Hypotension
Hypotension, or low blood pressure, occurs when blood pressure readings fall below approximately 90/60 mmHg, leading to potential symptoms that can impact daily functioning. It is regulated by a complex interplay of the nervous system, hormones, and organ systems, ensuring that blood flow is adequate to meet the body's needs. While low blood pressure can be benign—especially in fit individuals—it can also lead to serious complications such as kidney failure, strokes, and heart attacks when blood flow to organs is insufficient. Common symptoms include rapid heartbeat, dizziness, weakness, and fainting, with variations depending on the underlying cause.
Several factors contribute to hypotension, including adverse reactions to medications, certain diseases like diabetes that affect the nervous system, dehydration, and severe infections. A specific type, orthostatic hypotension, is particularly pronounced when a person stands up from a sitting or lying position. Treatment generally focuses on addressing the root cause, which may involve lifestyle changes or medical interventions, such as fluid resuscitation or discontinuing problematic medications. Understanding hypotension's causes and effects is essential for managing this condition effectively and improving quality of life.
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Subject Terms
Hypotension
Also known as: Low blood pressure
Anatomy or system affected: Blood vessels, brain, circulatory system, heart, kidneys
Definition: Blood pressure low enough to cause symptoms such as dizziness in the affected individual
Causes and Symptoms
The body has a complex system for regulating blood pressure, which ensures adequate blood flow to each organ and tissue. The sympathetic and parasympathetic branches of the autonomic nervous system, various hormones produced by the adrenal and pituitary glands, the kidneys, the heart, and local mechanisms in all parts of the body control the amount of blood in the vessels, how much blood is squeezed out of the heart with each beat, and how much blood is available to any body system at a given time. A failure in any of these regulatory areas can cause the blood pressure to become too low for the person to function normally.
Normal blood pressure varies depending on the demands put on the body, how fit a person is, and the age of the individual. For most adults, 120/80 is considered normal; however, the top number (systolic pressure) can be as low as 90, and the bottom number (diastolic) as low as 60 and still be considered normal. When the blood pressure is lower than about 90/60, and the individual develops symptoms related to the low pressure, then that individual is diagnosed with hypotension. Low blood pressure by itself is not unhealthy, especially in athletic people, but when the flow of blood to the organs of the body is inadequate, symptoms develop. They include rapid heartbeat, light-headedness or dizziness, weakness, and possibly fainting. Other symptoms vary with the cause of the low blood pressure.
Low blood pressure associated with insufficient blood flow to the body organs can cause kidney failure, strokes, and heart attacks. Orthostatic hypotension is low blood pressure and its associated symptoms that are most pronounced when a person goes from lying or sitting to standing.
Specific causes of hypotension include adverse drug reactions, diseases such as diabetes that damage the autonomic nervous system, hormone-producing tumors, fever, heart disease, dehydration, hemorrhage, excessive heat, alcohol use, heart attack, heart trauma, abnormal heart rhythms, overwhelming infection, anaphylaxis, burns, vomiting, and diarrhea.
Treatment and Therapy
The treatment of hypotension is primarily aimed at removing the underlying cause—for example, discontinuing a drug that causes blood vessels to dilate or wearing elastic stockings to improve blood flow back to the heart. If the low blood pressure is severe enough, then supportive treatment with fluids, oxygen, and other modalities may be required.
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