Monitoring end-tidal carbon dioxide tensions with high-frequency jet ventilation in dogs with normal lungs

The end-tidal carbon dioxide tension (PetCO2) measured after a single, large tidal-volume breath (15 ml/kg body weight) was compared to simultaneous measurements of PaCO2 in 6 dogs with normal lungs who were receiving high-frequency jet ventilation (HFJV). There was an excellent linear correlation between PetCO2 and the PaCO2 over the entire range of CO2 tensions commonly encountered in clinical practice (PetCO2 = 0.9 PaCO2 + 2.2 torr; n = 51, r = .98, p less than .001, range of PaCO2 = 12-72 torr). We conclude that when lung function is normal, a simple system of measuring PetCO2 after a large breath is an accurate method of monitoring the effectiveness of CO2 elimination during HFJV.