Quantification of Lipid Filtration and the Effects on Cerebral Injury During Cardiopulmonary Bypass

Abstract

Background: Lipid microemboli (LME) are formed in pericardial suction blood which, when returned to the cardiopulmonary bypass (CPB) circuit, can pass through filter materials and are returned to the arterial cannula. LME have been observed to enter all major organs and have been associated with small capillary arteriolar dilatations in the brains of patients who have died after CPB. However, a causal relationship showing correlation between LME and organ dysfunction has not been demonstrated, or whether removal of LME results in improved organ function.

Methods: A prospective, single center, randomized controlled trial examined 30 patients (15 per group) undergoing coronary artery bypass grafting using CPB with or without a lipid-depleting filter. The effects of LME filtration on neurocognitive injury were assessed using neuron-specific enolase (NSE).

Results: The study group showed a significant reduction in LME after filtration of the pericardial suction blood (p < 0.001), whereas the control group exhibited a significant rise in LME (p < 0.001). There was a significant reduction in peak NSE release (p = 0.013) and significant attenuation throughout the postoperative period (p = 0.002). Correlation and regression analyses showed a significant relationship between the number of LME post-CPB and peak NSE release (r = 0.42, p = 0.02).

Conclusions: Several methods of LME filtration have been proposed, but none provided a suitable, efficacious method for use within the clinical setting. The RemoweLL CPB system removes significant numbers of LME from the cardiotomy suction. Furthermore, LME correlate to the release of a known marker of neurologic injury.