The features of electric welding colorectal anastomosis creation in experiment and clinics

The frequency of colorectal anastomosis leak is significantly higher than other intestinal, up to 19%. The anastomosis, created by electro-weld method, had productive type of inside healing. Aim — to evaluate the technical features and efficiency of electro-welded colorectal anastomosis (EWCRA), in comparison with other types of intestinal welded anastomoses. 8 EWCRAs were created at chronic experiment in the distal third of the direct segment of the swine colon. After analyzing their effectiveness, EWCRA was applied in 4 patients: two at a distance of 3-4 cm from the anal sphincter, and two at the level of the upper ampulla unit. Previous radiation was received by 2 patients. The age of the patients was 40–79 years old. EWCRA was applied in a moment, end to end, by using a tool with circular electrodes, and devices — sources of electric welding impulses EK-300M1 and Patonmed EKVZ-300, produced by the Electric Welding Institute. In pigs weighing 45–75 kg. this instrument was inserted into the rectal lumen through proximal colotomy, in humans — via transanal. Welding influence at the EWCRA was controlled visually, and by the impedance curve flow on the control apparatus screen. In the experiment, EWCRA healing was morphologically investigated in the planned healing periods. When fixing the gut on the instrument, the rigidity of rectal walls was noted, which required additional efforts to compress the electrodes to smooth the walls along the electrodes surface. During the test of rectal swelling with colored liquid, all EWCRAs were sealed. Pigs got up after 6–12 hours in an attempt to drink; by the end of the day, 7 out of 8 pigs had already demanded food. In the 2 pigs, the gut was empty at the end of the first postoperative period, at 6 - during the second (on average 25.4±5.1 hours). The thickness of the EWCRA substrate reached 0.3 mm. Recovery of EWCRA occurred initially, without signs of destruction of the welded tissue substrate and the intestinal walls around the EWCRA, by the typical post-welding productive proliferation healing type. In one patient, the leak of the lower EWCRA was detected on the 7th day, against the stool continuity, after the intestinal contents appearance by drainage. The patient got a stoma and recovered. In patients first stool was observed after 29–57 hours after the operation, including a patient with anastomosis dehiscence (48 hours). None had a feeling of obstruction, unbridled imperative calls to the chair etc. According to the endoscopy, the ulceration of the EWCRA site was limited by the epithelial layer, and did not lead to bleeding or necrosis deepening. One patient with an electrically welded descendent-rectoanastomosis, died on the 4th day as a result of acute cerebrovascular disruption. According to autopsy, EWCRA did not show signs of failure, the pattern of healing was consistent with productive inflammation, with the presence of a continuous connection, a powerful fibrilogenesis of the permeation zone of collagen fibers, the network of functioning newly formed small vessels of granulation tissue, the absence of tissue fragmentation. Of the 3 patients with EWCRA, it was traced up to 2 years — 3 patients, 3 years — 2, 5 years — 1. They did not have purulent complications. There was no ulceration or narrowing of the intestine through the EWCRA line, the gut lumen was restored, the mucosal folds were restored near the connection line. So, the electric-welded tool with circular electrodes using enables the in-moment colorectal anastomosis creation after the low anterior resection of the rectum. The greater the thickness of the muscular lays of the human rectum, and its individual diameter variations require to use a number of special tools.

Electrophysiological characterization of human rectal afferents

It is presumed that extrinsic afferent nerves link the rectum to the central nervous system. However, the anatomical/functional existence of such nerves has never previously been demonstrated in humans. Therefore, we aimed to identify and make electrophysiological recordings in vitro from extrinsic afferents, comparing human rectum to colon. Sections of normal rectum and colon were procured from anterior resection and right hemicolectomy specimens, respectively. Sections were pinned and extrinsic nerves dissected. Extracellular visceral afferent nerve activity was recorded. Neuronal responses to chemical [capsaicin and “inflammatory soup” (IS)] and mechanical (Von Frey probing) stimuli were recorded and quantified as peak firing rate (range) in 1-s intervals. Twenty-eight separate nerve trunks from eight rectums were studied. Of these, spontaneous multiunit afferent activity was recorded in 24 nerves. Peak firing rates increased significantly following capsaicin [median 6 (range 3–25) spikes/s vs. 2 (1–4), P < 0.001] and IS [median 5 (range 2–18) spikes/s vs. 2 (1–4), P < 0.001]. Mechanosensitive “hot spots” were identified in 16 nerves [median threshold 2.0 g (range 1.4–6.0 g)]. In eight of these, the threshold decreased after IS [1.0 g (0.4–1.4 g)]. By comparison, spontaneous activity was recorded in only 3/30 nerves studied from 10 colons, and only one hot spot (threshold 60 g) was identified. This study confirms the anatomical/functional existence of extrinsic rectal afferent nerves and characterizes their chemo- and mechanosensitivity for the first time in humans. They have different electrophysiological properties to colonic afferents and warrant further investigation in disease states.

Biomechanical Modeling of the Rectum for the Design of a Novel Artificial Anal Sphincter

This paper discusses biomechanical issues that are related to the option of a novel artificial anal sphincter around the human rectum. The prosthesis consists of a compression cuff system inside and a reservoir cuff system outside, which is placed around the debilitated sphincter muscle. The micro-pump shifts fluid between the cuffs and thus takes over the expansion and compression function of the sphincter muscle. However, the human rectum is not a rigid pipe, and motion in it is further complicated by the fact that the bowel is susceptible to damage. With the goal of engineering a safe and reliable machine, the biomechanical properties of the in-vivo porcine rectum are studied and the tissue ischemia is analyzed.