Low blood pressure reading

Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps. If it is too lower than normal called as hypotension.

Blood pressure hypotension

• Systolic pressure: First number in a pressure reading that the heart generates when pumping blood through the arteries to the rest of the body.   
• Diastolic pressure: Second number in a pressure reading that refers to the amount of pressure in the arteries when the heart is at rest between beats.

Although one can get an accurate blood pressure reading at any given time, pressure isn't static. It can vary considerably in a short amount of time, sometimes from one heartbeat to the next, depending on body position, breathing rhythm, stress level, physical condition, medications you take, what you eat and drink, and even time of day. Pressure is usually lowest at night and rises sharply on waking.

Low blood pressure reading
Hypotension is much harder to quantify, current guidelines identify normal pressure as 120/80. Some experts define hypotension or low blood pressure readings that is lower than 90 systolic or 60 diastolic.

Even pressure reading with just only one number in the low range is enough to consider it as lower than normal. For example, if the one with systolic pressure of perfect 120, but the diastolic pressure is 50 is considered to have hypotension.

Blood pressure too low
If systolic drops below 60 or diastolic drops below 40 are consider as too low blood pressure.

High low blood pressure (dangerously low blood pressure)
If the systolic pressure drops below 50 or diastolic pressure drops below 33 are consider as dangerously high low blood pressure.

A sudden fall in pressure can be dangerous, a change of just 20 mm Hg a drop from 130 systolic to 110 systolic, for example can cause dizziness and fainting when the brain fails to receive an adequate supply of blood. And big plunges, especially those caused by uncontrolled bleeding, severe infections or allergic reactions can, be life-threatening.