Assessment Of Skin Blood Flow Research Articles

Time Course Of Dermal Anthracene Absorption Utilizing Intradermal Microdialysis

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants encountered through daily exposures, including smoking, vehicular exhaust, industry sources, and occupational settings, such as firefighting. Inhalation has received greatest attention as a major exposure route, with limited data regarding dermal absorption. PURPOSE: Utilizing the non-carcinogenic PAH, anthracene (ANT), we aimed to assess 1) time course of dermal ANT absorption and 2) effects of local skin temperature on the magnitude of dermal absorption. METHODS: Two intradermal microdialysis (MD) fibers were inserted in the ventral forearm of 6 healthy participants (32 ± 5 yrs, 5 male, 1 female). MD fibers were perfused with 10% 2-hydroxypropyl-β-cyclodextrin with lactated Ringer’s at 1 μl/min. A 2% ANT solution was applied to skin over each MD site with overlying local heaters (LH) housing laser Doppler flowmeters for assessment of skin blood flow (SkBf). LH were clamped at 33 °C during baseline dialysate sampling. Following baseline, LH were set to 1) 43 °C (Hot, HT) and 2) 33 °C as thermoneutral (TN) for the duration of the protocol. Dialysate samples were collected intermittently over 4 hours and 15 minutes, and SkBf, blood pressure and HR were recorded throughout the protocol. Atmospheric pressure chemical ionization tandem mass spectrometry was used to quantify ANT dialysate concentrations. RESULTS: Preliminary data indicate that no ANT was detected in any baseline samples. From 1 h30 to 1 h 45 min, ANT was detected in 3 of 6 and 0 of 6 samples for the HT and TN sites, respectively. One HT sample was quantifiable at 317.5 ppb. Sampling from 4 h to 4 h 15 min, ANT was detected in all samples at the HT site and quantified in one (344.9 ppb). ANT was detected in only 1 of 6 samples at the TN site during this sampling period. SkBf was significantly higher at HT versus TN at both 1 h 45 min (8.7 ± 5.7 and 29.2 ± 20.5 CVC%max, P < 0.05) and 4 h 15 min (12.8 ± 8.3 and 42.8 ± 22.3 CVC%max, P < 0.05). CONCLUSIONS: Preliminary data indicate that dermal absorption and recovery of the PAH anthracene is increased when skin is heated versus thermoneutral, increasing over time. This has potential implications for dermal absorption of contaminants in individuals working in the heat. These data also suggest that microdialysis may be an effective method of assessing dermal absorption of PAHs.

Contactless Monitoring of Microcirculation Reaction on Local Temperature Changes

Assessment of skin blood flow is an important clinical task which is required to study mechanisms of microcirculation regulation including thermoregulation. Contactless assessment of vasomotor reactivity in response to thermal exposure is currently not available. The aim of this study is to show the applicability of the imaging photoplethysmography (IPPG) method to measure quantitatively the vasomotor response to local thermal exposure. Seventeen healthy subjects aged 23 ± 7 years participated in the study. A warm transparent compress applied to subject’s forehead served as a thermal impact. A custom-made IPPG system operating at green polarized light was used to monitor the subject’s face continuously and simultaneously with skin temperature and electrocardiogram (ECG) recordings. We found that the thermal impact leads to an increase in the amplitude of blood pulsations (BPA) simultaneously with the skin temperature increase. However, a multiple increase in BPA remained after the compress was removed, whereas the skin temperature returned to the baseline. Moreover, the BPA increase and duration of the vasomotor response was associated with the degree of external heating. Therefore, the IPPG method allows us to quantify the parameters of capillary blood flow during local thermal exposure to the skin. This proposed technique of assessing the thermal reactivity of microcirculation can be applied for both clinical use and for biomedical research.

Skin blood flow measurements during heat stress: technical and analytical considerations.

During heat stress, the skin vasculature can greatly increase conductance secondary to vasodilation. The subsequent increase in skin blood flow allows for convective heat transfer from the core to the skin and between the skin surface and the surrounding environment. Measurement of skin blood flow, therefore, provides valuable information regarding heat exchange between the body and the environment. In addition, assessment of skin blood flow can be used to study vascular control mechanisms. Most often, skin blood flow is measured by venous occlusion plethysmography, Doppler ultrasound, laser-Doppler flowmetry, and, more recently, optical coherence tomography. However, important delimitations to each of these methods, which may be dependent on the research question, must be considered when responses from these approaches are interpreted. In this brief review, we discuss these methods of skin blood flow measurement and highlight potential sources of error and limitations. We also provide recommendations to guide the interpretation of skin blood flow data.

Assessment of Skin Blood Flow Following Acute Intravenous Alcohol, and Association with Subjective Perceptions, in Social Drinkers.

The objective of this study was to determine the effect of acute intravenous (IV) alcohol infusion on skin blood flow (SBF) response, measured at fingertip and earlobe, and subjective responses associated with SBF in social drinkers. Twenty-four social drinkers underwent a computer-assisted alcohol self-infusion study. SBF was measured continuously using laser Doppler flow meter, with the probe placed on the fingertip or earlobe. Perfusion recordings were collected at baseline, and at 0-minute (0 to 5minutes), 10-minute (10 to 15minutes), and 20-minute (20 to 25minutes) time points during the priming phase of IV alcohol self-administration paradigm at low breath alcohol levels of approximately 30mg%. Subjective response was measured using the Drug Effects Questionnaire (DEQ) and Biphasic Alcohol Effects Scale. Overall SBF (collective data from both fingertip and earlobe) and SBF by each site showed significant drop at 0minutes and then subsequent significant elevation with alcohol self-administration. Males showed higher overall SBF at baseline and 0minutes than the females. At fingertip site, lowering in 0-minute SBF compared to baseline, and subsequent significant increase at the 10- and 20-minute SBF recordings were observed. DEQ measures of "like" and "want more" alcohol were significantly associated with 10- and 20-minute SBF recordings collected at fingertip site. The changes in SBF following acute IV alcohol exposure are consistent with the sympathetic response of alcohol on the cardiovascular system. This acute hemodynamic effect characterizes differences in blood flow that are sensitive to relatively low levels of acute alcohol exposure. The association of subjective perceptions with the SBF response provides evidence of the psychophysiological effects of alcohol at low levels of exposure.

Non-invasive Imaging of Localised Scleroderma for Assessment of Skin Blood Flow and Structure.

Extensive morphoea causes major morbidity, disability and disfigurement; pathophysiology is poorly understood. The aim of this study was to investigate, with non-invasive imaging, the relationship between localised abnormalities of skin structure and perfusion, which characterise morphoea. Thirty-two patients with morphoea underwent imaging at affected and unaffected sites. Skin thickness was imaged with optical coherence tomography (OCT) and high-frequency ultrasound (HFUS). Perfusion was imaged with dual-wavelength laser Doppler imaging (LDI) and thermography. Epidermal thickness showed a small increase from affected to unaffected site (OCT, active and inactive plaques [p = 0.005 and p = 0.004], HFUS active plaques only [p = 0.03]). Deeper perfusion was higher within affected than unaffected sites (LDI p < 0.001, thermography p < 0.0001, active and inactive plaques). Epidermal thickness was inversely related to superficial (but not deeper) perfusion. This novel study of OCT, HFUS, LDI and thermography confirms loss of epidermal thickness and increased deeper perfusion in morphea plaques.

Methodological assessment of skin and limb blood flows in the human forearm during thermal and baroreceptor provocations

Skin blood flow responses in the human forearm, assessed by three commonly used technologies-single-point laser-Doppler flowmetry, integrated laser-Doppler flowmetry, and laser-Doppler imaging-were compared in eight subjects during normothermic baseline, acute skin-surface cooling, and whole body heat stress (Δ internal temperature=1.0±0.2 degrees C; P<0.001). In addition, while normothermic and heat stressed, subjects were exposed to 30-mmHg lower-body negative pressure (LBNP). Skin blood flow was normalized to the maximum value obtained at each site during local heating to 42 degrees C for at least 30 min. Furthermore, comparisons of forearm blood flow (FBF) measures obtained using venous occlusion plethysmography and Doppler ultrasound were made during the aforementioned perturbations. Relative to normothermic baseline, skin blood flow decreased during normothermia+LBNP (P<0.05) and skin-surface cooling (P<0.01) and increased during whole body heating (P<0.001). Subsequent LBNP during whole body heating significantly decreased skin blood flow relative to control heat stress (P<0.05). Importantly, for each of the aforementioned conditions, skin blood flow was similar between the three measurement devices (main effect of device: P>0.05 for all conditions). Similarly, no differences were identified across all perturbations between FBF measures using plethysmography and Doppler ultrasound (P>0.05 for all perturbations). These data indicate that when normalized to maximum, assessment of skin blood flow in response to vasoconstrictor and dilator perturbations are similar regardless of methodology. Likewise, FBF responses to these perturbations are similar between two commonly used methodologies of limb blood flow assessment.

A quantitative assessment of skin blood flow in humans

Various aspects of skin blood flow (SkBF) in human beings have been studied experimentally for more than seven decades. While reasonably complete phenomenological descriptions of individual factors have emerged from those investigations, little effort has been devoted to assembling the component parts into a coherent description of the entire system. This paper describes an effort to do that. Although the result is essentially a mathematical model of human SkBF, the model is firmly based on empirical data and not merely an abstract theoretical construct. We found that experimental data for human forearm blood flow (FBF) from many sources are well represented by an equation in which the rate of cutaneous blood flow (q (s)) is defined by the equation q (s) = q (s,r) AVD x CVCM x CVCL x CVCE. The coefficient q (s,r) is the perfusion rate at a reference state, and the four component factors are defined as follows: AVD defines centrally mediated active vasodilation as a function of central temperature (T (c)), mean skin temperature (T(s))d intensity of exercise (V(o)(2)) CVCM defines reflexly mediated cutaneous vasoconstriction as a function of (T(s)) CVCL defines locally mediated cutaneous vasoconstriction as a function of local skin temperature (T (s)); and CVCE defines the effect of exercise on cutaneous vasoconstriction and mean arterial pressure. The definition of each component function is based on experimental data. Two conclusions are particularly significant. One is that the study provides a rational explanation, based on the role of (T(s)), for previously disparate opinions about the non-thermal effect of exercise on active cutaneous vasodilation. The other is that it establishes that the four factors combine multiplicatively, and not additively, as previous investigators have suggested.

Psychophysical examination in patients with post-mastectomy pain

Chronic pain, lymphoedema, post-irradiation neuropathy and other symptoms are reported in as many as 75% of women following breast cancer treatment. This study examined pain and sensory abnormalities in women following breast cancer surgery. Sensory tests were carried out on operated and contralateral sides in 15 women with spontaneous pain and sensory abnormalities and 11 pain-free women. Testing included the VAS score of spontaneous pain, detection and pain threshold to thermal and mechanical stimuli, temporal summation to repetitive heat and pinprick stimuli, and assessment of skin blood flow during repetitive brush and pinprick stimulation. Sensory threshold to pinprick and thermal stimuli was significantly higher on the operated side in both groups while pressure pain threshold was significantly lower in pain patients on the operated side compared to the contralateral side. No side to side difference was seen in pressure pain threshold in the pain-free group. Evoked pain intensity to repetitive stimuli at 0.2 and 2.0 Hz was significantly higher on the operated side in pain patients compared to the control area while no such difference was seen in pain-free patients. Cutaneous blood flow measured by laser Doppler (flux) was significantly higher when the skin was tapped at 2.0 Hz on the operated side compared to contralaterally in pain patients, while no side to side difference was seen in pain-free patients. Pinprick-evoked pain was correlated to spontaneous pain but not to flux. Spontaneous pain was not correlated to flux. Sensitization seems to be a feature in breast cancer-operated women with pain, but not in pain-free women.

Distribution of breast skin blood flow in patients with breast cancer

Abstract Highly vascularized tumours are associated with fast growth and high grade. Accurate, objective assessment of skin blood flow in the breast can be obtained by the recent development of a laser Doppler imager (LDI) that creates an image of tissue blood flow over a wide area. The imager collects flow data without touching the breast skin. Breast skin blood flow was mapped using the LDI in an outpatient clinic on 100 patients (47 normal, 26 benign breast disease and 27 breast carcinoma). The findings were correlated with the results of examination by mammography/ultrasound and cytology/histology. The LDI blood flow images of the normal breasts were analysed in five breast regions (four quadrants and central area) and flow values for each region were averaged. The mean blood flow in normal patients was 299 ± 155 and 311 ± 157 flux (± SD) for the right and left breasts, respectively. In patients with benign breast disease it was 476 ± 210 flux and in patients with breast carcinoma it was 685 ± 278 flux. Breasts with carcinoma show the highest skin blood flow measurements. Our findings indicate that the technique is sensitive for large cancers. This new tool may have an application in the serial monitoring of early response to systemic treatment in patients with large superficial tumour masses.

Infrared radiometry of thermally insulated skin for the assessment of skin blood flow

The temperature increase of thermally insulated skin provides useful information about its blood flow and the blood temperature. The measurement of skin temperature by a contact thermometer, such as a thermistor, is not accurate, because it depends on the pressure exerted on the skin by the thermometer. In order to have reproducible measurement of the skin temperature, noncontact temperature measurement is preferable. Suitable insulation is achieved by using a cylinder of lowthermal-conductivity material, covered by polyethylene layers, which is applied on the skin. The polyethylene layers permit partial transmission of the infrared radiation through it. Preliminary results show that both the transient and the steady-state temperature increase can be obtained from measurements of radiation transmitted through the thermal insulation that was applied to the skin, and that the steady-state temperature increase is more closely related to tissue blood flow than the uncovered-skin temperature is.

Transcutaneous hydrogen clearance-a new non-invasive technique for assessing blood flow in human skin

A new technique for the noninvasive assessment of skin blood flow is described using a modified, commercially available transcutaneous oxygen electrode. Initially, experiments were carried out on normal volunteers at skin temperatures of 40 degrees C and 44 degrees C. Transcutaneous H2 (tcpH2) clearances were measured after the subject had breathed a mixture of 2% H2 in air until a saturation value in the skin had been reached. tcpH2 clearance results were compared with laser Doppler flux values measured simultaneously on adjacent sites and at the same temperatures under control and reactive hyperaemic conditions. Good reproducibility for the tcpH2 technique and significant correlation (p<0.002) between it and laser Doppler flux values at the same temperatures was demonstrated. In further experiments, (I125) 4-iodoantipyrine clearances (IAP) were carried out immediately prior to and at the sites as tcpH2 clearances in critically ischaemic lower limbs. The same correlation between the methods and the differences between tcpH2 values observed in normal and critically ischaemic skin were highly significant (p<0.002).

Relationship of PKA and Acute Skin Irritation in Humans

AbstractThe relationship between pKa and skin irritation in humans was studied for a homologous series of benzoic acid derivatives with predicted permeation through human skin at comparable rates (15-90 μg/cm2/hr). Skin irritation and pKa are strongly correlated, and, for pKa ≤4, skin irritation rapidly increases. Laser Doppler velocimetric assessment of skin blood flow, color meter readings, erythema, edema, and the primary irritation index are all linearly correlated and related to pKa; erythema at 24 hr appears to be the most sensitive variable.

System for monitoring peripheral circulation in the diagnosis of vibration hazards

Peripheral circulatory disorders such as Raynaud's phenomenon are thought to be basal symptoms of vibration hazards. The elucidation of their pathogenesis and their diagnosis between attacks is regarded as important. A system for monitoring the body surface circulation noninvasively and continuously has been developed, which enables the quantitative dynamic assessment of skin blood flow. This apparatus is based on the thermal diffusion method and uses a probe incorporating a Peltier stack. After fundamental studies on this system, the peripheral circulatory functions of workers using vibrating tools were studied. The workers were divided into three groups: group A, without any symptoms; group B, with numbness and/or pain but without Raynaud's phenomenon; and group C, with Raynaud's phenomenon. The finger blood flow (FBF) of group C at rest was significantly lower than that of group A (p < 0.01). In a handgrip test and with exposure to local vibration (60 Hz, 50 m/s2), the FBF of group A significantly changed compared to its value at rest, but that of group C showed no significant change.

The relationship of pKa and acute skin irritation in man.

The relationship between pKa and skin irritation in man is studied for a homologous series of benzoic acid derivatives, which permeate through human skin at comparable rates (15-88 micrograms/cm2/hr). Skin irritation and pKa are correlated for pKa less than or equal to 4. Laser Doppler velocimetric assessment of skin blood flow, color meter readings, erythema, edema, and the primary irritation index are all linearly correlated and related to pKa; erythema at 24 hr appears to be the most sensitive parameter to variation in pKa when pKa less than or equal to 4.

Laser Doppler assessment of skin blood flow in arteriopathic limbs.

In severely ischaemic lower limbs, the skin response to changing posture from lying to standing is a diagnostic flush. We investigated this observation by measurements of the microcirculation using the non-invasive laser Doppler technique. Eleven patients with ankle: brachial pressure (A:B) ratios less than 0.7 were compared with 13 age-matched controls (A:B ratios greater than 1). In normal subjects, mean horizontal skin blood flow (SBF) was 30.2 +/- 14.9 (+/- SD), significantly greater than mean SBF in the ischaemic group: 12.4 +/- 9.2 (P less than 0.01, Student's t test). Mean SBF fell in the normal group on dependency to 27.5 +/- 16.4 but this change was not significant. Unexpectedly mean SBF rose in the ischaemic limbs to 20.7 +/- 13.8 (P less than 0.05). The pattern of SBF response to change in posture is different in normal and arteriopathic limbs.

Reflection spectrophotometry for assessment of skin blood flow

Reflection spectrophotometry for assessment of skin blood flow

Predictive value of intracutaneous xenon clearance for healing of amputation and cutaneous ulcer sites.

A previously reported technique for the assessment of skin blood flow in the lower extremities of patients with ischemic lesions was evaluated using intracutaneous xenon clearance. The radioisotope was injected above and below both the ankle and the knee and flow was measured using a gamma camera with a low-energy collimator, 88-keV photopeak, and a 20% window. Healing was more frequent when skin blood flow was equal to or greater than 2.4 ml/min/100 g (38/39 patients) than when flow was less than 2.4 ml/min/100 g (4/7 patients). The authors conclude that this technique can be used to help determine the appropriate site for amputation in lower limb ischemic lesions.

Modification of the skin blood flow-body temperature relationship by upright exercise.

Modification of the skin blood flow-body temperature relationship by upright exercise.