Organ Hypoperfusion?
Hypotension?
Circulatory Optimisation
Monitor SV/SD & FTc
200ml Colloid Challenge
over 10 minutes
Patient losing fluid at
rate exceeding input
SV/SD increase >10%
Yes
Monitor SV/SD & FTc
No
No
Still compromised?
(eg Low BP, Oliguria)
Yes
No
Other therapies as appropriate eg:
Dilators (+
more fluid) if low FTc, low PV and BP acceptable.
Inotropes if low PV and low BP.
Vasopressors if high FTc, high SV and low BP.
The CardioQ Waveform
Treatment Algorithm
Treatm
ent Algorithm
sug
g
e
sted by Prof
. M. Singer, University Coll
ege Lo
ndo
n
Deltex Medical
Tel: +44(0)1243 774837
www.deltexmedical.com
The
green line
indicates the velocity/time envelope which the
monitor uses to make calculations. The
white arrows
indicate time and velocity values used for CardioQ
TM
calcula-
tions.
The Stroke Distance (SD) is the area under the waveform
and is the basic measured parameter upon which calcula-
tions of Stroke Volume (SV) and all other Cardiac Output
(CO) and indexed measurements are made. Stroke Volume
is the parameter of choice for fluid management protocols,
however changes in Stroke Distance (SD) or Stroke Volume
Index (SVI) can also be utilised.
The waveform base, (flow time) depends on heart rate, left
ventricular filling and afterload. The flow time corrected to a
heart rate of 60bpm (FTc) is inversely correlated with the
systemic vascular resistance (SVR).
The most common cause of a short FTc (<330 ms) is hypo-
volaemia. If a short FTc (<330 ms) does not increase after an
appropriate fluid challenge, other causes of vasoconstriction,
(eg excess vasopressors, cold temperature, or obstructed
circulation such as pulmonary embolus) should be consid-
ered. A long FTc (>360 ms) is seen in conditions associated
with a low SVR eg sepsis, pregnancy, vasodilators and some
anaesthetic agents.
Peak Velocity (PV) and Mean Acceleration (MA) are markers
of left ventricular contractility. Changes in afterload will also
affect the PV and MA - both decrease with an increase in af-
terload, and vice versa. Changes in preload predominantly
affect the FTc and only affect PV and MA at extremes.
Typical Parameter Values
(These values should not be confused
with a physiological target)
Flow Time Corrected (FTc)
330 - 360 milliseconds
NB -The effects of vasodilating
drugs may elevate the FTc (see
above).
Peak Velocity (PV)
20 years 90 - 120 cm/s
30 years 85 - 115 cm/s
40 years 80 - 110 cm/s
50 years 70 - 100 cm/s
60 years 60 - 90 cm/s
70 years 50 - 80 cm/s
80 years 40 - 70 cm/s
90 years 30 - 60 cm/s
