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CardioQ-ODM is designed to allow clinicians to guide fluid and drug administration during surgery and critical care

Guided fluid and drug administration during surgery and critical care

CardioQ-ODM enables hospital clinicians to deliver accurate, real-time, guided Intraoperative Fluid Management (IOFM). As such it is an important aid in avoiding the dangers of reduced oxygen delivery.

The CardioQ-ODM monitor is highly responsive in tracking changes in Stroke Volume and Cardiac Output during surgical intervention and in the critical care setting. Only oesophageal Doppler has been shown to have the precision to drive the 10% Stroke Volume Optimisation algorithm, widely acknowledged as the basis for IOFM.

Uniquely, oesophageal Doppler monitoring (ODM) directly measures blood flow in the central circulation. It is highly sensitive to changes in flow and measures them immediately and accurately. The system offers a high degree of precision (low repeatability error), which allows it to recognise the small changes in Stroke Volume, which is the basis of published Stroke Volume Optimisation protocols.

Extensive clinical trials have demonstrated that with direct measurement of blood flow, clinicians can correct individual patient circulating blood volume. It has been reported that 70% of patients have hypovolaemia (low blood volume) when they are prepared for surgery. This hypovolaemia can result from the combined effects of poor diet, dehydration, preoperative fasting, and the the vasodilatory effects of anaesthetic agents. It can be compounded by blood loss during the surgical procedure.

ODM guided fluid management is a cornerstone of Enhanced Recovery, delivering better quality and more cost-effective care as it means patients recover from their surgery faster and leave hospital sooner and in better health than they otherwise would.

Additional information

ODM Product Brochure

View the full range of mounting arms available from GCX which attach the monitor to anaesthesia stations, here.

For further information relating to this product or for any sales enquires please contact Customer Services quoting part code 9051-7103.


How the ODM works

The CardioQ-ODM is unique in its ability to directly measure central blood flow by way of a minimally invasive disposable probe. The probe is placed in the patient’s oesophagus and uses Doppler ultrasound to measure the velocity of blood flow in the adjacent aorta, hence the name of the technology which is abbreviated to ODM. The oesophagus is easy to access for placement of the ultrasound probe as it is close to the patient’s aorta at the level of T5/T6.

Access the Training Workbook for a deeper understanding of how to use this technology.

Ultrasound explained

Ultrasound emitted by the probe is directed into the aortic blood flow at angle of 45o. The ultrasound will be reflected by the blood’s red cells. As the blood is moving away from the probe tip each reflected wave is emitted from a position farther from the observer than the previous wave, so the arrival time between successive waves is increased, reducing the frequency. The distance between successive wave fronts is increased, so the waves “spread out”. The ODM receives the reflected frequency shifted wave and compares its frequency to that of the transmitted wave. The result of this calculation is that the velocity of the blood can be measured during each cardiac cycle.

Ultrasound Waveform

The ultrasound waveform is displayed in red and white with a dark centre and it is encapsulated by a green line, which follows the maximal velocity at that point in time. The monitor places three arrows on the screen; the first at the start of systole (on the baseline); the second at the peak velocity (at the top of the waveform) and the third at the end of systole (on the baseline).

Technical Review

The Technical Review is ideal for those seeking a deeper understanding of the ODM technology and contains information on:

  • A short history of the development of oesophageal Doppler monitoring
  • How oesophageal Doppler measures blood flow velocity in the aorta
  • Comparative results compared to pulmonary artery catheter data
  • Accuracy of measurement
  • Probe placement and focussing
  • Waveform and parameter explanation
  • A summary of Intraoperative Fluid Management (IOFM)
  • Results of clinical application
  • Limitations of use


Accuracy & Precision

Many publications cite device performance in terms of accuracy. Accuracy in this context is simply the ability to measure the actual Stroke Volume (SV) in millilitres. The pulmonary artery catheter (PAC) is regarded as the ‘gold standard’ in this respect but is known to be no better than ±20%.

For clinical use this is regarded as acceptable and within the clinical norm of ±30%. The basic measurement of Stroke Distance (SD) by ODM has an accuracy on a single waveform of ±3%. The conversion to SV through the nomogram results in a greater error, similar to that of a PAC.

However when using a device to guide IOFM in a 10% SVO protocol it is its precision that matters most of all, that is the ability to detect change in sequential measurements, in this case the effect of a fluid challenge on SD or SV. Precision is the ability to measure the same result repeatedly with minimal error.

Prof. Singer established that the error of repeatability of measuring SD for the ODM was 3.8% [1]. For an individual patient the diameter of the aorta will be a constant thus the SV precision will be equal to the known error for SD. [SV = SD x Aortic Root Diameter (from patient nomogram)].

This precision/repeatability error can then be used to determine the least significant change in SD/SV required to ensure confidence in measuring a real haemodynamic change and not just measurement error. With its calculated error of 3.8%, the user can be 99% confident that a measured change in SD/SV of >10% is real (this is based on 99% of normally distributed data points falling within 2.5 standard deviations of the mean).

The precision of a technology dictates its ability to guide fluid management. The 10% SV change algorithm  used to optimise SV is specific to the ODM, and is evidence-based. Other technologies that are less precise may not be as effective in guiding fluid management based on this algorithm.

For further information on Accuracy and Precision, please contact

1Singer, M., J. Clarke, and E.D. Bennett, Continuous hemodynamic monitoring by esophageal Doppler. Crit Care Med, 1989. 17(5): p. 447-52

Flow Parameters

The CardioQ-ODM monitor uses Doppler ultrasound technology to directly measure a patient’s central vascular blood flow velocity to deliver the following flow parameters:

Flow Based Parameters

Technical Specification

Below is the technical specification for the ODM monitor:

ODM Specification

Software Upgrades

Contact Customer Services direct 0845 085 001 to find out more, or click here to find your local Deltex Regional Sales Manager or Clinical Sales Specialist