Hypovolaemia Case Study

  • Case Study

    Meet Michael – a 68-year old man, who requires a right hemicolectomy.

    Michael

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  • Michael's haemodynamic status is monitored throughout surgery using oesophageal Doppler to measure central aortic blood flow.

    purpose statement
  • Patient during Surgery

    baseline SV

    Scenario: Patient’s clinical signs appear stable. However, while Cardiac Output/Index (CO/CI), Peak Velocity (PV), and Heart Rate (HR) may be at acceptable levels, Flow Time corrected to 60 beats/minute (FTc) is low (normal range in a resting healthy adult = 330-360 ms) and as such, Stroke Volume (SV) may be suboptimal for this patient.

    What would you choose to do: continue to monitor, or, add fluid?

  • Response to 200 ml Fluid Challenge

    The clinician felt that although the FTc had increased, it was still indicating an increased afterload/resistance. He chose to give a 200 ml rapid fluid challenge of less than 5 minutes duration.

    SV1
    baseline tn
    SV1 tn

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    In anaesthetised patients scheduled for elective surgery, it is common to present with a functional intravascular volume deficit.1

    Scenario: The greater than 10% increase in SV indicates that the patient is fluid responsive. The increase in other flow parameters is probably due to a reduction in afterload as less compensation is required for the drop in circulating blood volume.

    Would you repeat fluid challenge under these circumstances? Yes/No

    1 Bundgaard-Nielson et al. Acta Anaesthesiol Scand. 2010;54(4):464-9.

  • Response to 2nd Fluid Challenge

    The clinician decided to give a second 200 ml rapid fluid challenge, as FTc may increase above normal values in vasodilating situations.

    SV2
    baseline tn
    SV1 tn
    SV2 tn

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    Scenario: SV increased by more than 10% again (11%) indicating fluid responsiveness, but is SV now optimal?

    Note: it is always important to consider any underlying comorbidities when making decisions.

    Look at these parameters and consider whether you would continue to observe the patient or give a further 200ml fluid challenge.

  • Response to 3rd Fluid Challenge

    In this instance, the clinician chose to assess fluid response further and gave a third 200 ml rapid fluid challenge.

    Rationale: Flow is very sensitive to changes in circulating blood volume, whereas pressure often may respond more slowly.

    SV3
    baseline tn
    SV1 tn
    SV2 tn
    SV3 tn

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    Only slight increases were observed in flow parameters with the third fluid challenge.

    Do you consider SV to be optimal?

  • Clinical Decision

    As the patient was not responsive to fluid, indicated by an increase in SV of less than 10%, together with other acceptable parameters and general clinical assessment, the clinician decided to:

    • Reassess the patient after 15 minutes
    • Give more fluid only if other clinical signs of hypovolaemia emerged.
    10%
    • This 10% change is specific to oesophageal Doppler
    • It is based on Doppler technology's precision when measuring central blood flow
    • It was validated specifically with the ODM and no other device has a validated outcome benefit with this algorithm.(1)

    1 Singer. Curr Opin Crit Care 2009;15:244-8.

  • Patient Outcome

    The clinician felt that the low FTc probably indicated an increasing afterload/resistance. He chose to give a 200 ml rapid fluid challenge of less than 5 minutes duration.

    • The Doppler monitor was able to show a reduction in flow probably due to an increased afterload, where the most common cause is hypovolaemia (1,2,3)
    • The clinician was able to carefully and safely fluid optimize the SV with three fluid challenges
    • Doppler flow is the only technology to consistently show improved patient outcomes in surgery, because it offers great precision.

    This case study highlights some of the considerations required when evaluating fluid responsiveness:

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    1 Bundgaard-Nielson et al. Acta Anaesthesiol Scand. 2010;54(4):464-9.

    2 Singer and Bennett. Crit Care Med 1991;19:1132-7. 

    3 Singer et al. Crit Care Med 1991;19:1138-7.

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