Valsalva using a syringe: pressure and variation.

BACKGROUND: The Valsalva manoeuvre is commonly used in EDs to terminate supraventricular tachycardia by the patient blowing into a syringe. AIM: To identify whether a specific syringe size can be recommended for use in the ED. RESULTS: 20% of syringes 'stuck' and required high pressures to move. In the remaining 80% of syringes, a 20 mL syringe was the most appropriate size to achieve the recommended 40 mm Hg. Once 'released' plunger position did not make a difference. CONCLUSIONS: Use of a syringe of any size cannot be recommended if a consistent pressure is required.