The most striking advantage of CRRT (Tabled) is its excellent hemodynamic tolerance. Continuous and gradual fluid removal leading to adequate fluid recruitment from the interstitium is the major explanation for this hemodynamic stability. Convective (iso-osmotic) solute transport also contributes to efficient plasma refilling by limiting intracellular fluid shifts. The use of synthetic membranes avoids hypotension induced by bio-incompatibility. Absence of abrupt fluctuations in fluids and solutes prevents the increase of intracranial pressure that is frequently associated with intermittent techniques. Intermittent hemodialysis has been suspected of contributing to the prolongation of acute renal failure through either repetitive periods of hypotension or the use of low-flux bio-incompatible membranes with insufficient removal or generation of the mediators promoting renal failure. Therefore CrRt with biocompatible membranes could lead to a better preservation of residual renal function. Arrhythmias due to rapid changes in electrolyte concentrations are prevented. The tolerance to fluid removal allows unlimited nutritional support; this should take into account the eventual glucose content of the dialysate and a 10 to 15 per cent loss of infused amino acids in the ultrafiltrate.
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Htff Ml el rfsraflty rtttiitotj* Table 2 Advantages of CRRT
The continuous nature of CRRT permits equilibration between body compartments and therefore access to the total distribution volume. This improves solute removal, particularly if equilibration is slow. CRRT is flexible, allowing adaptation to the patient's situation at any time. It is managed by the intensive care nurse and thus obviates the need for a dialysis nurse.
At the time of its introduction the simplicity of CRRT was considered a significant advantage. The addition of blood pumps, combined diffusion and convection, automated balancing devices, ultrafiltration control, etc. has increased the complexity of these procedures but has greatly contributed to their efficiency and safety.
The potential continuous elimination of mediators of sepsis and multiple organ failure may represent a means of controlling not only the consequences of renal failure but also the underlying disease.
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