Possible equilibration of portal venous and central venous pressures during circulatory arrest

The mean circulatory filling pressure technique has been used to assess total body venous tone. It involves measuring central venous pressure (CVP) at 5-8 s following circulatory arrest. This study examines if CVP and portal venous pressure (PVP) equilibrate when circulation is stopped by inflating a balloon implanted in the right atrium. CVP and PVP were measured in the control condition and after intravenous bolus injections of norepinephrine (NE, 1.6 microgram/kg), angiotensin II (ANG II, 1.3 microgram/kg), and isoproterenol (Iso, 0.5 microgram/kg) in conscious and pentobarbital-anesthetized rats. In conscious rats, CVP was similar to PVP after circulatory arrest under conditions of normal, elevated, or reduced vascular tone. In anesthetized rats, CVP was similar to PVP in the control condition and after intravenous bolus injection of NE and Iso but was less than PVP after the administration of ANG II. Therefore, mean circulatory filling pressure may not fully reflect total body venous tone in anesthetized, surgically stressed rats.