The detection of carbon dioxide embolism during laparoscopy in pigs: a comparison of transesophageal Doppler and end-tidal carbon dioxide monitoring

Background: The aim of the study was to compare the value of transesophageal Doppler and end-tidal carbon dioxide monitoring to detect venous carbon dioxide embolism in pigs during laparoscopic cholecystectomy.
Method: Ten pigs were anesthetized under constant ventilation, and instrumented for laparoscopic cholecystectomy. CO₂ pneumoperitoneum was performed at 15 mmHg and then, successive increased intravenous gas boluses of 0.1 to 4 ml/ kg injectedthrough the femoral vein using a 55-mm long catheter. The responses indicative of embolism were defined as: 1) a change in Doppler tone placed facing the junction of the right atrium and inferior vena cava; 2)
Results: Doppler was more sensitive in detecting 0.1, 0.2 and 0.4 ml/mg of CO₂ embolism than end-tidal CO₂ ( P <0.05). Over 0.4 ml/mg no differences in sensitivity were found but the Doppler signal modifications occurred earlier than the changes in end-tidal CO₂. Moreover, these changes always consisted of a reduction of the value.
Conclusions: During laparoscopic cholecystectomy in pigs, transesophageal Doppler was a highly sensitive monitor which provided an earlier detection of CO₂ embolism and at lower doses than end-tidal CO₂ monitoring.