Peripheral neuropathy plays an important part in the development of foot complications in patients with diabetes. We studied the contribution of impairment of the dual sensory and inflammatory function of unmyelinated nociceptive C fibers in the foot complications of diabetes. The integrity of these fibers was assessed objectively by measuring axon reflex vasodilation in response to stimulation with 10 percent acetylcholine introduced by electrophoresis. This was related to the non-neurogenic capacity of the vessels to dilate in response to a mechanical stroke. These measurements were made on the soles of the subjects' feet. The function of the nociceptive C fibers was abnormal in 1 of 14 patients with longstanding diabetes who had no foot complications, 3 of 9 patients with diabetes and skin sepsis, 8 of 11 patients with typical neuropathic plantar ulcers, and all of 8 patients with neuroarthropathy. In patients with longstanding diabetes but no foot complications, the mean ratio of neurogenic to non-neurogenic vasodilation was not significantly different from that in controls; however, it was significantly lower in the other three groups (P less than 0.01 for those with sepsis; P less than 0.001 for those with ulcer or arthropathy). Impairment of the neurogenic vasodilator response, or flare, correlated with the clinical diminution of pain sensation. This study suggests that the loss of both components of nociceptive C-fiber function--neurogenic inflammation and pain sensation--is an important factor in the development of foot complications in diabetes.

Impaired neurogenic vascular response in patients with diabetes and neuropathic foot lesions.

The microvascular response of foot skin to minor thermal injury and the skin of the anterior abdominal wall to injury from a needle was assessed by laser Doppler flowmetry in 23 patients with type I diabetes and 21 healthy control subjects. After minor thermal injury mean (SD) maximum skin blood flow was significantly lower in the diabetic group than the control group (0.53 (0.11) v 0.72 (0.10) V, in arbitrary units of flow, respectively, p less than 0.001) and was negatively correlated with the duration of diabetes (r = -0.60; p less than 0.01). After needle injury a similar pattern of impairment was seen, the peak flow value recorded being significantly lower in the diabetic group than the control group (0.28 (0.10) v 0.41 (0.09) V, respectively; p less than 0.001) and also negatively correlated with the duration of diabetes (r = -0.61; p less than 0.01). There was a significant relation between the response obtained at the two sites of injury in the diabetic group (r = +0.72, p less than 0.001) but not in the control group. The impairment in response was not related to diabetic control and was not explicable in terms of a reduction in superficial skin capillary density. The inability of the diabetic skin microvasculature to respond normally to injury may be an important factor in the development of foot ulceration that often follows minor trauma.

Impaired microvascular hyperaemic response to minor skin trauma in type I diabetes.

Due to recent technological improvements, namely in the field of piezoelectric sensors, ballistocardiography – an almost forgotten physiological measurement – is now being object of a renewed scientific interest.

Transcending the initial purposes of its development, ballistocardiography has revealed itself to be a useful informative signal about the cardiovascular system status, since it is a non-intrusive technique which is able to assess the body’s vibrations due to its cardiac, and respiratory physiological signatures.

Apart from representing the outcome of the electrical stimulus to the myocardium – which may be obtained by electrocardiography – the ballistocardiograph has additional advantages, as it can be embedded in objects of common use, such as a bed or a chair. Moreover, it enables measurements without the presence of medical staff, factor which avoids the stress caused by medical examinations and reduces the patient’s involuntary psychophysiological responses.

Given these attributes, and the crescent number of systems developed in recent years, it is therefore pertinent to revise all the information available on the ballistocardiogram’s physiological interpretation, its typical waveform information, its features and distortions, as well as the state of the art in device implementations.

/pdf/theory-and-developments-in-an-unobtrusive-cardiovascular-12r03zhrhb.pdf

Theory and Developments in an Unobtrusive Cardiovascular System Representation: Ballistocardiography

The ability of the right ventricle to compensate as the pulmonary artery is constricted appears to be determined by four major factors: (1) there occurs the well-known increased force of contraction as the right heart becomes distended; (2) the adequacy of the coronary circulation determines to a great extent the Degrees of pulmonary arterial constriction which can occur before failure occurs; (3) the circulatory reflexes apparently aid the compensation to a moderate extent; and (4) the greater the blood volume, the greater is the limit of compensation before right ventricular failure occurs.

The Limits of Right Ventricular Compensation Following Acute Increase in Pulmonary Circulatory Resistance

Except for a few sporadically published reports, investigations of capillary pathology in diabetic patients have in the past been confined to the kidneys and retina. Recently, however, several physiological studies have indicated the possibility of occurrence of diabetic microangiopathy in the distal parts of the extremities. As early as 1930-, Starr maintained that he was able to. demonstrate a disorder in the minute blood vessels of diabetics. However, he also found that the presence or absence of abnormality of the histamine wheal test was related in part to the diabetic patient's general state of health, and that the results were thus not indicative of disease of the peripheral circulation alone. Handelsmann et al. examined sixteen diabetic subjects, between the ages of forty and sixty-nine, who showed no symptoms of vascular disease in the legs and feet. He measured the change in temperature of the toes after intravenous injection of priscoline and found impaired responses in 40 per cent of the group of asymptomatic patients. Megibow and his co-workers examined fortyseven diabetics, below the age of forty-five, who had no clinically or radiologically demonstrable arteriosclerosis. He studied plethysmographically the change in volume of toes after administration of nitroglycerin and tetraethylammonium bromide, and found evidence of a vascular disorder in fifteen of the patients. Mendlowitz et al. examined thirty-eight diabetics below the age of fifty, by taking calorimetric measurements on the great toe after indirect heating and injection of tetraethylammonium bromide, and found a subnormal blood-flow rate in nine out of the thirty-eight patients. Barany has also made calorimetric investigations after indirect heating. He examined juvenile diabetics under thirty years of age, and found a positive correlation between the duration of diabetes and heat loss, but no relation between the loss of heat and retinopathy. On the other hand Sigroth in a similar investigation on the fingers found a relation between abnormal temperature increase and xetinopathy and nephropathy. All the above-mentioned authors assumed that the

Light- and electron-microscopic study of skin capillaries of diabetics

Rôle of the “static blood pressure” in abnormal increments of venous pressure, especially in heart failure. ii. clinical and experimental studies

?? methylcholine urethane: its action in various normal and abnormal conditions, especially postoperative urinary retention

ACETYL-β-METHYLCHOLIN I. THE ACTION ON NORMAL PERSONS. WITH A NOTE ON THE ACTION OF THE ETHYL ETHER OF β-METHYLCHOLIN

ACETYL–β–METHYLCHOLIN: IV. Further Studies of Its Action in Paroxysmal Tachycardia and in Certain Other Disturbances of Cardiac Rhythm

Studies on the circulation of the feet in diabetes mellitus with and without gangrene

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