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You are in Home >> Resources >> Clinical anaesthesia >> Cardiac Output

Oesophageal Doppler variables

Created: 13/8/2005
Updated: 2/9/2021

 FT (Flow time)
The time of systolic aortic blood flow (sec)

 FTc (Flow time corrected)
This corrects flow time to a heart rate of 60 bpm (msec)

 PV (Peak Velocity)
Peak Velocity of blood flow. In systolic phase (cm/sec). This is the value at the peak of systole indicated by the white arrow at the top of the velocity waveform. It decreases linearly with age and is affected primarily by left ventricular contractility. A low PV occurs with left ventricular failure or beta-blockade. Peak Velocity rises with inotrope therapy and exercise. Changes in afterload also play a role.

 MA (Mean Acceleration)
The mean acceleration is the average acceleration of the blood between the start of systole and the time when the peak velocity is detected (cm/sec). Mean Acceleration is affected primarily by changes in left ventricular contractility, but
also by changes in afterload and, to a lesser extent,

 SV (Stroke Volume)
Blood ejected during each systolic phase (ml)

 CO (Cardiac Output)
Litres of blood pumped per minute (L/min)

 CI (Cardiac Index)
Cardiac output normalized for body surface area (l/min/m2)

 SVR (Systemic Vascular Resistance)
Resistance the left heart pumps against; afterload;

Normal ranges

 FTc: Flow Time corrected 330 -360 milliseconds

 PV: Peak Velocity-an index of contractility

20 yrs: 90 - 120 cm/sec 
50 yrs: 70 - 100 cm/sec
70 yrs: 50 -80 cm/sec

Concurrent shifts in FTc and PV indicates changes in after load

 MA: Mean Acceleration depends on the patient

 SD: Stroke Distance depends on the patient

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