Hypotensive effect of plasma exchange in immune complex nephritis

The effect of plasma exchange (PE) on blood pressure (BP) in 20 hypertensive patients (9 with mixed cryoglobulinemia, 7 with systemic lupus erythematosus, and 4 with idiopathic glomerulonephritis) was evaluated retrospectively. In each PE 1.5-2.5 L of plasma was replaced with an equal volume of 4% albumin polysaline solution. The frequency of PE was three times per week for the first 2 weeks and twice per week subsequently. Sixteen patients were on hypotensive treatment at the onset of PE. Their systolic/diastolic BP was 171 +/- 4.7/102 +/- 3.0 mm Hg (mean +/- 1 SEM). After 4 weeks, BP decreased to 141 +/- 2.8/89 +/- 2.3 mm Hg (p less than 0.001), although in 10 patients antihypertensive drug therapy had been reduced or discontinued. The most marked decrease of BP occurred after the first week (152 +/- 5.3/92 +/- 2.9 mm Hg), and this decrement correlated remarkably well with pressure levels before PE despite the great heterogeneity of the individual patients (for diastolic BP, r = 0.87, p less than 0.001; for systolic BP, r = 0.60, p less than 0.01). A mild decrease of serum creatinine was observed during PE, but its time course was different from that of BP, and did not correlate with this parameter.