荒木 淳

Colostomy is conventionally the only treatment for anal dysfunction. Recently, a few trials of anorectal transplantation in animals have been published; however, further development of this technique is required. Moreover, it is crucial to perform this research in dogs, which resemble humans in anorectal anatomy and biology. We designed a canine anorectal transplantation model, wherein anorectal autotransplantation was performed by anastomoses of the rectum, inferior mesenteric artery (IMA) and vein, and pudendal nerves. Resting pressure in the anal canal and anal canal pressure fluctuation were measured before and after surgery. Graft pathology was examined three days after surgery. The anal blood supply was compared with that in three beagles using indocyanine green (ICG) fluorescence angiography. The anorectal graft had sufficient arterial blood supply from the IMA; however, the graft's distal end was congested and necrotized. Functional examination demonstrated reduced resting pressure and the appearance of an irregular anal canal pressure wave after surgery. ICG angiography showed that the pudendal arteries provided more blood flow than the IMA to the anal segment. This is the first canine model of preliminary anorectal autotransplantation, and it demonstrates the possibility of establishing a transplantation model in dogs using appropriate vascular anastomoses, thus contributing to the progress of anorectal transplantation.

BACKGROUND: The concept of deep tissue injury under intact skin helps us understand the pathogenesis of pressure ulcers, but the best method for detecting and evaluating deep tissue injury remains to be established. METHODS: Intermediate-frequency (10-MHz) ultrasonography was performed to evaluate deep tissue injury. The authors analyzed 12 patients (nine male patients and three female patients aged 16 to 92 years) who showed deep tissue injury-related abnormal findings on ultrasonography at the first examination and were followed up until the pressure ulcer reached a final stage. RESULTS: The stage of ulcer worsened in six of 12 cases compared with baseline, and healed in the remaining six patients. The authors recognized four types of abnormal signs unique to deep tissue damage in ultrasonography: unclear layered structure, hypoechoic lesion, discontinuous fascia, and heterogeneous hypoechoic area. Unclear layered structure, hypoechoic lesion, discontinuous fascia, and heterogeneous hypoechoic area were detected at the first examination in 12, 10, seven, and five patients, respectively. Unclear layered structure and hypoechoic lesion were more commonly seen in pressure ulcers in deep tissue injury than the other features, but the follow-up study suggested that discontinuous fascia and heterogeneous hypoechoic area are more reliable predictors of future progression of pressure ulcers. CONCLUSIONS: The use of intermediate-frequency ultrasound reliably identified deep tissue injury and was believed to contribute to prevention and treatment of pressure-related ulcers. The results suggest that specific ultrasonographic characteristics may predict which pressure ulcers will progress.