J Thorac Cardiovasc Surg 2004;128:154
© 2004 The American Association for Thoracic Surgery
The effect of the dynamic air bubble trap on cerebral microemboli and S100ß
Reza Motallebzadeh, MRCS,
Marjan Jahangiri, FRCS
Department of Cardiac Surgery, St George's Hospital & Medical School, London, United Kingdom
To the Editor:
We read with interest the article by Schoenburg and colleagues1 regarding the use of an air bubble trap during coronary artery bypass grafting. The authors used measurement of S100ß as an indicator of cerebral injury. It is not clear, however, whether they took steps to minimize autotransfusion of S100ß from extracerebral sources. There is good evidence to show that blood aspirated from the surgical field and returned to the patient through cardiotomy suckers will result in significantly higher serum levels of S100ß.2,3
The study showed no significant difference in serum S100ß between the two groups at the end of the operation and 6 hours afterward. If the hypothesis that microemboli are the main cause of cerebral injury with a resultant rise in S100ß is correct, then a significant reduction in cerebral microemboli should be accompanied by a significant reduction in S100ß at these time points. In fact the higher, albeit not statistically significantly, mean S100ß levels in the placebo group could be accounted for by the longer mean cardiopulmonary bypass time in this group. A longer bypass time implies that more blood is suctioned from the mediastinum, with increased return of mediastinal blood rich in extracerebral sources of S100ß to the circulation, thus resulting in higher serum levels of S100ß.4
Furthermore, the statement that there was a significant difference in S100ß values at 48 hours is misleading. The Sangtec 100 immunoradiometric assay (Sangtec Medical AB, Stockholm, Sweden) that was used in the study has a lower detection limit of 0.2 µg/L. The mean S100ß value for both the bubble trap and placebo groups was below this level, and thus normal. We therefore do not agree with the conclusion that the dynamic air bubble trap reduces S100ß early after coronary artery bypass grafting. A more sensitive analysis of S100ß could have been carried out with the immunoluminometric method (Sangtec LIA 100; Sangtec Medical AB), which has a functional detection limit of 0.02 µg/L.
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References
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- Schoenburg M, Kraus B, Muehling A, Taborski U, Hofmann H, Erhardt G, et al. The dynamic air bubble trap reduces cerebral microembolism during cardiopulmonary bypass. J Thorac Cardiovasc Surg. 2003;126:1455–1460[Abstract/Free Full Text]
- Anderson RE, Hansson LO, Liska J, Settergren G, Vaage J. The effect of cardiotomy suction on the brain injury marker S100ß after cardiopulmonary bypass. Ann Thorac Surg. 2000;69:847–850[Abstract/Free Full Text]
- Jonsson H, Johnsson P, Alling C, Backstrom M, Bergh C, Blomquist S. S100ß after coronary artery surgery: release pattern, source of contamination, and relation to neuropsychological outcome. Ann Thorac Surg. 1999;68:2202–2208[Abstract/Free Full Text]
- Vaage J, Anderson R. Biochemical markers of neurologic injury in cardiac surgery: the rise and fall of S100ß. J Thorac Cardiovasc Surg. 2001;122:853–855[Free Full Text]
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