Simulator

Using the Oesphageal Doppler Simulator (ODS)

Welcome to Deltex Medical’s guide to using the ODS.

If you are not already familiar with the ODS, contact customer services for more details.

The course objectives will give you an understanding of:

• How to set up and use the ODS
• Probe insertion and focussing
• Doppler and arterial signal identification

You may also find the course Getting Started with the ODM+ useful for details on the monitor’s functions.

This course is for information only and is in no way intended to be a replacement for the Instructions for Use and the Operating Handbook, which should be referred to for full instructions.

Note: Local laws apply in all cases. The products shown in this course may not be available in all markets.

ODS - A Teaching Tool

The ODS is designed for teaching the placement and signal acquisition of the oesophageal Doppler probe.

Signal detection is more sensitive than in a patient, because there is less absorption of the Doppler wave.

The arterial line is also simulated and can be calibrated against the Doppler signal to give continuous cardiac output and unique combination parameters.

Connecting the ODM+

Simulator patient characteristics

After setting up the monitor, select ‘New patient’ followed by ‘Auto-number’ and enter the following patient data:

• Age – 68 years
• Weight – 83 kg (183 lb)
• Height – 180 cm (70 in)

…then press ‘Accept data’.

Note: In patients, the descending aorta increases in diameter as you get older so age has the biggest influence on the algorithm used by the ODM+ to calculate Stroke Volume.

Using the Doppler Probe

Insert the Doppler probe via the nose with the beveled edge facing upwards until Marker 3 is aligned with the nostril.

Slowly rotate the probe through 360 degrees to look for a signal.

Pause to allow the spring in the probe to relax. If the optimal signal is not located, withdraw the probe 1 cm at a time and turn in the opposite direction to look for a signal between Markers 2 and 3.

Simulator Control Panel

The control pad allows the simulator signal to alter to represent different clinical situations.

The Doppler Waveform

A Doppler waveform shows the velocities of the red blood cells as they pass through the descending thoracic aorta. The area under the curve is the Stroke Distance (SD) or Velocity-Time Integral (VTI).

SD is converted to Stroke Volume (SV) using a nomogram based on age, weight and height.

The Arterial Waveform

The ODS can also simulate the arterial waveform normally slaved from the main patient monitor. This is displayed below the Doppler signal.

Calibration against the Doppler signal is quick and easy at the touch of a button. Cardiac Output is then available from Pulse Pressure Wave Analysis.

The simulator also displays those parameters calculated from combining the dual technologies, such as Cardiac Power and Cardiac Power Index.

Please visit the course on ‘Pressure Monitoring Mode’ for more information.

Signal Identification

In real patients, the shape of the Doppler flow reflects the speed and direction of red blood cells, thus different waveforms will be reflected when the probe is positioned by different structures.

Optimal waveform: A strong orange and white edge with a trailing white edge and a dark centre. It will always have the loudest, sharpest ‘whip crack’ sound, accompanied by the tallest, brightest picture. In the ODS, this is around Marker 3.

Pulmonary artery wave: The pulmonary artery may be detected below the line. Flow above the line at this depth may indicate flow from other vessels. In the ODS, advance the probe until Marker 1 is near to the nostril.

Intracardiac wave: Intracardiac: a ‘galloping horse’ sound with signal above and below the line due to different flow directions through the heart. In the ODS, rotate the probe through 180 degrees and change depth to near Marker 2.

Venous waveVenous (azygous) signal: a ‘whooshy’ slower sound with a strong signal below the line as flow returns towards the probe. In the ODS, this is found just after Marker 3.

ODS - Using the Data

Once the optimal signal is found, the ODS can be used to experience the effect of a fluid challenge.

In real patients, data can be captured and downloaded to records as well as any change in response being tracked on the ODM+.

Helpful Hints

Poor signal

• Check that there is an adequate amount of gel in the ODS
• Use the probe to gently mix the gel to remove large pockets of air
• Increase the power on the control pad
• Change the probe.

Interference (noise) on waveform

• Consider locating further away from non-ODS electrical equipment
• Rotate ODS horizontally by 90 degrees.

Green light flashing on control panel

• This may happen if the probe has been moved up or down very quickly. Switch the power off to re-set.

Difficulty moving probe in simulator

• If probe movement is stiff, this usually indicates that too much gel has been added to the ODS.

ODS - Maintenance

• Switch off and disconnect the power cord prior to cleaning
• Clean the simulator at least once per month with mild detergent – refer to handbook

Thank You for Viewing this Course

If you would like to know more about the ODS, please contact Customer services for more details.

You may also find our other courses useful, including ‘Getting Started with the ODM+’.