Analysis and comparison of venous air embolism detection methods

Changes in precordial ultrasonic Doppler patterns in dogs were compared with changes of end-tidal carbon dioxide (EtCO₂) and pulmonary arterial pressure (PAP). Possible mechanisms of pulmonary arterial hypertension after air embolism in dogs are discussed. After the injection of air, an immediate change in the Doppler ultrasonic pattern was detected, including a shift of the base line. The duration of change of Doppler patterns varied depending upon the length of time that trapped air remained in the right heart. There was a delay of 15 to 30 seconds before the EtCO₂ and PAP responded. In a group of dogs pretreated with 0.3 mg of propranolol per kg, there was a significant decrease in the PAP response due to induced air embolism compared to the control group (P < 0.05). The authors found that the Doppler ultrasonic device was the most sensitive for detecting venous air embolism at a level as low as 0.05 ml of air per kg compared to 0.25 ml/kg for the PAP and EtCO₂ responses.