High-dose intravenous infusion of irrigating fluids containing glycine and mannitol in the pig

BACKGROUND: Large-scale absorption of electrolyte-free irrigating fluid during endoscopic surgery may result in a "transurethral resection syndrome." The severity of the syndrome can probably be modified by using mannitol 5% instead of the most widely used glycine 1.5%.

METHODS: Seventeen pigs with a mean body weight of 22 (range 19-26) kg received an intravenous infusion of 100 mL kg(-1) h(-1) of either glycine 1.5% or mannitol 5% over 90 min. Central hemodynamics, whole-body and brain oxygen consumption, intracranial pressure, blood hemoglobin, and the sodium concentrations in serum and urine were monitored for 120 min. Selected measurements were made on 6 other pigs given mannitol 3% and in 2 controls not given any fluid. Morphological examinations of the hearts were conducted.

RESULTS: Both glycine 1.5% and mannitol 5% transiently increased cardiac output, the aortic blood flow rate, and arterial pressures, but all of these parameters fell to below baseline after the infusions were ended. The intracranial pressure was lower (P < 0.05) and the oxygen consumption in the brain decreased (P < 0.001) during the infusion of mannitol 5%. Glycine 1.5% expanded the intracellular volume more than mannitol did (P < 0.002). Signs of myocardial damage were graded glycine 1.5% > mannitol 5% > mannitol 3%.

CONCLUSIONS: Massive infusion of glycine 1.5% and mannitol 5% left the pigs in a hypokinetic hypotensive state. Glycine 1.5% increased the intracranial pressure and injured the myocardium more than mannitol 5%, which then seems to be a more appropriate irrigating fluid to use during endoscopic surgery.