David T. Chang

Renal effects of CO2 insufflation: Oliguria and acute renal dysfunction in a rat pneumoperitoneum model☆

OBJECTIVE To determine the mechanism by which oliguria develops during raised intra-abdominal pressure secondary to CO2 insufflation, we created a rat pneumoperitoneum model. METHODS Male Sprague-Dawley rats (n = 67) were organized into three groups. Each group was subjected to abdominal pressures of 0 (control), 5, or 10 mm Hg, over one, two, and four hours. Fourteen additional rats underwent a two-hour period of 10 mm Hg insufflation pressure followed by desufflation to 0 mm Hg. Urine output (UO) and serum creatinine levels were measured both during insufflation at one, two, and four hours, and two, four, ten, and twenty-two hours following its release. These measurements were compared to control values at each time point. Ultrasonic flow probes placed around both the inferior vena cava (IVC) and abdominal aorta during insufflation characterized the effects of increased abdominal pressure on blood flow. The flow rate was determined at insufflation pressures of 0 (control, 100% flow) to 25 mm Hg. RESULTS Rats subjected to 10 mm Hg pressure had significant decreases in UO (oliguria) compared to controls for up to four hours (P < 0.01). There were no significant differences in UO in the control or 5 mm Hg groups over each time interval. While a reduction in UO was observed at two, four, and ten hours postrelease, significance was achieved only at ten hours (P < 0.006). By twenty-two hours postrelease, no differences in UO were observed. Serum creatinine elevations declined two hours postdesufflation. IVC flow was reduced by 92.9 percent at 10 mm Hg, while arterial flow decreased by 46.4 percent. Flow was restored to preinsufflation levels after release of pneumoperitoneum. CONCLUSIONS Oliguria can be produced in rats undergoing pneumoperitoneum. The renal effects of pneumoperitoneum are most likely related to renal vascular insufficiency from central venous compression.

Rapid reduction in blood flow to the rat ventral prostate gland after castration: Preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability.

Laser tissue soldering in urinary tract reconstruction: First human experience

OBJECTIVES Laser tissue soldering (LTS) in the urinary tract provides an immediate leak-free seal and may avoid complications seen with conventional repair (such as fistula and stricture). We have begun a Phase I clinical trial investigating the use of LTS in performing urologic reconstructive surgery. METHODS Ten patients (aged 3 months to 38 years) underwent urologic reconstruction using LTS with a protein solder composed of human albumin (42%) and indocyanine green dye. In each case standard microsuture repair preceded laser-soldered suture line reinforcement. Anastomotic closure time and immediate leak pressure were measured. Postoperatively, all patients were evaluated for evidence of complications, including stricture, fistula formation, or impaired healing. RESULTS Using LTS as an adjunct to suturing added an average of 7.9 +/- 3.0 minutes (28%) to the overall mean anastomotic time of 28.3 +/- 9.4 minutes. Intraoperative leak pressure measurements for laser-soldered anastomoses (> or = 94.2 +/- 24.2 mm Hg) were significantly higher (P < 0.001) than primarily sutured anastomoses (20 +/- 2.9 mm Hg). Two instances of suture disruption (20%) occurred during laser activation, neither of which were repaired with sutures. Average follow-up for all patients was 7.1 + - 2.2 months. There were no intraoperative or postoperative complications, including the 2 patients with suture disruption. CONCLUSIONS These initial clinical results indicate that LTS is safe, easy to perform, and, contrary to conventional suturing, provides an immediate leak-free closure. Follow-up in these and other patients, as well as those undergoing sutureless and stent-free procedures, will determine whether our method of LTS benefits patients undergoing urologic reconstruction.

The Malone Antegrade Continence Enema Procedure in the Management of Patients with Spina Bifida

BACKGROUND In patients with spina bifida, traditional bowel management programs such as suppositories, retrograde enemas, and manual disimpaction have been largely unsatisfactory. The Malone antegrade continence enema (ACE) procedure has largely changed our approach to bowel management in this patient group. STUDY DESIGN Over a 3-year period between January 1994 and January 1997, 27 patients with spina bifida underwent the Malone ACE procedure at our institutions. At the time of their ACE procedure, four patients underwent simultaneous continent urinary diversion and three had simultaneous small-bowel bladder augmentation. All the patients were evaluated for 9 months or more after their procedure, and 10 of the patients have been followed for more than 2 years. RESULTS Postoperatively, predictable bowel control and continence were achieved in 19 of the 27 patients, but 6 had some rectal soiling requiring a sanitary pad. All patients were out of diapers and none reported stomal leakage. Eighteen of the 27 patients were able to manage independently and 9 required assistance. Two patients had stopped using their ACE stoma despite good technical results. The appendix was used as a catheterizable stoma in 15 of the 27 patients. The appendix was not available in 12 patients, so a tubularized cecal flap was used in 9 and a small-bowel neoappendix was created in 3. Complications included stomal stenosis in 5 patients, cecal-flap necrosis in 1, and stomal granulations in 3. CONCLUSIONS We believe that the ACE procedure provides reliable colonic emptying and avoids fecal soiling in the majority of individuals, and we find it widely and enthusiastically accepted by patients with spina bifida.

TESTICULAR MICROLITHIASIS IN A CHILD WITH TORSION OF THE APPENDIX TESTIS

We report on an 8-year-old boy with a unilateral testicular mass and bilateral diffusely echogenic testes on sonography. At inguinal exploration torsion of an appendix testis with a reactive phlegmon was found and testis biopsy revealed significant testicular microlithiasis. To our knowledge our case demonstrates a previously undescribed presentation of testicular microlithiasis. The literature is reviewed and this disease entity is discussed.

Sutureless Rabbit Bladder Mucosa Patch Graft Urethroplasty Using Diode Laser And Solder

Fistula and strictures at the site of sutured anastomoses are frequent complications of major urethroplasty. We harvested bladder mucosa in 26 rabbits to repair large defects in the proximal urethra using laser-activated solder in the hope that such a repair would be stronger, faster to create and avoid common complications seen with conventional repair. Large oval defects were created in the proximal urethra in all animals undergoing urethroplasty. Twelve animals underwent bladder mucosa graft closure via diode (808 nm.) laser activation of an albumin-based solder (50% were suture-free). Fourteen additional animals underwent closure with 7-zero polydiaxanone suture (controls). Leak pressure and time of repair were recorded for each graft. Additional sections of bladder mucosa were harvested, transected and repaired by laser welding to determine tensile strength. In both groups, radiography, urethroscopy and clinical course were evaluated for as much as 6 weeks postoperatively. Urethroplasty time was significantly (p < 0.01) shorter for the laser group (13.8 +/- 2.5 minutes) than for the sutured repair group (24.0 +/- 5.3 minutes). Initial leak pressures for the lasered grafts averaged at least 4 times those of sutured grafts (p < 0.01). The tensile strength for lasered bladder mucosa was 3.16 +/- 1.12 kg./cm.2 Early retrograde urethrograms (RUG) performed at 7 days (n = 5) revealed urinary extravasation and fistula formation in 2 control animals compared with a normal urethral appearance in 3 lasered repairs. Early retrograde urethrograms performed at 21 days (n = 21) demonstrated smooth-walled urethras with no evidence of fistula, stricture, or urinary extravasation in the lasered group; varying degrees of reactive mucosal proliferation were seen in the controls. Urethroscopy confirmed these observations. At 6 weeks, histologic examination confirmed the presence of viable graft in all animals. We conclude that bladder mucosa patch graft urethroplasty using diode laser welding and albumin-based solder is an attractive alternative to conventional methods.

Laser welding with albumin-based solder: experimental full-tubed skin graft urethroplasty.

Fistula and stricture formation at the site of sutured anastomoses are frequent complications of major urethroplasty. We performed urethroplasty using laser‐welded skin tube grafts in the hope that in addition to being free of suture holes, grafts would be as strong as or stronger than sutured controls.

Laser Welding Versus Suturing in Tunica Vaginalis and Venous Patch Graft Corporoplasty

Congenital penile curvature may result from corporeal disproportion in nearly 40% of cases, while in adults scarring of the corporeal bodies or periurethral fibrosis accounts for the majority of cases. Some surgeons advocate lengthening the fibrosed corporeal bodies by excising tunica albuginea and grafting such defects to straighten the penis. Tunica vaginalis, dermis, dorsal vein and lyophilized dura have been used for this purpose. Traditionally, these graft biomaterials have been sutured to the tunica albuginea. We assessed the feasibility, short-term safety and efficacy of diode laser tissue welding using albumin based solder and indocyanine green dye to perform patch graft corporoplasty in the dog. Ten animals were subjected to bilateral transverse excision of 1 x 2 cm. sections of tunica albuginea. Corporoplasty was performed using grafts composed of saphenous vein (5) or tunica vaginalis (5). Microsurgical repair with 7-zero polydioxanone suture (10) was compared to contralateral laser welded repair (10) by recording operative time, initial and short-term bursting pressures (mean plus or minus standard deviation) and histological analysis. Operative time on the laser side (9.8 +/- 2.3 minutes) was significantly shorter (p < 0.05) than on the suture side (17.1 +/- 5.1 minutes). Leak pressures, initially (laser 105.7 +/- 23.8 mm. Hg versus suture 35.3 +/- 8.0 mm. Hg), at 3 to 5 days (greater than 333.3 +/- 62.4 mm. Hg versus 136.6 +/- 39.4 mm. Hg) and at 7 to 10 days (greater than 397.8 +/- 39.8 mm. Hg versus 191.5 +/- 46.4 mm. Hg) were higher (p < 0.05) in the laser side compared to controls. Graft failure (necrosis) occurred in 3 repairs (2 laser on day 4 and 1 suture on day 10). Viable tissue with minimal differences in foreign body reaction between groups was observed in the remaining grafts. We conclude that laser welded patch graft corporoplasty using tunica vaginalis or vein is easy to perform, and provides excellent initial and short-term leak pressures. The use of laser welding in conjunction with suturing may be beneficial in corporoplasty for congenital or acquired penile curvature.

Effects of diode laser welding with dye-enhanced glue on tensile strength of sutures commonly used in urology

Tissue welding using laser‐activated protein solders may soon become an alternative to sutured tissue approximation. In most cases, approximating sutures are used both to align tissue edges and provide added tensile strength. Collateral thermal injury, however, may cause disruption of tissue alignment and weaken the tensile strength of sutures. The objective of this study was to evaluate the effect of laser welding on the tensile strength of suture materials used in urologic surgery.

Incidence of external spermatic veinsin patients undergoing inguinal varicocelectomy

OBJECTIVES To determine the incidence of external spermatic veins at inguinal varicocelectomy. METHODS A prospective study was performed by making intraoperative observations on 78 varicocelectomies (47 patients) performed by a single surgeon. All patients were referred for evaluation of male infertility and had a palpable varicocele present when examined while performing a Valsalva maneuver in the upright position. Varicocelectomies were performed via the inguinal approach using x 2.5 loupe magnification. Presence of external spermatic veins was defined as visualization (with x 2.5 loupe magnification) of veins on the floor of the inguinal canal traveling posterolateral to the spermatic cord that then subsequently exited the spermatic cord before passing through the internal inguinal ring. Age, anesthetic technique, and need for incision of the external inguinal ring were also recorded for each patient. RESULTS One third of patients had undergone left-sided varicocelectomies, while two thirds had undergone bilateral procedures. External spermatic veins were identified in 15% of left-sided varicoceles and 19% of right-sided ones. Of 31 patients undergoing bilateral varicocelectomies, 19% had at least 1 external spermatic vein. Of these patients, only 2 (7%) had a unilateral right external spermatic vein, none had a unilateral left external spermatic vein, and 4 (13%) had bilateral external spermatic veins. Overall, of all patients studied, 16% had at least 1 external spermatic vein. Follow-up at 1 year showed no evidence of clinical recurrence in any patient. CONCLUSIONS These results emphasize the importance of distal gonadal venous anatomy in the surgeons choice of the proper approach to varicocele repair, since external spermatic veins are only accessible via an inguinal approach.