Question 16

The following questions relate to targeted critical care transthoracic echocardiography (Level 1 haemodynamic assessment) performed in the ICU.

a)    In a patient with suspected pericardial tamponade:

i.    Which view on transthoracic echocardiography would you use to assess the heart and why?    (10% marks)

ii.    Describe three features of pericardial tamponade that you would expect to see in this view.    (30% marks)

b)    In a patient with a history of ischaemic heart disease who is cold, clammy and hypotensive, describe how you would assess left ventricular systolic function in the parasternal short axis (PSSA) view.    (30% marks)

c)    In a previously healthy patient with a traumatic leg amputation, describe how you would assess volume status in the subcostal view.    (30% marks)
 

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College answer

Not available.

Discussion

a)

i. Subxiphoid view is the single best view, if you could only choose one view:

  • It is available while CPR is in progress, 
  • It is convenient to perform this in a supine patient, and
  • The most dependent portion of the heart is nearest to your probe, and that is where the effusion is most likely to be

ii. Features of tamponade in this view:

  • Dilated inferior vena cava
  • Right atrial collapse in systole
  • Diastolic collapse of right atrium and right ventricle
  • Hepatic vein flow reversal
  • Septal "bounce"

Theoretically, one could also list "a visible pericardial effusion", and that would accurate, but would probably score no marks because of obviousness.

b) A patient with a history of ischaemic heart disease who is cold, clammy and hypotensive? Surely it could not be cardiogenic shock? It's hard to know why that extra sentence was added. Also, the parasternal short axis is specified. From Mitchell et al (2019):

  • Linear dimensions (change in the LV cavity size on M-mode)
  • Wall motion abnormalities, scanning from base to apex
  • Ejection fraction by biplane disk summation

Also, though they might not be assessing LV systolic function strictly speaking, the PSAX view gives you an assessment of the ventricular size and wall thickness. 

c) Volume assessment on the subcostal view could be performed using:

  • Chamber volumes (ie. qualitatively collapsed looking ventricles, "kissing walls")
  • Size of the IVC: <10mm diameter suggests that the patient will respond well to a fluid challenge, but overall the static diameter of the IVC is not especially predictive of anything (Desai & Garry, 2018)
  • Distensibility index of IVC, in mechanically ventilated patients: the percentage variation of the IVC during inspiration verses expiration. 18% variation is 90% sensitive (Barbier et al, 2004)
  • Collapsibility index of SVC, in spontaneously breathing patients: the percentage variation of the IVC during expiration divided by the maximum diameter.