Traumatic Shock

Should continuous renal replacement therapy be used for 'non-renal' indications in critically ill patients with shock?

Accumulating experience with the use of continuous renal replacement therapy (CRRT) in critically ill patients with acute renal failure suggests that these treatment modalities have distinct advantages relative to conventional dialysis in terms of solute clearances, fluid removal and hemodynamics, which may translate in improved renal and patient outcome. Recent data point to a possible beneficial effect of CRRT on the clinical course, independent from an impact on fluid balance, in critically ill patients with shock which is attributed to the continuous elimination of inflammatory mediators from the circulation. This has raised the question as to whether CRRT might be used for 'non-renal' indications such as the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). In some animal models of experimental septic and non-septic shock, (short-term) hemodialysis and hemofiltration were found to improve hemodynamics and/or gas exchange. However, data were inconsistent and the clinical relevance questionable. Observations from both uncontrolled and controlled clinical studies (comprising only a small number of patients) support the hypothesis that CRRT may exert beneficial effects on the clinical course in critically ill patients with SIRS and MODS, independent from volume removal. Although several mediators known to play a role in the development of SIRS/MODS may pass hemofiltration membranes, quantitative data on the extent of its extracorporeal clearance relative to the production rate and endogenous clearance is often lacking. In addition, this aspecific elimination with CRRT may also effect levels of anti-mediators, which may be harmful. Ultrafiltrate properties include depression of cardiac performance, induction of proteolysis and immunosuppressive activity suggesting that water-soluble factors responsible for these deleterious effects are removed from the circulation by convection. However, no significant survival advantage has yet been shown for critically ill patients with SIRS/MODS when treated with CRRT as an adjunct to conventional therapy. Only prospective controlled studies of appropriate sample size, which requires a multicenter approach, might answer the question whether use of CRRT may alter the clinical course and outcome in critically ill patients with SIRS and MODS. Until such studies are performed, the rationale for the use of CRRT in the absence of conventional indications for dialytic support remains unproven.

Significance of homologous donor blood to the toxic reaction in dogs undergoing extracorporeal hemodialysis

Application of hemodialysis to dogs has been complicated by an acute reaction consisting of hypotension, bradycardia and respiratory depression followed by instability and a mortality rate of about 30 per cent. This reaction appears to be a response to homologous blood used to fill the dialyzers. Sensitization occurs in survivors, and accentuated reactions with marked hemolysis are noted on subsequent challenge. Cross matching the donor and recipient bloods has not permitted an adequate determination of compatibility under the conditions of hemodialysis. Satisfactory hemodialysis may be accomplished in dogs by using autogenous blood or blood substitutes to fill the dialyzers.