Free
Correspondence  |   April 2013
In Reply:
Author Affiliations & Notes
  • Henrik Sørensen, B.Sc.
    Rigshospitalet, University of Copenhagen, Copenhagen, Denmark and Zürich Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland. hs770@hotmail.com
  • (Accepted for publication December 13, 2012.)
    (Accepted for publication December 13, 2012.)×
Article Information
Correspondence
Correspondence   |   April 2013
In Reply:
Anesthesiology 04 2013, Vol.118, 982. doi:10.1097/ALN.0b013e3182877a6f
Anesthesiology 04 2013, Vol.118, 982. doi:10.1097/ALN.0b013e3182877a6f
We thank Grocott and Davie1  for their interest in spatially resolved near-infrared spectroscopy (SR-NIRS) evaluation of cerebral oxygenation and for their unique evaluation of skin influence on three commercially available SR-NIRS systems. We acknowledge that our findings may not apply to all SR-NIRS systems, and although unintended, the title of the article may be too general. Throughout the discussion and the conclusion, however, we meticulously specify that it is the INVOS machine that is evaluated.2  At the same time, we understand that Grocott and Davie1  suggest that cutaneous oxygenation affects evaluation not only by INVOS but also by Foresight and EQUANOX. We find it likely that vasoconstriction observed during administration of noradrenaline exerts a similar impact on the SR-NIRS–determined frontal lobe oxygenation as scalp ischemia.1  Cerebral blood flow or oxygenation was not measured in that study, but we find it unlikely that headband occlusion of skin blood flow influences cerebral variables and the reduction in SR-NIRS evaluation of cerebral oxygenation is, therefore, most likely explained by a flawed SR-NIRS methodology. Taken together, the evidence obtained by different experimental approaches1,2  suggests that not only the INVOS SR-NIRS is affected by cutaneous contamination of the signal. In fact, on-going evaluation suggests that INVOS SR-NIRS is less affected by skin oxygenation than other systems, although we, obviously, have not evaluated the influence of skin oxygenation on all SR-NIRS apparatus.
Henrik Sørensen, B.Sc.,* Niels H. Secher, M.D., D.M.Sc., Christoph Siebenmann, M.S.C., Henning B. Nielsen, M.D., D.M.Sc., Matthias Kohl-Bareis, Ph.D., Carsten Lundby, Ph.D., Peter Rasmussen, Ph.D. *Rigshospitalet, University of Copenhagen, Copenhagen, Denmark and Zürich Center for Integrative Human Physiology, University of Zürich, Zürich, Switzerland. hs770@hotmail.com
References
Davie, SN, Grocott, HP Impact of extracranial contamination on regional cerebral oxygen saturation: A comparison of three cerebral oximetry technologies.. Anesthesiology. (2012). 116 834–40 [Article] [PubMed]
Sørensen, H, Secher, NH, Siebenmann, C, Nielsen, HB, Kohl-Bareis, M, Lundby, C, Rasmussen, P Cutaneous vasoconstriction affects near-infrared spectroscopy determined cerebral oxygen saturation during administration of norepinephrine.. Anesthesiology. (2012). 117 263–70 [Article] [PubMed]