Role of Irrigating Fluid

The choice of irrigant is important in explaining the mechanisms of cerebral and visual dysfunction associated with TURP. A desirable irrigant fluid is clear (for better visualization), nonionized, nontoxic, inexpensive, and easily sterilized. Unfortunately, the best visualization occurs with use of hemolytic fluids (such as water) that dissolve red cells and thus dispel any cloudiness in the operative field. Solutes used to make irrigation fluid safe must be "effective osmoles" to prevent hemolysis and cerebral edema. Ionized solvents cause dispersal and weakening of the current from the cautery, thereby making cutting and coagulation ineffective. ^[267]

The most extensively used solution is probably 1.5% glycine. It is slightly hypo-osmolar, but it does not cause clinically significant hemolysis. ^[268] A 1.5% solution of glycine has an osmolarity of 200 mOsm/kg.^[257] The half-life of infused glycine in plasma is reported to be between 26 and 245 minutes, depending on the dose administered. ^[269] Glycine is metabolized to serine and ammonia, both of which are associated with CNS complications after TURP.^[270] Other important metabolites include glyoxylic acid, an inhibitor of oxidative phosphorylation, and methylene tetrahydrofolate, an inhibitor of presynaptic glutamate uptake.^[271]