Effect of hyperbaric oxygen on microvascular anastomosis healing and patency in the rat.

Recent evidence has shown that changes in blood viscosity and marked increases in both platelet count and fibrinogen concentration occur after exposure to hyperbaric oxygen (HBO). The purpose of the present study was to address whether repeated HBO therapy would increase either hematocrit or platelet count, and to determine if these changes would influence the patency of the microvascular anastomosis, as well as anastomotic healing. Eighty femoral arteries from 40 rats were divided into four groups (n = 10), and arterial anastomoses were performed on normal arteries in the first two groups, and on crushed arteries in the second two groups. One of the normal artery groups and one of the crushed artery groups received repeated HBO treatments for 5 days. Anastomotic patency rates, platelet count, hematocrit, and breaking strength were recorded. Among the results of this study were that: (1) there was no difference in patency rate following HBO treatment in both the normal and crushed artery groups; (2) platelet count was significantly higher following HBO treatment in the groups with the undamaged arteries; (3) breaking strength was significantly increased following HBO treatment in the groups with the crushed arteries. The authors concluded that HBO therapy may be useful in improving the healing of microvascular anastomoses in vessels that have undergone crush injury. Although HBO treatment results in an increased platelet count, this does not influence anastomotic patency.

Effect of hyperbaric oxygen on survival of the composite ear graft in rats.

In this study the authors set out to determine whether postoperative hyperbaric oxygen (HBO) therapy increases the survival rate of the composite graft in the rat ear model. A composite graft (1 x 0.5 cm2) that included skin, subcutaneous tissue, and cartilage was created from the left ear, and was transferred onto the posterior auricular site of the right ear. The animals were divided into two groups: a control group (N = 10) and an experimental group receiving HBO (N = 10). The experimental group was given HBO immediately following reattachment for 4 hours, and then for 6 hours each day for 5 days (2 atm). The results showed the average ear flap survival area in the experimental group was 82%, and it was 26.5% in the control group (p < 0.01). Histology demonstrated the existence of neovascularization in the experimental group. We have concluded that postoperative HBO therapy increases the survival of the rat ear composite graft, and that the effect of this therapy is influenced by the magnitude (size and thickness) of the graft.

Intestinal flora of the medicinal leech Hirudinaria manillensis.

Medicinal leeches are widely used to treat venous congestion in microvascular surgery. Aeromonas hydrophila infection, following application of the leech species Hirudo medicinalis, is a recognized complication. Administration of antibiotics directed at Aeromonas has been successful in minimizing complications of infection from this organism. A different leech species, Hirudinaria manillensis, has recently been introduced for microsurgical use. A study of the enteric content of 30 of these leeches showed that Aeromonas hydrophila was isolated in only 20 percent of animals, while the majority of remaining positive cultures were single and mixed gram-negative rods. All organisms isolated were sensitive to current recommended coverage for Aeromonas hydrophila. This study suggests that the enteric flora of different leech species may be variable and should be carefully characterized, to direct appropriate prophylactic therapy prior to release of new species for clinical use.

Aeromonas hydrophila infections following use of medicinal leeches in replantation and flap surgery.

Aeromonas hydrophila infections are a recognized complication of postoperative leech application, and can occur with measurable frequency in populations of patients treated with leeches. We review 11 previously reported leech-related Aeromonas infections and analyze seven unreported cases. These infections range from minor wound complications to extensive tissue loss and sepsis. Often, these infections followed leech application to tissue with questionable arterial perfusion. Onset of clinical infection in these patients ranged from within 24 hours of leech application to 10 days or more after leech application. Late infections may represent bacterial invasion from colonized necrotic tissue. Based on these observations, we recommend that leech applications be restricted to tissue with arterial perfusion to minimize contamination of necrotic tissue. We also recommend that patients treated with leeches receive antibiotics effective against Aeromonas hydrophila before leech application. Patients treated with leeches and discharged with eschars or open wounds might benefit from oral antibiotic therapy until wound closure. These precautions may minimize or eliminate this complication of leech use.

Postprandial Aeromonas hydrophila cultures and antibiotic levels of enteric aspirates from medicinal leeches applied to patients receiving antibiotics.

Increasing use of medicinal leeches has been accompanied by increasing numbers of reports of Aeromonas hydrophila infections after leech application on or near damaged tissue. We examined the enteric contents of postprandial leeches after their application to patients receiving antibiotics. We found measurable levels of antibiotic in the leech enteric contents, and in leeches applied to patients receiving an antibiotic effective against Aeromonas hydrophila, there was a significant decrease in positive Aeromonas enteric cultures. Suppression of leech enteric bacteria by antibiotic administration to the patient may be an effective strategy to prevent invasive infection by Aeromonas hydrophila as well as bacterial colonization of devitalized tissue that could be the source of late infection. Clinical studies will be required to clarify whether suppression of leech enteric flora results in a decrease in infections associated with leech use.

Aeromonas hydrophila infections following clinical use of medicinal leeches: a review of published cases.

Ten Aeromonas hydrophila infections following postsurgical leech applications have been reported. These cases indicate that postsurgical wounds and damaged tissue can provide entry for either acute or delayed A. hydrophila infection. These infections can range from localized cellulitis to progressive myonecrosis and sepsis. These infections may occur with measurable frequency in groups of patients exposed to leeches. Based on this review, it is recommended that leeches be applied only to tissue with a reasonably certain arterial supply; that patients receive antibiotics against A. hydrophila prior to leech administration; and that consideration be given to prolonged antibiotic administration to patients discharged home with open wounds or questionably viable tissue after leech administration.

Sensitivities of Aeromonas hydrophila cultured from medicinal leeches to oral antibiotics.

Infections associated with medicinal leech application are caused by Aeromonas hydrophila, an organism that resides in the leech gut. We cultured the intestinal tracts of 25 leeches and evaluated the efficacy of oral antibiotics against Aeromonas hydrophila. Cultures of this organism showed no sensitivity to ampicillin and inconsistent sensitivity to cephalothin (equivalent to cephalexin). The Aeromonas hydrophila cultures did show consistent sensitivity to ciprofloxacin, tetracycline, and trimethoprim-sulfamethoxasole. These three antibiotics should be considered if oral antibiotic coverage is used in association with leech application.

Quantitative fluorimetric effects of leeching on a replanted ear.

Leeching is used to relieve venous congestion in microscopically replanted tissues. A quantitative description of the effects of leech application on tissue perfusion has not been reported. We report a case of an ear replantation in which venous congestion was consistently improved with leeching. In four instances, quantitative fluorimetry, which indicated impaired circulation and prompted leech application, showed restoration of normal circulation patterns following leech application. The fluorometric studies suggested that arterial inflow improved and venous congestion was relieved.

Low residue nutritional supplementation as an adjunct to mechanical preparation for surgical treatment of the colon.

The mechanical and nutritional efficacy of a low residue nutritionally complete liquid diet was evaluated as an adjunct for colonic preparation in patients undergoing large intestinal operations. The complete liquid diet was identical to more traditional clear liquid diets in terms of cleanliness of the intestine and general profile of bacterial flora. This complete diet was well accepted by patients and was superior in its provision of energy, protein, vitamins, minerals and nitrogen. The use of this low residue supplemental diet was associated with a statistically earlier return of intestinal function and a trend toward shorter length of hospitalization. The results of this study indicate that low residue nutritionally complete liquid diets not only offer comparable mechanical cleanliness but also outstanding nutritional advantages not obtained with traditional preparatory diets.