The effect of priming techniques of ultrafiltrators on blood rheology: an in vitro evaluation

The increased interest of using ultrafiltration during cardiopulmonary bypa ss (CPB) has mandated a re-evaluation of the hematological effects of this blood conservation process. 'Rinse-free' ultrafiltrators can be primed usin g either crystalloid or blood prior to use. It is unknown whether one primi ng technique results in superior results in ultrafiltration quality. An in vitro circuit was designed to evaluate the Sorin/COBE HCl400 (n=6), the Lif estream HC70 (n=6), and the Terumo/Sarns HC11 (n=6). Ail test conditions we re conducted at a blood flow rate of 250 ml/min and a transmembrane pressur e of 250 mmHg. Samples were drawn and analyzed at four distinct time points for hematocrit, total protein, plasma free hemoglobin, interleukin-6 (lL-6 ), interleukin-8 (lL-8), and tumor necrosis factor-alpha (TNF alpha). The H C11 had significantly greater percent increases in hematocrit under the blo od priming protocol (29.2 +/- 7.9) than either the HC1400 (11.0 +/- 7.8, p< 0.03) or the HC70 (11.9 <plus/minus> 7.8, p<0.04), When crystalloid priming was compared to blood priming, the HC1400 and HC70 produced significant pe rcent increases in hematocrit and total protein levels. The HC1400 devices produced significantly less plasma free hemoglobin when primed with crystal loid rather than blood 143.6 <plus/minus> 38.3 vs 21.3 +/- 5.6. p<0.01). Th ere were no significant differences between devices or priming techniques f or lL-6. IL-8 or TNF<alpha> levels. In conclusion, the efficiency of the ul trafiltrators was elevated when primed with crystalloid before use. Cytokin e levels were relatively unchanged with priming techniques, while plasma fr ee hemoglobin levels were reduced with those devices previously primed with crystalloid.