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The Oesophageal Doppler Guidelines
The CardioQTM/CardioQ-ODMTM, when used for Individualised Doppler Guided Fluid
Figure 1 The CardioQ
Figure 2 The CardioQ-ODM
Figure 3 Oesophageal Doppler Probe Placement
Oral Placement
Nasal Placement
Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
Management (iDGFM) for patients undergoing surgery, has been shown to improve patient
outcomes and reduce hos pit al stay. Ple ase r efer to the bibliography at www.deltexmedical.com.
The CardioQ/CardioQ-ODM (figures 1 & 2), produces real time information about cardiac
function and fluid status. Oesophageal Doppler Probes (ODP), Doppler Probes (DPn) and
Instant Intervention Probes (I
n) are inserted into the patient’s oesophagus to
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approximately T5/T6, where the oesophagus & descending aorta lie within 1 cm of each
other (figure 3). Information regarding blood flow in the descending aorta is reflected back
to the CardioQ/CardioQ-ODM. DPn and ODP are used for sedated or anaesthetised
patients. The I
n probe can be used in not only sedated and anaesthetised patients, but
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also in awake patients.
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
Insertion and Use of Oesophageal Doppler Probes
Use and Indications
1.
Elective surgery for moderate and major risk patients;
2.
Emergency surgery;
3.
For peri-operative iDGFM, by monitoring Stroke Volume/Stroke Distance responses to
colloid challenges:
a
For use in patients with a significant change in circulatory status;
b
To assess cardiac output and effectiveness of treatment in the patient with a failing
heart and to aid titration of vasoactive drugs.
Contraindications
Doppler probes (ODP, DPn and I2n) should not be placed in patients under
16 years of age. A dedicated paediatric probe and monitor are available separately.
Do not use where nasal injuries are apparent or may have occurred.
Do not use where nasal polyps exist.
Do not use where there are circumstances of facial trauma.
Do not use where there is a risk of brain injury.
Do not use in patients undergoing intra-aortic balloon pumping.
Do not use with carcinoma of the pharynx, larynx or oesophagus.
Do not use with aneurysms of the thoracic aorta.
Do not use with tissue necrosis of the oesophagus or nasal passage.
Do use in close proximity to laser surgery.
For detailed precautions and warnings on probe usage, refer to the individual probe
packaging for instructions for use.
Special Considerati ons
Base of skull fractures;
Careful insertion in the patient with head injury;
Moderate to severe coagulopathies.
NB Please refer to Operating Handbook for full list of precautions, warnings and
contraindications.
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Preparation & Use
oppler training
workshop.
Before Insertion
sedated if using DPn probes.
Insertion & Set-up
• Plug in and switch on the CardioQ/CardioQ-ODM – please note the CardioQ/
the descending aorta. Once the correct signal is identified, activate the “auto gain”
Run Screen is now displayed and monitoring begins.
For additional set up features refer to the Operating Handbook or Q uick Reference Guides
(QRGs).
Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
The user should seek specific training and/or assessm ent on insertion of the oesophageal
Doppler probes by an experienced user, or attend an oesophageal D
• Consider any contraindications;
• Choose appropriate probe i.e. consider duration of expected use and if either an awake
or sedated procedure;
• Explain the procedure to the patient if using I2n probes, or ensure patient is adequately
CardioQ-ODM does not have an integral battery and must be plugged into the mains
supply;
• When usi ng a CardioQ, connect t he probe to the interface cable, to display the Patient
Data Screen. Follow the on-screen inst ructions to enter the patient’s age, weight and
height;
• When using a CardioQ-ODM, connect the probe to the int erface cable and select New
Patient. Enter hospital number ID or select Auto number. Follow the instructions on
Screen to enter patient gender, age, weight and height;
• Press Accept Data to display the Probe Focus Screen. The probe is now ready for use;
• Check the probe is new and free from damage or abrasions;
• Liberally smear the tip of the probe with a water based lubricant as this aids insertion
and signal acquisition;
• Insert the probe to a depth of 40cms (middle mark er), if in serting orally, or to a depth of
45cms (proximal marker) if inserting nasally;
• A descending aortic signal may be obtained between the distal and middle markers fo r
oral insertion and the middle and proximal markers for nasal insertion. The patients
torso length will dictate the depth of the probe;
• Increase the volume and alter depth of probe using small adjustments until a wavef orm
and audible signal, characteristic of descending aortic blood flow is located. Rotate the
probe to achieve optimum signal. The optimum signal has the clearest and sharpest
pitch, the brightest colour and tallest peak, indicating that the probe tip is lying closest to
button to achieve a clear outline to the waveform;
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
Troubleshooting
If a good trace cannot be obtained consider the following:
Interpreting Data
It is recommended that the data g ained from the CardioQ/CardioQ-ODM must be used in
conjunction with assessment of all other patient physiological data.
Descending Aortic Waveform
• Is the probe inserted using the appropriate depth markers?
• Could a nasogastric or other intraoesophageal tube be lying between the Doppler probe
and the oesophagus wall, i.e. is the signal diminished in any way? If possible, re-site
these to allow repositioning of the Doppler probe.
• If air is suspected to be present in the nasogastric tube, try inserting a small bolus of
fluid into the tube as this can aid focus, as ultra sound cannot be conducted through air.
• Allow 5 - 10 minutes for a better contact to build up between probe tip and wall of
oesophagus if focusing is proving difficult.
• A large hiatus hernia may prevent good contact against the oesophageal wall.
• If no signal can be obtained, remove the probe and re-apply a liberal amount of gel to
the probe tip, before re-inserting probe.
• Consider other orifice i.e. oral or nasal.
• Occasional interference may occur from other electrical devices in the vicinity. This may
affect monitoring. If so, use alternative socket.
• Some diathermy of the same frequency strongly interferes with the signal. Use beat-to-
beat cycle time to obtain information from individual beats if actively filling during
periods of diathermy.
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Key Results
Stroke Distance (SD)
Stroke Volume (SV)
Stroke Volume (SV) is the amount of blood ejected by the heart during each systolic
• A high value for SV/SVI may indicate decreased afterload.
Typical values should not be confused with a physiological target for a specific patient.
Flow Time Corrected (FTc)
Flow time corrected (FTc) is the duration of flow during systole corrected for heart rate.
Typical values for FTc in a healthy adult are 330-360 ms.
A low value for FTc may indicate hypovolaemia, or other causes of increased afterload.
A high value for FTc may be seen in patients with low afterload.
Typical values should not be confused with a physiological target for a specific patient.
Peak Velocity (PV)
• Peak velocity (PV) is the highest blood velocity detected during systole, and may be
Typical values should not be confused with a physiological target for a specific patient.
Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
• Stroke distance (SD) is the distance in cm that a column of blood moves along the
aorta with each contraction of the left ventricle of the heart.
• Values are age and size dependent.
• Changes in SD will be directly related to changes in stroke volume (SV).
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period.
• Typical values for SV in a healthy adult are 60-100ml.
• Stroke Volume Index (SVI) is the SV normalised for body surface area (BSA).
• Typical values for SVI in a healthy adult are 35-65ml/m2.
• A low value for SV/SVI may indicate hypovolaemia or an increased afterload.
• Administration of certain drugs may affect the SV/SVI.
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used as an indication of left ventricular contractility.
• Typical values for PV are: 90-120 cm/s for a 20 year old; 70-100 cm/s for a 50 year old;
and 50-80 cm/s for a 70 year old.
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NB References are available at www.deltexmedical.com
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
Individualised Doppler Guided Fluid Management (iDGFM)
When using iDGFM, consider SV/SD responses to fluid challenges. A rise of 10% in
iDGFM Algorithm
Stroke Volume or Stroke
200ml Colloid Challenge
NO
NO
YES
YES
SV/SD
SV/SD
SV/SD following a 200ml colloid challenge, indicates a positive response to filling. See
algorithm below.
Distance Optimisation
Monitor SV/SD & FTc
over 5 minutes
Increase
>10%
Decrease
>10%
Monitor SV/SD & FTc
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
Examples of Doppler Waveforms
1.
Hypovolaemia
This patient was having an emergency laparotomy and was suspected to be hypovolaemic.
2.
Vasodilated Circulation
This patient was undergoing an elective laparotomy, with an epidural infusion in progress.
iDGFM algorithm, a vasoconstrictor was commenced as the patient’s BP remained low.
Her SV/SD were low and the FTc was short indicating an increased afterload. The most
common cause of this is hypovolaemia. Following 200ml colloid challenge, the SV
increased to 50ml and the SD increased to 6.4cm indicating a positive response to filling.
His SV/SD we re high and FTc was lengthened. This may indicate a vasodilated circulation,
often seen in this situation. Following a 200ml colloid challenge, the SV increased to 118ml
and the SD increased to 14.2cm indicating a positive response to filling. A further fluid
challenge only increased the SV to 125ml and the SD increased to 14.8cm. Following the
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
3.
Vasoconstricted Circulation
This patient was undergoing elective bowel resection and a vasoconstrictor was
FTc and reduced PV.
4.
Cardiac Failure
This patient was having a hip replacement and has a history of left ventricular dysfunction.
This is indicated by low SV/SD, reduced PV with rounding of waveform.
administered, resulting in an increased afterload. This is indicated by the low SV/SD, short
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Guidelines for using the CardioQ and CardioQ-ODM in the Operating Theatre Department
5.
Poor Focus
Typically represented by reduced brightness of waveform, t herefore the green line cannot
follow the waveform. The audible sound will also be reduced. Re-focus the probe.
© Deltex Medical 2009 9051-5387 Issue 2
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