Arbitrary criteria for low blood pressure is upper BP lower than 90 or lower BP lower than 60 or a fall of more than 30 mm Hg in upper blood pressure acutely. If there is an acute fall in blood pressure the kidney shutdown is at risk. If the patient does not pass urine in the next 8 hours the patient can end up with acute kidney failure.
THERE IS nothing like low blood pressure. If it is low keep it low; it is good for the heart. Low blood pressure medically called hypotension, however can be a medical problem if there is an acute or chronic fall of blood pressure from a baseline blood pressure value.
Any fall of upper blood pressure of more than 30 mm Hg will be called as an acute low blood pressure and cause symptoms and reduced flow to vital organs. An acute fall in blood pressure can occur in heart failure, acute heart attack, and reactions to some drugs, acute allergic reaction, dehydration, blood infection or irregular heart rhythms.
Blood pressure may become permanently low in heart valve stenosis, chronic heart failure, some cardiac drugs. Some individuals routinely may have blood pressures of 90/50 with no symptoms and therefore do not have low blood pressure. However, others who normally have higher blood pressures may develop symptoms of low blood pressure if their blood pressure drops to 80/60 or a fall of 30 in the above reading.