Effect of moderate haemodilution with Fluosol-DA or normal saline on indocyanine green and (+)-propranolol kinetics

Abstract

Indocyanine green (ICG) and (+)-propranolol kinetics were determined in the rat following moderate (50%) blood exchange with either Fluosol-DA or 0.9% NaCl (saline). Rats received an intravenous ICG dose (5 mg kg-1) before an intravenous dose of (+)-propranolol (2.5 mg kg-1) 0.5, 24, 48 or 72 h after haemodilution and were compared with non-exchanged controls. Haemodilution with Fluosol-DA reduced the ICG elimination rate constant during the first 24 h while a significant reduction was seen 48 h after normal saline exchange. ICG clearances tended to be less than the control value, and were significantly reduced only at 24 h after Fluosol-DA exchange due to a reduced Varea. (+)-Propranolol half-life was significantly increased 48 and 72 h after saline exchange; (+)-propranolol clearance was also significantly reduced 72 h after Fluosol-DA exchange. ICG clearance may be reflecting a hypovolaemic change which occurs after haemodilution, which would reduce the hepatic blood flow. However, (+)-propranolol clearance was not altered, suggesting that the hepatic blood flow is not changed. It is possible that ICG clearance is changed due to alterations in its extraction ratio instead of hepatic blood flow changes.

The in-situ absorption of antipyrine as a measure of intestinal blood flow in Fluosol-DA haemodiluted rats

“…Antipyrine absorption was determined in unexchanged rats (control) and rats haemodiluted with 40 mL kg-' Fluosol using a reported procedure (Shrewsbury et al 1987). The antipyrine in-situ intestinal absorption was determined 0.5,24,48 and 72 h after haemodilution.…”

“…In these experiments though, indocyanine green was used as the dye reported by Shrewsbury et al(1987) as having a low hepatic extraction ratio in the rat, which led them to study the clearance of (+)-propranolol which has an extraction ratio greater than 0.9. In that study, hepatic blood flow was not altered by moderate haemodilution for 48 h but was significantly decreased at 72 h.…”

“…Antipyrine intestinal absorption has been shown to be flow limited in unexchanged (Winne 1978;Schulz & Winne 1987) or Fluosol-43 perfused rats (Takahashi et al 1988). Antipyrine absorption was studied a t various times after haemodilution since Fluosol is eliminated slowly (Lutz & Stark 1987) and hepatic blood flow was altered in a time-dependent manner in the rat (Shrewsbury et al 1987).…”

Cardiac output measurement by pulse dye densitometry in cardiac surgery

“…The amount of indocyanine green injected would thus not correspond with the amount detected, and the decreased area under the curve would produce an overestimation of cardiac output. Interestingly, Shrewsbury et al [28] found a decreased indocyanine green clearance during haemodilution with Fluosol-DA or normal saline in the presence of unchanged liver blood flow in rats. They hypothesised that indocyanine green clearance was altered due to changes in its extraction ratio [28].…”

“…Interestingly, Shrewsbury et al [28] found a decreased indocyanine green clearance during haemodilution with Fluosol-DA or normal saline in the presence of unchanged liver blood flow in rats. They hypothesised that indocyanine green clearance was altered due to changes in its extraction ratio [28]. However, there have been no further investigations of the influence of haemodilution on indocyanine green clearance and on the detection of indocyanine green concentrations using a finger probe or a nose probe.…”