Hypotension

Hypotension is low blood pressure.[1] Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood.[2] Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the diastolic blood pressure (the bottom number), which are the maximum and minimum blood pressures, respectively.[3] A systolic blood pressure of less than 90 millimeters of mercury (mm Hg) or diastolic of less than 60 mm Hg is generally considered to be hypotension.[4][5] Different numbers apply to children.[6] However, in practice, blood pressure is considered too low only if noticeable symptoms are present.[7]

Hypotension
Depiction of a hypotension (low blood pressure) patient getting her blood pressure checked
Image showing patient having blood pressure checked. Systolic blood pressure less than 90mmHg is considered hypotension (low blood pressure)
SpecialtyCritical care medicine, cardiology
SymptomsDizziness, clumsiness, giddiness, lightheadedness, fatigue, Nausea, blurred vision, shakiness
ComplicationsFainting, bleeding
Risk factorsOlder patient
Diagnostic methodPhysical examination, based on symptoms
TreatmentIntravenous fluid

Hypotension is the opposite of hypertension, which is high blood pressure.[2] It is best understood as a physiological state rather than a disease.[2] Severely low blood pressure can deprive the brain and other vital organs of oxygen and nutrients, leading to a life-threatening condition called shock.[3]

Hypotension can be caused by excessive exercise, excessive heat, low blood volume (hypovolemia),[8] hormonal changes,[9] widening of blood vessels,[10] anemia,[11] a lack of vitamin b12 and folic acid, [7][12] anaphylaxis,[7] heart problems,[13] or endocrine problems.[14] Some medications can also lead to hypotension.[15] There are also syndromes that can cause hypotension in patients including orthostatic hypotension,[16] vasovagal syncope,[17] and other rarer conditions.[18][19]

For many people, excessively low blood pressure can cause dizziness and fainting or indicate serious heart, endocrine or neurological disorders.[16]

For some people who exercise and are in top physical condition, low blood pressure could be normal.[20] A single session of exercise can induce hypotension and water-based exercise can induce a hypotensive response.[21]

Treatment of hypotension may include the use of intravenous fluids or vasopressors.[22] When using vasopressors, trying to achieve a mean arterial pressure (MAP) of greater than 70 mm Hg does not appear to result in better outcomes than trying to achieve a MAP of greater than 65 mm Hg in adults.[23]