What are the key clinical questions about haemodynamics that ultrasound can answer?

@icmteaching, @wilkinsonjonny and I are going to take you through the 10 most important…

starting with...

Q1. Is stroke volume abnormal?

#FUSIC #echofirst #POCUS #ultrasound #haemodynamics
Despite shock being such an important diagnosis, intensive care clinicians are rubbish at detecting a low or high cardiac output (CO) clinically.

Sensitivity of detecting cardiac index (CI) < 2 clinically in this study was 0!

From an apical 5- or 3-chamber view we can use PW Doppler to assess the velocity time integral (VTI) in the LVOT to determine blood flow.

Essentially, LVOT VTI is the average distance travelled by ejected blood during one contraction...

It is also known as stroke distance.
LVOT VTI can be combined with LVOT diameter measurement to calculate SV.

Incorrect measurement of LVOT Diam can significantly alter the result as any error is squared.

LVOT Diam hardly changes during the cycle, so measurement of VTI only is a useful surrogate for trends in SV
To obtain an optimal trace, the PW sample box should be placed at the level of the AV and then gradually moved back into the LVOT, past the ‘zone of acceleration’ immediately before the valve, until a clear trace is obtained. See @BSEcho guidance here 👇 doi.org/10.1530/ERP-20…
LVOT VTI & SV are affected by:

Preload (volume status, sepsis, mechanical ventilation etc)
Afterload (sepsis, pressors)
Contractility (inotropes)
LV chamber size (remodelling)
Valvular compromise (MR, SAM etc)

LVEF depends on all these factors, not only LV systolic function!
Two hearts could have the same SV, while one is dilated & chronically impaired (⬇️ LVEF) and the other acutely underfilled and hyperdynamic (⬆️ LVEF).

In acute, severe MR, a normal ventricle should appear hyperdynamic, so a normal SV, LV size and LVEF indicates LV impairment!
This is why assessment of LV systolic function in ICU should include a visual EF + measurement of systolic longitudinal function (MAPSE, TDI S') and forward flow (SV), all interpreted in the context of any reverse flow (MR) and loading conditions.

Clinical integration is key!
Guidelines for performing a complete haemodynamic exam can be found here bit.ly/3gxUvHh

Credit to @ICS_updates for running the #FUSIC acreditation programme, and @PARADicmSHIFT for this animation
Read the FUSIC HD paper here doi.org/10.1177%2F1751…
Our next question is all about SV responsiveness. So stay tuned folks!

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