Blood pressure measures the force exerted by circulating blood against the artery walls. This measurement includes two numbers: systolic pressure (when the heart beats) and diastolic pressure (when the heart rests between beats). While high blood pressure (hypertension) is widely recognized, chronic low blood pressure (hypotension) also warrants careful attention and evaluation. Hypotension is a state where blood circulates with insufficient force, potentially leading to inadequate blood flow to vital organs. Understanding the causes of this condition is the first step toward effective management.
Defining Chronic Hypotension and Recognizing Symptoms
Chronic low blood pressure is defined by readings where the systolic pressure is less than 90 millimeters of mercury (mm Hg) or the diastolic pressure is less than 60 mm Hg. For many healthy individuals, a low reading may be normal and cause no issues, but when it is chronic and symptomatic, it signifies a problem with blood circulation.
When the pressure is too low to supply sufficient oxygen and nutrients to the brain and other organs, a person begins to experience noticeable symptoms. Common signs include feeling dizzy or lightheaded, especially when moving positions, and a general feeling of fatigue or weakness. Other frequent complaints are blurred vision, unsteadiness, and nausea. Fainting, medically termed syncope, is one of the more serious symptoms that can occur when blood flow to the brain is suddenly restricted.
Underlying Medical Causes and Contributing Factors
Heart problems often contribute, as the heart’s pumping action is the main driver of blood pressure. Conditions like an abnormally slow heart rate (bradycardia), heart valve issues, or advanced heart failure can reduce the volume of blood the heart pushes out, resulting in lower pressure.
Endocrine disorders can also disrupt the body’s ability to regulate blood pressure due to hormonal imbalances. Specific issues include an underactive thyroid (hypothyroidism), adrenal insufficiency (Addison’s disease), and low blood sugar (hypoglycemia) often associated with diabetes. These conditions interfere with hormones responsible for fluid balance and blood vessel tone. Severe dehydration from inadequate fluid intake, persistent vomiting, or diarrhea can reduce the total blood volume, directly lowering pressure.
Nutritional deficiencies, particularly a lack of vitamin B12 and folate, can cause anemia, which is a reduced number of healthy red blood cells. This lower oxygen-carrying capacity can lead to chronic low blood pressure. Medications are another common contributing factor, especially those prescribed for other conditions. Diuretics, alpha blockers, certain antidepressants, and drugs for Parkinson’s disease can widen blood vessels or decrease blood volume, consequently lowering pressure.
Classifying Types of Chronic Low Blood Pressure
Chronic low blood pressure is classified based on the specific circumstances that trigger the pressure drop. Orthostatic hypotension, also called postural hypotension, is one of the most common types. This occurs when blood pressure drops significantly within two to five minutes of standing up from a sitting or lying position, due to a temporary failure of the nervous system to constrict blood vessels in the lower body.
Another distinct category is postprandial hypotension, which is a drop in pressure that happens one to two hours after eating a meal. This occurs because the digestive system requires a significant increase in blood flow to aid in digestion, temporarily diverting blood from the rest of the body. Meals high in carbohydrates can be problematic for this type of hypotension.
Neurally mediated hypotension (NMH) is caused by a communication problem between the heart and the brain. Prolonged standing can trigger a reflex that signals the heart to slow down and blood vessels to widen, leading to a sudden drop in pressure and symptoms like fainting.
Management Strategies and Lifestyle Adjustments
Management of chronic low blood pressure focuses on addressing the underlying cause and implementing practical lifestyle changes. Increasing fluid intake is an effective strategy, as water helps boost blood volume and prevent dehydration, a frequent cause of hypotension. Individuals may also be advised to moderately increase their salt intake, though this should always be done under a doctor’s guidance due to potential risks.
Dietary adjustments include eating smaller, more frequent meals throughout the day instead of three large ones. This reduces the significant blood flow demand to the gut after a large meal, which helps mitigate postprandial drops. For those who experience drops upon standing, physical maneuvers can be beneficial, including moving slowly when changing positions or crossing and gripping the legs while standing to help push blood back toward the heart.
Wearing compression stockings, also known as support stockings, can aid in management by applying pressure to the legs and abdomen. This pressure helps prevent blood from pooling in the lower extremities, promoting better circulation back to the heart. If lifestyle interventions are insufficient, a physician may consider medication to raise blood pressure, such as fludrocortisone or midodrine, but this remains a secondary option after optimizing non-pharmacological methods.