versus 14.75 cm3 for the multiple cyroprobe group (P=.06). The gross cryolesion surface area for the single cryoprobe multiplied by 3 was 13.14 cm2 versus 13.89 cm2 for the multiple probe group (P=.52). CONCLUSION: The cryolesion created by 3 simultaneously activated 1.47-mm probes appears to be larger than that of an additive effect. The lesions were significantly larger as measured by ultrasonography and nearly so (P=.06) as measured by the gross cryolesion volume.

A novel ex-vivo ureteral apparatus for assessing the impact of intraluminal pharmaceutical agents on ureteral physiology.

BACKGROUND AND PURPOSE: Safe intraluminal access to the ureter and kidney is essential for endourologic procedures. Pharmacologic manipulation of ureteral smooth muscle could conceivably ease access and decrease morbidity. To minimize systemic effects, local intraluminal administration would be optimal, but the urothelium presents a barrier to the passage of medications. We present a novel ex-vivo apparatus and technique to measure ureteral peristalsis and assess drug diffusion. MATERIALS AND METHODS: Excised 3-cm pieces of porcine or human ureters were placed inside a specially designed apparatus that allows separate manipulation of the intra- and extraluminal environments while measuring peristalsis. Intraluminal antegrade perfusion was maintained by a reservoir. A pressure transducer was placed at the inflow end of each ureter segment. After equilibration, phenylephrine (10 µM) was then added extraluminally to induce peristalsis. Nifedipine was then added to the intraluminal reservoir or the external organ bath. The concentration of nifedipine needed to cause aperistalsis was measured. RESULTS: In 12 trials, extraluminal nifedipine caused aperistalsis at a concentration of 1 ± 0.1 µM, while intraluminal nifedipine needed 10.2 ± 1.1 µM. Significantly higher concentrations of nifedipine were needed intraluminally to cause aperistalsis, (P < 0.0001). CONCLUSIONS: With our apparatus, we can control the intraluminal and extraluminal ureteral environments, and measure peristalsis before and after drug administration. This apparatus should help investigators who are interested in studying both the diffusion of a wide range of drugs, as well as the effects of those medications on ureteral physiology. In this study, the urothelium acted as a significant barrier to the diffusion of nifedipine.

Differences in grip forces among various robotic instruments and da Vinci surgical platforms.

INTRODUCTION: The da Vinci surgical platform is becoming increasingly available and utilized. Due to the lack of haptic feedback, visual cues are necessary to estimate grip forces and tissue tensions during surgery. We directly measured the grip forces of robotic EndoWrist instruments using the three available da Vinci robotic surgical platforms. METHODS: Robotic instruments were tested in the da Vinci S, Si, and Standard systems. A load cell was placed in a housing unit that allowed for measurement of the grip forces applied by the tip of each robotic instrument. Each instrument was tested six times, and all data were analyzed using Student's t-tests or analysis of variance when appropriate. RESULTS: Slight differences in grip force were seen when the instrument was tested through 2 degrees of freedom at the tip (p = 0.02, analysis of variance) and when comparing a new instrument to an older instrument (p = 0.001 at the neutral position). There was no statistical difference in grip force between the left and right robotic arms. There was a broad range of grip forces between the various robotic instruments. The lowest grip force was registered in the double fenestrated grasper (2.26 ± 0.15 N), whereas the highest was seen in the Hem-o-lok clip applier (39.92 ± 0.89 N). In comparison to the S and Si, the Standard platform appeared to have significantly higher grip forces. CONCLUSION: Different grip forces were observed among the various robotic instruments commonly used during urologic surgery and between the Standard and the S and Si platforms.

The impact of cavernosal nerve preservation on continence after robotic radical prostatectomy.

OBJECTIVE: • To evaluate associations between baseline characteristics, nerve-sparing (NS) status and return of continence, as a relationship may exist between return to continence and preservation of the neurovascular bundles for potency during radical prostatectomy (RP). PATIENTS AND METHODS: • The study included 592 consecutive robotic RPs completed between 2002 and 2007. • All data were entered prospectively into an electronic database. • Continence data (defined as zero pads) was collected using self-administered validated questionnaires. • Baseline characteristics (age, International Index of Erectile Function [IIEF-5] score, American Urological Association symptom score, body mass index [BMI], clinical T-stage, Gleason score, and prostate-specific antigen level), NS status and learning curve were retrospectively evaluated for association with overall continence at 1, 3 and 12 months after RP using univariate and multivariable methods. • Any patient taking preoperative phosphodiesterase inhibitors was excluded from the postoperative analysis. RESULTS: • Complete data were available for 537 of 592 patients (91%). • Continence rates at 12 months after RP were 89.2%, 88.9% and 84.8% for bilateral NS, unilateral NS and non-NS respectively (P= 0.56). • In multivariable analysis age, IIEF-5 score and BMI were significant independent predictors of continence. • CavernosalNS status did not significantly affect continence after adjusting for other co-variables. CONCLUSION: • After careful multivariable analysis of baseline characteristics age, IIEF-5 score and BMI affected continence in a statistically significant fashion. This suggests that baseline factors and not the physical preservation of the cavernosal nerves predict overall return to continence.

Prospective randomized trial of three different methods of nephrostomy tract closure after percutaneous nephrolithotripsy.

OBJECTIVE: • To evaluate the safety and efficacy of 'tubeless' nephrostomy tract closure in reducing postoperative morbidity after percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: • In all, 31 patients undergoing PCNL were randomized into three groups, each with a different method of nephrostomy tract closure: using either a gelatin matrix haemostatic sealant (FloSeal), fascial stitch or Cope loop nephrostomy tube. • We compared operative time, estimated blood loss (EBL), postoperative stay, analgaesics use, changes in creatinine and haemoglobin levels, and stone clearance rate, as well as postoperative short-form (SF)-36 quality-of-life and pain analogue scores at five different time points after surgery. • All data were analysed using a one-way anova test. • A repeated measures anova test was used selectively to assess the progression of SF-36 and pain analogue scores. RESULTS: • The preoperative variables operative time, EBL, postoperative stay (P = 0.45), analgaesia use (P = 0.79), changes in creatinine (P = 0.28) and haemoglobin (P = 0.09) levels, and postoperative SF-36 scores were not significantly different. • In contrast, the differences in analogue pain scales at 1 week after surgery (P = 0.02) and the trends of analogue pain score progression (P = 0.03) were statistically significant. • Three patients underwent second-look procedures for residual stones and there was one case of postoperative pyelonephritis in a multiple sclerosis patient. CONCLUSIONS: • The Cope loop closure patients recovered fastest, while FloSeal closure patients experienced initial increase in pain followed by resolution at 1 month. • As a result of the small study group sizes, it is difficult to show any significant difference in postoperative pain, especially in long-term follow-up; further clinical evaluation is necessary.

First prize: Chitosan and the urothelial barrier: effects on ureteral intraluminal drug penetration and peristalsis.

INTRODUCTION: Relaxing the ureter prior to endourologic procedures could ease instrument access. In an ex-vivo model, intraluminal nifedipine has been shown to relax the ureter. Chitosan is the deacetylation product of chitin and can alter bladder urothelium. This study examines the effect of nifedipine on peristalsis before and after pretreating the ureter with chitosan. METHODS: Intact 4-cm tubular porcine ureteral segments were placed in a novel organ bath. To induce peristalsis, phenylephrine (10 µM) was added. Chitosan (0.5% [w/v], 30 minutes) or Krebs (control) was then used to treat the urothelium. The rate and amplitude of ureteral peristalsis was then measured. Intraluminal nifedipine (1 µM) was then added to the intraluminal reservoir. Peristaltic rate and amplitude and the time to aperistalsis were measured. Methylene blue was then added after treatment with chitosan or control to measure diffusion. RESULTS: After Krebs pretreatment, intraluminal nifedipine (1 µM) significantly reduced peristaltic frequency (p = 0.0184) but did not stop peristalsis after 60 minutes of exposure in six trials. After chitosan, nifedipine (1 µM) stopped ureteral peristalsis within an average of 12.30 ± 4.72 minutes. Chitosan alone did not cause aperistalsis. Intraluminal methylene blue did not diffuse into the extraluminal bath after saline or chitosan pretreatment. Histological analysis of the ureter before and after pretreatment with chitosan showed no urothelial disruption. CONCLUSIONS: By pretreating the intraluminal surface of the ureter with chitosan, nifedipine blocks ureteral peristalsis at low concentrations. Chitosan changes ureteral urothelial permeability without barrier disruption and has no observed effect on ureteral contraction.

Ice burn: protecting the flank during renal cryotherapy.

INTRODUCTION AND OBJECTIVES: Cryoablation is a viable minimally invasive strategy for the treatment of small renal masses. One of the most common postoperative complaints is pain or paresthesia at the cryoprobe insertion site. The use of a 14-gauge angiocatheter to insulate the flank during renal cryotherapy was investigated. MATERIALS AND METHODS: Six Yorkshire swine underwent laparoscopy-guided percutaneous cryoablation of the upper and lower poles of both kidneys with a 1.47 mm (17 gauge) cryoneedle. Treatment consisted of a double 10-minute freeze separated by a 5-minute active thaw. Trials were randomized to placement of the cryoneedle directly through the flank or through a 14-gauge angiocatheter as an insulating sheath. Temperatures were recorded adjacent to the cryoneedle at two depths in the flank with a Multi-Point Thermal Sensor. RESULTS: Twelve trials were completed each with a bare and sheathed cryoneedle. The coldest temperature observed was -26 degrees C for the bare cryoneedle and -21 degrees C for the sheathed cryoneedle. At the outer sensor, there was a 4.1 degrees C increase in mean temperature for freeze 1, and 6.2 degrees C increase in mean temperature for freeze 2 with sheath use. At the inner sensor, there was a 3.0 degrees C increase in mean temperature for freeze 1, and 9.4 degrees C increase in mean temperature for freeze 2 with sheath use. There was a trend toward statistical significance of sheath insulation at the outer (p = 0.07) and inner (p = 0.08) temperature sensors. CONCLUSIONS: A 14-gauge angiocatheter may provide some insulation and thereby might help protect against "ice burn" during renal cryotherapy.

In vitro, ex vivo and in vivo isotherms for renal cryotherapy.

PURPOSE: Preoperative planning for renal cryotherapy is based on isotherms established in gel. We replicated gel isotherms and correlated them with ex vivo and in vivo isotherms in a porcine model. MATERIALS AND METHODS: PERC-17 CryoProbes (1.7 mm) and IceRods (1.47 mm) underwent trials in gel, ex vivo and in vivo porcine kidneys. Temperatures were recorded at 13 predetermined locations with multipoint thermal sensors. RESULTS: At the cryoprobe temperatures were not significantly different along the probe in any medium for either system (p = 0.0947 to 0.9609). However, away from the probe ex vivo and in vivo trials showed warmer temperatures toward the cryoprobe tip for each system (p = 0.0003 to 0.2141). Mean +/- SE temperature 5 mm distal to the cryoprobe tip in vivo was 19.2C +/- 16.1C for CryoProbes and 27.3C +/- 11.2C for IceRods. Temperatures were consistently colder with CryoProbes than with IceRods in gel (p <0.00005), ex vivo (p <0.00005) and in vivo (p = 0.0014). At almost all sites temperatures were significantly colder in gel and in ex vivo kidney than in in vivo kidney for CryoProbes (p = 0.0107 and 0.0008, respectively) and for IceRods (each p <0.00005). CONCLUSIONS: Gel and ex vivo isotherms do not predict the in vivo pattern of freezing. Thus, they should not be used for preoperative planning. The cryoprobe should be passed 5 mm beyond the tumor border to achieve suitably cold temperatures. Multipoint thermal sensor probes are recommended to record actual temperature during renal cryotherapy.

Impact of pneumoperitoneum on renal cryotherapy.

PURPOSE: Pneumoperitoneum is known to decrease blood flow to the kidney during laparoscopy. We investigated if this change in blood flow would increase the size of the cryolesion. MATERIALS AND METHODS: Twelve Yorkshire swine underwent laparoscopy-guided percutaneous cryoablation of the upper and lower pole of each kidney at four randomized pneumoperitoneum pressures (10, 15, 20, and 25 mm Hg). Cryolesions were made with a 1.47-mm IceRod (Galil Medical, Plymouth Meeting, PA). Each site underwent two 10-minute freeze cycles separated by a 5-minute active thaw with pressurized helium gas. At the conclusion of each freeze cycle, the iceball volume was measured with intraoperative ultrasound. After completion of the four cryolesions, the kidneys were harvested, and the cryolesion surface area was calculated. The lesions were fixed in 10% buffered formalin and then excised with a 1-mm margin to obtain a volume measurement using fluid displacement. RESULTS: Iceball volume was 3.41, 2.85, 3.44, and 2.36 cm(3) for freeze cycle 1 (p = 0.16) and 3.67, 3.34, 4.88, 3.95 cm(3) for freeze cycle 2 (p = 0.20) at 10, 15, 20, and 25 mm Hg, respectively. Cryolesion volume by fluid displacement was 4.06, 3.77, 3.97, and 3.93 cm(3) (p = 0.86) and cryolesion surface area was 4.55, 4.38, 4.39, and 4.20 cm(2) (p = 0.71) at 10, 15, 20, and 25 mm Hg, respectively. CONCLUSIONS: In this study, pneumoperitoneum pressure between 10 and 25 mm Hg did not affect iceball size as measured by intraoperative ultrasound, cryolesion volume by fluid displacement, or cryolesion surface.

Case report: omental splenosis discovered during robotic prostatectomy.

Splenosis describes ectopic splenic implants that usually occur after trauma and splenectomy. We present a case of omental splenosis discovered during robot-assisted prostatectomy.

Anatomic guide for port placement for daVinci robotic radical prostatectomy.

BACKGROUND AND PURPOSE: At present, robotic arm port placement for daVinci trade mark robot-assisted laparoscopic radical prostatectomy is based on the umbilicus. However, the robotic arm has a maximum manufactured required working distance of 25 cm. Accordingly, normal variability of patient height, weight, and umbilical location can leave the working arms too short to reach the membranous urethra. We present data to support port placement using the pubis, rather than the umbilicus, as the landmark. MATERIALS AND METHODS: If we assume the 25-cm working distance of the robot arm (Z) equals the hypotenuse of a triangle and the Y axis is the sum of the distance from the membranous urethra to the skin (Y1) plus the displacement of the skin secondary to CO(2) insufflation (Y2), then the horizontal distance X is from the robot port site to the pubis. To ascertain Y1, we randomly selected the CT scans of 25 men and measured the depth from the skin over the pubis to the membranous urethra. To determine Y2, we measured the change in height from the table of the port site after CO(2) insufflation in 11 robotic laparoscopic prostatectomies. RESULTS: The average distance of Y1 was 11 cm; Y2 was 6 cm. Using the formula (Z(2) - (Y1 + Y2)(2))(1/2), the maximum distance X from the port site to the pubis, for an average man, should not exceed 18 cm. CONCLUSION: The optimal landmark for calculating the placement of ports for the daVinci robotic arm placement should be the pubis and not the umbilicus. Tall men (>72 inches) are at risk for exceeding functional robot arm length, and in these men, port sites should not be more than 18 cm from the pubis.