The Valsalva manoeuvre: does syringe size really matter?

The Valsalva manoeuvre is a technique often used within pre-hospital care in an attempt to revert supraventricular tachycardia. The method of exerting against a closed glottis, (often using a syringe), to achieve this has been practised for many years. This study aimed to identify whether a specific syringe size can be recommended to achieve the suggested 40 mmHg pressure required when performing this manoeuvre.

Three syringe sizes (20 of each) were tested from one manufacturer: 5 ml, 10 ml and 20 ml using a manual sphygmomanometer to determine pressure by attaching the syringe to the end of the tube.

Each syringe was removed from its packaging and before doing anything else the syringe was attached to the sphygmomanometer and the initial pressure required to move the plunger was recorded.

The plunger was then moved manually to one-fourth of the syringe volume and the pressure to exert movement recorded. This was repeated for one-half and three-fourths of the volume of the syringe.