From the Guidelines
Vasovagal syncope is the type of syncope that occurs when a person passes out after receiving an injection or having blood drawn. This common form of fainting happens when the body overreacts to certain triggers, such as the sight of blood or the anticipation of pain during medical procedures 1. During a vasovagal episode, the vagus nerve is stimulated, causing a sudden drop in heart rate and blood pressure, which reduces blood flow to the brain, resulting in temporary loss of consciousness 1. People who experience this may feel lightheaded, nauseated, or sweaty before fainting.
Prevention and Management
To prevent vasovagal syncope during medical procedures, patients can try:
- Lying down during injections or blood draws
- Practicing deep breathing techniques
- Staying well-hydrated
- Informing healthcare providers about their tendency to faint 1 Most episodes resolve quickly without treatment, but maintaining a horizontal position after fainting helps blood return to the brain more efficiently. According to the 2019 American Heart Association and American Red Cross guidelines, if a person experiences signs or symptoms of presyncope, the priority is to maintain or assume a safe position, such as sitting or lying down, and using physical counterpressure maneuvers (PCMs) to avoid syncope 1.
Key Points
- Vasovagal syncope is a common form of fainting that occurs in response to certain triggers, such as medical procedures
- Prevention and management strategies include lying down, deep breathing, hydration, and informing healthcare providers about the tendency to faint
- Maintaining a horizontal position after fainting can help blood return to the brain more efficiently
- PCMs can be used to prevent syncope in people who experience presyncope 1
From the Research
Types of Syncope
- Vasovagal syncope is a type of syncope that occurs when a person passes out after receiving an injection or having blood drawn 2, 3.
- This type of syncope is also known as neurocardiogenic syncope and is caused by a complex neurologic reflex 2.
- Vasovagal syncope can be triggered by various factors, including emotional stress, orthostatic changes, and pain 4.
Characteristics of Vasovagal Syncope
- Vasovagal syncope is characterized by a sudden loss of consciousness, typically lasting for a short period of time 2.
- It is often preceded by presyncopal symptoms such as dizziness, nausea, and sweating 5.
- In some cases, vasovagal syncope can lead to injuries, particularly if the person falls or hits their head while fainting 5.
Prevention and Treatment
- Prevention of vasovagal syncope involves identifying and avoiding triggers, as well as taking measures to reduce stress and anxiety 3.
- Treatment options for vasovagal syncope include conservative measures such as increasing fluid intake and salt consumption, as well as pharmacological therapies like midodrine 2, 6.
- Midodrine has been shown to be effective in reducing the recurrence of syncope in patients with vasovagal syncope 6.