Ann Thorac Surg 2008;85:617. doi:10.1016/j.athoracsur.2007.10.087
© 2008 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited Commentary
Marco Ranucci, MD
Anesthesia and Intensive Care, IRCCS Policlinico S. Donato, Via Morandi 30 - San Donato Milanese, Milan, 20097, Italy
(Email: cardioanestesia{at}virgilio.it).
The article from Eggum and coworkers [1] addresses an important topic: Can we expect changes in temperature management during cardiopulmonary bypass to result in a different inflammatory response during and after a cardiac operation in pediatric patients? As the authors outlined, the current literature is not in agreement regarding this issue. Actually, I believe that this is basically a "negative" study, because the final results do not support any protective effect for either mild or moderate hypothermia, despite a slight "pro-inflammatory" profile attributable to the moderate hypothermia strategy. However, negative studies may carry important information to clinicians, and this article is certainly a demonstration of this concept.
As a matter of fact, no clinically relevant differences in the outcome were noticed between the two groups. Also, evidence of inadequate oxygen delivery did not differ between the groups. Despite a higher oxygen extraction rate in the mild hypothermia group, blood lactate levels were not higher than in the moderate hypothermia group, and both were quite low. Thus, both temperature strategies did not lead to severe postoperative impairment in oxygen delivery or peripheral oxygen extraction ability, or both.
The main information from this study is that duration of cardiopulmonary bypass is one of the main determinants of the release of inflammatory markers. As the authors admit, moderate hypothermia requires a longer cardiopulmonary bypass time, and this may explain the higher levels of interleukin-8 detected in the first group. The notion that the inflammatory reaction to foreign surface exposure compromises postoperative outcome is commonly accepted. Unfortunately, inflammatory markers very rarely correlate with the clinical outcome, and this study does not represent an exception to this observation. Other factors related to cardiopulmonary bypass technique exert detrimental effects (ie, hemodilution, transfusions, hemostasis and coagulation activation, pump flow adequacy, and so forth). Thus, perhaps we should hypothesize that different results may be obtained by comparing "true" normothermic management (36°C) to 25°C management. However, in such a study, significantly different durations of cardiopulmonary bypass and small differences in outcome measurements may pre-empt a conclusion. In addition the case mix itself of congenital heart diseases makes adequate unbiased sample sizes very difficult to create.
In conclusion, when deciding a cardiopulmonary bypass temperature strategy, surgeons should probably consider factors other than the potential impact of temperature on the inflammatory response.
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References
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- Eggum R, Ueland T, Mollnes TE, et al. Effect of perfusion temperature on the inflammatory response during pediatric cardiac surgery Ann Thorac Surg 2008;85:611-617.[Abstract/Free Full Text]
Related Article
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Effect of Perfusion Temperature on the Inflammatory Response During Pediatric Cardiac Surgery
- Rune Eggum, Thor Ueland, Tom E. Mollnes, Vibeke Videm, Pål Aukrust, Arnt E. Fiane, and Harald L. Lindberg
Ann. Thorac. Surg. 2008 85: 611-617.
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