Microvascular investigations in diabetes mellitus

Chittenden, S. J.; Shami, S. K.

doi:10.1136/pgmj.69.812.419

Cited by 16 publications

(13 citation statements)

References 78 publications

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“…The result is an increase in microvascular flow and capillary pressure [25], which subsequently induces an endothelial injury response. In a later stage, microvascular sclerosis does occur as a result of the thickening of the capillary basement membrane due to long-term structural adaptation and remodeling [82,83]. The elasticity of the vessel walls is reduced, which physically limits vasodilation.…”

Section: Haemodynamic Hypothesismentioning

confidence: 99%

Microvascular dysfunction in diabetic foot disease and ulceration

Chao

Cheing

2009

Diabetes Metabolism Res

166

129

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Diabetic foot disease and ulceration is a major complication that may lead to the amputation of the lower limbs. Microangiopathy may play a significant role in the pathogenesis of tissue breakdown in the diabetic foot. However, the precise mechanisms of this process remain unclear and poorly understood. Microvasculature in the skin is comprised of nutritive capillaries and thermoregulatory arteriovenous shunt flow. It is regulated through the complex interaction of neurogenic and neurovascular control. The interplay among endothelial dysfunction, impaired nerve axon reflex activities, and microvascular regulation in the diabetic patient results in the poor healing of wounds. Skin microvasculature undergoes both morphologic changes as well as functional deficits when parts of the body come under stress or injury. Two important theories that have been put forward to explain the abnormalities that have been observed are the haemodynamic hypothesis and capillary steal syndrome. With advances in medical technology, microvasculature can now be measured quantitatively. This article reviews the development of microvascular dysfunction in the diabetic foot and discusses how it may relate to the pathogenesis of diabetic foot problems and ulceration. Common methods for measuring skin microcirculation are also discussed.

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Section: Haemodynamic Hypothesismentioning

confidence: 99%

Microvascular dysfunction in diabetic foot disease and ulceration

Chao

Cheing

2009

Diabetes Metabolism Res

166

129

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“…The 133 Xenon-clearance technique (Chittenden and Shami 1993) is a reliable but invasive method that can be used to determine blood flow during external loading (Daly et al 1976). Using this method Daly et al (1976) found blood flow to reduce rapidly for pressures up to 10mmHg and then at a slower rate until cessation at systolic pressure.…”

Section: Assessing the Affects Of Pressure On The Microcirculationmentioning

confidence: 99%

“…The laser Doppler technique was identified as most appropriate for this application because of the fast response time, the small size and flexible geometry of the probe head and ability to obtain data continuously and noninvasively. The technique has also been used successfully, in other studies of cutaneous blood flow in diabetes mellitus (Chittenden and Shami 1993). However, commercial laser Doppler systems were found to be unsuitable, because the use of fibre optic connections to the probe head resulted in the Doppler signal being swamped by movement artefact noise.…”

Section: Re-evaluation Of Objectivesmentioning

confidence: 99%

“…As it is not possible to separate information on blood flow for each type of vessel from the Doppler signal (Chittenden and Shami 1993), the blood flux is dominated by the contribution from thermoregulatory vessels. In the present study, thermoregulatory blood flow has been controlled by maintaining the sampled tissue in a temperature range that minimises thermoregulatory flow for normal nutritional flow levels (Stevens et al 1993, Netten et al 1996.…”

Section: Measurement Validation -Types Of Vessel Sampledmentioning

confidence: 99%

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An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

Cobb¹,

Claremont²

2001

Medical Engineering & Physics

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An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot. Jonathan Edwin CobbPlantar ulceration is a complication of the diabetic foot prevalent in adults with type 11 diabetes mellitus. Although neuropathy, microvascular disease and biornechanical factors are all implicated, the mechanism by which the tissue becomes pre-disposed to damage remains unclear. Recent theories suggest that the nutritional supply to the tissue is compromised, either by increased flow through the arteriovenous anastomoses ('capillary steal' theory) or through changes in the micro vascu I ature (haemodynamic hypothesis). Clinical data to support these ideas has been limited to assessment of the unclad foot under rest conditions. A limitation of previous studies has been the exclusion of static and dynamic tissue loading, despite extensive evidence that these biornechanical factors are essential in the development of plantar ulceration. The present study has overcome these problems by allowing assessment of plantar blood flow, in-shoe, during standing and walking.The system comprises a laser Doppler blood flux sensor operating at 780nm, load sensor, measurement shoe, instrumentation, and analysis software. In-vitro calibration was performed using standard techniques. An in-vivo study of a small group of diabetic subjects indicated differences in the blood flux response between diabetic neuropaths, diabetics with vascular complications and a control group. For example, following a loading period of 120s, relative increases in response from rest to peak were: Control (150% to 259%), Vascular (-70% to 242%), Neuropathic (109%-174%) and recovery times to 50% of the peak response were: Control (33s to 45s), Vascular (43s to >120s), Neuropathic (>120s). Dynamic re-perfusion rates (arbitrary units per millisecond) obtained for the swing phase of gait were: Control (6.1 a. u/ms to 7.9 a. u/ms), Vascular (4 a. u/ms to 6.2 a. u/ms), Neuropathic (2.3 a. u/ms to 4.5 a. u/ms).

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“…Damage caused by hyperglycemia leads to important implications for transcapillary transport and the cirulation of endothelial products like the Von Willebrand factor and the angiotensin converter enzymes that can lead to platelet aggregation abnormalities and interfere in the inflammatory process of the healing 15 . Many of the complications of diabetes are the result of damage caused to the microcirculation vessels 24 . High glucose concentrations activate the aldose reductate which converts glucose to sorbitol.…”

Section: Introductionmentioning

confidence: 99%

Effects of hyperglycemia and ageing on the healing of colonic anastomoses in rats

Biondo-Simões

Ioshii

et al. 2009

Acta Cir. Bras.

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Introduction:Despite the significant advances in the knowledge of the healing process, there is a limited number of studies demonstrating the relationships of this healing with ageing and elevated levels of glycemia. Purpose: To evaluate the effects of ageing and hyperglycemia on the healing of colonic anastomosis. Methods: 138 young and old male rats were utilized. Some of them were normoglycemic and others had hyperglycemia induced by streptozocin (50mg/kg). They were maintained under control for 90 days. They were then submitted to a termino-terminal anastomosis in the left colon. On the third, seventh and fourteenth days after surgery, their resistance was evaluated and a histopathological study of the anastomosis was carried out. Results: Gain in resistance was similar for both groups. The additive effect of age with hyperglycemia made a significant difference to the collagen I (p<0.001), III (p=0.022) and total (p<0.001). Among the old animals, the glycemia was a determining factor for the occurrence of a significant difference in total collagen (p=0.029) and collagen I (p=0.013). Among the normoglycemics, age determined a lower density of collagen I (p=0.002). Conclusion: There is delayed collagen synthesis and maturation of the scars of older animals, a situation that becomes more serious in older hyperglycemic animals, but insufficient to adversely affect the gain in resistance. Key words: Diabetes Mellitus, Experimental. Hyperglycemia. Collagen. Wound Healing. Colon. Anastomosis, Surgical. RESUMO Introdução: Apesar dos significantes avanços no conhecimento do processo cicatricial há um restrito número de estudos demonstrando as relações deste reparo com o envelhecimento e com níveis elevados de glicemia. Objetivo: Avaliar os efeitos do envelhecimento e da hiperglicemia na cicatrização de anastomoses colônicas. Métodos: Utilizaram-se 138 ratos machos, adultos jovens e velhos. Parte deles era normoglicêmico e parte teve hiperglicemia induzida pelo streptozocin (50mg/kg). Foram mantidos controlados por 90 dias. Após fez-se uma anastomose término-terminal no cólon esquerdo. No 3.º, 7.º e 14.º dia de pós-operatório avaliou-se a resistência e fez-se o estudo histo-patológico da anastomose. Resultados: O ganho de resistência foi semelhante entre os grupos. O efeito aditivo da idade com a hiperglicemia determinou diferença significativa nos colágenos I (p<0,001), III (p=0,022) e total (p<0,001). Entre os velhos a glicemia foi determinante para ocorrer diferença significativa no colágeno total (p=0,029) e colágeno I (p=0,013). Entre os normoglicêmicos a idade determinou menor densidade de colágeno I (p=0,002). Conclusão: Existe atraso na síntese do colágeno e na maturação das cicatrizes nos animais velhos, situação que se agrava nos animais velhos e hiperglicêmicos, não suficiente para prejudicar o ganho de resistência. Descritores: Diabetes Mellitus Experimental. Hiperglicemia. Colágeno. Cicatrização de Feridas. Colo. Anastomose Cirúrgica.

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Microvascular investigations in diabetes mellitus

Cited by 16 publications

References 78 publications

Microvascular dysfunction in diabetic foot disease and ulceration

Microvascular dysfunction in diabetic foot disease and ulceration

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

Effects of hyperglycemia and ageing on the healing of colonic anastomoses in rats

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