Compare and contrast a focused cardiac ultrasound with a formal diagnostic transthoracic echocardiogram (TTE), using the following headings in your answer:
a) Indications (20% marks)
b) Assessments made (40% marks)
c) Limitations (40% marks)
Most candidates described the indications for a focused cardiac ultrasound, however, the indications for formal diagnostic TTE were less well described (very few candidates included stroke, arrhythmia, peripheral embolus).
The assessments of a focused cardiac ultrasound were generally well described although the assessments of TTE were less well described, and the windows and modes were infrequently described. The limitations of each study could have been better answered with only a few candidates including TTE cannot exclude IE, left atrial appendage clot, and PFO)
The difference between "indications" and "assessments made" is subtle, i.e. the candidates may not have appreciated that "windows and modes" were expected. Is a pericardial effusion an indication, or is it an assessment made of the pericardial space, and in that case, which window should you be mentioning (subxiphoid, parasternal, apical?) In short it is not clear what was expected from the answer, and this appears to be reflected in the marks, where 45% of the candidates scored poorly. It seems from the distribution of marks that the examiners probably did not want a lot of indications to be listed. Thus, in the suggested model answer below, for "indications" only pathologies or broad scenarios are listed, whereas "assessments made" include the specific game-changing findings or answered questions.
| Focused bedside TTE | Formal TTE | |
| Indications |
Cardiac arrest Pulmonary embolism Suspected tamponade Undifferentiated shock |
Stroke Cardiac ischaemia Heart failure Investigations for murmurs Stress testing Investigation of syncope and arrhythmias |
| Assessments |
Pericardial effusion Cardiac tamponade LV systolic function Volume status RV dilatation (PE) Cardiac activity during cardiac arrest |
LVOT obstruction Valvular abnormalities Aortic dissection Myocardial ischemia (i.e. regional wall motion abnormalities) RV systolic function Pulmonary hypertension Diastolic function assessment |
| Limitations |
Specific, not sensitive Usually done on smaller machines with poor resolution. Windows and probe orientation are not always standardised. Staff performing this assessment may be variably trained, increasing error. Trained staff may be unfamiliar with the limitations of the technique, and may underestimate its accuracy. Poor windows or views may result in inaccurate chamber size comparisons, leading to the wrong diagnosis. Defined scope of practice, limited to specific views (i.e. not a diagnostic investigation) |
Requires a skilled sonographer or TTE-trained accredited ICU staff. Time-consuming; may not be suitable for rapidly making decisions More difficult to perform serial assessments within a short timeframe. Otherwise static: a snapshot assessment in a dynamically changing ICU scenario. For many ICU patients, all classic views may not be possible. Not cost-effective (usually requires dedicated staff) |
| Limitations of both |
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