engleski

Continuous renal replacement therapy(CRRT) or intermittent hemodialysis(IHD) in ARF and MOF

Acute renal failure is as a rule only a part of the problem in patients with multiple organ failure. All supportive procedures are in the function of maintenance of impaired organ function, and they mostly aid in overcoming acute disorders in critically ill. The most important condition for a favorable outcome is control of the underlying disease, mainly sepsis. In the light of this knowledge the place of intermittent hemodialysis procedures should be viewed, compared to continuous hemofiltration procedures and their effect on the survival of critically ill. Multiple organ failure is a clinical syndrome burdened with a high mortality rate. It is well known that a higher number of failing organs results in an increased death rate. One organ failure results in the death rate of 25–30%, two organs 50–60%, three organs 80% or more, and four organs 100%. As pointed out in the introduction, evaluation of the role of a supportive procedure is hindered by the fact that the principal indicator of the outcome is the underlying disease itself. In current literature there is no prospective randomized study, which showed better patient survival on continuous in relation to intermittent procedures. In order to answer the question what is the procedure of choice in critically ill patients, one must eliminate certain forms of intermittent hemodialysis which by themselves carry frequent problems during extracorporeal circulation. Since the machines with controlled ultrafiltration and bicarbonate dialysate imply smaller incidence of complications, only these devices can be considered comparable with continuous hemofiltration. Meta-analysis of a number of studies, which compared biocompatible to bioincompatible membranes gave advantage to biocompatible membrane, we used machines with controlled ultrafiltration, bicarbonate dialysate solution, and biocompatible polysulfone membrane in our study. It is indisputable that hemodialysis can affect hyperkalemia and volume excess faster, and it solves more rapidly the acute threat of electrolyte and water derrangements. Weekly dose of hemodialysis in chronic renal failure is defined, mainly by the quotient Kt / V > 1.2. The required dose of extracorporeal elimination in acute renal failure is not defined well enough, however it does not essentially differ from the said quotient. The length of intermittent procedure is also not well defined. It mostly lasts 3–4 hours, but some used prolonged intermittent dialysis lasting 9 hours and did not obtain different survival compared to continuous procedures. It has been well established that cytokines affect the severity of the septic process. The possible removal of proinflamatory mediators may permit a blocade of systemic inflammation, a modulation of the altered immune response in these patients, and it may lead to a partial or total restoration of the lost homeostasis). A statistically significant reduction in heart rate, increase in systemic vascular resistance an systolic blood pressure were documented in the group of patients who underwent CRRT. On the other side according meta analysis in published and unpublished trials in any language CRRT in comparison to IHD does not improve survival or renal recovery in unselected critically ill patients with ARF. On the other hand, continuous procedure of hemofiltration has less effect on the stability of circulation. Comparison of value of intermittent hemodialysis with continuous procedures of hemofiltration should therefore be considered in the light of the mentioned fact. In our prospective randomised study with 104 patients, we also did not observed any difference in 28 days survival, in total survival, as well as in circulatory instabilitiy between two treatment modalities. Even in subgroup of 80 patients with sepsis and septic shock there were no difference in survival. Sepsis was the underlying disorder in 52 and septic shock in 28 patients out of 104 patients analyzed in this study. The statistical evaluation of the obtained data revealed no significant difference in patient outcome between the two observed methods of renal replacement therapy [2]. The number of hypotensive attacks defined by blood pressure fall over 10 mmHg in our group of patients on continuous procedures was not significantly smaller. However, there is a randomized prospective study which showed better survival with high volume hemofiltration 35 ml/kg/h compared to low volume ultrafiltration in which 25 l of volume are replaced in 24 hours. We were not able to validate this difference. When choosing the method of extracorporeal circulation, despite the fact that prospective randomized studies did not prove better survival using one of them, intensivists are advised to use the method with less side effects, and of greater benefit in a given case. Our prospective randomized study did not show a statistically significant difference between the two methods of renal replacement therapy. Survival rates were not affected and neither was the occurrence of hemodynamic instability. We therefore believe that the management of the underlying condition outweighs the choice of the procedure of renal replacement. We believe that both methods are complementary ; IHD for faster elimination of electrolytes and waste products elimination, CRRT for regulation of higher calories requirements and for hemodynamically unstable patients. The expectations that one method is superior to the other in the term of better survival have not been corroborated by the current data available in the literature. The choice of the method should be individualized because both methods have advantages and disadvantages. ARF, which is an integral part of MOF, is a problem frequently encountered in critically ill patient treated in the ICU, but outcome of these patients depends closely on the control of basic event. Evaluation of each of the supportive procedures is therefore hindered by the fact that the underlying disease has the crucial effect on survival and the type of supportive procedure less so.

continuous renal replacement therapy; intermittent hemodialysis; ARF; MOF

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