What is the RUSH Protocol?
The RUSH (Rapid Ultrasound in SHock and Hypotension) protocol is a systematic bedside ultrasound examination designed to rapidly identify the etiology of undifferentiated shock by evaluating three key anatomic areas: the "Pump" (heart), "Tank" (volume status and fluid collections), and "Pipes" (major vessels). 1
Protocol Structure and Application
The RUSH exam follows a stepwise algorithmic approach to evaluate shock patients:
The Three Components:
1. Pump (Cardiac Assessment)
- Evaluate left ventricular function and contractility
- Assess for pericardial effusion/tamponade
- Identify right ventricular strain (suggesting pulmonary embolism)
- Detect valvular dysfunction
- Look for wall motion abnormalities suggesting acute coronary syndrome
2. Tank (Volume Status and Fluid Collections)
- Assess inferior vena cava (IVC) size and collapsibility to estimate volume status
- Perform thoracic examination for pleural effusions and pneumothorax
- Evaluate abdominal compartments for free fluid or hemorrhage
- Extended FAST examination when appropriate
3. Pipes (Vascular Assessment)
- Examine the abdominal aorta for aneurysm or dissection
- Assess for deep vein thrombosis in lower extremities
- Evaluate major vessel integrity
Clinical Performance and Accuracy
The protocol demonstrates strong diagnostic reliability when performed by trained emergency physicians. Studies show a Kappa index of 0.7-0.84, reflecting substantial to almost perfect agreement between RUSH findings and final clinical diagnosis 2, 3, 4. The examination can typically be completed within 11.5 minutes in emergency settings 5.
Diagnostic Performance by Shock Type:
- Hypovolemic and Obstructive Shock: Sensitivity of 100%, NPV above 97% - excellent for ruling out these etiologies 2, 3
- Cardiogenic Shock: All reliability indices above 90% 3
- Distributive/Mixed Shock: PPV of 100% but lower sensitivity 2, 3
Guideline Support and Recommendations
Current critical care guidelines strongly recommend bedside cardiac ultrasound (BCU) for all patients with hemodynamic instability to identify underlying treatable causes and guide fluid resuscitation (Grade 1B recommendation) 6. The guidelines emphasize that BCU effectively identifies mechanical etiologies including valve dysfunction, pulmonary embolism, tamponade, and aortic dissection, allowing clinicians to narrow the differential diagnosis and decrease time to diagnosis in patients with undifferentiated hypotension 6.
The 2025 Society of Critical Care Medicine guidelines acknowledge that while robust outcome data remain limited, CCUS (critical care ultrasonography) is conditionally recommended due to minimal adverse events and superior safety compared to invasive alternatives like pulmonary artery catheters 7.
Key Clinical Advantages:
- Rapid execution: Designed to be performed in under 2 minutes for experienced providers 8
- Point-of-care decision making: Provides real-time anatomic and physiologic data 1
- Differentiates shock types: Helps distinguish between hypovolemic, obstructive, cardiogenic, and distributive shock 9
- Guides immediate interventions: Informs fluid resuscitation decisions and identifies life-threatening conditions requiring urgent intervention 6
Important Caveats:
Ultrasonography is highly user-dependent - accuracy relies on adequate training and experience 9. The protocol is prone to error in unskilled hands 7. Emergency physicians and advanced practice providers should receive formal education in the RUSH protocol before implementation 9.
RUSH is one component of clinical assessment - it supplements but does not replace clinical examination and should be integrated with patient history and other diagnostic modalities 7. The protocol works best for ruling out specific shock etiologies rather than definitively confirming all types 2, 3.
The examination maintains accuracy even in challenging environments - recent data shows paramedics can perform RUSH with handheld devices in moving ambulances without significant loss of diagnostic accuracy 10, and it has proven feasible in low-resource settings 5.