Tissue ischemia

Intermediate (within 24 AH hours) Blisters and bullae indicate severe skin and tissue ischemia. 

Describe the mechanisms by which tissue ischemia and muscle spasm lead to pain... 

Tissue ischemia. When blood flow to a tissue is decreased or interrupted, the tissue becomes painful within a few minutes. In fact, the greater the rate of metabolism in the tissue, the more rapid is the onset of pain. The causes of pain due to tissue ischemia include ... 

Release and activation of noxious chemicals in the area of tissue ischemia due to tissue damage (see Table 8.1)... 

Muscle spasm. The pain induced by muscle spasm results partially from the direct effect of tissue distortion on mechanical nociceptors. Muscle spasm also causes tissue ischemia. The increased muscle tension compresses blood vessels and decreases blood flow. Furthermore, the increased rate of metabolism associated with the spasm exacerbates the ischemia. As discussed earlier, ischemia leads to stimulation of polymodal nociceptors. 

Severe metabolic lactic acidosis often develops secondary to tissue ischemia and causes localized vasodilation, which further exacerbates the impaired cardiovascular state. 

Like other forms of chronic anemia, iron deficiency anemia leads to pallor, fatigue, dizziness, exertional dyspnea, and other generalized symptoms of tissue ischemia. The cardiovascular adaptations to chronic anemia—tachycardia, increased cardiac output, vasodilation—can worsen the condition of patients with underlying cardiovascular disease. 

Muorohara, T., Asahara, T., Silver, M., Bauters, C., Masuda, H., Kalka, C., Kearney, M., Chen, D., Symes, J.F., Fishman, M.C., Huang, P.L., and Isner, J.M. 1998. Nitric oxide synthase modulates angiogenesis in response to tissue ischemia J. Clin. Invest. 101 2567-2578. 

Conventional treatment of raised ICP in this condition consists of artificial ventilation, osmotherapy, and barbiturate administration. The value and duration of these measures has come under scrutiny. Prolonged hyperventilation has been discouraged, as the potential decrease in cerebral arterial blood flow resulting from additional hypocarbia might exacerbate tissue ischemia (34). Early use of agents such as glycerol or mannitol, at least in theory, may actually hasten tissue shifts and therefore lead to an aggravation of brain edema (35). Barbiturate therapy has to date failed to prove to be of therapeutic benefit in the treatment of postischemic brain edema (36). 

Correct answer == C. Ergotamine acts to counteract cerebral vasodilation that plays a rale in migraine headaches. Vasoconstriction leading to tissue ischemia is one of the toxic complications associated with an overdose of these drugs. The ergot aikaioids interact with adrenergic, dopaminergic, and serotonin receptors. They... 

Phosphate An intracellular shift of phosphate occurs along with potassium as fluid rehydration commences.The phosphate deficit can also be worsened with correction of the metabolic acidosis. Controlled, randomized studies have shown that routine phosphate repletion is not necessary, but some practitioners think it prudent to provide supplemental phosphate if serum phosphate levels are less than 1 mEq/L, potentially reducing the risk of seizure or tissue ischemia. During intravenous phosphate administration, serum calcium concentrations should be monitored carefully to avoid hypocalcemia and tetany (Fisher and Kitabchi, 1983). 

Ergot Claviceps purpurea Hallucinations, hypertension, tissue ischemia, St. Anthony s fire... 

Occasionally, the local tissue necrosis expands as the tissue ischemia spreads from the initial bite site. 

Tissue ischemia is a universal event in various forms of trauma and life-threatening emergencies. Reduced blood flow or disturbed oxygen supply results in the discrepancy of energy production and utilization. The cessation of blood flow not only halts the influx of oxygen and nutrients, but also stops carrying away toxic wastes. While many of the factors determining the flnal fate of the... 

Tissue ischemia may result from many causes in general, hypoperfusion leads to hypoxia of cells, which results in anaerobic metabolism with the attendant accumulation of organic (mainly lactic) acids. The kidneys (and brain) are especially sensitive to hypoperfusion, such that acute renal failure often is a contributing factor m the high anion gap metabolic acidosis associated with global tissue ischemia (as may occur in major trauma). 

Atherosclerosis (athero = fatty and sclerosis = scarring or hardening) of the coronary and peripheral vasculature is the leading cause of morbidity and mortality worldwide. Lesions (called plaque) are initiated by an injury to endothelium and thicken the intima of arteries, occlude the lumen, and compromise delivery of nutrients and oxygen to tissue (ischemia). Atherosclerotic lesions primarily occur in large and medium-sized elastic and muscular arteries and progress over decades of life. These lesions cause ischemia, which can result in infarction of the heart (myocardial infarction) or brain (stroke), as well as abnormalities of extremities. The proximate cause of occlusion in these pathological conditions is thrombus formation. 

The elevated calcium-phosphate product results in precipitation in arteries, joints, soft tissues, and the viscera. This can result in tissue ischemia, termed calciphylaxis. 

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