Role of Perfusion Pressure in Major Organ Blood Flow during Cardiopulmonary Bypass in Canines / 대한마취과학회지

BACKGROUND: There has been no report about the effects of blood pressure (BP) on the change of blood flow (BF) to major organs when pump flow is maintained during cardiopulmonary bypass (CPB). We evaluated the changes of the BF and oxygen consumption of major organs when BP was controlled by vasopressors or vasodilators during CPB. METHODS: Carotid, femoral, hepatic and renal arteries and veins were exposed and arteries were cannulated for pressure monitoring, except the hepatic artery and arteries on the opposite side were exposed for the measurement of BF in 7 dogs. Temperature was lowered to 30oC after initiation of CPB and phenylephrine or sodium nitroprusside was infused to increase or decrease BP about 30% under the same pump flow. BP and BF were measured before CPB, before the infusion of drugs and when BP was changed by vasoactive drugs. Blood gas analyses were performed from the artery and each vein while the BF was measured. RESULTS: The change of BP didn't affect carotid and renal BF. However, hepatic BF decreased about 50% when BP was reduced and femoral BF changed in the opposite way of BP change. Oxygen consumption of each organ wasn't influenced by BP. CONCLSIONS: When pump flow was constantly maintained, changes in BP redistributed BF to major organs but didn't affect oxygen consumption. The brain and kidney have the ability of autoregulation of BF unlike the liver or legs. Hepatic BF was dependent on perfusion pressure and a decrease in BP by vasodilators during CPB may be not good for the liver.

The Effect of Norepinephrine on Blood Pressure and Blood Flow of the Brachial and Femoral Arteries / 대한마취과학회지

BACKGROUND: Arterial pressure is the most commonly utilized guideline for the management of critically ill patients. However, the site of arterial pressure monitoring can impact the observed pressure. In patients undergoing cardiac surgery, peripheral arterial pressure can underestimate central aortic pressure and vasodilators magnify this phenomenon. There was also a large discrepancy between radial and femoral artery pressure in endotoxemic patients treated with vasopressors or hypothermic patients. We evaluated the effect of the continuous infusion of norepinephrine, the most commonly used vasopressor, on pressure and blood flow in both the brachial and femoral artery in dogs in normal condition. METHODS: Both the brachial and femoral arteries were cannulated for pressure monitoring and the other side arteries were exposed for the measurement of blood flow in 10 dogs. Two doses of norepinephrine (NE), 0.05 microgram/kg/min and 0.1 microgram/kg/min, were infused for 10 minutes each in sequence. Hemodynamic variables and blood flow were measured before the infusion of NE, and immediately after the infusion of the two doses of NE. RESULTS: NE increased both brachial and femoral arterial pressures with no difference between the two pressures. NE decreased blood flow in both brachial and femoral arteries even though cardiac output was maintained constantly which means NE caused the redistribution of blood flow. CONCLUSIONS: Unlike endotoxemic shock conditions or hypothermic vasoconstriction, NE didn't show different effects on pressure monitoring sites regardless of their diameter in normal condition. NE increased blood pressure and decreased blood flow in the same degree in both the brachial and femoral artery.