Limb
Inadequate blood supply to a limb may results in acute limb ischemia or chronic limb threatening ischemia. Cutaneous
Reduced blood flow to the skin layers may result in mottling or uneven, patchy discoloration of the skin. Kidney Ischemia
Kidney Ischemia is a loss of blood flow to the kidney cells. Several physical symptoms include shrinkage of one or both kidneys, renovascular hypertension, acute renal failure, progressive azotemia, and acute pulmonary edema. It is a disease with high mortality rate and high morbidity. Failure to treat could cause chronic kidney disease and a need for renal surgery. Causes
Ischemia is a vascular disease involving an interruption in the arterial blood supply to a tissue, organ, or extremity that, if untreated, can lead to tissue death. It can be caused by embolism, thrombosis of an atherosclerotic artery, or trauma. Venous problems like venous outflow obstruction and low-flow states can cause acute arterial ischemia. An aneurysm is one of the most frequent causes of acute arterial ischemia. Other causes are heart conditions including myocardial infarction, mitral valve disease, chronic atrial fibrillation, cardiomyopathies, and prosthesis, in all of which thrombi are prone to develop. Occlusion
The thrombi may dislodge and may travel anywhere in the circulatory system, where they may lead to pulmonary embolus, an acute arterial occlusion causing the oxygen and blood supply distal to the embolus to decrease suddenly. The degree and extent of symptoms depend on the size and location of the obstruction, the occurrence of clot fragmentation with embolism to smaller vessels, and the degree of peripheral arterial disease (PAD).
Unconsciousness, such as due to the ingestion of excessive doses of central depressants like alcohol or opioids, can result in ischemia of the extremities due to unusual body positions that prevent normal circulation

Pathophysiology
Ischemia results in tissue damage in a process known as ischemic cascade. The damage is the result of the build-up of metabolic waste products, inability to maintain cell membranes, mitochondrial damage, and eventual leakage of autolyzing proteolytic enzymes into the cell and surrounding tissues. Restoration of blood supply to ischemic tissues can cause additional damage known as reperfusion injury that can be more damaging than the initial ischemia. Reintroduction of blood flow brings oxygen back to the tissues, causing a greater production of free radicals and reactive oxygen species that damage cells. It also brings more calcium ions to the tissues causing further calcium overloading and can result in potentially fatal cardiac arrhythmias and also accelerates cellular self-destruction. The restored blood flow also exaggerates the inflammation response of damaged tissues, causing white blood cells to destroy damaged cells that may otherwise still be viable. Treatment
Early treatment is essential to keep the affected organ viable. The treatment options include injection of an anticoagulant, thrombolysis, embolectomy, surgical revascularization, or partial amputation. Anticoagulant therapy is initiated to prevent further enlargement of the thrombus.