Non-invasive in vivo diffuse optical spectroscopy monitoring of cyanide poisoning in a rabbit model**Presented in part in Chest 128 (4) 301S (October 2005) and Journal of Investigative Medicine 53 (1) S113 (January 2005) as abstracts.

Abstract

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 (∼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.