Hyperspectral Tissue Oxygenation Mapping: A Vital Tool

In the current issue of Vascular Disease Management, Neville and Gupta¹ use hyperspectral tissue oxygenation mapping (HTOM) technology to determine tissue oxygen delivery, oxygen extraction and oxygen saturation in the lower and upper extremities of normal individuals without vascular disease. HTOM quantifies oxyhemoglobin, deoxyhemoglobin and oxygen saturation in the dermis by measuring light absorption at specific wavelengths between 450 and 650 nm. The authors demonstrated that HTOM measurements are reproducible, and that oxyhemoglobin, deoxyhemoglobin and oxygen saturation measurement correlate in near real time with cuff induced ischemia. This technology has the ability to precisely map tissue oxygen delivery, extraction and saturation in specific areas, and demonstrated that the plantar surface of the foot and the palmar surface of the hand have the highest levels of oxyhemoglobin and oxygen saturation in the extremities. Previous work has shown possible clinical efficacy for HTOM in determining the ability of wounds to heal, and in the management of extremity wounds such as ulcers in patients with critical limb ischemia. The current study compliments this earlier work, by determining normative ranges for tissue oxygen delivery, extraction and saturation in individuals with no evidence of arterial or venous disease. This baseline information is essential if HTOM is to be used clinically. HTOM has the potential for assisting vascular surgeons in deciding which wounds are likely to heal in patients with arterial and venous disease. Over the years many techniques, such as ankle brachial index, toe pressure measurement, transcutaneous tissues oxygen saturation and skin temperature measurement, have been used to predict wound healing. None has demonstrated significant benefit over the sound clinical judgment of an experienced vascular surgeon. HTOM has the unique ability to map oxygen delivery, extraction and saturation to a precise area of the extremity, such as the region of a wound. This may be a significant advantage over these other techniques, and may prove useful to vascular surgeons faced with difficult clinical decisions. Additionally, HTOM may be useful as a tool to determine the effectiveness of endovascular and open surgical revascularization, as well as a method to follow the patency of those procedures. HTOM may indeed become a technology with clinical importance to vascular surgeons in the future.

Reference

1. Neville R. Gupta S. Establishment of normative perfusion values using hyperspectral tissue oxygenation mapping technology. Vasc Disease Mgmt 2009;6:156–161.

Address for correspondence: Marc E. Mitchell, M.D. James D. Hardy Professor and Chair, Department of Surgery, University of Mississippi, 2500 North State Street Jackson, MS 39216. Email: memitchell@surgery.umsmed.edu