Hemodynamic evaluation during plasma-exchange with intermittent flow.

Plasma-exchange (PE) represents an effective therapeutic approach employed in several immunological nephropathies, poisonings and various other diseases. Hemodynamic changes during intermittent flow PE were studied--using the thermodilution technique--in 8 patients (3 male and 5 female) aged between 36 and 73 years (mean 46.4). The mean values for the following parameters were measured before, during every cycle--exchanging about 300 ml of fresh frozen plasma--and at the end of the session: mean arterial pressure (MAP), heart rate (HR), cardiac index (Cl), stroke index (SI), total peripheral resistence (TPR), central venous pressure (CVP), pulmonary arterial pressure (PAP) and pulmonary capillary wedge pressure (PCWP). During the first exchange the systemic circulation showed hemodynamic changes similar that of an acute hemorrhagic condition: decrease in MAP (from 106 to 97 mmHg), Cl (from 4.27 to 3.7 L/m'/m2), SI (from 53 to 49 ml/beat/m2) and CVP (from 6.9 to 4.4 mmHg); increase in TPR (from 1230 to 1339) dynes/sec/cm-5), while HR showed only mild changes. In the following cycles all the parameters progressively returned toward the previous values. During the first cycle the pulmonary circulation showed a decrease in PAP (from 15.5 to 13 mmHg) and PCWP (from 8.9 to 6.6 mmHg). PAP also increased constantly in the following cycles reaching at the end of the session levels which were higher than the initial ones. Our data demonstrate that in PE treatment especially when is employed a low volume of fluid, has to be substituted at every cycle in order to prevent the major hemodynamic complications i.e. hypovolemic shock and heart failure.