Acute dialysis and continuous renal replacement: the emergence of new technology involving the nephrologist in the intensive care setting.
The emergence of dialytic support for patients with reversible renal failure was one of the most significant advances in critical care medicine. Supporting a patient with a failed organ till organ recovery has not had the same success with other organ failures. Despite the indispensable nature of the support, dialysis was intermittent at best, and carried its own morbidity. The emergence of a "continuous" dialysis delivery system, originally through an arteriovenous access and later through veno-venous methodology, began to simulate the continuity of the natural kidney, and lifted much of the fluid and drug restrictions imposed by the intermittent nature of standard dialytic therapies. Components of the system were next reviewed for improvement and biocompatability. Differences in patient outcome were documented with various component comparisons, and disparate patient tolerance of delivery modality was also clearly proven. The hemodynamic stability of continuous treatment created utilization to be focused on the more unstable, the more severely compromised patient group. In this context, comparative studies with intermittent delivery methods showed improved hemodynamic stability among patients treated with continuous renal replacement therapies (CRRT), but no clear difference in patient mortality. Patient characteristics and severity scoring have recently been undertaken to better describe the population, and attempts at dialysis dosing is currently being developed for ARF dialysis recipients. Early results seem to point toward a dialysis dose effect on mortality in certain groups of ICU acute renal failure patients. However, the dialytic process is only depurative and artificial. Plastic membrane bio-incompatibility, human physiological responses to foreign material exposure, either in the circuit material itself or introduced from therapy methodology, pose practical and theoretical problems. Recent advances in the field of bio-artificial technology have allowed the development of functioning hybrid "blood processors," which function as a renal tubule and may be able to not only "clean" blood, but also allow for other cellular functions not currently possible with dead membrane technology. Combining living cells with a continuous delivery method may be the next significant step toward a fully functional renal replacement therapy.
Yagi
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Department of Nephrology/Hypertension, Cleveland Clinic Foundation, OH 44195, USA.
Paganini
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EP
D006440:Hemofiltration / Q000379:methods / Q000592:standards / Q000639:trends; D006801:Humans; D007362:Intensive Care Units / Q000592:standards / Q000639:trends*; D009398:Nephrology / Q000379:methods*; D006435:Renal Dialysis / Q000379:methods / Q000592:standards / Q000639:trends; D051437:Renal Insufficiency / Q000628:therapy*; D016896:Treatment Outcome; D014481:United States