[Hemofiltration in acute kidney failure. Experiences of a surgical intensive care station]

Until recently acute renal failure (ARF) in critically ill patients has been known to have a very poor prognosis, particularly when associated with multiple organ failure (MOF). Mortality rates for ARF in combination with at least two other failing organ systems have ranged over 90%. Despite the use of intermittent hemodialysis no better outcome was possible until continuous arteriovenous hemofiltration (CAVH) was introduced by Kramer in 1977. From several extracorporeal clearance methods we chose to evaluate the pump-driven intermittent venovenous hemofiltration (HF) system in the ICU and its effect on mortality in MOF. PATIENTS and METHODS. Over a period of 39 months we evaluated 63 patients, 58 of them with MOF undergoing altogether 532 sessions of HF. The reason for the development of ARF was prerenal in 47% (circulatory shock, hypovolemia), renal in 43% (septic) and other problems in 10% (ARDS, cardiac failure). After special optimizing therapy for patients with ARF (10), HF was required for treatment as defined by a serum creatinine greater than 3 mg/dl (BUN greater than 150 mg/dl), oliguria of less than 30 ml/h or a creatinine clearance of less than 20 ml/min. Vascular access was obtained by a double lumen venous cannula inserted into the subclavian vein. HF was performed by a machine equipped with 3 roller pumps and an electronic fluid equilibration system using a hollow fiber filter running for 6-8 h. The average flow of ultrafiltrate was 74 ml/min. RESULTS. The average decrease per hemofiltration of creatinine levels was 1.97 +/- 0.77 mg/dl, of BUN 73.5 +/- 28.3 mg/dl. Moreover, we noticed decreasing platelet counts, fibrinogen and osmolarity levels, as well as a slight increase in pH values. Mortality was 37%. DISCUSSION. When comparing HF with other clearance methods such as hemodialysis there are some remarkable advantages: easier handling of the fluid and electrolyte balance; the possibility of total i.v. alimentation in septic, hypercatabolic patients, safe and precise administration of antibiotics, glycosides and sedatives because of their highly predictable and steady elimination rates throughout HF; last but not least, the removal of renal and vasoactive toxins. There was practically no impairment of the cardiovascular system during HF. Our experiences in the ICU show that HF has been successfully used with decreasing mortality. This kind of treatment improved the fate of the critically ill patient with ARF alone or combined with MOF to the extent that the patient's prognosis was excellent if the main surgical problems could be solved.