Blood lactate level (LL) is a useful predictor of physiological issues during extracorporeal circulation (ECC) treatment. To determine variations in LL depending on the hemocompatible coatings used for ECC, in vitro experiments were performed using whole human blood samples.

Three types of experimental circuits were used, consisting of polymer-coated (PC), heparin-coated (HC), or noncoated (NC) membrane oxygenators (n = 5), in which blood was circulated while heparin diluted with a glucose solution was continuously administered. Blood was collected at 0, 1, 3, 6, 12, and 24 h of circulation to measure LL, glucose level (GL), partial pressure of oxygen (PO), and oxygen saturation (SA) in each experiment. Each value was categorized according to coating type and compared using two-way repeated-measures or one-way analysis of variance.

The mean LL values at each time point were significantly lower in the PC circuits than in the HC and NC circuits, whereas those in the HC and NC circuits were not significantly different. The mean GL values at each time point were significantly lower in the NC circuits than in the PC and HC circuits, whereas those in the PC and HC circuits were not significantly different. The mean PO and SA values at each time point were not significantly different among the different coating types.

In ECC circuits, PC may inhibit lactate production because of its hemocompatibility. Additionally, NC may enhance glucose consumption; however, the underlying mechanism remains unclear. Further research on the relationship between NC and GL is warranted.