The Impact of the Micro-Lightguide O2C for the Quantification of Tissue Ischemia in Diabetic Foot Ulcers

Abstract

OBJECTIVE -Tissue oxygen supply is crucial for wound healing. Especially in diabetic foot lesions, the chances for healing are mainly dependent on the presence or absence of ischemia. This study investigates the impact of the tissue O2 analysis system "O2C" for noninvasive quantification of tissue oxygenation in diabetic foot ulcer patients.RESEARCH DESIGN AND METHODS -O2C assessed relative blood flow (flow), flow velocity (velo), and hemoglobin concentration (rHb) and hemoglobin oxygenation (SO 2 ) at 2 and 6 mm depth (means Ϯ SE). 1) Measurements were performed on intact skin of the forefoot and forearm of 20 healthy volunteers on 2 consecutive days. 2) Parameters were assessed on intact skin of the forefoot of diabetic foot ulcer patients (n ϭ 14). 3) Measurements were performed directly at the wound site in diabetic patients (n ϭ 14).RESULTS -1) Flow, velo, rHb, and SO 2 at 2 and 6 mm depth were not significantly different when measured at 2 consecutive days. 2) There were no significant differences between diabetic subjects and healthy volunteers. Only flow in 6 mm depth was significantly higher in diabetic subjects (75 Ϯ 13 vs. 51 Ϯ 0.4 arbitrary units [AU], P Ͻ 0.05). When diabetic foot ulcer patients were split into healers and nonhealers, initial readings of SO 2 at 2 mm (32 Ϯ 6 vs. 44 Ϯ 3%, P Ͻ 0.05) and flow in 6 mm (28 Ϯ 1 vs. 51 Ϯ 0.6 AU, P Ͻ 0.05) were significantly reduced in nonhealers compared with control subjects, whereas in healers flow in 6 mm (70 Ϯ 0.6 vs. 51 Ϯ 0.6 AU, P Ͻ 0.05) was significantly higher than that in control subjects. 3) Initial SO 2 , rHb, flow, and velo were significantly lower in nonhealing compared with healing wounds.CONCLUSIONS -O2C is a new reliable and valid method for noninvasive measurement of tissue oxygenation and microvascular blood flow in patients with diabetic foot ulcers. Diabetes Care 27:2863-2867, 2004F oot ulcers are severe long-term complications in diabetic patients. In addition to local wound therapy, adequate tissue oxygenation is crucial for healing since oxygen is necessary for collagen formation, bactericidal activity of neutrophils, and endothelial cell function. Prognosis of diabetic foot lesions is mainly dependent on the presence or absence of tissue ischemia. However, quantitative assessment of peripheral perfusion and microcirculation is still challenging. Different methods like Doppler ultrasound or angiography are able to evaluate macrocirculation, but a reliable, easy technique to assess microcirculation, i.e., tissue perfusion, is not available. Previous studies have shown that healing might be predictable by measurement of transcutaneous oxygen tension (TcPO 2 ) (1-3). If TcPO 2 is Ͻ30 mmHg, complete healing cannot be expected (4). However, TcPO 2 is only a qualitative, not a quantitative, approach for evaluating peripheral perfusion and has a main limitation due to the need for heating the skin before measurement. This affects the resistance of skin vasculature and attenuates reflex mechanisms.Lightguide tissue spectrophotometry (O2C), ...

Haemodialysis is associated with changes in cutaneous microcirculation in diabetes mellitus

“…Those with diabetes demonstrated a significantly higher median relative blood flow at 6 mm tissue depth [25 vs. 14 arbitrary units (AU) (5)(6)(7)(8)(9)(10)(11)(12)(13)(14); P = 0.048] at baseline compared with the non-diabetic group (Table 1).…”

“…Measurements were performed on intact skin on the dorsum of the forefoot over the first intermetatarsal space, as previously described [12]. None of the patients had peripheral oedema at baseline or during the course of haemodialysis.…”

Analysis of healthy sitting behavior: Interface pressure distribution and subcutaneous tissue oxygenation

“…The data are analyzed by comparison with prerecorded deoxygenated and oxygenated hemoglobin spectra. The O2C has four output parameters [21] of which only the percentage of oxygen saturation (SO 2 ), which is a relative measure and reflects the oxygen saturation of hemoglobin, was used in this study. The fiber-optic probes used by O2C incorporate both the laser Doppler method and broadband light spectroscopy techniques and measures at a maximum depth of approximately 8 mm.…”

Prognostic value of intraoperative renal tissue oxygenation measurement on early renal transplant function

“…Of all patients, 54% required at least one postoperative hemodialysis (median 1, range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Grafts with delayed function had a longer Cit (mean 11 h 36 min) compared with those not requiring any postoperative hemodialysis (mean 7 h 45 min)(P < 0.05).…”

“…The O2C device combines these techniques in one probe, allowing assessing tissue oxygenation and microvascular blood flow simultaneously. It has been shown to provide reproducible intraoperative evaluations of the hepatic microcirculation [15], to quantify tissue ischemia in diabetic foot ulcers [16], and to evaluate the sublingual microcirculatory effects of vasopressors applied in patients during constant flow cardiopulmonary bypass [17]. The tissue penetration depth of the signals is restricted to a maximum of 8 mm.…”