Colonic anastomosis healing. The effect of topical povidone-iodine

Efeito do uso de povidine-iodine na cicatrização de anastomoses de cólon direito de ratos

RACIONAL: Dados da literatura sugerem que, possivelmente, a lavagem intraluminar de segmentos do tubo digestivo com povidona-iodine antes da execução de uma anastomose poderia favorecer a cicatrização dessas anastomoses e prevenir a formação de aderências perianastomóticas, podendo ser útil se empregada em pacientes submetidos cirurgias do trato digestivo. OBJETIVO: Avaliar a eficácia da lavagem das bordas entéricas com povidona-iodine a 5% sobre a cicatrização do cólon direito de ratos. MATERIAL E MÉTODOS: Estudaram-se 20 ratos Wistar divididos nos seguintes grupos: A (n = 10), limpeza das bordas da ferida colônica com solução salina a 0,9%; B (n = 10), limpeza das bordas da ferida colônica com solução de povidona-iodine a 5%. Os animais foram submetidos a laparotomia, secção de 75% da circunferência do cólon, preservando 25% da borda mesentérica e tratamento das bordas a serem anastomosadas segundo o grupo descrito acima. Após a realização das anastomoses, os animais foram observados durante 7 dias e, no 7º dia pós-operatório, mortos. Foram coletadas amostras de sangue para dosagem da albumina sérica e feita análise macroscópica das anastomoses, observando-se presença de fístula, aderências e dilatação acima da anastomose. O segmento contendo a anastomose colônica foi retirado com 3 cm de cólon intacto em torno da anastomose e feita medida da pressão de ruptura. RESULTADOS: Não se observou presença de fístula em nenhum animal dos grupos estudados. Não houve diferença significativa em relação à presença de estenose da anastomose, aderências ou no valor da pressão de ruptura quando comparados os dois grupos. CONCLUSÃO: O emprego da povidona-iodine não resultou em aumento da resistência tênsil das anastomoses do cólon direito de ratos.

Local and systemic effects of intraoperative whole-colon washout with 5 per cent povidone-iodine

BACKGROUND

Segmental intraluminal instillation of several tumoricidal agents including povidone-iodine has been advocated to prevent anastomotic recurrence after colonic resection for colorectal cancer. The local and systemic effects of on-table whole-colon washout using 5 per cent povidone-iodine were assessed in patients undergoing elective surgery for colorectal cancer.

METHODS

The local effect of 5 per cent povidone-iodine on the colonic mucosa and the effect of colonic mucosal damage by povidone-iodine on tumour take was first investigated in Fischer 344 rats. In 12 euthyroid non-allergic patients, on-table whole-colon lavage via the appendix was performed. Systemic (thyroid function) and local (mucosal damage assessed by repeat biopsies) effects were studied, as well as the in vitro tumoricidal effect of the final anal effluent on tumour cell suspensions.

RESULTS

After 30 min of contact with povidone-iodine the rat colonic mucosa was severely injured, with detachment of the epithelial cell layer. Povidone-iodine-induced 'colitis' did not result in tumour development after inoculation of 10(6) Mtln3 carcinoma cells in ten rats. Epithelial desquamation was also observed, in all but one patient, 1 and 4 h after colonic lavage. However, epithelial restitution started within 1 day and no abnormality was revealed after 3-7 days. Urinary iodine excretion increased markedly and was not within normal values after 1 week. Levels of thyroid hormones decreased significantly but became normal within 1 week. The anal effluent containing povidone-iodine was found to be tumoricidal in vitro on a human colonic carcinoma cell line and on a tumour cell suspension produced from the patient's tumour.

CONCLUSION

On-table whole-colon washout using 5 per cent povidone-iodine seems clinically feasible. This technique deserves further study as a substitute for preoperative bowel preparation and may help to prevent recurrent cancer due to implantation of viable exfoliated tumour cells.

[Revascularization of colonic anastomoses]

The revascularization of colonic anastomosis after colon segmental resection in rabbits in 9 different end-on-end and inverting suture techniques was examined macroscopically, microangiographically, micropreparatorily and histologically. Independently of the suture technique revascularization started 4 days after surgery. 8 days postoperatively the suture line is mainly bridged, 14 days postoperatively the vasal connection to the opposite side is completed. The new vessels mainly originate from the subserosal and submucosal tissue. The adhesions participate in the revascularization, too. It (the revascularization) directly correlates with the development of granulation tissue. This is evident from the excess reactive revascularization of abscesses and ulcers in the anastomoses. There always results a vascular scar in the angioarchitecture of the colonic wall. Start and extent of the revascularization cannot--in contrast to former literature--be looked at as a guarantee of quality for the healing of anastomoses.

Povidone-iodine enema as a preoperative bowel preparation for colorectal surgery. A bacteriologic study

To evaluate the effects of povidone-iodine (PI) enema on the bacterial flora of colorectal mucosa, the authors studied 113 patients who were candidates for colorectal surgery. The study of the rectum included 72 patients. Total bacterial concentrations after a PI enema (N = 44) were significantly lower than after a simple water enema (N = 12, P less than 0.001), or than after a water enema associated with intravenous metronidazole (N = 16, P less than 0.01). The study of the colon included 41 patients. Total bacterial concentrations did not differ after a PI enema (N = 24) than after a water enema (N = 11); both groups were associated with intravenous metronidazole. In contrast, both preparations significantly reduced bacterial concentrations when compared with oral administration of polyethyleneglycol (N = 6, P less than 0.01). Similar results were observed in rectal and colonic studies, when analysis was restricted to the anaerobic flora. PI is an antiseptic that, when administered alone in an enema or in association with metronidazole, significantly reduces bacterial concentrations in the mucosa of the colon and rectum. It may be proposed as a simple preoperative preparation for colorectal surgery.

Prevention of intraperitoneal adhesions: a comparison of noxythiolin and a new povidone-iodine/PVP solution

Peritoneal adhesions were induced in 250 female Wistar rats by the excision and closure of a right lower quadrant parietal peritoneal defect. After closure of the defect each rat was randomly allocated to one of five treatment groups: A, control with no instillate; B, control with Ringer solution; C, noxythiolin 0.5 per cent solution; D, noxythiolin 1 per cent solution; E povidone-iodine/PVP solution. Two millilitres of the appropriate solution were injected into the peritoneal cavity just before closure of a standard 4-cm midline incision. Assessment of adhesion formation was made at 1 week in ignorance of the treatment group. Noxythiolin 1 per cent was more effective than Ringer solution and noxythiolin 0.5 per cent in reducing the mean number of adhesions (P less than 0.05) but was inferior to povidone-iodine/PVP (P less than 0.05). Povidone-iodine/PVP solution significantly reduced the number of adhesions compared with the four other groups. In addition, it significantly reduced the mean length of attachment of each adhesion compared with the two control groups (P less than 0.001).

Topical noxythiolin in colonic healing

Rats were subjected to division and anastomosis of the colon just proximal to the rectum to study the healing of colonic anastomoses. The effect of noxythiolin irrigation of the divided colon before and after anastomosis was investigated and compared with controls. Healing was assessed using five variables--macroscopic and microscopic inspection, bursting pressure and tensile strength estimations and angiography for new vessel formation. The study shows that noxythiolin irrigation of the colon in the rat significantly increases the chance of a sound anastomosis without interfering with healing. Furthermore, it inhibits the formation of adhesions.