No abstract

Thirteen patients undergoing transurethral resections of the prostate (TURP) using iso-osmolar 5% mannitol as an irrigating fluid were studied. Mannitol was determined in serum (plasma), as were sodium, prostatic acid phosphatase protein (PAP) and osmolality as probable indicators of absorption of irrigating fluid. The plasma level of mannitol (mean 2.7 g/l = 15 mmol/l) immediately postoperatively, the increase in serum PAP (mean 93 micrograms/l) and the decrease in serum sodium (mean 8.7 mmol/l) all reflect the amount of irrigating fluid absorbed during TURP. The three variables are intercorrelated. The plasma osmolality was unchanged (mean -1 mosmol/kg). A small but constant fraction of mannitol was found in the erythrocytes 2 hours after the operation, amounting to about 3% of the simultaneous plasma concentration. The mean plasma half-life of mannitol was 127 min in the absence of uraemia. In two cases showing a slight increase in serum creatinine the half-lives were prolonged. An estimate of the volume of fluid absorbed was made from the observed plasma mannitol levels. A fluid absorption of up to 3 litres (mean 1.1 l) was found. A strong diuretic effect was observed in some cases when irrigation with mannitol was combined with i.v. furosemide. We conclude that the i.v. diuretic should be withheld until the extent of fluid absorption has been estimated. If the sodium concentration in the serum is largely unchanged immediately postoperatively, diuresis can be induced by an intravenous diuretic.

In 17 men undergoing transurethral resection of the prostate (TURP), an isosmotic solution of 2.2% glycine was used for irrigation. The plasma glycine concentration was determined before and immediately after TURP and 2, 6, 24 and 48 hours later. The serum concentrations of sodium, albumin and prostatic acid phosphatase protein (PAP) were used as indicators of fluid absorption. Calculation of the absorbed fluid volume was based on the plasma concentration of glycine, and the disappearance rate of glycine from plasma was estimated. The mean disappearance rate (T 1/2) was 85 min, which was midway between previously observed rates for sorbitol and mannitol. The observed plasma glycine increase after TURP correlated well with fall in serum sodium and rise in serum PAP, with the blood loss during and up to 15 min after TURP, and also with the weight of the resected tissue. The plasma glycine level, highest immediately after TURP, normalized 24-48 hours postoperatively. No signs of ammonia intoxication or marked serum urea increase were seen in these patients, although some had very high plasma glycine values after TURP (mean 10.2, maximum 23 mmol/l) as compared with the preoperative levels (mean 0.2 mmol/l). There was some increase of plasma serine (a normal metabolite of glycine) after TURP. The authors conclude that the irrigating fluid should have a minimal concentration of glycine, near to the level of haemolysis onset, to minimize the plasma dilution effects, including hyponatraemia, and the appearance of metabolites when the irrigating fluid is absorbed.

The dielectric properties of proteins in polar solvents have been extensively studied, and recently some linear polyelectrolytes-nucleic acids, nucleohistone, and hyaluronic acid-in polar solvents have been investigated at this l a b o r a t~r y .~-~ Most proteins studied have been highly polar and belong to the relatively small group of substances which give dielectric increments in solution. This is also the case for the linear macromolecules mentioned above, and these are still more polar so that they may be investigated in very dilute solutions. For these substances with axial ratios exceeding 10: 1, it was possible to calculate molecular weights from the relaxation times obtained dielectrically. --6 A number of polyelectrolytes have similar pliysicochernical properties aiid are better defined chemically and might thus serve as "model substances" for dielectric investigation. Though it may not be looked upon as a dipolar ion, the sodium salt of a carboxymethylcellulose (CMC) was chosen for this study. EXPERIMENTALA pharmaceutical sample of CMC (kindly supplied by AB Hassle, HEssleholm, Sweden) was purified by centrifuging a 1% solution at 20,OOOg for 1 hour to remove a slight amount of insoluble material, followed by dialysis against distilled water. The "salt-free" solution was then freezedried. The white porous material obtained had a moisture content of 7.4% (the specimen was dried at 95°C. and 0.1 mm. Hg over phosphorus pentoxide for 20 hours). The sodium content of the "moisture-free" substance was 5.78% (determined with flame photometer), corresponding to a ratio of carboxymethylglucose to glucose in CMC close to 1 : 1 if the sodium found is assumed to correspond to the carboxyl groups only, which seems reasonable when considering the pretreatment of the specimen.The viscosity of CMC (specimen IV) in aqueous solutions below 0.1% (20 "C. in an Ostwald viscometer) showed similar dependence upon concentration as for other polyelectrolytes, vs,/c varying between 35 (0.1%) and 50 (0.02%) and falling again at still lower concentrations (c = concentration in grams per 100 ml.).The solutions investigated were prepared by dissolving weighed amounts of substance in redistilled water, using a shaking machine. Complete dis-229

20 patients undergoing transurethral resection of the prostate (TURP) using 5% sorbitol (N = 13) or Cytosol (N = 7) (5% sorbitol and 0.25% acetic acid) as an irrigating fluid were studied. The sorbitol concentration was determined in serum (plasma), as were sodium, prostatic acid phosphatase protein (PAP) and osmolality, as possible indicators of absorption of irrigating fluid. The plasma level of sorbitol immediately postoperatively, the increase in serum PAP and the decrease in serum sodium all reflect the amount of irrigating fluid absorbed during TURP. The three variables are intercorrelated. The plasma osmolality was not significantly changed. The maximum sorbitol concentration immediately postoperatively in any patient was 6.0 g/l (33.5 mmol/l). The mean for the series was 1.2 g/l (6.8 mmol/l). The mean serum PAP increase was 31 micrograms/l. The serum sodium decrease ranged between 0 and 14 mmol/l, mean 5.0 mmol/l. The mean half-life of sorbitol in plasma was short: 35 min, reflecting rapid metabolism. An estimate of the volume of fluid absorbed was made from the plasma sorbitol levels observed. A fluid absorption up to 2.3 l (mean 0.6 l) was found. A marked diuretic effect up to 14.1 ml/min (mean 7.8 ml/min) was observed in some cases when irrigation with sorbitol was combined with intravenous furosemide given postoperatively.