Subcutaneous Tissue Blood Flow Research Articles

Perception of Foot Temperature in Young Women with Cold Constitution: Analysis of Skin Temperature and Warm and Cold Sensation Thresholds

To examine the disease state of cold constitution, physiological measurements of the foot were conducted by investigating thermal sensations under an environmental condition of 25 degrees C-26 degrees C (neutral temperature) in 29 young women with and without cold constitution. The subjects were classified into 3 groups according to their experiences with cold constitution: cold constitution, intermediate, and normal groups. Foot skin temperature was measured by thermography. Thermal sensations were measured on the dorsum of the left foot using a thermal stimulator. Cold and warm spots on the dorsum of the right foot were ascertained. Thermal stimulation was delivered by a copper probe. No significant differences in foot skin temperature among these 3 groups were identified as measured in a laboratory under neutral temperature conditions. However, the mean warm sensation threshold was +6.3+/-1.09 degrees C (mean+/-SEM) for the cold constitution group (n=14), +3.4+/-2.10 degrees C (mean+/-SEM) for the intermediate group (n=7), and -0.25+/-1.96 degrees C (mean+/-SEM) for the normal group (n=6). The difference was significant between the cold constitution and normal groups. No significant differences among the 3 groups were found in the cold sensation threshold. This may be attributable to the distribution of thermal receptors and to chronically reduced blood flow in subcutaneous tissues, where the skin temperature receptors responsible for temperature sensation are located.

A novel approach to age determination of traumatic injuries by reflectance spectroscopy

Aging of injuries on a victim's body is an important aspect of forensic medicine. Currently, visual assessment and colorimetry based on empirical criteria are the most common techniques for this task, although the results are uncertain. A trauma causing localized vessel damage will rapidly result in a pool of blood in subcutaneous tissues. The color of the bruise is, however, primarily due to hemoglobin transport into dermis and secondarily to its breakdown products. This transport is analyzed in terms of hemoglobin diffusion followed by clearance by macrophage activity, lymphatic flow, and conversion to breakdown products such as bilirubin. The color of a bruise is caused by hemoglobin and hemoglobin breakdown products. The color will change with time, and such color changes can be recorded using reflectance spectroscopy. The aim of this study was to develop a mathematical model to describe blood diffusion within bruised skin, and to use this method to retrieve the age of a bruise from measured skin reflectance. An analytic model was established to describe the development and fading of bruise color. The model, which is based on Darcy's law of convection flow and Fick's law of diffusion, describes the distribution of blood and hemoglobin breakdown products within a hematoma as a function of time after injury. The initial phase after injury is described by a convective extravascular blood flow in subcutaneous tissues, and further development of the bruise is described by diffusion and breakdown of whole erythrocytes and hemoglobin in dermis. Experimental data were used to verify the model. Reflection spectra in the 400-850 nm wavelength range were collected from normal and bruised skin using an integrating sphere setup. The subjects were adult patients admitted to the Department of cardiothoracic surgery, St. Olav's Hospital, Trondheim, Norway. The skin hematomas were caused by external trauma, cardiothoracic examinations, or surgery. Preliminary results show that measured and simulated skin reflectance agrees well. The model predicts the age of a hematoma with an accuracy of approximately 1 day. The accuracy of the method depends on precise information of skin thickness in the injured area. The quality of the estimates from the model will thus be enhanced if a reliable measure of skin thickness is collected concurrently with the reflection measurement. The time development of a skin hematoma is described with good accuracy by the implemented model. The analytic method provides a theoretical basis for developing an apparatus to determine the age of injuries in forensic medicine.

In vivo subcutaneous adipose tissue glucose kinetics after glucose ingestion in obesity and fasting

The kinetic pattern of subcutaneous adipose tissue extracellular glucose following glucose ingestion was investigated in vivo with a microdialysis technique in normal-weight (n=21) and obese subjects (n=18) before and after a 7-day fast (n = 9). A dialysis probe (4×0.5 mm) was implanted subcutaneously, and was continuously perfused (5 μl/min). The tissue dialysate glucose concentration was determined in 15-min samples before and during a period of 180 min after a 75-g oral glucose load. A comparison was made between the tissue dialysate concentrations and the venous blood glucose levels. In all study groups the increase in subcutaneous tissue dialysate glucose following glucose ingestion paralleled that in blood, with a time-lag of up to 15 min. In the normal-weight subjects the maximum relative increase in abdominal adipose tissue dialysate glucose was 25% higher (p <0.005) than the corresponding blood glucose level, and the total relative glucose level (area under curve, AUC) in abdominal fat was 20% (p<0.01) higher than in blood. In contrast, the kinetics of gluteal subcutaneous tissue dialysate and blood glucose levels were similar. In the obese patients before the fasting period the maximum relative glucose level in abdominal fat was almost twice as high as in blood (p<0.005), and the total glucose level (AUC) was 50% higher than the blood glucose AUC (p<0.005). After the fast, on the other hand, almost identical relative dynamics of abdominal subcutaneous tissue and blood glucose levels were found. It is concluded that ingested glucose is rapidly distributed to the interstitial compartment of subcutaneous adipose tissue. In normal-weight subjects the hexose is retained to some extent in the abdominal, but not in the gluteal, fat depot, which indicates regional differences in subcutaneous tissue glucose kinetics following glucose ingestion. In obesity the accumulation of glucose in abdominal fat is markedly increased, whereas after fasting the abdominal subcutaneous tissue glucose level closely resembles the venous blood glucose level. It remains to be elucidated whether the observed effects of obesity and fasting on the handling of glucose by adipose tissue following glucose ingestion are due to changes in subcutaneous tissue blood flow and/or tissue glucose utilization.

Arteriolar hyalinosis does not interfere with the local veno-arteriolar reflex regulation of subcutaneous blood flow in insulin-dependent diabetic patients

The function of the local nervous veno-arteriolar reflex regulation of blood flow in subcutaneous tissue of the lower leg was studied in diabetic patients. The material comprised 11 long-term insulin-dependent diabetic (IDDM) patients with retinopathy and nephropathy and eight short-term IDDM patients without retinopathy or nephropathy and 11 non-diabetic subjects. The diabetic patients had no or a slight to moderate degree of peripheral autonomic and sensoric neuropathy. Blood flow was measured by the local 133Xe wash-out technique. Blood flow was determined before, during and after an approximately 40 mmHg increase in venous transmural pressure, induced by lowering the lower leg 50 cm below heart level. During lowering of the leg, the subcutaneous blood flow decreased to the same level in long-term IDDM patients (mean: 46%), short-term IDDM patients (53%) and control subjects (53%). There was no association between the relative local blood flow during lowering and the degree of terminal arteriolar hyalinosis studied in skin biopsies from the same tissue area. Our results suggest that terminal arteriolar hyalinosis does not interfere with the local sympathetic-mediated veno-arteriolar reflex regulation of blood flow. Moreover, the vasoconstriction mediated by the veno-arteriolar reflex probably occurs in the larger arterioles (greater than 50-100 micron) or small arteries.

The regulation of subcutaneous blood flow in patient with Dercum´s disease

Dercum´s disease or adiposis dolorosa is a poorly understood disorder with painful fatty deposits in the skin localized to the lower extremities. The etiology is unknown. In such a patient the mechanisms of local regulation of blood flow in subcutaneous tissue was investigated by the local 133Xenon washout technique. The patient was reinvestigated one week after treatment with intravenous lidocaine. The local vasoconstrictor response to increase in venous transmural pressure was not present in this patient, but reappeared after lidocaine treatment. Autoregulation of blood flow in subcutaneous tissue was present before as well as after lidocaine treatment. It seems likely that a pain elicited increase in sympathetic activity in the vasoconstrictor fibres abolished the normal vasoconstrictor response to increase in venous transmural pressure. The mechanism of pain relief after intravenous lidocaine infusion is uncertain, but central as well as peripheral mechanisms may be considered.

Effects of small changes of plasma vasopressin on subcutaneous and skeletal muscle blood flow in man.

The effect of vasopressin (AVP) on subcutaneous blood flow was studied by the 133Xenon wash-out method in 13 healthy subjects during three consecutive infusions of synthetic AVP, using increasing infusion rates. In seven of them, both subcutaneous and skeletal muscle blood flows were measured during the first infusion. The preinfusion, and infusion pAVP levels were 1.6 +/- 0.4, 3.4 +/- 0.4, 4.9 +/- 0.5 and 8.8 +/- 0.7 pg ml-1, respectively (mean +/- SE). The values are within the range normally found during dehydration. During the AVP infusions, the blood flow in subcutaneous tissues decreased 30-40% and the vascular resistance increased 60-80%. Neither heart rate nor blood pressure change significantly during the infusions. Plasma renin activity (PRA) decreased significantly. After cessation of the infusions, blood flow and vascular resistance rapidly returned to preinfusion values, while PRA increased very slowly. Skeletal muscle and subcutaneous tissues blood flows were found to be equally sensitive to small changes in the pAVP level. The present study has demonstrated that even minor increments of pAVP levels, as seen during dehydration, can significantly alter the regional blood flow in subcutaneous and skeletal muscle tissues in man.

Impaired autoregulation of blood flow in subcutaneous tissue of long-term type 1 (insulin-dependent) diabetic patients with microangiopathy: an index of arteriolar dysfunction.

Autoregulation of blood flow in subcutaneous tissue was studied at the level of the lateral malleolus in eight long-term Type 1 (insulin-dependent) diabetic patients with clinical microangiopathy, eight short-term Type 1 diabetic patients without clinical microangiopathy and seven healthy control subjects. Blood flow was measured by the local 133Xenon washout technique. Mean arterial blood pressure was reduced by a maximum of 23 mmHg by elevating the limb above heart level and elevating to a maximum of 70 mmHg by head-up tilt; in the latter position venous pressure was kept constant and low by activation of the leg muscle vein pump (heel raising). Mean arterial blood pressure was thus varied between 60 and 160 mmHg. In normal and short-term diabetic subjects blood flow remained within 10% of control values during the changes in arterial blood pressure. In six of the eight Type 1 diabetic patients with clinical microangiopathy, autoregulation of blood flow was impaired, blood flow changing approximately 20% per 10 mmHg change in arterial blood pressure; the slope of the autoregulation curves was significantly higher compared with the two control groups (p less than 0.02). Resting mean arterial blood pressure was significantly elevated in long-term diabetic patients (median: 107 mmHg) compared with short-term diabetic (median: 85 mmHg) and control subjects (median: 91 mmHg) (p less than 0.01 and p less than 0.02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of therapy on 24-h subcutaneous blood flow in the leg in patients with severe ischemia.

The effect of vascular surgical reconstruction or Buerger's exercises upon average subcutaneous blood flow for a 24-h period was studied in 14 patients with severe leg ischemia due to occlusive arterial disease. Blood flow was estimated proximally in the calf and in the foot by a 133Xe washout technique. Seven patients underwent vascular surgery. Postoperatively subcutaneous blood flow increased in the calf and the foot in all patients except one in whom a decrease in blood flow in the foot was seen. In this case a decrease in systolic blood pressure occurred following the operation. Buerger's exercises did not alter subcutaneous blood flow either in the calf or in the foot in the seven patients studied. Buerger's exercises seem to be of no value for these patients. The measurement of blood flow in subcutaneous tissue over a period of 24 h seems to be a useful test of the effect of different treatments.

Loss of autoregulation of blood flow in subcutaneous tissue in juvenile diabetes.

The autoregulation of blood flow in subcutaneous tissue was investigated at the level of the lateral malleolus by the local 133Xenon washout technique. We have investigated eight long-term insulin-dependent diabetics and seven healthy controls. All diabetics had moderate diabetic nephropathy and retinopathy. The blood flow remained constant in all normal subjects, when the arterial perfusion pressure was varied between 70 and 150 mm Hg. All diabetics had impaired or reduced autoregulation of the subcutaneous blood flow. The blood flow increased and decreased almost linearly with the changes in arterial perfusion pressure. The mechanism underlying the defect autoregulation of blood flow in diabetics is uncertain; possibilities include structural changes of the arterioles and/or alterations of local metabolic factors.

手部皮下組織の循環動態に関する研究 ＩＩ し位による血流量の変動と交感神経系について

In an earlier work in normal subjects, We demonstrated that the subcutaneous tissue blood flow in the hand region was found to be significantly reduced by the postural change from the supine to the upright position. In order to investigate the possible role of central mechanisms in the observed changes in blood flow rate during the postural change, the acute effects of the postural change from the supine to the upright position on the subcutaneous tissue blood flow in the hand region were studied in seven subjects with shoulder-arm-neck syndrome after an acute sympathetic denervation using the hydrogen washout technique.Acute sympathetic denervation was achieved by stellate ganglion block induced by lidocaine, 1 per cent, without adrenaline. Horner's syndrome was taken as evidence of effective sympathetic denervation.During the postural change from the sppine to the upright position after sympathetic denervation, the blood flow rate decreased to the mean value of 62.5 per cent of the initial value in the denervated hand and to the mean value of 63.6 per cent of the initial value in the non-denervated hand. The difference was not significant.These findings suggest that the vascular adjustments to postural changes may not be altered by the sympathetic denervation. This interpretation is consistent with Henriksen's evidence which suggests that vascular reactions to postural changes in vascular transmural pressure are not mediated via sympathetic ganglia.

Effect of orthostatic blood pressure changes upon capillary filtration-absorption rate in the human calf.

The effect of postural changes upon fluid filtration rate in the calf was studied in 3 healthy subjects placed in supine position. Volume changes in the calf were measured by a water plethysmograph. Relative changes in blood flow in subcutaneous tissue and anterior tibial muscle were measured by the local 133Xe washout technique. Lowering the calf from 5-25 cm caused a linear increase in filtration rate whereas blood flow in subcutaneous tissue of the segment studied and anterior tibial muscle remained constant. Based on this average CFC was about 0.0012 ml X min-1 X 100 g-1 X mmHg-1. Further lowering of the calf caused a decrease in blood flow in subcutaneous tissue and skeletal muscle by about 50% corresponding to an increase in total vascular resistance by about 100%. During these circumstances the increase in infiltration rate was reduced by about 33%. The resulted indicate that the local veno-anterior reflex responsible for the observed vasoconstriction in the tissue under study together with intrinsic vascular mechanisms reduces transcapillary fluid filtration in the lower position. The mechanism appears to be mainly due to a reduction of the increase in mean capillary pressure whereas CFC seems to remain almost constant.

Local regulation of blood flow in subcutaneous tissue in patients with acute myocardial infarction.

1. Local regulation of subcutaneous blood flow in the forearm was studied in the acute phase of myocardial infarction. Blood flow was measured by the local 133Xe-washout technique. 2. Plasma concentrations of noradrenaline and adrenaline were increased on day 1, suggesting an increase in sympathetic neuronal activity, but gradually returned to normal thereafter. 3. Subcutaneous blood flow on day 1 was far below normal (38%) and steadily increased to reach normal at day 7 after coronary occlusion. The sympathetic vasoconstrictor activity that caused the initial reduction in flow could be blocked by proximal nervous blockade, increasing the subcutaneous blood flow by 130, 63 and 14% on days 1, 3 and 7 respectively after coronary occlusion. A normal response to decrease in arterial perfusion pressure was observed, suggesting that intrinsic vascular reactions responsible for autoregulation of blood flow were not affected by the increase in sympathetic vasoconstrictor activity. The vasoconstrictor response to increase in venous transmural pressure could not be demonstrated on day 1 after coronary occlusion but gradually reappeared during the following days. 4. Abolition of the vasoconstrictor response is most likely to be due to a centrally elicited increase in sympathetic activity, as a normal vasoconstrictor response was obtained after proximal nervous blockade. Thus the local sympathetic reflex mechanism underlying the vasoconstrictor response appears to be suppressed by a centrally elicited increase in sympathetic discharge rate.

Adipose tissue blood flow and insulin disappearance from subcutaneous tissue

The disappearance rate of labeled insulin from subcutaneous tissue has shown wide variation, even using labeled insulin with biological properties identical to that of the unlabeled insulin. The aim of this study is to evaluate the influence of adipose tissue blood flow (ATBF) on the disappearance rate of soluble 131I‐labeled insulin from an injected depot subcutaneously in the frontal femoral region of 10 insulin‐treated diabetics. Changes in ATBF were induced by leg exercise on a bicycle ergometer in an upright position, by dynamic arm exercise in a supine position, and by local heating and cooling. The mean resting ATBF of the diabetics was 5.3 ±3.1 (ml · min−1 · 100 gm−1) and 6.7 ± 6.0 of the control subjects, difference (ns). Bicycling increased ATBF in 5 patients from 3.0 ± 0.7 to 7.7 ± 1.1, the disappearance constant (k) value of insulin from 0.484 ± 0.201 (min−1 · 10−2)to 0.937 ± 0.306, and the amount of insulin absorbed per hr from 24.7 ± 9.1% to 42.3 ± 10.5% (p &lt; 0.05). Local cooling decreased ATBF in 6 diabetics from 6.6 ± 3.9 to 2.4 ± 1.1, the k value of insulin from 0.685 ± 0.163 to 0.362 ± 0.158, and the absorbed amount from 33.7 ± 3.9% to 17.4 ± 6.9% (p &lt; 0.02). Dynamic arm exercise and local heating increased the ATBF, insulin disappearance, and absorbed amount of insulin. The skin and subcutaneous temperatures did not show any significant changes, except during local cooling and the subsequent local heating (p &lt; 0.02). There was a correlation between ATBF and insulin absorbed per hr (r = 0.969, p &lt; 0.001), which indicates that changes in subcutaneous tissue blood flow in the anterior thigh induce changes in insulin absorption from the injection site and might be of clinical importance.

Local Regulation of Blood Flow in Subcutaneous Tissue in Generalized Scleroderma

The effect of orthostatic changes in vascular transmural pressure on blood flow in subcutaneous tissue was studied in 10 patients with the acrosclerotic type of generalized scleroderma. Blood flow was measured on the back of the hand by the local 133xenon washout technique. The blood flow remained constant when the hand was elevated 20 cm above the jugular notch, indicating that there is autoregulation of blood flow, When the hand was lowered 40 cm below by 50% observed in normals. Thus, intrinsic vascular reactions responsible for the autoregulator response are present, whereas the normal "vasoconstrictor response" to an increase in venous transmural pressure is almost abolished in tissues with sclerodermic changes. The abolition of the vasoconstrictor response is probably due to sympathetic neuropathy associated with the sclerodermic changes.

Local reflex in microcirculation in human cutaneous tissue.

Blood flow in cutaneous tissue measured by the local 133Xenon washout technique decreased about 35 per cent during venous stasis of 40 mmHg in three normal subjects. The response was unaffected by block of the nerve three cm proximally to the labeled area. When the tissue was infiltrated with lidocaine or with phentolamine, blood flow remained constant, indicating that the decrease in blood flow is due to an arteriolar vasoconstrictor response to increase in venous transmural pressure. Local venous stasis elicited a vasoconstrictor response in an adjoining area not affected by the stasis. The response was blocked by lidocaine applied to the side of stasis. In 2 chronically sympathectomized patients, the vasoconstrictor response was abolished in the denervated limbs but present on the non-operated side (1 patient with unilateral sympathectomy). The results indicate that the vasoconstrictor response to an increase in venous transmural pressure is due to a local nervous mechanism involving sympathetic adrenergic fibres, most likely a sympathetic axon reflex.

Vascular resistance in peripheral blood vessels at normotension and at local orthostatic hypertension in healty humans.

The effect of changes in orthostatic pressure on vascular resistance in subcutaneous adipose tissue was examined in the forearm at normal tension and in the leg at local orthostatic hypertension in three normal subjects. Blood flow in subcutaneous tissue was measured by the local xenon-133 washout technique. Changes in orthostatic pressure were achieved by postural changes of the extremity. At levels above the heart where venous pressure is constant, there was autoregulation of blood flow over a wider arterial blood pressure range in leg than in forearm. When transmural pressure increased 25 mm Hg or more vascular resistance increased about 50 per cent in the dependent forearm and 300 per cent in the dependent leg. The effect of ischemia on vascular resistance was investigated in cutaneous tissue of hand and foot by means of the 131I-Antipyrine initial slope technique. Vascular resistance after maximum dilatation achieved after 20, 30, and 35 min of ischemia was less in vessels of the hand than in vessels of the foot. Thus, adaptive structural changes of vessels subjected to increased blood pressure are present in cutaneous and subcutaneous adipose tissues in normal subjects.

Effect of Spinal Sympathetic Blockade upon Local Regulation of Blood Flow in Subcutaneous Tissue

The influence of spinal sympathetic blockade upon local regulation of blood flow in subcutaneous adipose tissue was investigated in six subjects. The effect of changes in orthostatic pressure on blood flow in subcutaneous tissue in the crus and distal forearm was measured before and after sympathetic blockade obtained by epidural anesthesia in 4 subjects and by a bilateral sympathectomy in 2 patients suffering from manual hyperhidrosis. Blood flow in subcutaneous tissue measured by 133Xe washout technique decreased by about 40 per cent when the limb was lowered, and remained constant during 30 cm elevation. This was found both before and after the blockade, though in one of the patients, the orthostatic decrease in blood flow was less pronounced 24 h after sympathectomy. Hence central sympathetic reflexes do not alter local orthostatic changes of blood flow in subcutaneous tissue. These changes therefore are most likely due to local mechanisms.

Clinical Physiology: The Effect of Induced Arterial Hypertension upon Regional Blood Flow in Subcutaneous Tissue in Patients with Arterial Insufficiency of the Legs

In nine patients with arterial insufficiency of the legs, the effect of induced arterial hypertension upon blood flow in subcutaneous tissue was correlated to the changes of blood flow in subcutaneous tissue during dependency. Arterial pressure was increased by constant intravenous infusion of angiotensin. Blood flow in subcutaneous tissue was measured 10 cm distal to the head of fibula, at the lateral malleolus, and at the base of the first toe by means of the xenon washout technique. It was found that in areas where blood flow decreased during dependency, blood flow decreased during angiotensin infusion. An increase in blood flow during angiotensin infusion was seen in areas where blood flow increased during dependency. It is concluded that the effect of angiotensin infusion on blood flow and of therapeutically induced hypertension can be predicted from the effect of orthostatic changes on blood flow. The results obtained support the hypothesis that the vessels behave as passive channels (i.e. blood flow depends mainly upon arterial perfusion pressure) in areas where the normal vasoconstrictor response to increased transmural pressure is abolished.

The effect of guanethidine and propranolol on capillary blood flow in subcutaneous tissue and muscle in essential hypertension.

Local capillary blood flow in subcutaneous tissue and muscle was measured by tissue clearance of Na 131I at rest and during vasomotor reactions in 33 patients with essential hypertension an

Autoregulation of blood flow in human adipose tissue.

AbstractThe presence of autoregulation of blood flow was investigated in subcutaneous adipose tissue of the distal part of the forearm by means of the local xenon‐133 washout technique. 89 studies were performed on 4 healthy subjects. Blood pressure changes were obtained by passive displacement of the investigated area to various test levels above and below the reference level, the jugular notch. Above heart level, where venous pressure was constant, elevation of the arm to a level corresponding to an arterial blood pressure reduction of 20 mm Hg did not alter adipose tissue blood flow. At higher elevation autoregulation was not seen as blood flow fell in proportion to the reduction in perfusion pressure. Below the heart, where arterial and venous pressures in the forearm increase in parallel, blood flow in subcutaneous tissue remained constant. This indicates adjustments in arteriolar resistance to oppose the distending force of the increased transmural pressure. In this orthostatic pressure range blood flow was maintained until a level corresponding to an increase in pressure of about 15 mm Hg beyond which blood flow was reduced to about 60 per cent.