Diabetic Foot - Diagnosis

Transcutaneous Oxygen Pressure (TcPO) - updated: 15 March 2008

Altered postural regulation of foot skin oxygenation and blood flow in patients with type 2 diabetes mellitus

Exp Clin Endocrinol Diabetes. 2007 Jul;115(7):444-7

Iwase M, Imoto H, Murata A, Nakamura U, Nohara S, Uchizono Y, Iino K, Iida M.

AIMS: Although skin oxygenation is an important factor in the development and healing of foot ulcers, its regulation was not fully understood. We studied changes in foot skin oxygenation and blood flow during postural changes in patients with type 2 diabetes mellitus. METHODS: Skin oxygenation was measured using transcutaneous oxygen pressure (TcPO(2)) and skin blood flow by laser Doppler flowmetry in 40 patients with type 2 diabetes mellitus without evidence of peripheral arterial disease and 13 healthy control subjects. RESULTS: TcPO(2) in the supine position was significantly lower in patients with type 2 diabetes mellitus compared with control, although skin blood flow was not different. In the sitting position, TcPO(2) significantly increased in control and diabetic patients. The postural change-related increase in TcPO(2) was significantly enhanced in diabetic patients. On the other hand, skin blood blow significantly decreased in the sitting position from the supine position in control subjects but remained stable in diabetic patients. Orthostatic drop in systolic blood pressure correlated negatively with TcPO(2) in the supine position while correlated positively with %change in TcPO(2) and blood flow by postural changes. CONCLUSIONS: The present study demonstrated the dissociated regulation of skin oxygenation and blood flow in response to leg dependency. Impaired postural vasoconstriction was associated with altered regulation of skin oxygenation probably due to sympathetic vascular dysfunction in diabetic patients.

Transcutaneous oxygen tension and toe blood pressure as predictors for outcome of diabetic foot ulcers

Diabetes Care. 1999 Jan;22(1):147-51

Kalani M, Brismar K, Fagrell B, Ostergren J, Jörneskog G.

OBJECTIVE: The present study was undertaken to compare the predictive values of transcutaneous oxygen tension (TcPO2) and toe blood pressure (TBP) measurements for ulcer healing in patients with diabetes and chronic foot ulcers. RESEARCH DESIGN AND METHODS: Investigated prospectively were 50 diabetic patients (37 men) with chronic foot ulcers. The age was 61 +/- 12 (mean +/- SD), and the diabetes duration was 26 +/- 14 years. TBP (mmHg) was measured in dig I and TcPO2 (mmHg) at the dorsum of the foot. Ulcer healing was continuously evaluated by measuring the ulcer area every 4-6 weeks. After a follow-up time of 12 months, the patients were divided into three groups according to clinical outcome: healed with intact skin, improved ulcer healing, or impaired ulcer healing. RESULTS: Of the 13 patients who deteriorated, 11 had TcPO2 < 25 mmHg, while 34 of the 37 patients who improved had TcPO2 > or = 25 mmHg. The sensitivity and specificity for TcPO2 were 85 and 92%, respectively, when a cutoff level of 25 mmHg was used for determination of outcome of ulcer healing (healing or nonhealing). The corresponding values for TBP at 30 mmHg were 15 and 97%. Measurement of TcPO2 provided a higher positive predictive value (79%) than TBP (67%). CONCLUSIONS: The results indicate that TcPO2 is a better predictor for ulcer healing than TBP in diabetic patients with chronic foot ulcers, and that the probability of ulcer healing is low when TcPO2 is < 25 mmHg.

Early detection of microcirculatory impairment in diabetic patients with foot at risk

Diabetes Care. 2001 Oct;24(10):1810-4

Zimny S, Dessel F, Ehren M, Pfohl M, Schatz H.

OBJECTIVE: To assess microcirculatory impairment and alterations of the skin oxygen supply in diabetic patients with foot at risk. RESEARCH DESIGN AND METHODS: This study evaluated skin blood flow in 21 type 2 diabetic patients with a foot at risk (defined as a foot with neuropathy but without ulceration or previous ulcerations), 20 type 2 diabetic patients without foot lesions or neuropathy, and 21 normal subjects as a control group. The skin blood flow was determined by measuring the transcutaneous oxygen pressure (TcPO(2)) at the dorsum of the foot in supine and sitting position. The clinical assessment included standard measures of peripheral and autonomic neuropathy, but peripheral vascular disease was excluded by Doppler ultrasound. RESULTS: In supine position, TcPO(2) was significantly reduced (means +/- SE) in diabetic patients with foot at risk (6.04 +/- 0.52 kPa) compared with diabetic (7.14 +/- 0.43 kPa, P = 0.035) and nondiabetic (8.10 +/- 0.44 kPa, P = 0.01) control subjects. The sitting/supine TcPO(2) difference was higher in diabetic subjects with foot at risk (3.13 +/- 0.27 kPa) compared with both diabetic (2.00 +/- 0.18, P = 0.004) and nondiabetic (1.77 +/- 0.15 kPa, P = 0.0003) control subjects. The mean sitting/supine ratio was 1.70 +/- 0.12 in diabetic patients with foot at risk, 1.32 +/- 0.04 in diabetic control subjects, and 1.25 +/- 0.03 in nondiabetic control subjects (P = 0.007). The sitting/supine TcPO(2) ratio was negatively correlated with the heart rate variation coefficient at rest (r = -0.32, P = 0.044) and at deep respiration (r = -0.31, P = 0.046). CONCLUSIONS: Our data indicate that skin oxygen supply is reduced in type 2 diabetic patients with foot at risk. This is probably due to an impaired neurogenic blood flow regulation and may contribute to capillary hypertension, followed by disturbed endothelial function leading to edema and skin damage of the foot. The determination of TcPO(2) appears to be a useful tool in screening type 2 diabetic patients for foot at risk.

Transcutaneous oxygen pressure (TcPO2): advantages and limitations

Diabetes Metab. 1998 Sep;24(4):379-84

Got I.

The measurement of transcutaneous oxygen pressure (TcPO2), a non-invasive method to quantify skin oxygenation, is particularly useful in advanced stages of arteriopathy of the lower limbs for evaluation of cutaneous ischaemia. It is a predictive factor for spontaneous healing when pressure is above 30 mmHg or, on the contrary, of an unfavourable course when pressure is less than 10 mmHg. Dynamic tests (change in limb position, exercise test, induced ischaemia test, O2 inhalation) have been used to improve prognostic value for measurements between 10 and 30 mmHg. TcPO2 provides additional support for the decision to perform revascularisation surgery and serves as an indicator of amputation level and as a means of quantifying the benefit offered by a surgical procedure or a drug treatment. It is widely used in assessment of trophic disorders of the foot in diabetic patients.

Publication Types:

• Review

Transcutaneous oxygen tension in hyperbaric condition as a predictor of ischaemia in non-healing diabetic foot ulcers

Vnitr Lek. 2002 Oct;48(10):971-5

Cechurová D, Rusavý Z, Lacigová S, R?zicka J, Novák M, Jankovec Z.

The aim of the study was to evaluate the contribution of basal and modify transcutaneous oxygen tension measurement (TcpO2) to diagnosis of ischaemia and indication of angiography in non-healing diabetes foot ulcers: METHOD: 69 patients with non-healing diabetic ulcers localised on 76 legs underwent angiography (DSA) and basal and modify TcpO2 measurement after 100 % O2 exposition under normo- and hyperbaric conditions. CHARACTERISTIC OF PATIENTS: mean age 66 years (42 81), diabetes duration 14.3 years (1 - 36), glycated hemoglobin 7.9 % (+/-1,35). RESULTS: Clinically important angiographic findings were obtained in 80 % (61/76) all ulcers. Basal TcpO2 < or = = 30 mm Hg was detected in 82 % diabetic ulcers with positive DSA (sensitivity - SN). The specificity (SP), positive and negative predictive value (PPV, NPV), relative risk (RR) and accuracy (A) of test were 60 %, 89 %, 47 %, 1.7 and 78 % respectively. TcpO2 with hyperbaric 100 % O2 was determined as the strongest predictor of ischaemia by statistical logistic regression. SN (91%), SP (77%), PPV (94 %), NPV (67 %, RR (2.8) and A (88 %) of test were increased (cut off 270 mmHg). CONCLUSION: TcpO2 measurement contributes to the diagnosis of ischaemia in non-healing diabetic ulcers. Modify TcpO2 increases the test value.

Publication Types:

• Review