Reply to Ener and Yilmaz

We fully agree with Dr Serdar Ener when he states that many perioperative variables may have an interactive effect on SIR.

This is particularly true regarding the various anaesthetic agents, the techniques and equipments used for the extracorporeal circulation (CEC), and post-operative medications.

We did not specifically mention it in the article, but, except for the post-operative medications, these various parameters are fully standardized in our department (cf Methods; Technique of the CPB).

They are the object matter of a well defined protocol applied to all our patients undergoing coronary surgery.

Statistics: To compare the three independent patients groups, we used the Mann–Whitney U-test which is the method most frequently utilized in all other studies quoted in our article.

Oxygen-free radicals (OFR): We agree that the early (post-aortic cross-clamp release) peak of OFR level may be related to myocardial injury.

As a matter of fact, it would be interesting in a further study to measure an eventual correlation between the high rate of free radicals and specific markers of myocardial injury such as Troponin.

However, the main purpose of our study was to show the effectiveness of the corticosteroids on some known specific parameters of the inflammation induced by CPB.

At the present time there is not enough literature about correlation between the increase of Troponin levels during heart surgery, and the increase of proinflammatory cytokines and the OFR.

Therefore, to assess the effect of corticosteroids, we tested in our study the markers of CPB related inflammation already known in the literature.

Our second care was to use a new method, specific and direct, for the measurement of OFR. This method, based on cytoflurometry, has two advantages over traditional methods:

1. Analysis is performed on whole blood without isolation of polynuclear neutrophiles (PMN), thereby avoiding their activation. Furthermore, by isolating PMN from the whole white blood cell population, on the basis of different side and forward scatter plots, enables the detection of OFR production exclusively within the PMN population.

2. This technique enables the direct detection of OFR, based on the oxidation of DCFH by OFR, and avoids, contrary to the other test methods, oxygen degradation intermediate products.

Corrections: You are right to call the attention to the error appearing in the text of the legend of Figs. 2 and 3. For each figure group A corresponds to a square, group B to a circle, and group C to a triangle. We apologize also, for the wrong word in the first sentence of the results (Section 3.1.1): the rate of TNF-α starts to increase after and not before the aortic cross-clamping.

Conclusion: We totally agree with you that there is a need for further detailed studies to better understand the inflammatory response induced by extracorporeal circulation and the correlation between circulating cytokines, clinical course, and myocardial damage. Our study realizes a first stage on the matter.