The Modern Treatment of Anuria

There are few conditions which offer a greater challenge to the medical and nursing staff than that of acute renal failure. There are also few conditions where the application of modern techniques and careful clinical biochemical assessment are more essential to the achievement of success. True or complete anuria rarely occurs except where there is mechanical obstruction and, as early recognition of oliguria is essential in acute renal failure, it is important to define it in a recognizable form. The normal output of urine varies between one and two litres per day. On a mixed diet it is obligatory to pass a minimum volume of approximately 500 ml. in 24 hours (Gamble, I947). This entails good renal function and the ability to concentrate fully to a maximum specific gravity of I.o35 (I,I55 m. osm./l.). Oliguria has been defined as less than 700 ml. in 24 hours. Where good renal function is present such urine will concentrate sufficiently to produce a specific gravity of i.oi8 (595 m. osm./l.) or more. Where renal damage is present, a low specific gravity of i.oo8 (265 m. osm./l.) to 1.o014 (460 m. osm./l.) is to be expected (Joekes, I957). Severe oliguria may be defined as a urine output of 500 ml. or less in 24 hours. Where there is a urine output of 300 ml. or less, such will be the inability of the kidneys to keep pace with the production of metabolites, the condition might well be called metabolic anuria. The object of therapy in oliguria and anuria is to tide the patient over until the kidneys have time to recover their function. At this time, it is probably true to say that suppression of urine due to malignant hypertension, chronic nephritis and polycystic kidneys developing into oliguria, and the rare condition of bilateral cortical necrosis, is, in the main, not reversible. The reversible causes of acute renal suppression may be listed as: (a) Mechanical-obstruction of the ureters, by: operative procedures; bilateral renal calculi; carcinoma of the prostate and cervix; procidentia, etc. (b) Dehydration and electrolyte depletion, e.g. low salt syndrome. (c) Tubular necrosis such as follows: gross dehydration; prolonged hypertension; separation of placenta; abortion; crush syndrome; missmatched blood transfusion; nephrotoxins, e.g. mercuric chlorides, bismuth, sulphonamides. (d) Acute nephritis. The history of a successfully treated case of acute suppression of urine normally falls into four phases: (a) The precipitating condition or cause. (b) The anuric phase. (c) The diuretic or pre-recovery phase. (d) The recovery phase.