Chandra – RUSH Ultrasound

Amitabh Chandra, MD, Assistant Professor of Emergency Medicine at University of Maryland SOM and Chief of Emergency Medicine at UMMC – Midtown Campus, presents the weekly multi-departmental critical care fellows’ lecture on “RUSH ultrasound exam.”

Lecture Summary by Dr. Jason Nam         

Note: lecture has excellent videos and animations which highlight what one should look for while doing RUSH.

History of RUSH

Why? RUSH exam allows one to break up shock in four major categories: cardiogenic, hypovolemic, obstructive, or distributive. How to better make differential dx.

• RUSH– rapid ultrasound for shock/hypotension
  • For patients with unknown cause of shock
  • Helps identify type of shock and guide therapy
• Shock= low MAP; you want a high MAP
• How to do RUSH: HIMAP– heart, IVC, Morrison’s Pouch (FAST), Aorta, and pulmonary

How RUSH allows you to eval for Shock.

• Cardiogenic- pump and valve failure
• Hypovolemic- hemorrhage and dehydration
• Obstructive- tamponade, pneumothorax, and massive PE
• Distributive- sepsis, anaphylaxis, and neurogenic
  • Not directly detected by ultrasound
  • Supported by ultrasound

Pump

• Focus on cardiogenic and hypovolemic shock, obstructive shock. Review on 4 cardiac exam windows.
  • Parasternal long axis- R heart not visualized, good for EF, can assess for valve dysfunction; parasternal short axis- see more of L heart, better for EF.
  • EF- visual estimation. Comparable accuracy to complex quantitative methods. However, this might be easier technique. Use visual estimation. Categorize broadly as very low, low, normal, or hyper-dynamic.
  • Longitudinal EF pitfall- the beam must be centered to visualize EF accurately. Visual estimation most suited for ED. Steep but short learning curve.
• Tamponade- look for pericardial effusion, R atrial collapse during systole, or R ventricle collapse during diastole. No effusion= no tamponade.

• Pulmonary embolism- Massive or sub-massive PE causes RV outflow obstruction. Not always common to see actual thrombus. Absence of findings do not exclude PE. Ventricular ratio- measure diastolic width at base of ventricles. Beam alignment for VR. The RV is a complex 3-D chamber. TAPSE- Tricuspid Annular Plane Systolic Excursion. Place M-mode line through junction of TV and RV free wall. Measure TV excursion. Abnormal septal movement- D sign. TAPSE > 16 mm = normal. McConnell’s Sign- hypokinesis of RV free wall.

Tank

• A naturally compliant vessel so measurements grossly estimate CVP. IVC can dilate under mechanical inspiration. Two most common calculations. Caval or collapsibility index in spontaneous breathing patient. Subcostal longitudinal view. 2-3 cm inferior to R atrium. Measure at end expiration and inspiration. Use cine scroll to select exact images.
• An important IVC measurement is Caval Index= 100 (Exp-Insp)/Exp. Pitfalls- IVC collapses more with a strong inspiration or sniff. Measure IVC during normal respirations.
• Distensibility Index (for MV patients) = 100 (Insp-Exp)/Exp. 18% or higher is volume down. Pitfall is that inhibited IVC flow will increase IVC size.

Review on FAST Exam

• Looks for free fluid pools in dependent areas of abdomen. RUQ- Morrison’s Pouch. LUQ is splenorenal area. One pelvic area each for male and female. There are no fluid stripes in pelvis. Can be especially tricky in pelvis. 
• Can easily confuse IVC vs Aorta. Follow the take-off from celiac trunk for aorta. Straight regular caliber in aorta.
• To assess for pneumothorax, orient probe longitudinally and look for pleural sliding. M-mode: seashore vs. barcode sign. Can’t diagnose tension PTX by US. Tension and non-tension look same on US. Look for B-lines as sign for pulmonary edema. 3 or more in rib space is pathologic.
• Sepsis can be tricky because they can present initially with high EF. Variable findings in RUSH exam.
• Cases- interesting case of splenic rupture as complication of colonoscopy.

Suggested Reading

• Perera, Phillips, et al. “The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll.” Emergency Medicine Clinics 28.1 (2010): 29-56. https://www.sciencedirect.com/science/article/abs/pii/S0733862709001175?via%3Dihub

Uploaded by Sami Safadi, MD