Quantitative echocardiographic analysis of retained intracardiac air in pooled form: an experimental study

We report that a "pooled form" of retained intracardiac air, in addition to the "bubble form" of air, often is present in patients undergoing open heart operations. This "pooled form" of air can amount to several milliliters. The purpose of this study was to quantify the pooled air by echocardiographic methods in an experimental model. Incremental volumes of air were injected into two types of left ventricles (a geometric dome-shaped model and a canine left ventricular model) and were visualized by echocardiography. The heights and widths of each amount of air were measured with an echocardiographic probe and the volume of air was calculated using five different models to approximate the shape of the air. The coefficient for the correlation between the estimated volume and the injected volume was greater than 0.96 in every model, although some overestimation or underestimation occurred in every model. The cube and cylinder models were advantageous for smaller volumes and the hemiel-lipsoid and bullet models were most appropriate for larger volumes. The cube model was advantageous in determining whether the air volumes were more or less than 0.5 mL.