Venous air embolism: artefactual air entrapment and autopsy technique.

Venous air embolism (VAE) is a rare cause of death for which special procedures are needed for autopsy diagnosis. The current one of choice was devised by Richter in 1905 to prevent introduction of gas into the right heart while opening the thorax. We could find no published data demonstrating that that this occurs during standard autopsy technique. Two scenarios were investigated. In the first, the study group included cases using the traditional method to open the thoracic cage; in the control group, Richter's method was used. Gas was collected under water and measured in a calibrated tube. The second scenario involved cases in which an intracardiac catheter was present at autopsy. In these, 50 mL of air was injected prior to chest opening and the amount of intracardiac air was measured. The first (non-injected) study and control groups consisted of 28 and 26 cases, respectively. Gas was identified in 3 cases (10%) in the study group and 2 cases (7%) in the control group. In the ten injected cases, there was a significant difference in the amount of the gas recovered (10 mL in the standard cases and 30 mL in the Richter group). No significant artifactual gas entrapment occurs in the right heart using the standard autopsy technique. However, it is possible that this technique may cause loss of intracardiac gas and if there is a clinical suspicion of VAE, Richter's technique should be used.