When the heart pumps out blood to circulate throughout the body, the force that it creates against the walls of the arteries is called systolic pressure. As it relaxes to receive returning blood, this force is referred to as diastolic pressure. Blood pressure is too low when the systolic reading is less than 90 mm Hg and the diastolic reading is lower than 60 mm Hg, both of which are dramatic drops from the normal level of 120/80 mm Hg. Since low blood pressure or hypotension is a function of many factors, medical professionals do not consider it an emergency unless accompanied by increased pulse rate or other low blood pressure symptoms such as dizziness, fainting, or seizures. Whenever blood pressure is low, it means that something is wrong with the heart, the blood vessels, or the overall blood volume within the body, which could indicate serious underlying health problems.
For example, blood pressure is too low when the heart is too weak to release enough blood to achieve normal systolic pressure levels. This happens when the cardiac muscles fail to contract because of a valve disease, blockage in the coronary arteries, or as a result of heart failure common among the aging population. Cardiac output is also affected by certain medications taken by patients with hypertension to slow down the heart or pulse rate.
Low blood pressure may also indicate that the arteries and veins are excessively dilated to offer enough blood flow resistance, which would then reduce the overall pressure. The most likely cause of this condition is a brain injury where the nervous system fails to communicate to the blood vessels to function normally. Blood poisoning, where the vessel lining might be affected by the toxin, could also be a possibility. An elevated acidity level in the blood due to over production of body acids or the kidney’s inability to excrete acids may also bring about the same effect.
Even when the heart, arteries, and veins are healthy, it is still possible for blood pressure to be too low when the blood volume is reduced below safe levels. This may be caused either by severe blood loss due to hemorrhage or reduced body water from dehydration, both of which would provide many other underlying symptoms. Among the elderly, who might experience a loss of thirst, extreme hypotension could become life-threatening in a very short period of time.
All of the above cases illustrate that, when blood pressure is low, it is linked to very poor circulation or a lack of oxygen-carrying blood in the body. The situation becomes dangerous when the blood pressure numbers remain persistently far below what would be considered a normal level or when they do not improve on their own, which is why the monitoring of low blood pressure is especially important for those with a history of problems. A patient may experience shock from any of the above conditions without immediate medical treatment, and this complication could be fatal.