Heparin in the treatment of experimental peritonitis.

Two experiments were performed to determine the effect of heparin on experimental fibrinopurulent peritonitis in dogs. Peritonitis was induced by the creation of a 10 cm long isolated loop of terminal ileum. In a first experiment comprising 24 dogs the necrotic loop was removed 24 hours later without cleaning or irrigating the peritoneal cavity. All dogs showed fibrino-purulent peritonitis at that time. No antibiotics were given. All dogs received 500 ml of Ringer's lactate during surgery and were allowed p.o. fluids on the first postoperative day. At the time of excision the dogs were blindly randomized into a control group and two treatment groups receiving heparin 100 u/kg i.p. or s.c. respectively. Of the eight animals in the control group, five died of peritonitis and two showed residual intraperitoneal sepsis at the time of sacrifice 14 days after the initial surgery. Thus, only one dog cleared his peritoneal infection spontaneously. Of the heparin treated dogs six out of eight in the i.p. treated and seven out of eight in the s.c. treated group cleared their peritonitis spontaneously within 14 days (p </= 0.05 and 0.02 respectively). In a second experiment peritonitis was induced in 24 dogs as described above, but the necrotic loop was not removed. The dogs were blindly randomized to daily low dose heparin (50 u/kg s.c. b.i.d.) or no therapy. Only two out of 12 dogs of the control group survived the observation period of 14 days compared with eight out of 12 of the heparin treated group (p </= 0.05). However, in all dogs in this experiment residual i.p. sepsis was found. We conclude that heparin has a therapeutic effect in experimental canine peritonitis by preventing the additional apposition of fibrin and, thus, rendering the bacteria more susceptible to cellular and noncellular clearing mechanisms.