Dermal substitutes for full‐thickness wounds in a one‐stage grafting model

We tested different biodegradable matrix materials as dermal substitutes in a porcine wound model. Matrixes were covered with a split-skin mesh graft and protected with a microporous, semipermeable membrane, which prevents blister formation, wound infection and provides ultimate healing conditions. Evaluation parameters were as follows: epithelization, dermal reconstitution, wound contraction, and cosmetic and functional aspect. A microfibrillar matrix of nondenatured collagen gave the best result, with immediate fibroblast ingrowth and epidermal outgrowth. Slight inflammatory reaction and minimal wound contraction were observed. Application of a split-skin mesh graft, in combination with this collagen matrix, generated a thicker dermal layer than did a split-skin mesh graft directly applied on a wound bed. However, the histologic dermal architecture was less optimal than one obtained with a full-thickness punch graft method. Other matrixes caused inflammatory reactions, interfering with epithelization and dermal reconstitution. We conclude that a nondenatured collagen matrix, in combination with a split-skin mesh graft, can provide a substitute dermis in a full-thickness wound. This combination is preferable to a split-skin mesh graft directly applied on the wound bed. With our microporous semipermeable membrane, the combined use of a dermal substitute and a split-skin mesh graft can be applied in a single-stage operatio

LATE AIRWAY CHANGES CAUSED BY CHRONIC REJECTION IN RAT LUNG ALLOGRAFTS

Airway disease after lung or heart-lung transplantation is one of late major complications, affecting the prognosis of the transplants. Little is known about the causes of airway changes. We performed rat lung transplantation and investigated the late airway changes of the long-term surviving lung grafts: allografts, BN to Lewis; isografts, BN to BN rat. All recipients were treated with CsA. We found airway changes, i.e., mucosal ulceration, granulation, submucosal fibrosis, which was located in the large airways, in four of five allografted lungs. The lung isografts showed no pathological abnormalities. Immunopathological studies disclosed the localized expression of MHC class II antigens on the bronchial epithelium of the large airways where recipient type dendritic cells accumulated in the submucosa and CD4 positive predominant lymphocytes infiltrated. These findings support the idea that the late airway changes in lung transplants are caused by immunologically mediated chronic rejection

Myocardial performance in elderly patients after cardiopulmonary bypass is suppressed by tumor necrosis factor

The aim of this study was to determine whether elderly patients (aged > 65 years, n = 20) in comparison with younger patients (aged < 55 years, n = 23) demonstrate a different biochemical and hemodynamic response to coronary artery bypass operations. In the elderly group, we calculated a smaller body surface area (p < 0.01) than that in the younger group, and more female patients were included in this group (p < 0.05). During cardiopulmonary bypass, the elderly had higher endotoxin plasma concentrations (p < 0.01) than the younger patients, and significantly more circulating tumor necrosis factor-alpha was found after operation (p < 0.04). In the intensive care unit, the elderly patients had a significantly higher pulmonary capillary wedge pressure (p < 0.001), a higher mean pulmonary artery pressure (p < 0.01), and a lower calculated left ventricular stroke work index (p < 0.05). Multivariate analysis for the postoperative outcome showed that the intergroup differences in tumor necrosis factor-alpha, mean pulmonary artery pressure, and pulmonary capillary wedge pressure could be explained mainly by the difference in age between the groups and that the calculated left ventricular stroke work index difference could be explained by the difference in circulating tumor necrosis factor-alpha levels. Thus in elderly patients higher circulating endotoxin and tumor necrosis factor-alpha concentrations were detected than in younger patients, which clinically resulted in a suppressed myocardial performance. (J THORAC CARDIOVASC SURG 1995;110:1663-9)

Health care service for ostomy patients: profile of the clientele

Background. Endothelin is involved in the control of cardiovascular and renal functions and acts as a neuromodulator. Methods. In a prospective study among 15 male patients who underwent coronary artery bypass grafting, we investigated the release pattern and possible stimuli of circulating endothelin. Results. We detected a steep increase in endothelin concentrations after the onset of cardiopulmonary bypass (CPB), and a second minor increase during CPB. The steep increase in endothelin concentrations correlated with the change in arterial pressures at the onset of CPB (r = 0.57; p < 0.03). The slow increase in endothelin concentrations during CPB, however, correlated with mean endotoxin levels during and after CPB (r = 0.60; p < 0.02). Conclusions. The change in arterial pressure at the onset of CPB seems to induce a steep and fast increase in circulating endothelin level, which is probably mediated through the baroreceptors. The slow increase in endothelin level during CPB is associated with increased circulating endotoxin concentration. It may be that either endothelin-mediated vasoconstriction induces endotoxin transmigration from the intestine or endotoxin stimulates endothelin secretion from endothelial cells

Reduced complement activation and improved postoperative performance after cardiopulmonary bypass with heparin-coated circuits

A randomized controlled trial that involved 30 patients undergoing elective coronary artery bypass grafting was done to determine the effect of heparin-coated circuits and full heparinization on complement activation, neutrophil-mediated inflammatory response, and postoperative clinical recovery. Peak concentrations of terminal complement complex were 38% lower (p = 0.004) in 15 patients treated with heparin-coated circuits (median 775 μg/L, interquartile range 600 to 996) compared with those in 15 patients treated with uncoated circuits (median 1249 μg/L, interquartile range 988 to 1443). Although no significant intergroup differences in concentrations of polymorphonuclear neutrophil elastase were found, a positive correlation (r s = 0.74, p < 0.0007) was calculated between peak concentrations of terminal complement complex and polymorphonuclear neutrophil elastase. Differences in patient recovery were analyzed with use of a score composed of fluid balance, postoperative intubation time, and the difference between rectal temperature and skin temperature. The score was significantly lower in patients treated with heparin-coated circuits (p = 0.03), whereas its components showed no intergroup significance. We conclude that the use of heparin-coated circuits with full systemic heparinization results in improved biocompatibility, as assessed by complement activation, and leads to an improved postoperative recovery of the patient. (J THORAC CARDIOVASC SURG 1995;110: 829-34)