Circulatory failure is a blood circulation disorder that occurs in all organs in the body. The disease manifests various symptoms in organs that lack blood supply, reducing function and causing many dangerous complications.

Paraclinical tests are medical procedures performed to detect, diagnose or monitor diseases, and evaluate response to treatment. With the advancement of modern medicine, there are many types of paraclinical tests with different values. Choosing which paraclinical test to perform is appropriate and requires a doctor's examination, assessment and reasoning.

Cerebral circulation is the vascular system that supplies blood to the brain. Only when cerebral circulation function is guaranteed can the brain parenchyma function stably. Therefore, checking circulatory function is also an important component in general examinations, especially in subjects at high risk of stroke.

According to the law on medical examination and treatment, taking a medical history is part of diagnosing and prescribing appropriate treatment. When a doctor prescribes a drug, it must also be based on the results of clinical and paraclinical examinations, along with medical history, family, occupation and epidemiology.