Postischemic syndrome is a complex of symptoms that occurs as a result of long-term circulatory problems. Depending on the location and size of the affected area, postischemic syndrome can be life-threatening.
What is postischemic syndrome?
There are many causes of ischemia. Conceivable causes include vascular occlusion by blood clots (thrombosis) or by deposits on the walls of the blood vessels (arteriosclerosis). Ischemia refers to an abnormally reduced or even abolished blood flow to a tissue. In relative ischemia, blood flow is still detectable; in absolute ischemia, there is no arterial blood flow at all. Tissues with a high oxygen demand, such as the brain, usually tolerate only brief reductions in supply. Even a short interruption of blood flow of a few minutes can lead to serious and irreversible damage. However, the symptoms of postischemia syndrome are not directly caused by the lack or absence of blood flow, but result from the restored blood flow after the cause of the ischemia has been removed. This process is also titled reperfusion injury. Because it seems quite contradictory at first glance that restored blood flow causes more damage than the lack of blood flow, the postischemic syndrome is also referred to as a reperfusion paradox.
Causes
Postischemia syndrome can occur with an occlusion time as short as five hours. The causes of ischemia are very diverse. Conceivable causes include vascular occlusion by blood clots (thrombosis) or by deposits on the vessel walls (arteriosclerosis). A disease characterized by progressive occlusion of the vessels in the arms and legs is peripheral arterial occlusive disease, or pAVD for short. In most cases, pAVD is caused by arteriosclerosis. Smokers are particularly at risk of developing pAVD. Rheumatic diseases such as endangiitis obliterans or collagenoses can also lead to obstruction of blood vessels, resulting in ischemia. The same applies to diseases of the blood that are associated with an increased cell count. Due to the altered viscosity of the blood, vascular occlusion occurs more rapidly. Examples of such hematological diseases are polycythaemia vera or essential thrombocythemia. Of course, ischemia can also result from external blockages, such as ligature or tourniquet of an extremity. Most notably, blunt trauma, that is, trauma that does not cause open wounds, can cause compartment syndrome. In this case, the tissue pressure increases due to the trauma, so that the arterial blood flow is interrupted. Other typical causes of postischemia syndrome include Leriche syndrome and paraphimosis. In paraphimosis, a constricted foreskin pinches the glans of the penis and also cannot be pulled back.
Diseases with this symptom
- Thrombosis
- Polycythaemia vera
- Compartment syndrome
- Arteriosclerosis
- Thrombangiitis obliterans
- Leriche syndrome
- Peripheral arterial occlusive disease
- Collagenosis
- Paraphimosis
Diagnosis and course
During ischemia, potentially toxic substances such as myoglobin, lactate, and potassium are produced and accumulated in the affected areas of the body in increased amounts. When the tissue is reperfused postischemically, these substances are flushed from the tissue and distributed throughout the body. The potassium causes hyperkalemia, which means the serum potassium level is above 5.2 mmol/l. Hyperkalemia can cause severe cardiac arrhythmias, in addition to symptoms such as muscle weakness and paraesthesia in the extremities. These can lead to ventricular fibrillation and asystole, i.e. cardiovascular arrest. The increased attack of myoglobin can result in crush kidney with the complication of absolute kidney failure. The high lactate levels in the blood also cause metabolic acidosis. The blood pH drops below 7.36. This situation is life-threatening. As a result of the ischemia, the vessel walls in the affected area are particularly permeable. This is referred to as increased vascular permeability. If blood now flows through these vessels again, fluid escapes from the vessels and flows into the tissue. This is how edema develops.Depending on the size of the ischemic area, the loss of fluid into the tissue can cause hypovolemic shock. In the first stage, this is manifested only by moist, cool and pale skin. In the second stage, systolic blood pressure drops and pulse increases. Patients complain of thirst. Little to no urine is produced and excreted. In the third stage, blood pressure falls below a value of 60 mmHg. The pulse is barely palpable. There are disturbances of consciousness and finally death. In addition, the edema recompresses the vessels that have now regained blood flow, so that ischemia may again occur. This is the beginning of a vicious circle.
Complications
Postischemic syndrome (Tourniquet syndrome) usually results from an atherosclerotic process. In this process, a vessel is occluded and subsequent tissues of the vessel occlusion are no longer adequately supplied with blood, resulting in ischemia. This ischemia can be endured for a long time without complications, but after a certain time, usually from five to six hours, the tissue dies, necrosis develops. The cells die and various substances such as lactate, potassium and myoglobin are released. Too much potassium in the blood (hyperkalemia) can cause dangerous cardiac arrhythmias such as ventricular fibrillation, which can quickly lead to cardiac death if left untreated. In addition, the release of the substances can cause a so-called crush kidney, which can lead to kidney failure (renal insufficiency). In addition, metabolic acidosis develops, which can also lead to cardiac arrhythmias and cause unconsciousness. Ischemia causes the vessels to become more permeable. When the area is re-exposed, there can be increased leakage of fluids, leading to painful edema that can become inflamed. In addition, so much fluid can leak out that there is a lack of volume in the circulation, which can result in lowered blood pressure in terms of shock. In addition, the edema can compress vessels that supply various muscle groups. This results in reduced supply to the muscle and compartment syndrome, which can lead to muscle death.
When should you see a doctor?
If postischemic syndrome is suspected, a physician should be consulted immediately. If left untreated, circulatory disturbances develop into life-threatening symptoms that can lead to further complications. A visit to the doctor is recommended at the latest when there is kidney pain or a twinge in the heart area. In general, pain of the internal organs as well as warm extremities indicate a circulatory disorder, which can develop into a postischemic syndrome if left untreated. Patients who already suffer from heart or kidney disease should talk to their doctor as soon as possible if they suspect a circulatory disorder. Typical symptoms of disturbed blood circulation include visual disturbances, confusion, disorientation and pain when walking. In addition, there are feelings of tightness in the chest, which mainly occur during physical exertion, as well as temporary numbness in the arms and legs. If one or more of these symptoms occur, a visit to the doctor is recommended. In most cases, blood flow can be re-regulated by simple measures and postischemia syndrome averted.
Treatment and therapy
Postischemia syndrome is a life-threatening condition, so intensive medical care must be provided. Potassium levels are checked at regular intervals, and blood gas analyses are also performed to monitor pH. Fluid is substituted to prevent hypovolemic shock. Edema formation and renal stress from myoglobin are prevented with diuretics. If metabolic acidosis is present, therapy is by sodium bicarbonate buffering. Diuretics are also administered to treat hyperkalemia. In addition, so-called cation exchangers are administered. Insulin, glucose, sympathomimetics and sodium bicarbonate are used to ensure that the potassium is transferred from the blood into the cells. Of course, in postischemic syndrome, the cause should always be completely eliminated. In case of strangulations, it is enough to remove them. In case of paraphimosis, the foreskin must be reduced or, if necessary, removed. Emboli are treated with lysis therapy. In case of a severe postischemic syndrome, amputation may be necessary.
Outlook and prognosis
Postischemia syndrome is a life-threatening condition that needs medical attention as soon as possible. A great deal of blood work is done to check PH levels. If postischemic syndrome is detected quickly based on symptoms, the chances of recovery are very high. Fluid is substituted so that hypovolemic shock can be avoided. If postischemic syndrome is too advanced, amputation must be performed. Under no circumstances should the affected patient wait. Waiting too long will cause the blockages to become even greater. Blood flow can then no longer take place properly and the patient must expect even more complications. Heart attacks are not infrequently the result of waiting too long in postischemic syndrome.
Prevention
Postischemic syndrome can be prevented only to a limited extent. If there is evidence of reduced blood flow of any etiology, a physician should be consulted as soon as possible. This is the only way to prevent prolonged ischemia and, subsequently, postischemia syndrome.
What you can do yourself
In the event of postischemic syndrome, an emergency physician must always be consulted. As mentioned earlier, it is a life-threatening condition following a prolonged circulatory disturbance. Without emergency medical treatment, the affected part of the body initially dies. Due to the distribution of toxic metabolic products throughout the body, the organism is in high danger. For these reasons, self-medication is not possible. Attempts at self-help are to be urgently refrained from in this disease, because any delay of professional medical treatment is counterproductive. Necrosis of the tissue releases lactate, myoglobin and potassium. These substances accumulate in the blood and lead to cardiac arrhythmias, kidney failure and hyperacidity of the organism. Their values must be constantly monitored and balanced by intensive care. This can only be done in the intensive care unit of a hospital. After successful treatment of the vascular occlusion, the underlying disease must be treated. Depending on the disease in question, self-medication may be used in some cases, although this must be discussed with the physician. Permanent medication with blood thinning agents may be necessary to prevent the formation of thrombi. Furthermore, constant medical check-ups are important. The patient can also prevent renewed vascular occlusion by eating a balanced diet, getting plenty of exercise, and refraining from smoking and alcohol.
