Transthoracic Echocardiography

OVERVIEW

• Increasing useful bedside test with increasing role in critical care
• position marker on right

SCANNING PLANES

(1) Parasternal Long Axis (PLAX)
(2) Parasternal Short Axis (PSAX)
(3) Apical 4 Chamber
(4) Subcostal

Parasternal Long Axis (PLAX)

• position marker to right shoulder
• transducer @ 2nd and 4th ICS to left of sternum
• best view and gives most information

Parasternal Short Axis (PSAX)

• keep transducer in same position on chest
• rotate 90 degrees so that position marker is towards left shoulder
• you will need to slow fan to apex of heart

Apical 4 Chamber View

• move transducer to apex
• keep position maker towards left shoulder
• helpful if patient can role 30 degrees to left

Subcostal

• place transducer below xiphoid process in transverse orientation
• push down
• a modified 4 chamber view can be seen

CLINICAL APPLICATIONS

Cardiac Arrest

• organised activity= good, no activity = bad
• use PALX: observe organised activity among valves and LV
• tamponade: fluid in pericardium
• PE: large RV
• hypovolaemia: empty LV
• confirmation of ventricular standstill assists in decision to stop CPR

Pericardial Effusion

• < 1cm posterior = small
• 1cm circumferential = large

Pericardial Tamponade

• diastolic collapse of RV
• LV collapse (late)
• IVC dilatation due to increased venous pressure

Shock

• hypovolaemic: small LV, hyperdynamic
• obstructive: dilated RV in PE, RV collapse in tamponade, IVC dilation
• distributive: hyperdynamic LV though good LV size
• cardiogenic: dilated LV, hypokinetic, IVC dilated

CVP Measurement

• view IVC as it passes diaphragm through liver
• sniff-test
  -> if > 50% collapse then CVP < 10mmHg -> if < 50% collapse then CVP > 10mmHg
  -> if IVC does not collapse then the IVC pressure is significantly elevated

Undifferentiated Hypotensive Examination

• looks for readily reversible causes of hypotension that can be detected on U/S
• 3 limited views: limited ECHO, RUQ for haemoperitoneum, short axis of aorta

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