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The CardioQ-ODM+ is the world’s first fluid management and cardiac output monitoring system to measure both flow and pressure directly.

Oesophageal Doppler, PPWA and HD-ICG in one monitoring solution

CardioQ-ODM+ is the world’s first fluid management and cardiac output monitoring system to directly measure both flow and pressure in adults and paediatrics. An exciting new upgrade to the proven Doppler technology, CardioQ-ODM+ adds Pulse Pressure Waveform Analysis (PPWA) to the proven CardioQ-ODM Doppler flow-based platform. The result is a highly sensitive “Flow Monitoring Mode” to guide intervention, combined with the simpler calibration of a “Pressure Monitoring Mode” for extended continuous monitoring.

The Pulse Pressure Waveform (PPWA) mode is quickly and easily calibrated from the Doppler signal and provides continuous monitoring in postoperative and medical patients in critical care. In sedated patients, the PPWA algorithm can be recalibrated at any time from the Doppler waveform.

And now, in yet another first, Deltex has added non-invasive High Definition Impedance Cardiography (HD-ICG), thereby adding a non-invasive central blood flow monitoring option for the awake patient.

HD-ICG provides continuous, accurate and sensitive measurements of cardiac output and other haemodynamic parameters. HD-ICG disposable electrodes are placed on the neck and chest, the electrodes transmit and detect electrical and impedance changes in the thorax. After stabilising, using HD-Z signal filter technology, these electrical currents are then utilised to measure and calculate haemodynamic parameters

Previous cardiac output monitors have either been interventional devices (fast, precise responsive flow-based measurement but non-continuous) or less responsive, pressure-based continuous monitors. The latter require complex calibration and frequent recalibration to be effective.

Deltex’s ODM+ leads the haemodynamic monitoring field by combining the real-time accuracy of oesophageal Doppler with PPWA and HD-ICG.

Why CardioQ-ODM+?

CardioQ-ODM+ provides an unparalleled range of functional haemodynamic parameters for intensive care and high risk surgical applications. The system is purpose-designed for clinicians to guide fluid and drug administration during critical care. The monitor is highly responsive in tracking changes in Stroke Volume and Cardiac Output during intervention. Indeed only oesophageal Doppler has been shown to have the precision to drive the 10% Stroke Volume Optimisation algorithm, widely acknowledged as the basis for Intraoperative Fluid Management (IOFM).

Patients can be continuously monitored for extended periods between intervention and calibration episodes.

Monitor Mounting Arms

A range of mounting arms is available which attach the monitor to anaesthesia stations. click here.

Interface Cables

When making a connection to the ODM+ to the High End Monitor (HEM), an interface cable is required.  Deltex Medical provide a Blood Pressure (ABP) Cable Guide which is available here; Download Guide.

ODM+ Product Brochure (PDF)

In surgery the CardioQ-ODM+ offers the following advantages:
  • Only surgical CO monitor offering both ODM & PPWA
  • Ease of PPWA calibration and recalibration
  • Continuous monitor ‘bridge’ during diathermy episodes
  • ‘Bridge’ in surgical cases where oesophagus is displaced or removed
  • Only device able to guide 10% SVO (Doppler guided)
  • Offers fluid responsiveness parameters including:
    • Corrected flow time (FTc)
    • Stroke volume variation (SVV –  flow and pressure)
    • Pulse pressure variation (PPV)
  • Provides post operative monitoring for 6 to12 hrs in awake patients in recovery/ICU (dependent on probe type)
In the Intensive Care Unit CardioQ-ODM+ offers the following advantages:
  • Only critical care monitor offering both ODM & PPWA
  • Ease of PPWA calibration and recalibration
  • Continuous monitor capability
  • Only device able to guide 10% SVO (Doppler)
  • Offers fluid responsiveness parameters including:
    • Corrected flow time (FTc)
    • Stroke volume variation (SVV flow and pressure)
    • Pulse pressure variation (PPV)
  • Offers Cardiac power output (CPO) and Cardiac power index (CPI), combined flow and pressure parameters (German regulations indicate a benefit in managing and monitoring patients at risk of Cardiogenic shock)

For further information relating to this product or for any sales enquires please contact Customer Services quoting part code 9051-7104.

The CardioQ-ODM+ directly measures central blood flow in the same way as the CardioQ-ODM by way of a Doppler ultrasound probe. In addition the device also takes the standard Arterial Blood Pressure (ABP) measurement and calculates a range of Pressure Based Parameters. It is unique in that it can take the Cardiac Output as measured by Doppler flow to calibrate a Pulse Pressure Waveform Analysis algorithm. The PPWA algorithm provides secondary pressure based measures of Stroke Volume and Cardiac Output as well as new flow and pressure combined parameters.

The CardioQ-ODM+ by combining both flow and pressure based measurements allows the user to reduce the inherent weaknesses of PPWA by way of a quick and simple calibration and recalibration from the Doppler flow based measurements of Cardiac Output.

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

Flow and Pressure Monitoring Modes

The CardioQ-ODM+ user interface provides two new screens for Flow Monitoring Mode and Pressure Monitoring Mode.

Users selecting Pressure Monitoring Mode initially calibrate the parameters by pressing the calibrate button. In a matter of seconds the proven Liljestrand and Zander Pulse Pressure Waveform Analysis algorithm is calibrated from the current flow based Cardiac Output.

Pulse Pressure Waveform Analysis (PPWA)

PPWA is a group of methods which use Arterial Blood Pressure (ABP) as a means of estimating Cardiac Output. The techniques have been called Pulse Contour Analysis, Pulse Pressure Analysis and Pulse Power Analysis, however all are variations in their approach to use ABP to estimate flow. Any measure from the artery includes the changes in pressure associated with changes in arterial function (compliance, impedance etc). Pressure based estimates of Cardiac Output are inherently limited by confounding blood pressure changes which may accompany actual output flow staying the same or decreasing.

Physiologic or therapeutic changes in vessel diameter are assumed to reflect changes in flow. Pulse Pressure (PP) methods measure the combined performance of the heart and the vessels thus limiting the application of PP methods for measurement of flow. This has to be compensated for by regular calibration of the waveform (as CardioQ-ODM+) to another flow measurement method (such as Doppler) and then monitoring the PP waveform. Recalibration is recommended after changes in patient position, therapy or condition, including known or suspected arterial compliance changes.

These methods use characteristics of the pulse pressure waveform to calculate aspects of heart function. The basic Pulse Contour method provides the following information; a. relates to myocardial contractility (similar to Mean Acceleration from Doppler), b. the area under the curve can be calibrated against another source of cardiac output to estimate cardiac output, c. systolic time (similar to Flow Time from Doppler), d. diastolic time.

p

Uncalibrated pulse pressure devices utilise an algorithm that is based on the principle that pulse pressure is proportional to Stroke Volume (SV). The algorithm uses statistical analysis of the arterial pressure wave to generate an estimate of stroke volume. These systems use a multivariate polynomial equation that continuously quantifies arterial compliance and vascular resistance. By analysing the shape of the arterial pressure waveform, the effect of vascular tone is assessed allowing calculation of SV and Cardiac Output is then derived.

All PPWA systems have limitations in that measurement of pressure in the artery to calculate the flow in the heart is physiologically irrational, simply pressure and flow do not necessarily rise and fall together and often are in opposition. For example, as impedance increases pressure may rise and flow may fall.

The dynamic variables SVV and PPV displayed with arterial pressure monitoring is also limited to patients with an invasive arterial line, who are fully mechanically ventilated, with closed chest, a tidal volume of >7-8 ml/Kg, are in sinus rhythm. Changing the patient’s position or altering PEEP or tidal volumes may alter the ‘cut off’ or ‘grey zone’ threshold.

ODM+ Technical Specification

Below is the technical specification for the ODM+ monitor:

ODM+ Specification

For detailed information concerning Arterial Lines please click the following link: Arterial Line

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.

Pressure Parameters

The CardioQ-ODM+ uses the proven Doppler technology to control both its Flow Monitoring Mode of use and the calibration of the chosen Pulse Pressure Waveform Analysis (PPWA) algorithm for its Pressure Monitoring Mode of cardiac output (CO). Pressure parameters and flow based parameters are available on the CardioQ-ODM+ monitor.

Flow Based Parameters

Stroke Distance (SD)

Stroke Distance is a Doppler flow based parameter only. SD is simply the distance the blood ejected by the left ventricle travels down the aorta every beat. It is measured in centimeters per second. If the aorta approximates to a cylindrical pipe then the SD can be represented a series of cylinders of blood moving down the aorta as each pulse of the left ventricle propels them into the bodies arterial system.

Stroke Distance (SD)

Stroke Distance (SD)

The CardioQ-ODM is distinct from other devices in possessing the ability to calculate Stroke Volume and Cardiac Output from its own patient nomogram. The patient nomogram was created as a result of research by Prof. Mervyn Singer. The patient nomogram is a calibration of Stroke Distance against the total Cardiac Output as measured by a Pulmonary Artery Catheter (PAC) for patients of both genders and various races, ages, weights and heights.

SD is the basic parameter for IOFM and Stroke Volume (SV) is automatically calculated by the monitor. The patient’s age, weight and height are input during the monitor set up. This information accesses the nomogram which effectively provides the dynamic aortic root diameter.

SV = SD x Aortic Root Diameter

As a result ODM has been found to be equivalent in terms of accuracy to a PAC. However it is the precision of ODM in tracking change that is key to recognising how and why ODM guides Stroke Volume Optimisation (SVO) so effectively which has resulted in an unparalleled evidence base.

Stroke Volume (SV)

Stroke Volume is the amount of blood in millilitres pumped from the human heart every heart beat. It is the volume ejected from the left ventricle due to the contraction of the heart muscle which compresses the left ventricle. Stroke Volume can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

The CardioQ-ODM calculates Stroke Volume by multiplying the Stroke Distance by a constant accessed from the built in patient nomogram. The patient nomogram was created as a result of research by Prof. Mervyn Singer. The patient nomogram is a calibration of Stroke Distance against the total Cardiac Output as measured by a Pulmonary Artery Catheter (PAC) for patients of various ages, weights and heights. The calibration factor is functionally the dynamic aortic root diameter for typical patient of the input age, weight and height.

Stroke Volume

Stroke Volume

Heart Rate (HR)

Heart Rate is displayed on the CardioQ-ODM and CardioQ-ODM+ from Doppler based measurement. From the Doppler the heart beats per minute is calculated from the analysed waveform.

The monitor updates the heart rate display after each calculation period depending on the number of cycles set.

Cardiac Output (CO)

The CardioQ-ODM and CardioQ-ODM+ can calculate Cardiac Output in Doppler flow mode.

Cardiac Output is the volume of blood being pumped by the left ventricle in the time interval of one minute. The units of Cardiac Output are litres per minute (l/min). The CardioQ-ODM calculates the Cardiac Output based on the setting of ‘cycles for calculation’. If set at ‘every beat’ the individual Stroke Volume in millilitres of each beat is multiplied by the Heart Rate at that time and is displayed in litres per minute.

Cardiac Output = Stroke Volume x Heart Rate

Peak Velocity (PV)

Peak Velocity is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+ as the maximal velocity of the blood.

PV is an indicator of contractility and typical values change with age. The peak velocity of 20 year old may be 90 – 120 cm/s whereas at age 90 it may only be 30 – 60 cm/s. Thus a PV markedly below the typical expected value may be an indicator of increased afterload or decreased cardiac function. A higher than normal PV may be indicative of decreased afterload.

Minute Distance (MD)

Minute Distance is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. MD is simply the distance blood moves in one minute down the aorta.

Minute Distance = Stroke Distance x Heart Rate

Peak Velocity

Peak Velocity

Flow Time corrected (FTc)

Flow Time corrected is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. Flow Time (FT) is the duration of time of the flow from the left ventricle during systole.  Flow Time corrected (FTc) is Flow Time duration of blood flow in the aorta normalised to 60 beats/min using Bazett’s equation.

Corrected Flow Time

Corrected Flow Time

Typically FTc is one third of the cardiac cycle. When standardised to 60 beats/min one cycle is one second. FTc is then 0.33 seconds or 333 milliseconds.

Thus typical values for normally hydrated resting healthy individuals is 330 – 360 milliseconds. This can be used as an indicator of hypovolaemia.

FTc is inversely related to afterload/resistance and the most common cause of an increased afterload/resistance is hypovolaemia.  Other causes of increased afterload/resistance should be considered.  High FTc is usually seen in low afterload/resistance states such as the vasoactive effects of drugs and sepsis.

Flow Time to peak (FTp)

Flow Time to peak is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. Flow Time to peak is the time in milliseconds from the start of systole to the point of peak velocity. Flow Time to peak is when combined with Peak Velocity and Mean Acceleration, a parameter for evaluating cardiac contractility and the effects of preload and afterload.

Flow Time to Peak (FTp)

Flow Time to Peak (FTp)

Cardiac Index (CI)

The CardioQ-ODM and CardioQ-ODM+ can calculate Cardiac Index in Doppler flow mode.

Cardiac Index relates the Cardiac Output to body surface area (BSA), thus relating heart performance to the size of the individual. The unit of measurement is litres per minute per square metre (l/min/m2).

Cardiac Index = Cardiac Output/Body Surface Area.

Stroke Volume Index (SVI)

Stroke Volume Index is the amount of blood in millilitres pumped from the human heart every heart beat indexed for body surface area. Stroke Volume Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Stroke Volume Index relates the Stroke Volume to body surface area (BSA), thus relating heart performance to the size of the individual. The unit of measurement is millilitres per square metre (ml/m2).

Stroke Volume Index = Stroke Volume/Body Surface.

Stroke Volume Variation (SVV)

The CardioQ-ODM and CardioQ-ODM+ can calculate Stroke Volume Variation in Doppler flow.

Stroke Volume Variation is widely considered as a useful indicator of fluid responsiveness. The mechanism of generation of this parameter relates to the observation of variations in left ventricular ejection volumes (Stroke Volume).  It has been shown that return blood flow through the thorax is affected by the positive pressure of the ventilator.  As the ventilator cycles it creates varying periods of higher and lower flow. These fluctuations traverse the lung and are manifest as variations in stroke volume of the heart.

These variations can be detected as variations in flow and pressure. The CardioQ-ODM uses these variations in flow to calculate the percentage variation between the maximum stroke volume and the minimum.

The limitations of this parameter is that the patient must meet the following criteria: Fully mechanically ventilated, sinus rhythm, tidal volume ≥ 7-8 mL/kg and higher tidal volumes elicit higher variations. Increasing PEEP will result in higher variations. HR: Respiratory rate ratio ≥4. Changes in lung or chest compliance, or patient position and right ventricular dysfunction or  abdominal insufflation may affect readings.

Caution is advised and clinicians need to be aware of the particular ‘cut off’ or ‘grey zone’ threshold values for the technology being used and the limitations described in the literature.

Stroke Distance Variation (SDV)

Stroke Distance Variation is a linear mode only parameter and is an indicator of fluid responsiveness when patients are outside the nomogram range of the CardioQ-ODM (typically in bariatric surgery).

The mechanism of generation of this parameter is identical to that of Stroke Volume Variation and relates to the observation of variations in left ventricular ejection volumes (Stroke Volume) due to variations in ejection volumes.

The limitations of this parameter is that the patient must meet the following criteria: Fully mechanically ventilated, sinus rhythm, tidal volume ≥ 7-8 mL/kg and higher tidal volumes elicit higher variations. Increasing PEEP will result in higher variations. HR: Respiratory rate ratio ≥4. Changes in lung or chest compliance, or patient position and right ventricular dysfunction or  abdominal insufflation may affect readings.

Systemic Vascular Resistance (SVR)

Systemic Vascular Resistance can be calculated as a Doppler Flow Based Parameter.

Systemic Vascular Resistance is the resistance to blood flow due to the peripheral vascular system. The formula used in the CardioQ-ODM is as follows:

SVR = 80 (MAP-CVP)
CO

Where MAP is the Mean Arterial Pressure, CVP is the Central Venous Pressure and CO the Cardiac Output.

The Cardiac Output is automatically provided from the flow readings calculated from Stroke Volume and Heart Rate. The user is required to input the MAP and CVP from other sources. The monitor then provides the measurement continuously as the CO is derived.

Systemic Vascular Resistance Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Systemic Vascular Resistance Index (SVRI)

Systemic Vascular Resistance Index is the resistance to blood flow due to the peripheral vascular system indexed for patient body size. The formula uses the Body Surface Area as calculated from the input weight and height is as follows:

SVRI = SVR x BSA

Where BSA is the Body Surface Area.

The SVRI is automatically updated as SVR changes with CO calculated from the flow readings calculated from Stroke Volume and Heart Rate.

Delivered Oxygen (DO2)

Delivered Oxygen can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Delivered Oxygen is the amount of oxygen in the blood delivered to the body’s tissues. The CardioQ-ODM and CardioQ-ODM+ can calculate this parameter but require the user to input measurements of haemoglobin concentration and the saturated oxygen concentration. The Cardiac Output as calculated by the monitor is automatically updated as DO2 changes with CO calculated from the flow readings, the formula used is as follows:

DO2 = 1.34 x Hb x SaO2 x CO

Where Hb is the concentration of haemoglobin, SaO2 is the saturation of haemoglobin and the amount of dissolved oxygen all multiplied by the Cardiac Output (CO).

Delivered Oxygen Index (DO2I)

Delivered Oxygen Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Delivered Oxygen Index is the amount of oxygen in the blood delivered to the bodies tissues indexed for patient body size. The CardioQ-ODM and CardioQ-ODM+ can calculate this parameter but require the user to input measurements of haemoglobin concentration (Hb) and the saturated oxygen concentration (SaO2). The Body Surface Area (BSA) is calculated by the monitor from the input patient weight and height and this used to automatically updated as DO2 changes with CO calculated from the flow readings, the formula used is as follows:

DO2I = DO2
BSA

Pressure Based Parameters

Stroke Distance (SD)

Stroke Distance is a Doppler flow based parameter only. SD is simply the distance the blood ejected by the left ventricle travels down the aorta every beat. It is measured in centimeters per second. If the aorta approximates to a cylindrical pipe then the SD can be represented a series of cylinders of blood moving down the aorta as each pulse of the left ventricle propels them into the bodies arterial system.

Stroke Distance (SD)

Stroke Distance (SD)

The CardioQ-ODM is distinct from other devices in possessing the ability to calculate Stroke Volume and Cardiac Output from its own patient nomogram. The patient nomogram was created as a result of research by Prof. Mervyn Singer. The patient nomogram is a calibration of Stroke Distance against the total Cardiac Output as measured by a Pulmonary Artery Catheter (PAC) for patients of both genders and various races, ages, weights and heights.

SD is the basic parameter for IOFM and Stroke Volume (SV) is automatically calculated by the monitor. The patient’s age, weight and height are input during the monitor set up. This information accesses the nomogram which effectively provides the dynamic aortic root diameter.

SV = SD x Aortic Root Diameter

As a result ODM has been found to be equivalent in terms of accuracy to a PAC. However it is the precision of ODM in tracking change that is key to recognising how and why ODM guides Stroke Volume Optimisation (SVO) so effectively which has resulted in an unparalleled evidence base.

Stroke Volume (SV)

Stroke Volume is the amount of blood in millilitres pumped from the human heart every heart beat. It is the volume ejected from the left ventricle due to the contraction of the heart muscle which compresses the left ventricle. Stroke Volume can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

The CardioQ-ODM calculates Stroke Volume by multiplying the Stroke Distance by a constant accessed from the built in patient nomogram. The patient nomogram was created as a result of research by Prof. Mervyn Singer. The patient nomogram is a calibration of Stroke Distance against the total Cardiac Output as measured by a Pulmonary Artery Catheter (PAC) for patients of various ages, weights and heights. The calibration factor is functionally the dynamic aortic root diameter for typical patient of the input age, weight and height.

Stroke Volume

Stroke Volume

Heart Rate (HR)

Heart Rate is displayed on the CardioQ-ODM and CardioQ-ODM+ from Doppler based measurement. From the Doppler the heart beats per minute is calculated from the analysed waveform.

The monitor updates the heart rate display after each calculation period depending on the number of cycles set.

Cardiac Output (CO)

The CardioQ-ODM and CardioQ-ODM+ can calculate Cardiac Output in Doppler flow mode.

Cardiac Output is the volume of blood being pumped by the left ventricle in the time interval of one minute. The units of Cardiac Output are litres per minute (l/min). The CardioQ-ODM calculates the Cardiac Output based on the setting of ‘cycles for calculation’. If set at ‘every beat’ the individual Stroke Volume in millilitres of each beat is multiplied by the Heart Rate at that time and is displayed in litres per minute.

Cardiac Output = Stroke Volume x Heart Rate

Peak Velocity (PV)

Peak Velocity is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+ as the maximal velocity of the blood.

PV is an indicator of contractility and typical values change with age. The peak velocity of 20 year old may be 90 – 120 cm/s whereas at age 90 it may only be 30 – 60 cm/s. Thus a PV markedly below the typical expected value may be an indicator of increased afterload or decreased cardiac function. A higher than normal PV may be indicative of decreased afterload.

Minute Distance (MD)

Minute Distance is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. MD is simply the distance blood moves in one minute down the aorta.

Minute Distance = Stroke Distance x Heart Rate

Peak Velocity

Peak Velocity

Flow Time corrected (FTc)

Flow Time corrected is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. Flow Time (FT) is the duration of time of the flow from the left ventricle during systole.  Flow Time corrected (FTc) is Flow Time duration of blood flow in the aorta normalised to 60 beats/min using Bazett’s equation.

Corrected Flow Time

Corrected Flow Time

Typically FTc is one third of the cardiac cycle. When standardised to 60 beats/min one cycle is one second. FTc is then 0.33 seconds or 333 milliseconds.

Thus typical values for normally hydrated resting healthy individuals is 330 – 360 milliseconds. This can be used as an indicator of hypovolaemia.

FTc is inversely related to afterload/resistance and the most common cause of an increased afterload/resistance is hypovolaemia.  Other causes of increased afterload/resistance should be considered.  High FTc is usually seen in low afterload/resistance states such as the vasoactive effects of drugs and sepsis.

Flow Time to peak (FTp)

Flow Time to peak is a Doppler only parameter and is available on both the CardioQ-ODM and CardioQ-ODM+. Flow Time to peak is the time in milliseconds from the start of systole to the point of peak velocity. Flow Time to peak is when combined with Peak Velocity and Mean Acceleration, a parameter for evaluating cardiac contractility and the effects of preload and afterload.

Flow Time to Peak (FTp)

Flow Time to Peak (FTp)

Cardiac Index (CI)

The CardioQ-ODM and CardioQ-ODM+ can calculate Cardiac Index in Doppler flow mode.

Cardiac Index relates the Cardiac Output to body surface area (BSA), thus relating heart performance to the size of the individual. The unit of measurement is litres per minute per square metre (l/min/m2).

Cardiac Index = Cardiac Output/Body Surface Area.

Stroke Volume Index (SVI)

Stroke Volume Index is the amount of blood in millilitres pumped from the human heart every heart beat indexed for body surface area. Stroke Volume Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Stroke Volume Index relates the Stroke Volume to body surface area (BSA), thus relating heart performance to the size of the individual. The unit of measurement is millilitres per square metre (ml/m2).

Stroke Volume Index = Stroke Volume/Body Surface.

Stroke Volume Variation (SVV)

The CardioQ-ODM and CardioQ-ODM+ can calculate Stroke Volume Variation in Doppler flow.

Stroke Volume Variation is widely considered as a useful indicator of fluid responsiveness. The mechanism of generation of this parameter relates to the observation of variations in left ventricular ejection volumes (Stroke Volume).  It has been shown that return blood flow through the thorax is affected by the positive pressure of the ventilator.  As the ventilator cycles it creates varying periods of higher and lower flow. These fluctuations traverse the lung and are manifest as variations in stroke volume of the heart.

These variations can be detected as variations in flow and pressure. The CardioQ-ODM uses these variations in flow to calculate the percentage variation between the maximum stroke volume and the minimum.

The limitations of this parameter is that the patient must meet the following criteria: Fully mechanically ventilated, sinus rhythm, tidal volume ≥ 7-8 mL/kg and higher tidal volumes elicit higher variations. Increasing PEEP will result in higher variations. HR: Respiratory rate ratio ≥4. Changes in lung or chest compliance, or patient position and right ventricular dysfunction or  abdominal insufflation may affect readings.

Caution is advised and clinicians need to be aware of the particular ‘cut off’ or ‘grey zone’ threshold values for the technology being used and the limitations described in the literature.

Stroke Distance Variation (SDV)

Stroke Distance Variation is a linear mode only parameter and is an indicator of fluid responsiveness when patients are outside the nomogram range of the CardioQ-ODM (typically in bariatric surgery).

The mechanism of generation of this parameter is identical to that of Stroke Volume Variation and relates to the observation of variations in left ventricular ejection volumes (Stroke Volume) due to variations in ejection volumes.

The limitations of this parameter is that the patient must meet the following criteria: Fully mechanically ventilated, sinus rhythm, tidal volume ≥ 7-8 mL/kg and higher tidal volumes elicit higher variations. Increasing PEEP will result in higher variations. HR: Respiratory rate ratio ≥4. Changes in lung or chest compliance, or patient position and right ventricular dysfunction or  abdominal insufflation may affect readings.

Systemic Vascular Resistance (SVR)

Systemic Vascular Resistance can be calculated as a Doppler Flow Based Parameter.

Systemic Vascular Resistance is the resistance to blood flow due to the peripheral vascular system. The formula used in the CardioQ-ODM is as follows:

SVR = 80 (MAP-CVP)
CO

Where MAP is the Mean Arterial Pressure, CVP is the Central Venous Pressure and CO the Cardiac Output.

The Cardiac Output is automatically provided from the flow readings calculated from Stroke Volume and Heart Rate. The user is required to input the MAP and CVP from other sources. The monitor then provides the measurement continuously as the CO is derived.

Systemic Vascular Resistance Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Systemic Vascular Resistance Index (SVRI)

Systemic Vascular Resistance Index is the resistance to blood flow due to the peripheral vascular system indexed for patient body size. The formula uses the Body Surface Area as calculated from the input weight and height is as follows:

SVRI = SVR x BSA

Where BSA is the Body Surface Area.

The SVRI is automatically updated as SVR changes with CO calculated from the flow readings calculated from Stroke Volume and Heart Rate.

Delivered Oxygen (DO2)

Delivered Oxygen can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Delivered Oxygen is the amount of oxygen in the blood delivered to the body’s tissues. The CardioQ-ODM and CardioQ-ODM+ can calculate this parameter but require the user to input measurements of haemoglobin concentration and the saturated oxygen concentration. The Cardiac Output as calculated by the monitor is automatically updated as DO2 changes with CO calculated from the flow readings, the formula used is as follows:

DO2 = 1.34 x Hb x SaO2 x CO

Where Hb is the concentration of haemoglobin, SaO2 is the saturation of haemoglobin and the amount of dissolved oxygen all multiplied by the Cardiac Output (CO).

Delivered Oxygen Index (DO2I)

Delivered Oxygen Index can be calculated as a Doppler Flow Based Parameter by CardioQ-ODM and CardioQ-ODM+.

Delivered Oxygen Index is the amount of oxygen in the blood delivered to the bodies tissues indexed for patient body size. The CardioQ-ODM and CardioQ-ODM+ can calculate this parameter but require the user to input measurements of haemoglobin concentration (Hb) and the saturated oxygen concentration (SaO2). The Body Surface Area (BSA) is calculated by the monitor from the input patient weight and height and this used to automatically updated as DO2 changes with CO calculated from the flow readings, the formula used is as follows:

DO2I = DO2
BSA