Moderate and extreme haemodilution in open-heart surgery: electrolytes, urea, creatinine and osmolality.

Two different programs of treatment, called moderate and extreme haemodilution, respectively, have been compared in patients undergoing aortic valve replacement. Serum electrolytes, urea, creatinine and osmolatity were satisfactory in both groups during and after surgery. A substantial retention of sodium took place in the moderately diluted patients. The extreme group lost more potassium in the urine than the moderate one. A small post-operative rise in creatinine indicates a slight kidney damage in the moderate group. Increased serum urea following moderate dilution might partly be due to increased protein catabolism.