Diagnostic Strategy
The findings from the RUSH protocol assessment can be used to narrow down the differential diagnosis.
| Hypovolaemic Shock | Cardiogenic Shock | Obstructive Shock | Distributive Shock | |
| Pump | Small underfilled chambers give the LV kissing sign Hyperdynamic state | Dilated heart Reduced global contractility Reduced ejection fraction | Evidence of tamponade RV strain and dilatation Thrombus in-situ | Hyperdynamic heart in early sepsis Hypodynamic in late sepsis |
| Tank | Flat IVC with high collapsibility index Third spacing with pleural or peritoneal fluid present | Distended IVC with low collapsibility index B lines, pleural effusions or peritoneal fluid | Distended IVC with low collapsibility index Absent lung sliding and barcode sign (pneumothorax) | Normal or flat IVC in early sepsis with high collapsibility index Peritoneal or pleural fluid as source of sepsis |
| Pipes | Aneurysm Dissection | Normal | DVT | Normal |
Table 1- Rush protocol diagnostic strategy, adapted from Perera, P. et al. The RUSH Exam.
IFEM approach (SHOc)
Performing the full RUSH protocol can take time. To help streamline the bedside scan, the International Federation for Emergency Medicine (IFEM) has produced a consensus statement for Sonography in Hypotension and Cardiac arrest (SHoC).
A review of international data found LV dynamic changes, IVC abnormalities and pericardial effusion were the most common findings on ultrasound in patients who presented with undifferentiated shock.
| Finding | Frequency |
| LV dynamic change | 43% |
| IVC abnormalities | 27% |
| Pericardial effusion | 16% |
| Pleural fluid | 8% |
| Peritoneal fluid | 5% |
| AAA | 2% |
Table 2- International Data for Prevalence of Findings in Undifferentiated Hypotension, adapted from Milne, James et al.
The SHoC statement recommends the 4F approach to assess:
- Fluid
- Form
- Function
- Filling
Summary target style graphic for the combined SHoC protocols: Atkinson P et al: IFEM SHoC Protocol Consensus Statement
The 4 Fs can be assessed with the 4 core views:
- Subcostal cardiac view – assess for pericardial fluid, cardiac form and ventricular function.
- PLAX cardiac view – assess for pericardial fluid, cardiac form and ventricular function.
- Apical lung views – assess for pleural fluid and B-lines for filling status
- IVC view – assess filling status
Supplementary views which provide further information are the PSAX and A4C cardiac views.
Additional views are then performed when clinically indicated, including AAA, FAST and DVT imaging.
Learning bite
Performing the four core views (subcostal cardiac view, PLAX cardiac view, apical lung views and IVC imaging) would cover more than 80% of the pathologies seen in patients with shock.