Low Blood Pressure Hypotension Slideshow Pictures
Reviewed by Benjamin Wedro, MD, FACEP, FAAEM on Monday, July 28, 2008
Blood pressure is generated by the heart pumping blood into the arteries and is regulated by the response by the arteries to the flow of blood.
When blood flow is too low to deliver adequate oxygen to the body's organs, they may not function normally and may be permanently damaged.
Systolic blood pressure for healthy adults falls between 90 & 120mm of mercury. Normal diastolic blood pressure falls between 60 & 80mm of mercury.
The pulse that we can feel when we place our fingers over an artery is caused by the contraction of the left ventricle, pumping blood through the body.
Blood pressure is determined by the strength of the heart contraction when it beats, heart valve function, and blood vessel wall tension.
The body has mechanisms to alter or maintain blood pressure by specialized nerve cells called baroreceptors.
If blood pressure falls, the heart is signaled to beat faster and to try to increase cardiac output.
Baroreceptor signals can trigger veins to expand or narrow. Narrowing returns more blood to the heart which may raise blood pressure.
The arteries can expand and narrow. When blood pressure is low, the receptors signal the arterioles to narrow and raise blood pressure.
The kidney can respond to receptor changes in blood pressure by increasing or decreasing the amount of urine that is produced.
Lower blood pressure readings are acceptable as long as it is not too low to cause symptoms and potentially damage the organs of the body.
If low blood pressure is symptomatic, patients may feel a wide variety of symptoms from dizziness and lightheadedness to shortness of breath and chest pain.
Low blood pressure may result from many causes including decreased blood volume, weakened heart muscle, and loss of artery wall tension.
Bleeding, infections, dehydration, heart disease, and pregnancy are examples of non-neurological conditions that may cause low blood pressure.
Low blood pressure is a hallmark for septicemia, a situation where the body is subject to an overwhelming infection.
Anaphylaxis is a potentially fatal allergic reaction to items such as penicillin, peanuts, and insect stings which may lead to a severe drop in blood pressure.
Postural or orthostatic vital signs may be taken to uncover low blood pressure. Blood pressure readings are taken in both the lying (supine) & standing positions.
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