Evaluating the potential risks of bubble studies during echocardiography

Cardiac shunts are often identified using bubble studies in echocardiography, with agitated saline. Previous studies have recommended various safe amounts of agitated saline. This poses a potential risk for air microembolism. The purpose of this study was to quantify the bubbles created by various quantities of agitated saline.

A closed circuit was constructed with a HeartMate pneumatic ventricular assist pump and a cardiotomy reservoir to remove air during recirculation. One empty 10 mL syringe and one 10 mL syringe containing 1 mL of air and 9 mL of saline were attached to a three-way stopcock. The air/saline bolus was then agitated between the two syringes five times to create bubbles and injected into the tubing proximal to the HeartMate. An EDAC bubble detector sensor was attached prior to the saline injection site and distal to the HeartMate I to measure the size and volume of the bubbles. This technique was repeated using 0.5 mL of air and 9.5 mL of saline bolus and 2 mL of air and 8 mL of saline bolus. Each bolus was tested 20 times.

This study identifies the potential risks of air administration and proposes a safer air volume to agitate for the administration of a bubble study.

Further studies should be conducted to create either a guideline or a standard for agitated saline administration by the Intersocietal Commission for the Accreditation of Echocardiography Laboratories (ICAEL) in order to minimize the risk of air microembolism.