Bengt Zederfeldt

Respiratory gas tensions and pH in healing wounds.

Abstract The technic of Schilling, Joel, and Shurley [2] has been adapted to the study of oxygen tension, carbon dioxide tensions, and hydrogen ion concentration in wound fluid. The gas tensions have been shown to be characteristic of those present at the advancing edge of the granulation tissue. Oxygen tensions were very low in the early phases of healing and rose as healing progressed. Carbon dioxide tensions were low five days after wounding but rose thereafter, probably because of increased production of carbon dioxide by the healing tissue. The low hydrogen ion concentration primarily reflects the high carbon dioxide tensions of wound fluid. The significance of these data is discussed.

Oxygen and healing

Abstract Measurements of oxygen tension of wound fluid and of oxygen gradients across the wound edge lead to the tentative conclusion that most wounds heal in an environment which is poor in oxygen. The rate of wound healing, therefore, may be limited by the oxygen supply. This implies that under some conditions, wound healing may be improved by the addition of oxygen. There is some support in the literature for this concept. Oxygen transport to tissue is easily decreased by a variety of physiologic conditions. At the present state of our knowledge, it appears particularly important for the surgeon to provide adequate wound oxygenation by maintaining blood volume and insuring that all factors influencing tissue perfusion are optimally supported.

Healing of experimental colonic anastomoses: I. Bursting strength of the colon after left colon resection and anastomosis☆

Abstract Mechanical strength of the left colon with anastomosis and the intact transverse colon was studied by the bursting strength technic from four to fourteen days after standardized left colon resection in the rat. Two different single layer inverting suture technics were used, continuous suture and interrupted sutures. Bursting strength was tested by determinations of both bursting pressure and bursting wall tension, both of which provided the same information concerning mechanical strength of the colon. The bursting strength test measures the anastomotic strength only during the early stages of healing, since more than 90 per cent of the left colon segments ruptured outside the anastomosis as early as day 7. The two different suture technics resulted in the same bursting strength of the left colon segment with anastomosis. Both types of anastomoses showed a moderate narrowing at the anastomotic line upon inflation. This was due to the fact that the anastomosis constituted a relatively firm fibrotic ring from day 7, and both types of anastomoses had an equal inner diameter at that time. By supporting the colonic wall above and below the anastomosis, it could be calculated that the anastomosis on day 7 withstood at least 50 per cent higher circular wall tension than the surrounding colonic wall. There was no correlation between collagen concentration of the colonic wall and bursting strength of the colon either in unoperated controls or after resection and anastomosis. When interrupted sutures were used for anastomosis of the left colon, bursting strength of the intact transverse colon was significantly higher on day 7 than when continuous suture was used. It actually exceeded that of the transverse colon in unoperated controls by almost 50 per cent on the seventh postoperative day, although the collagen concentration in the transverse colon was within normal range. This finding indicated changes in the proximal colonic wall after left colon resection, which are probably related to changes in the structure or arrangement of collagen.

Healing of experimental colonic anastomoses

The present experimental study in rats has demonstrated a marked difference in the healing process of anastomoses in the left colon following two different suture technics: continuous and interrupted sutures. Rats having anastomoses constructed of continuous suture showed a high incidence of complications and a marked decrease of collagen concentration in the anastomosis and in the colonic wall proximal to the anastomosis during the first week of healing. In animals with anastomoses made of interrupted sutures there were fewer complications, the decrease in collagen concentration was confined to the anastomotic region, and the recovery of collagen concentration occurred earlier. The findings indicate that the interrupted suture technic is preferable for anastomosis in the left colon.

Healing of experimental colonic anastomoses. III. Collagen metabolism in the colon after left colon resection.

Abstract In a previous study it was shown that resection and anastomosis of the left colon is accompanied by a marked reduction of collagen concentration in the colon. These changes were not confined to the immediate vicinity of the anastomosis but extended a considerable distance along the bowel and were more marked proximally than distally. Whether the decrease in collagen concentration is due to decreased synthesis or increased breakdown of collagen was studied in the present work by measuring the rate of collagen synthesis and comparing the observations with changes in net amounts of collagen. Synthesis of collagen was studied using pulse labeling with 3H-proline. Studies on the time course of incorporation showed a biphasic pattern with maximal specific activities of collagen 4 and 24 hours after injection of the precursor. The maximal labeling occurred after 24 hours. At that time 75 to 90 percent of the label was present in insoluble collagen, indicating a high rate of turnover. Comparison of net amounts with the rate of synthesis indicates an increased breakdown of collagen. The reaction was clearly most pronounced proximal to the anastomosis. During the first 4 postoperative days breakdown (lysis) dominated. On the 7th day increased net amounts of collagen indicate that synthesis had begun to outbalance processes that break down collagen. The results indicate that the entire colon reacts to the trauma of resection and anastomosis and that in healing of the colon a delicate balance exists between the synthesis and breakdown of collagen.

Breaking strength of small intestinal anastomoses

The breaking strength of standardized small bowel anastomoses at different times after surgery was studied in the rat. The anastomotic strength with sutures in place successively decreased during the first 3 postoperative days to approximately 15 percent of the immediate postoperative value. This indicates a rapid decrease in the suture holding capacity of the gut wall in the early postoperative course. From the fourth day onward a rapid increase in strength was recorded. This could be due not only to deposition of collagen in the tissue bridging the anastomosis but also to the regained capacity of the gut wall to withstand tearing forces. After 14 days the strength of the anastomosis was due mainly to healing, and the relative contribution from the sutures was negligible. It may be that tearing of sutures through the tissue is more important than defective healing for anastomotic complications.

Healing of experimental colonic anastomoses: IV. Effect of suture technique on collagen metabolism in the colonic wall

Abstract A previous study showed that after left colon resection an early and marked reduction of collagen concentration occurred not only in the anastomotic region but also proximally in the colon. This reaction was influenced by the suture technique used. In the present study collagen turnover in different segments of the colon was studied using 3 H-proline as a precursor. There was an increased synthesis of collagen in all colonic segments at an early stage after operation, indicating that the entire colon reacted to the trauma of resection and anastomosis. The changes were asymmetrical in relation to the anastomotic line, with a higher rate of both lysis and synthesis of collagen proximal to the anastomotic line. During the first days after operation lysis dominated over synthesis. It was found that the suture technique influenced the rate of collagen turnover. Continuous suture led to more marked disturbance of the balance between lysis and synthesis and to retarded restoration of collagen concentration. Colonic dilatation and fecal stagnation proximal to the anastomosis were observed in some animals with continuous suture. This condition was associated with an enhanced rate of collagen turnover and a greater breakdown of collagen in the colonic wall than in animals with uncomplicated healing. This may be the cause of the higher frequency of anastomotic complications after continuous suture observed in this and previous studies.

Clinical comparison of surgical wounds closed by suture and adhesive tapes

Abstract Provided the surgeon has closed the subcutaneous dead spaces and secured hemostasis, tape closure of the skin yields advantages over suture closure. By avoiding percutaneous needle tracks, one avoids the risk of suture canal scarring, infection, actual wound infection, and separation. This difference in wound complications is most pronounced in clean-contaminated wounds. The problems in application of this method to wound closure are analyzed and solutions offered. Tape is indicated in the cutaneous closure of all clean-contaminated wounds except those which are mechanically inaccessible or those with profuse drainage.

Collagen metabolism in small intestinal anastomosis

Collagen metabolism in the small intestinal wall during the first week of anastomotic healing in operated and nonoperated rats was studied. During this period, marked changes in anastomotic strength have been observed. A general and marked increase of collagen synthesis was found throughout the intestine already on the second day. This resulted in increased collagen content. Collagen concentration remained relatively unchanged despite an increase in collagen content as a result of concomitant increase of noncollagenous substances. The previously reported loss of anastomotic strength in the early phase of healing could not be explained by changes in collagen content or metabolism in this study. Cutting of sutures seems to be due to a local process. After 4 days, collagen content increased predominantly in the anastomotic region. It correlated well to the previously observed increase of anastomotic strength.

Effect of diverting colostomy on breaking strength of anastomoses after resection of the left side of the colon: studies in the rat

In the present investigation, the effect of a proximal diverting colostomy on suture holding capacity and on anastomotic strength of the excluded left colon was studied. Suture holding capacity was increased 7 days after fecal diversion. Anastomotic strength development, however, was significantly delayed. These differences were accompanied by a diminished collagen response in the anastomotic region after fecal diversion. This might suggest impairment of healing in the excluded colon. The gross appearance of the anastomoses would, however, indicate that increased collagen formation and greater strength development in animals without colostomy is a result of more complicated healing.