ECHO AND FOCUSED ECHO IN LIFE SUPPORT

Focused echo in life support (FELS) or basic focused cardiac ultrasound (FCU) utilises basic bedside echo views looking for important qualitative cardiac findings. These findings can be integrated with other PoCUS findings, and the patient clinical picture, in order to aid diagnosis, guide investigation, and improve targeted management. In general the focus of the examination should be answering a few specific binary questions:

1. Is there a pericardial effusion and the size (+/- Tamponade)

2. Qualitative LV and RV size and function

3. Determining fluid status (at extremes)

As well as qualitative echo, with appropriate training, some simple quantitative measures can be undertaken to help guide your cardiac assessment, and help define particular patterns of pathology.

AIMS

• Understand the anatomy

• Attain standard echo views

  • PLAX- parasternal long axis

  • PSAX- parasternal short axis

  • A4CH (extension views - A5CH/A2CH )

  • SUBCOSTAL and IVC

  • SUPRASTERNAL

• Identify normal qualitative echo findings

• Identify cardiac activity during CPR and in cardiac arrest

• Recognise and interpret potential abnormal findings and physiology

  • Qualitative assessment of structure and chamber sizes

  • Qualitative assessment of LV - size, function, contraction

  • Qualitative assessment of RV size and function

  • Identify a pericardial effusion and signs of tamponade

  • IVC assessment - size and variability

• Recognise Limitations of your focused cardiac assessment

• Appreciate some potential characteristic echo findings of different pathologies

  • Pericardial effusion and tamponade

  • Acute PE with RV strain

  • Impaired systolic LV cardiac function

  • Sepsis

  • Appreciate abnormal valve appearance (not function)

  • Help differentiate causes of shock

• Understand simple quantitative measures and limitations

  • LV systolic function - MV EPSS (end point septal separation), FS (fractional shortening)

  • RV systolic function- TAPSE (tricuspid annular plane systolic excursion)

  • IVC size and variation

• Integrate findings with clinical picture

indications

Introduction to Focused Cardiac Ultrasound (A/Prof Sam Orde - Nepean)

Basic focused cardiac ultrasound should focus on limited binary questions. The user should recognised their limitations in experience and the interpretation of images obtained. More detailed examination and interpretation of echo findings should be only carried out with appropriate supervision and credentialed training. Always discuss and show your images to a credentialed supervisor if there is clinical concern, or any abnormal or unexpected findings. Formal investigation/imaging should always be sought if there is any clinical concern.

Some general clinical indications:

• Cardiac arrest - assessment for cardiac activity

• Assess gross LV and RV size and function

• Assess for pericardial fluid and tamponade

• Help in the determination of volume assessment

• As part of a shock examination/determination of shock

• Help guide vasopressor and inotrope therapies

• Signs of RV strain in PE

LIMITATIONS

• This is not a formal or quantitative echo !

• Cardiac windows, positioning, body habitus and clinical condition

cardiac ultrasound probe and ORIeNtATION

The phased array/cardiac probe should be used for your cardiac ultrasound as it has the ideal parameters for attaining the desired views.

phased array PROBE

• Small foot print enabling positioning between intercostal spaces

• Wide field of view at depth and narrow superficially allowing interrogation of deep cardiac structures via a small ultrasound window.

• Medium to low frequency transducer for adequate penetration depth

PRESET AND ORIENTATION

A cardiac preset should be used, with the screen orientation marker being at the top right of the screen image.

BASIC CARDIAC VIEWS AND positioning

There are 5 basic cardiac views that should be obtained. Often one or more of these views may be difficult to obtain in different patients and scenarios.

Parasternal Long axis view (PLAX)

Parasternal Short axis view (PSAX)

Apical 4 Chamber view (A4CH)

Subcostal view (SUB)

Subcostal IVC view

The apical 4 chamber view can be extended to:

• Apical 5 chamber view (by slightly tilting the probe cephalad/tail to the bed) revealing the aortic outflow tract and aortic valve

• Apical 2 chamber view (by probe rotation anticlockwise approximately 90 degrees) providing a view of the LA and LV chamber with anterior and inferior walls

• Apical 3 chamber view (by rotation slightly further anticlockwise from the apical 2 chamber view) extends to include aortic valve and LV outflow tract, and shows the anteroseptal and posterior LV walls.

A sixth cardiac view is the suprasternal window which reveals the ascending and arch of the aorta.

Patient positioning

Positioning will depend on the patients ability tolerate movement and their ability to be placed more supine.

For parasternal and apical views ideally a patient should be positioned rolled towards their left side (left lateral decubitus), right arm by the side, and left hand placed on their head. The patient does not need to be completely supine.

For subcostal view the patient is spine ideally with their knees flexed up.

BASIC CARDIAC VIEW ACQUISITION

parasternal long axis view (plax)

At a parasternal location position the probe in the 3-4th intercostal space with the probe marker aimed at the patient’s right shoulder. The intercostal space will vary depending on the individual.

• Slide the probe within the intercostal space to attain a clean window

• Tilting the probe within the space to attain the view and avoid rib shadowing

• Align the probe marker with the patients right shoulder - rotate to gain an elongated view of the LV (usually the apex will be slightly obscured)

The PLAX view should be obtained with enough depth to visualise the structures deep to the descending thoracic aorta. This ensures visualisation of the potential posterior pericardial and pleural spaces to help exclude effusions.

RV - right ventricle outflow tract

LV- left ventricle

Ao- aorta and valve

LA - left atrium

Mitral valve:

• AML - anterior mitral valve leaflet

• PML - posterior mitral valve leaflet

Once an adequate view has been attained the depth can be adjusted to focus on the cardiac structures.

parasternal short axis view (PSAX)

At the probe location used to obtain the PLAX view the probe is rotated anticlockwise approximately 90 degrees so the probe marker is orientated to the patients L shoulder.

In the PSAX view there are four main levels of imaging to obtain as you fan/tilt from the Aortic valve down towards the LV apex tilting the tail of the probe towards the R shoulder.

1. Aortic valve level - Mercedes Benz sign of the aortic valve

2. Mitral valve level - Fish mouth of the mitral valve

3. Mid papillary muscle level

4. LV apex - often not fully visible

APICAL VIEWS (A4CH/A5CH/A2Ch)

The apical view is often difficult to attain, generally it is best gained with the patient in the left lateral decubitus position ( they do not have to be supine). In the clinical scenario positioning is often limited by the patients illness and potential distress.

The apical view is the most important view for doing more advanced haemodynamic assessments of cardiac and valvular function. It is also the best view to compare relative LV to RV size.

Probe position:

From the PSAX view the probe is moved down and lateral so that the transducer will interrogate from below the apex of the heart. In the left lateral decubitus position or in any supine position it is usually easiest to start the probe from the lateral chest wall near the bed in the 5-6th intercostal space (below the breast/mammary fold in a female).

• The probe marker should be orientated towards the patients left axilla.

• The depth should be increased from the parasternal views

• Place the probe in the 5-6th IC space near the bed

• Slide along the space medially until the apex is in view

• Tilt the tail of the probe towards the bed to open up the 4 chamber view

• Subtle rotation/tilt will be required too optimise the view

• Ideally the interventricular septum should be orientated in the vertical midline of the image

For the A5CH view, from the A4CH view tilt the tail of the probe towards the bed/feet so the probe face is at a more acute angle to the chest.

To attain the apical 2CH/3CH views from the A4CH position rotate anticlockwise 60-90 degrees orientating the probe marker between the L shoulder and mid clavicle.

The 2CH view shows the true anterior and inferior LV walls

The 3CH view is obtained be rotating slightly clockwise from the 2CH view. The 3CH view reveals the aortic outflow/ aortic valve. The LV posterior wall and anteroseptal walls are now in view.

SUPRASTERNAL VIEW

The suprasternal view the cardiac probe is placed in the suprasternal notch:

• Position the patients neck slightly extended and turn the head towards their left shoulder.

• Place the probe with marker at 12 o’clock, rotate slowly clockwise towards the left shoulder

The aortic arch should be visible variable amounts of the ascending and descending aorta will be visible.

The aorta can be assessed for visible dilation/aneurysm, dissection, thrombus, flow and coarctation.