Monitoring of respiratory variations of aortic blood flow velocity using esophageal Doppler
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The purpose of this study was to determine whether monitoring of respiratory changes in aortic blood flow velocity, recorded by esophageal Doppler, could be used to detect changes in volume depletion.
Animals and interventions
After general anesthesia and tracheotomy, ten New Zealand female rabbits, weighing 4–4.5 kg were studied under mechanical ventilation at a fixed tidal volume; during this time 5-ml blood samples were withdrawn (in increments up to a total of 30 ml) and then retransfused.
Measurements and results
At each step, systolic (SBP), diastolic (DBP), pulse (PP) pressures and maximum descending aortic blood flow (V) were recorded. Respiratory changes of V (ΔV), SBP (ΔSBP) and PP (ΔPP) were calculated as the difference of maximal and minimal values divided by their respective means and expressed as a percentage. The amount of blood withdrawn correlated negatively with SBP, DBP, PP and V and positively with ΔSBP, ΔPP and ΔV. Among these parameters, ΔV correlated best with the amount of blood withdrawn (r=0.89, p<0.001) and it was the most accurate index of volume depletion.
Monitoring of the respiratory variation in V, calculated by esophageal Doppler technique, seems to be a highly accurate index of blood volume depletion and restitution.
KeywordsEsophageal Doppler Hypovolemia Stroke volume variation Cardiac preload
Very special thanks to Olivier des Horts and Sophie Mourier from Agilent technologies (Philips Medical Systems), who made it possible for us to carry out this study by lending us an echocardiographic machine, and to Olivier Fructus from Arrow who lent us the esophageal Doppler advice.
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