The natural history of and therapy for perirenal fluid collections following renal transplantation.

Fluid collections following renal transplantation are not rare and may be associated with serious complications. We studied the incidence, clinical features, pathology and treatment outcome of perirenal fluid collections after kidney transplantation. Between January 1977 and June 1985, 386 consecutive renal transplants were performed at our university. All allografts were studied with B-mode ultrasonography together with a renal scan in the immediate post-transplant period, at 6-month intervals or when clinically indicated. Symptomatic fluid collections, those associated with rejection episodes and those containing more than 50 to 100 ml. fluid were aspirated under sonographic control via aseptic techniques. There were 190 fluid collections (49 per cent) observed during followup (2 to 11 years). Of these collections 98 (51 per cent) were estimated to be less than 50 ml. in volume, were clinically insignificant and resulted in no morbidity. A total of 92 collections was aspirated with 1 aspiration being diagnostic and therapeutic in 57 instances (serous or serosanguinous fluid). The 35 collections remaining were revealed to be lymphoceles on biochemical grounds. Of 13 lymphoceles associated with rejection episodes 8 resolved on initial aspiration. Of the recurrent lymph collections 27 were treated with repeated aspiration, tetracycline sclerotherapy or an operation (10 were treated with marsupialization into the peritoneal cavity). No large collections of urine or blood were detected and 1 infected lymphocele required external drainage. No renal allograft was lost as a result of a fluid collection and over-all graft survival was not affected by the development of perirenal fluid collections. We conclude that perirenal fluid collections are detected commonly in the post-transplant period using B-mode ultrasonography. The majority of these collections are small and will require careful observation only or they will resolve with a single aspiration. Aggressive diagnostic and therapeutic measures are used only for those collections that are symptomatic or result in allograft dysfunction. A rational approach to the diagnosis and treatment of peritransplant fluid collections is described in the form of an algorithm.

Mechanisms of cimetidine protection following thermal injury.

Experimental studies have shown that treatment with cimetidine within 30 minutes of severe thermal injury decreases resuscitative fluid volume requirements by 70 percent. In treated animals, marked hemodynamic improvement was shown as compared with the untreated animals. Administration of the histamine (H2)-receptor antagonist ranitidine was not effective in reducing resuscitative fluid volume, leading to the hypothesis that cimetidine acts via predominantly non-H2-receptor antagonist mechanisms. Evidence is presented for a multifactorial mechanism by which cimetidine offers protection from burn shock. The mechanisms under investigation include inhibition of the hepatic cytochrome P-450 enzymes, cimetidine/copper scavenging of oxygen free radicals, inhibition of thromboxane synthesis, and imidazole buffering capacity. Acting via one or all of these mechanisms, cimetidine may protect against the vascular permeability changes and circulatory collapse that can follow severe thermal injury.

Modeling of intervertebral discs.

A model with rotational symmetry of an intervertebral disc is studied. The nucleus pulposus is assumed to consist of an incompressible fluid, and the annulus fibrosus is modeled by 11 fiber layers with alternating fiber inclination. The spaces between the fiber layers are assumed to be filled with an incompressible fluid. The pressures in the fluid compartments, the fiber strains, and the bulge are calculated under different assumptions regarding fiber inclination, fiber force-elongation relation, initial fiber layer bulges, and so on. The agreement with experimental results is very good. Possible extensions of the model are briefly discussed.

Salicylate poisoning complicated by fluid retention.

We have presented two cases of salicylate poisoning that demonstrate fluid retention in the face of adequate hydration, resembling the syndrome of inappropriate secretion of ADH. These cases necessitated marked alterations from normal fluid therapy. Mannitol was found to be an effective, albeit transient, diuretic for treating the acute symptoms associated with fluid retention, but only strict fluid restriction resulted in a prompt and satisfactory diuresis.

Observations of the role of body fluid volumes and plasma renin activity in the management of hypertension.

Reduction of the (expanded) body fluid volumes found in some patients with renal hypertension may be essential in the management of these cases. Illustrative examples are given of this "volume dependent" form of hypertension. In such patients, plasma renin activity (PRA) is low. Other forms of hypertension may be regarded as caused by "inappropriate renin secretion". Most often, however, both factors are operative. This concept is supported by experimental evidence obtained in animals. The combined effect of salt depletion (which increases PRA) and beta-adrenergic blockade with propranolol (during which treatment PRA is lowered) was systematically studied in 3 groups of hypertensive patients (including one group with chronic renal insufficiency). The results indicate that this combined therapy lowers the blood pressure in various types of hypertension, the effect being sometimes more than additive. There was, however, no correlation between the PRA levels and the blood pressure decrease after salt depletion or after propranolol. Consequently, on the basis of the PRA values, no group of patients could be identified for which this treatment would be specifically indicated.