Deltex Medical > Education > Decision Tree
Overview of the Decision Tree

At the heart of ODM+ is Deltex’s oesophageal Doppler monitoring technology, now supplemented by Pulse Pressure Wave Analysis (PPWA) and High Definition Impedance Cardiography (HD-ICG). The combination of best-in-class modes make the ODM+ system the most versatile fluid management tool for all haemodynamic monitoring requirements across the hospital environment.

This page focuses oesophageal Doppler monitoring, an extremely precise, yet relatively non-invasive system for measuring cardiac output. Specifically it provides  a rational approach to using Doppler flow-based measurements to guide therapy. The Decision Tree is the result of a review of the available evidence by an expert panel of senior clinicians.Importantly it considers patients in both perioperative and critical care settings.

Clinical background

Oesophageal Doppler monitoring was initially developed as a less invasive alternative to the pulmonary artery catheter. However, from its early inception it was recognised that the technology is uniquely adept at driving flow-based treatment algorithms. Doppler-guided fluid management protocols have been proven to improve outcomes in a variety of patient groups.

Several clinical outcome studies have shown Doppler-guided stroke volume optimisation to be beneficial to patients. It is also clear that both excessive fluid volumes and inadequate volume are extremely detrimental to patient outcome. The decision tree is a consolidation of this evidence base and a useful guide to the use of vasoactive and inotropic interventions as part of a global haemodynamic protocol.


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Using the Decision Tree

Navigation is by a series of Yes/No boxes. Commands are in blue boxes and questions are in grey boxes. Please note that caveats are presented which may lead to an alternative pathway. Caveats are in a red box with red pathways. Caveats should be ignored if inappropriate to the patient.

A good understanding of cardiovascular physiology is important. Ensure optimal focus is obtained before interpretation of data.

Visit the Decision Tree website:

Trigger Points and Concerns

The decision tree was developed to be used in conjunction with flow measurements using the Oesophageal Doppler Monitor.

A good understanding of cardiovascular physiology is essential, including preload, afterload and contractility. Always ensure optimal focus of the Doppler probe is achieved before analysing the data.

NOTE – These trigger points and concerns:​

        • Should not be assessed in isolation.
        • Are not the same as physiological targets
        • Are indicative and not absolute
        • Are not prioritised

Primary Clinical Indicators

        • Hypotension: e.g. Systolic < 100 mmHg, MAP < 60 -70 mmHg or a clinically significant drop in MAP – e.g. 30 – 40 mmHg from assumed ‘normal’ or baseline
        • Tachycardia: e.g. > 90 bpm
        • Oliguria: < 0.5 ml/kg/h
        • Low Cardiac Output State ​​

Flow Indicators

        •  Reduced FTc: < 330 ms or considered low for clinical condition e.g. any high resistant state
        •  Low Cardiac Output: significantly below ‘normal’ e.g. CO < 4– 6 L, CI < 2.5 L/min/m​²
        •  Low Stroke Volume: significantly below ‘normal’ e.g. SV < 50 – 70 ml, SVI < 30 ml

Supplementary Clinical Indicators

        •  Hypertension: e.g. Systolic > 180 mmHg or > 30 – 40 mmHg above baseline
        •  Lactate: > 2 mmol/L
        •  Base Excess: -3 or +3 mEq/L​
        •  Peripheral Shutdown: – Looks ‘unwell’ e.g. pale, sweaty or a clinical picture of poor perfusion
        •  SaO2: < 93% or having to increase FiO2 by 20% to maintain sats.
        •  ​Low ScVO2: < 65 – 70%
        •  Reduced Consciousness Level: any deterioration rather than a score​


        • Temperature
        •  DO2
        •  CVP
        •  SVR
        •  ​SVV/PPV

For further information please contact us.