Please see Bibliography of References for a list of abstracts, manuscripts and posters.

Other Studies

Near-infrared spectroscopy to monitor tissue oxygenation in critically ill patients

Rokuss K, Kalenka A, Bender HJ, Hinkelbein J. J fur Anasthesie und Intensivbehandlung. 2007;14(4):108.

Background: Sufficient and continuous monitoring of oxygenation is essential during medical treatment on an ICU. Near-infrared Spectroscopy technique (NIRS; InSpectra¢â Hutchinson Technology Inc, USA) uses a thenar sensor to measure Iocal oxygen saturation of tissue (StO₂; e.g. muscle) non-invasively and to estimate oxygen consumption and perfusion of tissue [1]. This parameter is historically estimated by central venous oxygen saturation (SvO₂) intermittently determined by blood gas analysis. The aim of the present study was to evaluate correlation of StO₂ and SvO₂ in critically ill patients.

Material and Methods: After approval of the local ethics corn committee and written informed consent, StO₂ was monitored continuously for 24 hours. The NIRS sensor was placed standardized at the right thenar. Addi,tionalIy SvO₂ was determined every eight hours via blood gas analysis (ABL8OO flex; Radiometer; Br©ªnsh©ªj, DK) of a central venous blood sample. Measurement error (bias, accuracy, ASO₂) was calculaled as ¥ÄSO₂= StO₂-SvO₂. StO₂ and SvO₂ were correlated using regression analysis and the Bland-Altman method [2]. T-test was used for statistical analysis, P<0.05 was considered significant.

Results: N=20 critically ill patients (means: 60.3¡¾19.0 years old; 14 male, 6 female; body-mass-index 26.9¡¾4.7 kg m^-2) were Investigated and N=80 data pairs were collected (N=4 each). Underlying diseases were: sepsis with multi organ failure, multiple trauma, subarachnoid and intracerebral bteeding. Mean StO₂ (79.5¡¾8.4 %) correlated weakly with SvO₂ (74.4¡¾7.5 %), resulting in a ¥ÄSO₂ (mean bias) of +5.2¡¾10.4 % (p=0.0003). Bland-Altman analysis revealed no significant measurement error for the following influencing factors (vs. control): gender (male: +4.75 ¡¾ 11.93 vs. female: +5.99¡¾6.35; P=0.5827), sepsis (+4.2¡¾12.1 vs. +6.4¡¾7.7; P=0.3713). The following influencing factors (vs. control) showed significant differences in ¥ÄSO₂: analgosedation (+0.81¡¾9.63 vs. +8.78¡¾9.65; P=0.0014), and application of catecholamines (+2,1¡¾9.4 vs. +9.9¡¾10.2; P=0.003).

Conclusions: Statistical correlation between StO₂ and SvO₂ was found to be weak in critically Ill patients with multiple influencing factors. NIRS facilitates continuous monitoring of StO₂ in contrast to intermittent SvO₂ values. Further research with larger patient numbers is required for sufficient interpretation of data for critically ill patients.

1. Myers DE et al. (2005) J Biomed Opt 10:034017

2. Bland JM el al. (1986) Lancet 1: 307-310