The Effect of Surrounding Infection upon the Healing of Colonic Wounds:

E x p e r i m e n t a l S t ud i e s a n d C l i n i c a l E x p e r i e n c e s ~

PE'I'Ek RYAN, M.S.

Honora~ 3, Surgeon, St. Vincent's Hospi ta l , Melbourne, Victoria, Australia

INFECTION Of a sutured wound will cer- tainly delay, and may prevent, healing by destroying growing ceils and matr ix and by interposing pus between the edges. T h a t infection is not the only cause of wound breakdown is strikingly illustrated by burst abdomen, where gross infection is uncommon and other factors--e.g., tension, inadequate suturing, poor blood supply and poor nutr i t ion--predominate . I t is generally agreed that the most impor tan t requirement for healing of colonic anasto- moses (assuming correct apposition of un- diseased, undamaged bowel edges) is a normal blood supply unimpaired by ten- sion or tight sutures.

T h e Role of Sepsis: "Contamina t ion" or "Infect ion"?

T h e role of "sepsis" in colonic wound healing has remained ambiguous. Because the high mortali ty of elective colonic anas- tomoses in the preantibiotic era was equated with "sepsis," surgeons then tried nnmerous ways of avoiding bacterial con- taminat ion of the suture line: by "aseptic" anastomosis;S, s, is. i6. 19, 2~ by prel iminary defunctioning colostomy; 4 by mechanical cleansing of the bowel (shown to be as effective experimental ly as oral antisepsis by Cohn and associates3). The ul t imate "antiseptic" measure was the introduction of intestinal antibacterial drugs b y Poth and co-workers. ~s Even s~rgeons -wi~o no

Read at the meeting of the American Procto- logic Society, Boston, Massachusetts, June 16 to 18, 1969.

124

longer use oral antibiotics 6, 11, 17 still me- chanically cleanse the bowel before colonic surgery, tacitly practicing bowel asepsis.

I f internal bacterial contaminat ion of the colonic suture line has been accepted as a clanger to healing, external contami- nation has been regarded as being an even greater hazard. Tradi t ional ly , innnediate colonic anastomosis in the presence of peritonitis or after accidental or war t rauma has been avoided.

Yet bacterial contaminat ion does not nec- essarily cause bacterial infection. Whether infection becomes established in a contami- nated colonic suture line probably depends, among other things, npon the "dose" of bacteria, the blood supply there, and the antiseptic effect of the per i toneum. 2, 7; 11, 27 i t has not been shown conclusively that mere contaminat ion of the bowel ends to be anastomosed will cause infection that is sufficiently severe to prevent anastomotic healing,, providing there are no other ad- verse factors (e.g., ischemia).

Clinical Experiences with Immedia t e "Septic" Colonic Anastomoses

I have established anastomoses imme- diately after emergency resection in 13 patients who had nonlocalized peritonitis due to perforat ion of nonobstructed colon (ten had sigmoid diverticulitis, 21, 22 and

three, sigmoid carcinoma). One pat ient with carcinoma (aged 87 years) died oc~ the fifth day of renal failure, following pro- longed hypotension at operation. T h e 12 survivors recovered without evidence of

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anastomotic leakage, except that in one patient with perforated diverticulitis a local intraperitoneal abscess was drained in the postoperative period, without ensuing for- mation of a fistula. Others have had simi- lar experiences.*, 9, 10, 12.13, 20, 26

The successful healing of these anasto- moses, made in unprepared colon in the presence of peritonitis, seems to throw doubt upon the traditional view that sep- sis (at least in the sense of bacterial con- tamination) is an important factor in causing breakdown of colonic wounds.

Experimental Studies: Method

To test this theory, I carried out an experiment in which abscesses were in- duced arountl sutured wounds and anasto- moses in clogs' descending colons which already had been extraperitonealized in continuity for two or more months to avoid peritonitis--in othgr words, the bowel had been placed in a subcutaneous "pouch," at which time care was taken to divide no mesocolic vessels, to avoid tension (no bowel was resected), and to make sure that no bowel that was abnormal in ap- pearance was used. This controlled, as far as possible, other factors concerned in bowel healing, ea Then, when the surgical operation on the bowel was done, con- comitant "pouch" abscess formation adja- cent to the healing colonic suture line was

encouraged by not preparing the bowel (either mechanically or with antibacterial drugs), by the use of nonantiseptic technic (usually with gross fecal soiling) and, in

some cases, by deliberate contamination of the pouch at operation with a suspension of exogenous coliform organisms. In a control group of ten dogs, the bowel was prepared, two days before operation, with 2 g framycetin,~- which effectively removed coiifoi~n organisms from the howe1. 24

j - F r a m y c e t i n was i so la t ed by Descar is f rom a s t r a in of Streptomyces lavenduiae, w h i c h is n o w c o m m o n l y ca l l ed S. descaris. !It is c losely related chemically to Neomycin B. (Trade name: Sofra- mycin.)

Macroscopic and Microscopic Healing: First Series

Exogenous coliform bacteria were placed in the "pouches" of 13 of 18 unprepared dogs. In nine of the 18, colonic anasto- moses were made, and in the other nine colonic wounds were made and closed. At reoperation or necropsy (two clogs) one to 17 weeks after the initial operation, ab- scesses were found in the "pouches" of 16 clogs. In all 18 dogs there had been macro- scopic healing of the colonic sutnre line (with no fistula formation) and rapid re-

sumption of normal bowel function. In spite of framycetin preparation, pouch

abscesses also developed around the su- tured colonic wounds in nine of the ten "control" dogs; again, macroscopic healing was complete in all ten clogs at re-explora- tion one to three weeks later, and normal bowel function had been resumed.

Histologic healing was complete in nine sutured colonic wounds that were exam- ined two to six weeks after the initial operation, but incomplete in six of nine examined at one week (incomplete in three of four "unprepared" and in three of five control or "prepared").

Resistance to ~Bursting Pressure: Second Series

In a further series of experiments, burst- ing-pressure tests were carried ou t , using the method described by Nelson and Dud- ley. 14 These experiments were done one week after operation in 14 dogs which had extraperitoneal colonic anastomoses (seven with and seven without framycetin bowel preparation). Pouch abscesses (small in three of prepared and two unprepared dogs, large in the others) were found in all 14 cases. In all dogs, macroscopic heal- ing was complete at re-exploration, and bowel function was normai in ai! except two. In these two incomplete obstruction of the colon had developed proximal to the fixed colonic loop (perhaps due to too- tight fxat ion of the loop). Leakage a t t h e

126 RYAN Dis. CoL & Rect. 5Iar.-Apr. 1970

suture line occurred at a pressure of 300 m m Hg. or less in four dogs (three pre- pared and one unprepared) . Leakage oc- curred elsewhere than at the suture line in two instances, possibly due to damage to the specimen at the time of removal.

Conclusions

Under the conditions of these experi- ments, the concomitant development of gross infection (pouch abscess) adjacent to sutured colonic wounds and anastomoses did not prevent macroscopic healing of the bowel in any o~ the 39 dogs in which such abscesses were found.

Bowel prepara t ion with framycetin (used in 17 of 42 clogs) (lid not produce any obvious difference in macroscopic healing of colonic wounds and anastomoses; nor was there any difference in microscopic healing_ , or resistance to bursting pressure, a l though the numbers of experiments in these two categories were too small to be signi fi can t.

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