Late obstruction after subureteral collagen injection.

We present a case with distal ureteral obstruction after a single subureteral collagen injection. Postnatally, the girl presented with bilateral vesicoureteral reflux (VUR). At one year of age, a bilateral subureteral collagen injection was carried out. Postoperatively, the girl was followed up regularly and showed no pathological findings. But three years later, hydronephrosis with a distal ureteral obstruction on the right side was found. An ureteral reimplantation was performed on that side and the histological finding was a ureteral stenosis, consisting of collagen with a knotty sclerosis and a histiocytic and granulomatous reaction. This is the first case with a late obstruction at the ureteral orifice three years after a single collagen injection. We found an inflammatory reaction against the collagen, which led to a sclerosis of the implant. Further surveillance of patients after subureteral injections should focus on this kind of complication.

Comparison of different training models for laparoscopic surgery in neonates and small infants.

BACKGROUND: Minimally invasive surgery in small children and infants requires special skills and training. This experimental study compares the efficiency of an in vitro pelvic trainer (PT) and an a in vivo animal model (AM). METHODS: For this study, 12 residents were prospectively randomized into two groups. Initially, all had to pass a basic skill assessment (3 tasks). Then endoscopic small bowel biopsy was performed (8 times) either with the in vitro PT (group A) or the in vivo AM (group B). Finally, all had to demonstrate this procedure in the in vivo AM and repeat the basic skill assessment. A quality index (complications, suture, biopsy) was evaluated. RESULTS: Initially, there was no difference between the two groups. Interestingly, the mean regression gradient of the index for the in vitro PT (group A) was significantly better than for the in vivo AM (group B). In the final in vivo operation, however, the mean index for the in vitro PT (group A) worsened significantly, whereas it increased for the in vivo AM (group B) (p = 0.037). CONCLUSION: Adequate training for an isolated mechanical task such as gut biopsy can be supplied using a pelvic trainer or animal model with similar effects. However in vivo performance of the same task requires secondary surgical skills, which are conveyed during live training with greater success. Consequently, stepwise teaching with both modules seems reasonable before these procedures are approached in neonates or small children.

Advanced paediatric laparoscopic surgery: repetitive training in a rabbit model provides superior skills for live operations.

TOPIC: The rapid development of advanced laparoscopic techniques is a strong challenge for the skills and competence of the paediatric surgeon. It is therefore mandatory that training must offer adequate preparation. The present experimental study investigates how surgical residents perform laparoscopic bowel biopsy and defect repair after training with a pelvitrainer versus a rabbit model. METHODS: New Zealand white rabbits, 3 mm instruments, a 5 mm scope and a 6 - 0 prolene suture were used. Twelve surgical residents were randomised into two groups. Their basic task was to take a seromuscular bowel biopsy laparoscopically and to repair the defect using an intracorporeal suture. Group I trained 8 times (on 8 occasions) with a pelvitrainer (PT), group II trained similarly using a rabbit model (RM). Each participant took a final test to demonstrate the operation in the rabbit. Operating time, suture time and perforation of the bowel were analysed. RESULTS: In the PT group, mean operating times decreased from 11.18 (+/- 5.04) min to 4.91 (+/- 0.89) min (p < 0.01), however the final test procedure in the rabbit model lasted 9.62 (+/- 5.11) min. In the RM group mean operating times also decreased from 10.04 (+/- 3.39) min to 6.38 (+/- 1.40) min (p < 0.01) during the eight training operations. Within this group the final live operation lasted 5.45 (+/- 0.67) min and was significantly faster than in the PT group 9.62 (+/- 5.11) min (p < 0.1). The suture times showed a similar pattern. A significant difference with respect to the rate of perforation was not found. CONCLUSIONS: Repetitive training in the rabbit provides superior skills for live operations. In paediatric surgical centres with advanced laparoscopic procedures, an animal model should be considered as an important step in training which may contribute to a beneficial outcome in patients.

Dielectric properties of skeletal muscle during ischemia in the frequency range from 50 Hz to 200 MHz.

The complex dielectric properties of canine skeletal muscles were measured at 25 degrees C during ischemia in the frequency range from 50 Hz to 200 MHz. The dielectric spectrum of skeletal muscle shows an alpha-dispersion below 1 kHz and a beta-dispersion with a relaxation frequency of about 100 kHz. The alpha-dispersion disappears between 450 and 500 min of ischemia time, the same time during which mechanical contraction was observed, and was restored later. During ischemia, the beta-dispersion is shifted continuously to higher frequencies; and at frequencies above 50 MHz, a decrease of the real part of the dielectric permittivity was measured. The dielectric loss factor decreases during ischemia at frequencies below 500 kHz, only interrupted by a short increase, coinciding with the disappearance of the alpha-dispersion. The principal processes that happen during ischemia inside the skeletal muscle tissues were studied with the help of a model especially designed to simulate membrane effects on the dielectric spectrum. The disappearance of the alpha-dispersion is explained by an increase of conductivity in the membrane of the sarcoplasmic reticulum. Shifting beta-dispersion to higher frequencies is a result of metabolically produced ions and therefore increasing conductivity of the intracellular medium. Decreasing dielectric permittivity at frequencies above 50 MHz and decreasing dielectric loss factor at low frequencies are caused by the cell edema.