High molecular weight linear polymers improve microvascular perfusion after extracorporeal circulation.

High molecular weight linear polymers (HMWLP) have earned the name "drag-reducing polymers" due to their ability to reduce drag in turbulent flows. Recently, these polymers have become popular in bioengineering applications. This study investigated whether the addition of HMWLP in a venoarterial extracorporeal circulation (ECC) model could improve microvascular perfusion and oxygenation. Golden Syrian hamsters were instrumented with a dorsal skinfold window chamber and subjected to ECC using a circuit comprising of a peristaltic pump and bubble trap. The circuit was primed with lactated Ringer's (LR) containing either 5 ppm of polyethylene glycol (PEG) with a low molecular weight of 500 kDa (PEG500k) or 5 ppm of PEG with a high molecular weight of 3500 kDa (PEG3500k). After 90 minutes of ECC at 15% of the animal's cardiac output, the results showed that the addition of PEG3500k to LR improved microvascular blood flow in arterioles and venules acutely (2 h after ECC), while functional capillary density showed improvement up to 24 h after ECC. Similarly, PEG3500k improved venular hemoglobin O2 saturation on the following day after ECC. The serum and various excised organs all displayed reduced inflammation with the addition of PEG3500k and several of these organs also had a reduction in markers of damage with the HMWLPs compared to LR alone. These promising results suggest that the addition of small amounts of PEG3500k can help mitigate the loss of microcirculatory function and reduce the inflammatory response from ECC procedures.