Figure 1From: Equipment review: New techniques for cardiac output measurement – oesophageal Doppler, Fick principle using carbon dioxide, and pulse contour analysisOesophageal Doppler. (a) Schematic representation of oesophageal Doppler probe in a patient, demonstrating the close relation between oesophagus and descending thoracic aorta. (b) Characteristic velocity waveform obtained in the descending aorta. The spectral representation shows that most red blood cells (orange-white color) are moving at the maximum velocity (close to the green envelope) during systole, and that diastolic flow is minimal.Back to article page