low blood pressure

Low blood pressure is a term for blood pressure that is abnormally low.

 

Blood pressure is expressed in millimeters of mercury, abbreviated as mm Hg. The systolic blood pressure is the top number of a blood pressure reading. This shows the maximum pressure in the blood vessels as the heart contracts and circulates blood throughout the body. The diastolic blood pressure is the bottom number of a blood pressure reading. It shows the lowest pressure in the blood vessels between heartbeats, when the heart is at rest.

 

Many conditions can cause low blood pressure.

 

Low blood pressure may or may not cause symptoms. Many symptoms get worse when the person stands. Common symptoms include:

 

Other symptoms depend on the cause. In general, if a person's blood pressure is high enough for the person not to experience symptoms, it is high enough.

 

There are many possible causes of this condition, including: medications, such as those used to treat high blood pressure. In this case, the medication may work too well and make the blood pressure too low. Many other medications, such as diazepam (i.e., Valium) or amitriptyline (i.e., Elavil), can cause low blood pressure in some people.heart conditions, such as abnormal heartbeats called arrhythmias or congestive heart failure. Cardiac tamponade, a condition in which fluid builds up around the heart and prevents it from pumping well, is another possible cause.excessive blood lossdehydration, which may be due to vomiting, diarrhea, or not getting enough fluidsa very serious blood infection known as sepsis hypothermia, or an abnormally low body temperaturesevere allergic reactions of any kind, often called anaphylaxis low levels of oxygen in the blood, called hypoxia, which may be due to severe asthma, pneumonia, or other conditionsa hormone imbalance known as adrenal insufficiency, known as Addison disease high levels of acid in the blood, such as respiratory acidosis or metabolic acidosis nervous system conditions. One example is diabetic neuropathy, or nerve damage caused by high glucose levels when diabetes is not well controlled. Serious head injuries or other nervous system damage may also cause low blood pressure.

Prevention is related to the cause. Avoiding dehydration can prevent cases due to this cause. Avoiding medications known to cause low blood pressure can prevent cases due to this cause. A person who takes medication to treat high blood pressure is instructed not to double up on medication if he or she misses a dose, because this can lead to low blood pressure.

Blood pressure is usually measured with a tool called a blood pressure cuff. Other special devices are sometimes used. Sometimes, the reason for low blood pressure is obvious to the healthcare professional from the history and physical exam. In other cases, further tests are needed. For example, a complete blood count (CBC) can help diagnose infections. Low oxygen in the blood can be detected by arterial blood gases. A heart tracing (ECG) can help diagnose abnormal heartbeats. A chest x-ray can help diagnose pneumonia.