Letters to the Editor: Letter to the Editor
We are pleased that our study generated such interest and that Dr. Ariès agrees with our conclusion that decreased cardiac index and increased mean transit and downslope times with renal replacement therapy (RRT) are caused by thermodilution measurement errors rather than real hemodynamic changes. In our discussion, we presented several different explanations for erroneous thermodilution measurements caused by the extracorporeal circulation during RRT, one of which is turbulent blood flow. We agree with Dr. Ariès that indicator injection into an area of turbulent blood flow could explain our findings, and we did not disregard turbulences in blood flow as an explanation. Because, as opposed to a case report by Martínez-Simón et al,1 we did not record individual thermodilution curves as part of our study, though, we did not have the data to conclusively prove this hypothesis. In our opinion, studies examining thermodilution curve forms during turbulent blood flow and RRT will be necessary to address and further characterize the issue of erroneous thermodilution measurements with RRT.
Sven Schmidt, MDDepartment of NephrologyCharité University Medicine BerlinCampus Benjamin FranklinBerlin, Germany
Timm Westhoff, MD, PhDDepartment of Medicine IUniversitätsklinikum Marien Hospital HerneRuhr-Universität BochumHerne, Germany
Peter Schlattmann, MD, PhDDepartment of Medical Statistics, Informatics andDocumentationJena University HospitalJena, Germany
Walter Zidek, MD, PhDDepartment of NephrologyCharité University Medicine BerlinCampus Benjamin FranklinBerlin, Germany
Friederike Compton, MDDepartment of NephrologyCharité University Medicine BerlinCampus Benjamin FranklinBerlin, Germanyfriederike.email@example.com
1. Martínez-Simón A, Monedero P, Cacho-Asenjo E. Erroneous measurement of haemodynamic parameters by PiCCO monitor in a critically ill patient with renal replacement therapy: a case report. Crit Care. 2006;10:410.