Respiratory variations of aortic VTI: a new index of hypovolemia and fluid responsiveness.
In 12 mechanically ventilated and anesthetized rabbits, we investigated whether the magnitude of respiratory changes in the aortic velocity time integral (VTI(Ao)), recorded by transthoracic echocardiography (TTE) during a stepwise blood withdrawal and restitution, could be used as a reliable indicator of volume depletion and responsiveness. At each step, left and right ventricular dimensions and the aortic diameter and VTI(Ao) were recorded to calculate stroke volume (SV) and cardiac output (CO). Respiratory changes of VTI(Ao) (maximal - minimal values divided by their respective means) were calculated. The amount of blood withdrawal correlated negatively with left and right ventricular diastolic diameters, VTI(Ao), SV, and CO and correlated directly with respiratory changes of VTI(Ao). Respiratory VTI(Ao) variations (but not other parameters) at the last blood withdrawal step was also correlated with changes in SV after blood restitution (r = 0.83, P < 0.001). In conclusion, respiratory variations in VTI(Ao) using TTE appear to be a sensitive index of blood volume depletion and restitution. This dynamic parameter predicted fluid responsiveness more reliably than static markers of cardiac preload.
Slama
Michel
M
Laboratoire de Pharmacologie et de Physiologie Cardiovasculaire, Université de Picardie Jules Vernes, Amiens 80054, France. MSlama0508@aol.com
Masson
Henri
H
Teboul
Jean-Louis
JL
Arnout
Marie-Luce
ML
Susic
Dinko
D
Frohlich
Edward
E
Andrejak
Michel
M
D000818:Animals; D001011:Aorta / Q000000981:diagnostic imaging / Q000502:physiology*; D004452:Echocardiography / Q000592:standards; D005260:Female; D020896:Hypovolemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011817:Rabbits; D015203:Reproducibility of Results; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology*