During cardiopulmonary bypass, a significant increase in the concentration of unbound propofol occurred without alteration in the total propofol concentration in blood. The effect of the changes of propofol's protein binding on its kinetics was consistent with the predictions based on the well-stirred model of hepatic elimination for an intravenously infused high-clearance drug. Our finding on propofol pharmacokinetics may be the first example demonstrating the theoretic prediction of the well-stirred model.

Hepatic sinusoidal endothelial cells (SECs) are pivotal in the regulation of sinusoidal blood flow. This study showed that SEC function might be impaired during and after cardiopulmonary bypass, irrespective of the temperature management.

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P Pu ur rp po os se e: : To assess and compare the effects of normothermic and mild hypothermic cardiopulmonary bypass (CPB) on hepatosplanchnic oxygenation.M Me et th ho od ds s: : We studied 14 patients scheduled for elective coronary artery bypass graft surgery who underwent normothermic (>35°C; group I, n=7) or mild hypothermic (32°C; group II, n=7) CPB. After induction of anesthesia, a hepatic venous catheter was inserted into the right hepatic vein to monitor hepatic venous oxygen saturation (ShvO 2 ) and hepatosplanchnic blood flow by a constant infusion technique that uses indocyanine green.R Re es su ul lt ts s: : The ShvO 2 decreased from a baseline value in both groups during CPB and was significantly lower at ten minutes and 60 min after the onset of CPB in group I (39.5 ± 16.2% and 40.1 ± 9.8%, respectively) than in group II (61.1 ± 16.2% and 61.0 ± 17.9%, respectively; P <0.05). During CPB, the hepatosplanchnic oxygen extraction ratio was significantly higher in group I than in group II (44.0 ± 7.2% vs 28.7 ± 13.1%; P <0.05).C Co on nc cl lu us si io on n: : Hepatosplanchnic oxygenation was better preserved during mild hypothermic CPB than during normothermic CPB.

Adrenomedullin is a potent vasodilatory peptide. Plasma adrenomedullin (AM) concentrations increase during and after cardiopulmonary bypass (CPB). However, the cause of this increase and its site of production have not been identified. We investigated the role of the hepatosplanchnic and cerebral circulations in the increase of plasma AM and investigated whether tissue hypoxygenation is a cause of the AM increase seen during CPB. We measured plasma total AM (AM-T) and the biologically active form of AM, mature AM (AM-m), in seven patients undergoing CPB. Both plasma AM-T and AM-m concentrations increased significantly 60 min after weaning from CPB. At this time point, arterial AM-T and AM-m concentrations were 18-fold and 10-fold larger, respectively, than baseline values measured after the induction of anesthesia. The plasma AM-m concentration and the ratio of AM-m/AM-T in blood from the hepatic vein were significantly larger than those from the radial artery or jugular bulb. The AM-m/AM-T ratio decreased during CPB, suggesting that production of the intermediate form of AM, AM-glycine, is more than that of AM-m. The oxygen tension of the hepatic venous blood (PhvO2) was significantly less during CPB. Plasma AM-m concentrations sampled from the hepatic vein showed a significant negative correlation with PhvO2 at 10 min (r = 0.824; P < 0.02) and 60 min (r = 0.828; P < 0.02) after the onset of CPB. These data suggest that the hepatosplanchnic circulation is an important source of AM-m during CPB. Furthermore, hypoxygenation of the hepatosplanchnic region may be an important cause of this AM-m increase.

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Fatigue properties of as-rolled and shot-blasted mild steel plates were investigated in air, in sea water and under impressed current cathodic protection. By shot-blasting the fatigue limit in air rises about 20% over that of as-rolled plate. The reasons why the S-log N diagrams of two surface conditions are close to each other in the corrosion-fatigue test and the fatigue limits under cathodic protection are lower than those in air were considered.Introduction.