What Causes Blood Pressure To Fall?

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Blood pressure should be kept within a healthy range: not too high, not too low. While blood pressure changes throughout the day, it sometimes falls too low due to various causes, leading to symptoms and problems.

That’s why it is important to know the symptoms of low blood pressure (“hypotension”) and some of the most common reasons why blood pressure falls. 

Generally speaking, low blood pressure develops when 1. Your heart doesn’t pump hard enough, 2. There is not enough fluid in the blood vessels, or 3. The blood vessels relax too much, get wider, and there is not enough blood to keep them full.

Symptoms Of Low Blood Pressure

Hypotension is defined as lower-than-normal blood pressure. It develops when the systolic blood pressure drops below 90 mmHg and the diastolic blood pressure falls below 60 mmHg. Many people may not experience any symptoms, while others have symptoms like:

  • Fatigue
  • Dizziness, especially when standing up
  • Lightheadedness
  • Cold, pale, sweaty skin 
  • Nausea
  • Depressed mood
  • Blurry vision
  • Loss of consciousness (in severe cases)
  • Untreated low blood pressure can be life-threatening

Postprandial Hypotension 

Postprandial hypotension means there is an excessive drop in blood pressure that develops after a meal. It rarely affects younger people but is common among older adults (one in three). Researchers believe this happens because the elderly are more likely to have high blood pressure or problems that affect the brain centers that regulate the autonomic nervous system. These problems can include Parkinson’s disease or diabetes. 

In normal conditions, the blood flow to the digestive system increases after a meal, to help digest foods. Heart rate also increases and blood vessels from the rest of the body try to maintain the blood pressure at a normal range. However, this process is not optimal in older individuals. The blood flow increases in the gut, but the heart rate does not increase enough. Vessels are unable to keep the blood pressure in check. The result is postprandial hypotension.

How do you prevent postural hypotension? First of all, it’s important to measure your blood pressure before and after meals so you know whether or not you have it. Notice if you experience dizziness, light headaches, or other symptoms.

To avoid postural hypotension, eat small, low-carb meals more often than large, high-carb meals. If you take blood pressure medications, make sure you do not take them before meals, and try to lie down after you eat. Drinking coffee before breakfast or lunch may also be beneficial. If postprandial hypotension is severe and does not respond to other measures, the drug octreotide may be recommended. This drug works by lowering the blood flow to the gut.  

Orthostatic Hypotension 

Orthostatic (postural) hypotension is defined as a drop in blood pressure when you stand up from a sitting or lying down position. This condition is diagnosed when the drop in systolic blood pressure is more than 20 mmHg systolic and/or diastolic blood pressure drops more than 10 mmHg within 2-5 minutes of standing, or if standing causes symptoms.

Orthostatic hypotension can make you feel dizzy, lightheaded, confused, and maybe even cause you to faint. These symptoms occur within seconds to minutes of standing up, and rapidly resolve when you lay down. Exercise or a heavy meal can aggravate the condition. Occasional short episodes may be simply caused by dehydration, low blood sugar, a hot environment, drinking alcohol, or spending too much in bed. In these cases, avoiding the triggers can help prevent the drop in blood pressure levels. 

However, chronic or severe cases of low blood pressure should be investigated, because it is very likely there are underlying causes. These can include heart diseases (low heart rate, heart valve problems, heart failure, coronary artery disease), hormonal imbalances (especially thyroid, adrenal and pancreatic hormones), or neurological conditions such as Parkinson’s disease.

How do you manage orthostatic hypotension? In addition to monitoring the blood pressure, a doctor may order blood tests, an EKG, and a heart ultrasound. 

Lifestyle changes include drinking enough water, avoiding alcohol or excessive heat, elevating your head in bed, and standing up slowly. Small, low-carb meals may also help. If the above measures fail, medications like midodrine and droxidopa are recommended. 

Medications

A number of prescription medications can cause a drop in blood pressure, usually in the form of orthostatic blood pressure. These include antihypertensive drugs like diuretics, alpha and beta-blockers, ACE inhibitors, calcium channel blockers, and nitrates. Antidepressants, anti-Parkinson’s, muscle relaxants may also raise the risk of a sudden decrease in blood pressure.

Sometimes the combination of drugs with over-the-counter medications can lead to orthostatic hypotension. In addition to using the above tips for orthostatic hypotension, your doctor may review and adjust the medications you are taking.