Non-invasive in vivo diffuse optical spectroscopy monitoring of cyanide poisoning in a rabbit model.

The objective of this study is to establish a cyanide toxicity animal model and to investigate the ability of broadband diffuse optical spectroscopy (DOS) to non-invasively monitor physiological changes that occur during the development of cyanide toxicity in a rabbit model. Broadband DOS combines multi-frequency frequency-domain photon migration (FDPM) with time-independent near-infrared spectroscopy (NIRS) to quantitatively measure bulk tissue absorption and scattering spectra between 600 nm and 1000 nm. Serum cyanide concentration and arterial and venous blood gas analysis at pre- and post-cyanide infusion were presented. To investigate the ability of DOS to non-invasively monitor physiologic changes occurring during development of CN toxicity, tissue concentrations of deoxyhemoglobin [Hb-R], oxyhemoglobin [Hb-O2], cytochrome c oxidase oxidized state [CcO_Ox] and reduced state [CcO_Re] were determined from absorption spectra acquired in 'real time' during cyanide infusions (NaCN 6 mg/60 ml normal saline) in six pathogen-free New Zealand white rabbits. During cyanide infusion, in vivo tissue oxygen saturation increased ( approximately 10%). In addition, broadband DOS was able to detect a concurrent increase in [CcO_Re] and decrease in [CcO_Ox]. Changes in tissue scattering properties in all six animals were detected during these events, confirming the need for DOS-based methods over traditional NIR spectroscopy to obtain accurate results.