Effect of temperature on fluidity of irrigation fluids

Background. Fluid overload is a major complication during surgical hysteroscopy and transurethral resection of the prostate. We evaluated the role of temperature on absorption of the irrigation solution (IRRSOL) in endoscopic surgery when warm fluids are used to minimize hypothermia. Methods. We measured the density and dynamic fluidity of five IRRSOLs (0.9% saline, Ringer's lactate, 1.5% glycine, 5% dextrose, and 2.5/0.54% sorbitol/mannitol) at three different temperatures (17 degrees C, 27 degrees C, and 37 degrees C). Next, a hypothetical typical endoscopic resection surgery was defined as the reference: total IRRSOL absorption (750 ml), resection time (30 min), and IRRSOL temperature (17 degrees C). On the basis of Poiseuille's law, we calculated new values for intravasation using the predetermined dynamic fluidity values at 27 degrees C and 37 degrees C to assess the influence of the IRRSOL temperature on intravascular absorption (under identical conditions) and then estimated the time to reach fluid overload at each temperature with both electrolyte and non-electrolyte IRRSOLs. Results. Density and fluidity varied with temperature. In these specific conditions, when the temperature of the IRRSOL was increased from 17 degrees C to 37 degrees C, the mean absorption rate was predicted to increase about 54% and the theoretical 'safe' duration of surgery decreased by similar to 65%, for both electrolyte and non-electrolyte IRRSOLs. The reduction in the 'safe' duration of surgery averaged 21.1 min for non-electrolyte IRRSOL (reduced from 60.0 to 38.9 min) and 35.2 min when electrolyte IRRSOLs were used (reduced from 100.0 to 64.8 min). Conclusions. Compared with cold fluids, isothermic IRRSOL may increase the risk of fluid overload because dynamic viscosity decreases at higher temperatures.