[Protein loss in critically ill patients during continuous veno-venous hemofiltration]

To evaluate protein loss in critically ill patients with acute renal failure during continuous veno-venous hemofiltration (CVVH) and analysis the major factor impacting protein clearance.

A analysis was carried out in eighteen (twelve male and six female) sepsis or severe acute pancreatitis patients with acute renal failure from September 2008 to September 2009. The average age was 45 years (39 - 62 years). CVVH was conducted for 24 h in all patients. Effluent volume, blood speed, ultrafiltration rate and transmembrane pressure (TMP) were 4000 ml/h, (277 ± 89) ml/h, (179 ± 4) ml/min and (173 ± 48) mm Hg (1 mm Hg = 0.133 kPa) respectively. Blood samples were collected before and after filtration in order to detect protein concentration. Ultrafiltrate was obtained hourly to measure protein concentration and calculate protein loss during session.

Mean protein concentration was (231 ± 67) mg/L and protein loss was (22 ± 6) g/d in ultrafiltrate samples. The difference in serum protein level during hemofiltration was not significant [(56 ± 6) g/L vs. (55 ± 10) g/L, P > 0.05], while there was a weak, but statistically significant correlation between the ultrafiltrate protein concentration and the corresponding value for serum protein (r = 0.481, P < 0.05). However, there was a strong and statistically significant correlation between the ultrafiltrate protein concentration and the TMP (r = 0.564, P < 0.01). Stepwise multiple regression analysis showed that TMP and serum protein concentration played a pivotal role in ultrafiltrate protein loss.

In addition to renal replacement therapy, serum protein would be cleared through hemofilter during CVVH. TMP and serum protein concentration are the main factors that affect protein loss in ultrafiltrate. As a result, it is necessary to take account of the protein loss in ultrafiltrate when setting nutritional schedule.