This Article Full Text (PDF) Submit a scholarly reply Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Nollert, G. Search for Related Content PubMed PubMed Citation Articles by Nollert, G.

Clinical evaluation of near-infrared spectroscopy

Siemens Medical Solutions, Munich Germany, E-mail: gnollert{at}t-online.de

To the Editor:

I read with great interest the paper published by Taillefer and Denault¹ "Cerebral near-infrared spectroscopy in adult heart surgery: systematic review of its clinical efficacy". In my view, the citations present a biased selection of articles on near-infrared spectroscopy (NIRS), because the search presented mainly articles describing the use of Somanetics^TM devices (INVOS® Cerebral Oximeter, Somanetics Corporation, Troy, MI, USA). It would not be surprising that Somanetics^TM would include positive results of investigations of their device in their reference list. The Hamamatsu^TM devices (NIRO 1000, 500, 300, 200, Infrared Oxygenation Monitors NIRO Series, Hamamatsu Photonics K.K., Hamamatsu, Japan) do not have the Food and Drug Administration approval; however they have been used frequently. Tamura et al.² published the first clinical report on NIRS monitoring in coronary artery bypass patients in 1994; I published two reports in the same patient population in 1995.^3,4 The omission of these studies and others⁵ suggests that the database for the systematic review of Taillefer and Denault may have been incomplete. Interestingly, there are very few articles on animal studies using the Somanetics^TM device.

The principal difficulty with NIRS is its limited value in the setting of hemodilution, and particularly with deep hypothermic circulatory arrest. With decreasing hemoglobin concentration, the optical pathlengths in tissue become longer, because the light is less well absorbed and becomes scattered. However, this phenomenon is wavelength-dependent, and therefore the algorithms for measuring hemoglobin (minor errors) or cytochrome (very large errors) become false. In my opinion, the solution to this problem is to measure absolute pathlength, which is technically challenging but possible.

Footnotes

Accepted for publication October 26, 2005.

References

1 Taillefer MC, Denault AY. Cerebral near-infrared spectroscopy in adult heart surgery: systematic review of its clinical efficacy. Can J Anesth 2005; 52: 79–87.[Abstract/Free Full Text]

2 Tamura M. Non-invasive monitoring of brain oxygen metabolism during cardiopulmonary bypass by near-infrared spectrophotometry. Jpn Circ J 1991; 55: 330–5.[Medline]

3 Nollert G, Mohnle P, Tassani-Prell P, Reichart B. Determinants of cerebral oxygenation during cardiac surgery. Circulation 1995; 92: II327–33.

4 Nollert G, Mohnle P, Tassani-Prell P, et al. Postoperative neuropsychological dysfunction and cerebral oxygenation during cardiac surgery. Thorac Cardiovasc Surg 1995; 43: 260–4.[Medline]

5 Nollert G, Shin‘oka T, Jonas RA. Near-infrared spectrophotometry of the brain in cardiovascular surgery. Thorac Cardiovasc Surg 1998; 46: 167–75.[Medline]

This Article Full Text (PDF) Submit a scholarly reply Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Nollert, G. Search for Related Content PubMed PubMed Citation Articles by Nollert, G.