From the Guidelines
To manage a patient with a history of vasovagal syncope during bloodwork, it is essential to prioritize preventive measures, including having the patient lie down during the procedure and using physical counter-pressure maneuvers (PCMs) as recommended by the 2019 American Heart Association and American Red Cross guidelines 1. When managing a patient with vasovagal syncope, it is crucial to consider the patient's history and the potential for recurrent episodes. The patient should be educated on the diagnosis and prognosis of vasovagal syncope, as recommended by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.
Key Interventions
- Have the patient lie down during blood collection to prevent blood pooling in the lower extremities and maintain cerebral perfusion.
- Ensure the patient is well-hydrated and has eaten before the procedure to stabilize blood pressure.
- Instruct the patient to perform PCMs, such as leg crossing with tensing, to increase blood pressure and prevent syncope, as supported by the 2019 ILCOR systematic review 1.
- Consider prescribing a one-time dose of an anxiolytic like lorazepam 0.5-1mg 30-60 minutes before the procedure for severe cases.
- If syncope occurs despite precautions, immediately position the patient supine with legs elevated, loosen tight clothing, and monitor vital signs until they recover fully. These interventions work by counteracting the parasympathetic nervous system activation that causes the drop in heart rate and blood pressure characteristic of vasovagal reactions.
Additional Considerations
- Educate the patient on recognizing the signs and symptoms of presyncope, such as pallor, sweating, lightheadedness, visual changes, and weakness, to enable early intervention.
- Encourage the patient to assume a safe position, such as sitting or lying down, if they experience presyncope symptoms.
- Consider the use of distraction methods like deep breathing, conversation, or looking away from the needle to reduce anxiety.
From the Research
Management of Vasovagal Syncope
To manage a patient with a history of vasovagal syncope during bloodwork, the following strategies can be employed:
- Conservative measures are first line, including liberalizing fluid and salt intake, unless contraindicated, and teaching physical counterpressure maneuvers 2
- Midodrine can be used as a medical therapy to prevent recurrence of vasovagal syncope, particularly in patients with frequent presyncope or syncope, or those with brief or no prodromes 3, 4, 5, 2
- The use of beta-blockers, serotonin-specific reuptake inhibitors, fludrocortisone, and pacemakers is generally discouraged as routine treatment for vasovagal syncope 2
Pharmacological Treatment
Pharmacological treatments for vasovagal syncope aim to modulate the neurologic reflex that causes the condition. Midodrine, an alpha-1 stimulant, has been shown to be effective in preventing vasovagal syncope in several studies 4, 6, 5. The typical dose of midodrine is 2.5-5 mg twice daily, with efficacy assessed through repeated head-up tilt testing and long-term follow-up 5.
Patient Education
Patient education is crucial in managing vasovagal syncope. Patients should be taught to recognize prodromal symptoms, such as lightheadedness or nausea, and to use physical counterpressure maneuvers to prevent syncope 2. Additionally, patients should be encouraged to maintain adequate fluid and salt intake to help prevent vasovagal syncope 2.