Orthostatic hypotension

Orthostatic Hypotension

Chemical structure of Tetrahydrocannabinol (THC)

Orthostatic hypotension (OH), also known as postural hypotension, is a form of low blood pressure that happens when you stand up from sitting or lying down. It can make you feel dizzy or lightheaded, and maybe even cause you to faint.

Pathophysiology

Orthostatic hypotension occurs when the body's normal mechanisms for maintaining blood pressure fail to respond adequately to the change in posture. Normally, when a person stands up, gravity causes blood to pool in the veins of the legs and trunk. This pooling reduces the amount of blood returning to the heart, and consequently, the heart pumps less blood, leading to a drop in blood pressure. The body compensates by increasing heart rate and constricting blood vessels to maintain blood pressure and blood flow to the brain.

In individuals with orthostatic hypotension, these compensatory mechanisms are impaired. This can be due to various reasons, including dehydration, prolonged bed rest, certain medications, or underlying medical conditions such as Parkinson's disease, diabetes, or autonomic neuropathy.

Symptoms

The primary symptoms of orthostatic hypotension include:

• Dizziness or lightheadedness upon standing
• Blurred vision
• Weakness
• Fatigue
• Nausea
• Palpitations
• Headache

In severe cases, it can lead to syncope (fainting), which can result in falls and injuries.

Diagnosis

Diagnosis of orthostatic hypotension is typically made by measuring blood pressure in different positions. A significant drop in blood pressure when moving from a lying or sitting position to a standing position is indicative of the condition. A drop of 20 mmHg in systolic blood pressure or 10 mmHg in diastolic blood pressure within three minutes of standing is considered diagnostic.

Treatment

Treatment of orthostatic hypotension focuses on the underlying cause and may include:

• Increasing salt and fluid intake to expand blood volume
• Wearing compression stockings to reduce blood pooling in the legs
• Medications such as fludrocortisone or midodrine to increase blood pressure
• Lifestyle changes, such as rising slowly from a sitting or lying position, avoiding alcohol, and eating smaller, more frequent meals

Related Pages

• Hypotension
• Autonomic nervous system
• Syncope
• Blood pressure