Pedal blood flow and transcutaneous PO2in normal subjects and in patients suffering from severe arterial occlusive disease

Transcutaneous Oximetry is Useful in Vascular Pathology If a Cutaneous Reference Map and a Maximal Exercise Test are Used

The measurement of partial oxygen pressure in arterial blood by use of transcutaneous pulse oximetry (tcPo2) is a technique relatively new to clinical practice. However, there are notable differences of values both in healthy and arteriopathic subjects, depending on which part of the limb the measurement is carried out. The authors define a cutaneous reference map for oximetric measurements in both healthy and arteriopathic subjects. In a group of 200 healthy subjects and a group of 82 subjects affected by obliterative arteriopathy of the lower limbs at the second Fontaine stage, oximetric measurements were carried out under rest conditions. By comparing the oximetric ranges at all examined levels, it can be seen that there is a wide band of overlap between the minimum values of healthy subjects and those of the arteriopathic subjects.

In a group of 30 healthy subjects and in a group of 30 subjects affected by obliterative arteriopathy of the lower limbs at the second Fontaine stage, oximetric measurements were taken at I, II, III back levels of the leg during maximal treadmill test. In this case, by comparing the oximetric ranges between the two groups, it can be seen that all arteriopathic subjects present significantly lower values as compared with those of the healthy subjects at each examined level. This permits a confident diagnosis of pathology.

The authors conclude that in order to make a correct diagnosis of arteriopathy by using transcutaneous oximetry, it is necessary to consider both the measurements carried out under rest conditions and those carried out during maximal treadmill test.

A Review of Microvascular Measurements in Wound Healing

The microcirculatory evaluation in patients affected by arteriopathic or venous ulcers is usually carried out using laser Doppler flowmetry, transcutaneous oxygen (transcutaneous pressure of oxygen, TcPO2), and carbon dioxide (transcutaneous pressure of carbon dioxide, TcPCO2) measurements and capillaroscopy. These techniques provide significant pathophysiologic and prognostic information. TcPO2 and TcPCO2 diagnose and classify the extent of arterial disease in the leg ulcers caused by arterial disease; the prognostic value is recognized, though doubts about its prognostic potential exist in the case of leg ulcer. Laser Doppler flowmetry is able to identify the first functional impairment in the early stages of the arterial disease and in the complicated venous insufficiency. Capillaroscopy gives us morphological and quantitative parameters of the capillary bed that is damaged in arteriopathic and venous ulcers; nevertheless, it does not provide us with definite prognostic indexes. Combining the 3 methods may contribute to yield objective measures in the clinical management of lower extremity ulcers.

The effects of leg/body position on transcutaneous oxygen measurements after lower-extremity arterial revascularization

A postoperative nursing goal in a patient with peripheral artery disease requiring lower-extremity arterial reconstruction surgery is to maintain blood flow and tissue oxygenation to the revascularized extremity. This may be achieved through extremity positioning. Transcutaneous oxygen (TcPO(2)) measurements provide a noninvasive objective determination of oxygen at the skin surface and assessment of underlying circulation and tissue oxygenation. The purpose of this study was to determine which lower-extremity position afforded the highest TcPO(2) in 10 subjects with a lower-extremity arterial revascularization procedure preoperatively and 24 and 48 hours postoperatively. Hypotheses included comparing preoperative and postoperative TcPO(2) measurements, leg skin temperatures, and limb volumes. The subjects were studied in three different leg/body positions: supine with legs extended, sitting with legs extended, and supine with legs-elevated 20 degrees using the Radiometer TCM30 (Radiometer; Copenhagen) and PhysitempTH-5 Thermalert (Physitemp; Clifton, NJ) monitors. There was no change in the postoperative leg TcPO(2) measurements or limb volumes compared with preoperative measurements (P = .12-.92). A small sample size and lack of peripheral artery disease stratification were among study limitations. Significant to the nursing care of patients with vascular dsease is the finding that any of the leg/body positions in this study could be used postoperatively on the revascularized extremity without decreasing TcPO(2) measurements.

Interobserver and intraobserver reproducibility of peripheral blood and oxygen pressure measurements in the assessment of lower extremity arterial disease

INTRODUCTION

Peripheral blood pressure measurements play a prominent role in the diagnosis and follow-up of patients with peripheral vascular diseases. Toe pressure of the hallux (TP1) and second toe (TP2) and transcutaneous oxygen pressure (TCPO2) measurements are becoming more important. The ankle/brachial pressure index (ABPI) is known to be a reliable parameter, but the toe pressure and TCPO2 are evaluated less thoroughly. Therefore, we evaluated the reproducibility of TP1, TP2, TCPO2, ABPI, ankle pressure (AP), and brachial pressure (BP).

PATIENTS AND METHODS

In 54 patients with various stages of peripheral vascular disease, the intraobserver and interobserver reproducibility of BP, AP, ABPI, TP1, TP2, and TCPO2 was investigated by calculating the repeatability coefficient (RC) and the intraclass correlation coefficient (ICC) and by using Bland-Altman plots.

RESULTS

The intraobserver and interobserver reproducibility at 1 day and after 1 week of BP, AP, ABPI, and TP1 was substantial and comparable (ICC range, 0.80-0.99), except for the BP after 1 week. The TP2 and TCPO2 were less reproducible (ICC range, 0.62-0.98). The interobserver RC of BP was 31 mm Hg; of AP, 44 mm Hg; of ABPI, 27%; of TP1, 41 mm Hg; of TP2, 67 mm Hg; and of TCPO2; 30 mm Hg. The difference plot showed that the observer variability was equally distributed across the range of pressure in all measurements.

CONCLUSION

The BP, AP, ABPI, and TP1 have a substantial intraobserver and interobserver reproducibility, whereas TP2 and TCPO2 show worse reproducibility. Especially when low values (or values around a cutoff value) are measured, the RC should be taken into account, and repetition of the measurement is advocated.

Outcome criteria in patients with peripheral arterial disease

To adequately evaluate patients with chronic occlusive arterial disease several factors will need to be taken into account and documented. These include associated diseases such as diabetes mellitus. When surgical or endovascular therapy is applied, analysis of outcome must include the symptomatic status of the patient, the anatomic evidence of patency of the procedure and of the proximal and distal disease, the hemodynamic result, limb preservation, and mortality. All of these factors will provide a better global picture of the disease and information on how it can be best treated.

Effects of oxygen inhalation on skin microcirculation in patients with peripheral arterial occlusive disease

BACKGROUND

Oxygen administration is currently used in clinical medicine to improve peripheral oxygen delivery to tissues threatened by ischemia. However, conflicting results have been reported on the effects of oxygen in ischemic areas. This study was aimed at investigating the effects of 40% oxygen inhalation on the skin microcirculation in the feet of patients with peripheral arterial occlusive disease (PAOD).

METHODS AND RESULTS

Transcutaneous oxygen tension (tc PO2) was measured on the dorsal skin of the foot, and the nailfold microcirculation was investigated by a combination of laser Doppler flowmetry (LDF) and dynamic capillaroscopy (CBV) in the great toes of 17 legs of 11 patients, with 13 legs of eight normal subjects as a control group. Inhalation of oxygen induced a significant decrease of both the total (delta LDF, -307%, p less than 0.02) and nutritional (delta CBV, -17%, p less 0.002) skin microcirculation in normal legs compared with baseline values. A similar response was observed in 10 legs of patients who showed a significant increase of the tc PO2 (greater than or equal to 10 mm Hg) (delta LDF, -14%, NS; delta CBV, -13%, p less than 0.005). By contrast, both the total (+21%, p less than 0.03) and nutritional (+52%, p less than 0.05) circulation significantly increased in the seven legs without significant tc PO2 increase. In addition, the flow motion, which was impaired in the patients, was significantly (p less than 0.05) improved by oxygen inhalation.

CONCLUSIONS

Inhalation of 40% oxygen induces a vasoconstriction in the skin microcirculation of toes of the normal subjects and patients with moderate PAOD but induces an increase of the skin microcirculation in patients with severe PAOD.

Effect of buflomedil chlorhydrate on local oxygen delivery in peripheral vascular disease

Modifications in transcutaneous oxygen pressure (TcPO2), induced by the administration of 3 mg/kg/day buflomedil chlorhydrate for seven days were evaluated in 12 subjects suffering from peripheral vascular disease (PVD). After the treatment a significant increase in TcPO2 basal values was observed in Stage III and Stage IV PVD patients (+32.2%) while a significant reduction of 12% in the half-recovery time to basal values after an induced ischemia was recorded in Stage II PVD patients by the seventh day. Buflomedil did not, however, cause any significant variations in the ankle/arm pressure ratio or in the plethysmographic peak flow.

Transcutaneous oxygen tension behavior in the different stages of peripheral vascular disease and its correlation with ankle/arm pressure ratio and calf blood flow

The practical utility of transcutaneous oxygen tension (TcPO2) has been evaluated in 22 normal subjects and in 54 patients suffering from peripheral vascular disease (PVD) at various stages (II, III, IV), to define its clinical use in the diagnosis of PVD. Basal TcPO2 values can distinguish normal subjects only from stages III and IV PVD patients. In the case of stage II PVD patients the evaluation of the half-recovery time of TcPO2 basal values after an induced ischemia of the limb is mandatory. The study also showed that there are no significant statistical correlations among the TcPO2 values, Doppler, and plethysmographic parameters.