Accuracy and limitations of continuous oesophageal aortic blood flow measurement during general anaesthesia for children: comparison with transcutaneous echography-Doppler

Background: Because it is noninvasive and easy to use, oesophageal Doppler ultrasonography appears to be a worthwhile alternative for continuous assessment of cardiac output measurement during anaesthesia. A new oesophageal Doppler-echography device (Dynemo 3000(TM), Sometec, Paris, France) can simultaneously determine aortic diameter and aortic blood flow at the same anatomical level (DEeso). The purpose of this study was to assess the accuracy and the potential limitations of this device during general anaesthesia among 20 children, using transcutaneous Doppler-echo cardiography for comparison (DEtra). Methods: The reproducibility of paired measurements of mean aortic blood flow velocity (MAFV), aortic diameter (empty set Ao) and aortic blood flow (ABF) was analysed with both methods. Second, haemodynamic values were measured simultaneously in a blinded manner by both methods before and after surgery. Results: The percent change (%Delta) in MAEV and ABF was calculated with both methods for each child. The age and weight of children included in this study was 8.3 +/- 2.5 years and 27 +/- 8 kg, respectively. Intraoperator reproducibility of MAFV(tra), ABF(tra), MAFV(eso) and ABF(eso), was 5.0 +/- 4.1%, 7.0 +/- 5.6%, 20.1 +/- 17.5% and 22.0 +/- 16.6%, respectively. ABF(tra) was significantly linked to ARF(eso) (R = 0.55, P < 0.01). Bias +/- SD of ABF measurements between both methods was 2.2 +/- 1.1 1 . min(-1). %<Delta>ABF(tra) was significantly linked to %Delta ABF(eso) (R = 0.62, P < 0.01). The bias +/- SD inherent to %<Delta>ABF measurements with both methods was -0.02 +/- 18%. Conclusions: These results suggest that this new oesophageal Doppler method is unsuitable to measure accurately absolute CO values and relative CO changes in children during anaesthesia.