Simultaneous measurement of digital artery and skin perfusion pressure by the laser Doppler technique in healthy controls and patients with peripheral arterial occlusive disease

The Influence of Heating on Toe pressure in Patients with Peripheral Arterial Disease

BACKGROUND AND AIM

The toe skin temperature in vascular patients can be low, making reliable toe pressure measurements difficult to obtain. The aim of this study was to evaluate the effect of heating on the toe pressure measurements.

MATERIALS AND METHODS

A total of 86 legs were examined. Brachial pressure and toe pressure were measured at rest in a supine position using a laser Doppler device that also measured skin temperature. After heating the toes for 5 min with a heating pad, we re-measured the toe pressure. Furthermore, after heating the skin to 40° with the probe, toe pressures were measured a third time.

RESULTS

The mean toe skin temperature at the baseline measurement was 24.0 °C (standard deviation: 2.8). After heating the toes for 5 min with a warm heating pad, the skin temperature rose to a mean 27.8 °C (standard deviation: 2.8; p = 0.000). The mean toe pressure rose from 58.5 (standard deviation: 32) to 62 (standard deviation: 32) mmHg (p = 0.029). Furthermore, after the skin was heated up to 40 °C with the probe, the mean toe pressure in the third measurement was 71 (standard deviation: 34) mmHg (p = 0.000). The response to the heating varied greatly between the patients after the first heating-from -34 mmHg (toe pressure decreased from 74 to 40 mmHg) to +91 mmHg. When the toes were heated to 40 °C, the change in to toe pressure from the baseline varied between -28 and +103 mmHg.

CONCLUSION

Our data indicate that there is a different response to the heating in different clinical situations and in patients with a different comorbidity.

Assessment of the characteristics and detectability of skin perfusion pressure measured using a thermostatic heating probe

OBJECTIVES

To assess the characteristics of skin perfusion pressure (SPP) measured using a thermostatic heating probe and whether a thermostatic heating probe improves SPP detection.

METHODS

We studied 8 feet of healthy young subjects and 31 feet of elderly patients suspected to have severe limb ischemia. We measured SPP at the dorsum and plantar aspects of each foot using a plain laser Doppler probe and a thermostatic heating probe heated at 44°C. Results were expressed as median. Comparisons were analyzed using a non-parametric test.

RESULTS

In the healthy subjects, the SPP values at both the dorsum and the plantar aspect were not significantly different after heating. The thermostatic heating probe did not improve the SPP detection rates. In the patients with ischemic limb, the SPP values at both the dorsum and the plantar aspect significantly increased after heating (p <0.001 for both). The SPP detection rate at the dorsum remained at 96.8%; however, it was improved from 87.1% to 100% at the plantar aspect after heating.

CONCLUSION

The thermostatic heating probe was shown to be useful for improving the detectability of SPP in the ischemic limbs. An SPP increase after heating may be considered as a parameter of limb ischemia.

Skin perfusion pressure in chronic venous disorders

OBJECTIVE

To examine whether a patient group with chronic venous disorders (CVDs) would show a different response to a pressure provocation test, such as skin perfusion pressure (SPP) of microcirculatory function.

DESIGN

A cuff inflation technique was applied to the gaiter area of the lower legs to induce complete occlusion of the microcirculation. The cuff was then released to measure the pressure at which perfusion resumed, and SPP was measured with a laser Doppler flowmeter (LDF). The measurements at reperfusion were taken of skin of the lower legs of individuals with CVD and compared with the lower-leg skin of control participants.

MAIN OUTCOME MEASURES

To establish whether a measurable difference in SPP exists between the group with CVD and the group without CVD, the means of 9 measurements taken were compared using the Student t test. The lowest value of the 9 measurements of minimum pressure (LMV) was used to estimate the pressure at which reperfusion occurred (SPP). The means of those estimates were then compared using the Student t test.

MAIN RESULTS

The mean LMV measured in the CVD group was slightly higher than that measured in the group without CVD. Although this could be considered a clinically significant result, it was not statistically different.

CONCLUSIONS

For this study, SPP was not significantly different for those with CVD compared with those without. These results suggest that SPP conducted with an LDF has little potential to detect "invisible" changes in the microcirculatory function of the skin affected by CVDs.