The dynamic air bubble trap reduces cerebral microembolism during cardiopulmonary bypass

Abstract

Objective Neuropsychologic disorders are common after coronary artery bypass operations. Air microbubbles are identified as a contributing factor. A dynamic bubble trap might reduce the number of gaseous microemboli. Methods A total of 50 patients undergoing coronary artery bypass operation were recruited for this study. In 26 patients a dynamic bubble trap was placed between the arterial filter and the aortic cannula (group 1), and in 24 patients a placebo dynamic bubble trap was used (group 2). The number of high-intensity transient signals within the proximal middle cerebral artery was continuously measured on both sides during bypass, which was separated into 4 periods: phase 1, start of bypass until aortic clamping; phase 2, aortic clamping until rewarming; phase 3, rewarming until clamp removal; and phase 4, clamp removal until end of bypass. S100β values were measured before, immediately after, and 6 and 48 hours after the operation and before hospital discharge. Results The bubble elimination rate during bypass was 77% in group 1 and 28% in group 2 ( P < .0001). The number of high-intensity signals was lower in group 1 during phase 1 (5.8 ± 7.3 vs 16 ± 15.4, P < .05 vs group 2) and phase 2 (6.9 ± 7.3 vs 24.2 ± 27.3, P < .05 vs group 2) but not during phases 3 and 4. Serum S100β values were equally increased in both groups immediately after the operation. Group 2 patients had higher S100β values 6 hours after the operation and significantly higher S100β values 48 hours after the operation (0.06 ± 0.14 vs 0.18 ± 0.24, P = .0133 vs group 2). Age and S100β values were correlated in group 2 but not in group 1. Conclusion Gaseous microemboli can be removed with a dynamic bubble trap. Subclinical cerebral injury detectable by increases of S100β disappears earlier after surgical intervention.