RUSH ("Rapid Ultrasound for Shock") Protocol

Introduction

  • One of multiple described ultrasound protocols for evaluation of patients presenting to ED with undifferentiated hypotension
  • Provides a framework for rapid and systematic evaluation of cause of hypotension
  • Three categories
    • Pump – Cardiac evaluation
    • Tank – Volume status
    • Pipes – Vascular system
  • Equipment: Ultrasound machine with phased array (3.5-5MHz) and linear probes (7.5 – 10MHz)

Pump: Cardiac Evaluation

Determine the Presence of Pericardial Effusion

  • Appears as anechoic fluid surrounding the heart
  • Possible pitfall is to misdiagnose an effusion
    • Distinguish pericardial fat pad from pericardial effusion by mild echogenicity of fat pad and know that fat pads tend to move in concert with myocardium
    • Pericardial effusion appears anterior to descending aorta in parasternal long axis view as opposed to pleural effusion that appears posterior to descending thoracic aorta
  • Look for evidence of cardiac tamponade
    • Right ventricle and atrium may have diastolic collapse, plethoric IVC

Assess LV Contractility

  • Assessing LV ejection fraction – hyperdynamic, normal, moderately or severely decreased
    • Visual assessment by emergency physicians generally accurate
    • E point Septal Separation (EPSS; distance of E wave of anterior MV leaflet from septum in M mode) or calculating fractional shortening may allow more objective assessment

Assess RV Strain

  • Normal RV/LV ratio is 0.6:1
  • RV/LV ratio >0.9 suggestive of right heart strain, may suggest acute pulmonary embolism
  • Parasternal short axis may underestimate size of RV, use other views
  • Bowing of septum into LV suggests elevated right heart pressure (“D sign”)
  • Thickened RV wall suggests chronic right heart strain (e.g. pulmonary htn, COPD)

Tank: Volume Status

“Tank Fullness” – IVC Evaluation

  • Measure IVC 2cm distal from cavoatrial junction or immediately superior to insertion of hepatic veins
  • IVC diameter < 2cm with >50% collapse correlates with CVP < 5mmHg and suggests fluid responsiveness
  • IVC diameter > 2cm with < 50% collapse correlates with CVP > 10mmHG, argues against fluid responsiveness

“Tank Leakiness” – FAST Exam and Lung Ultrasound

  • Evaluates peritoneal compartment for free fluid
  • In non-traumatic setting and depending on the clinical scenario, presence of free fluid may suggest ruptured AAA, ectopic pregnancy, or ruptured hemorrhagic cyst

“Tank Overload” – Assessment for Pleural Effusion and Pulmonary Edema

  • As part of the FAST exam, the views of the RUQ and LUQ should include views above the diaphragm to assess the presence of pleural effusion
  • To assess for pulmonary edema, use the phased array probe in the anterolateral chest, between the 2nd and 5th intercostal spaces
    • Presence of multiple B lines (vertical reverberation artifact extending from the pleural line to the far field) suggests pulmonary edema
    • Finding of poor LV contractility, multiple B lines, and plethoric IVC is suggestive of cardiogenic shock

“Tank Compromise” – Assessment for Pneumothorax as Cause of Obstructive Shock

  • Place linear probe in mid-clavicular line between 3rd and 5th intercostal spaces
  • Assess for normal lung sliding or “waves on a beach” pattern on M mode
  • Lack of lung sliding or “bar code” sign is suggestive of pneumothorax

Pipes: Circulatory System

Aorta (AAA)

  • Measurement of the aorta should begin at epigastrium and extend distally to bifurcation of iliac arteries
  • Measurement of the aorta should be from outer wall to outer wall; abnormal if >3cm
  • In a hypotensive patient with AAA > 3cm, acute rupture should be considered

Aortic Dissection

  • Thoracic aortic dissection may be detected on parasternal long axis view with aortic root measuring > 3.8cm
    • Aortic root best seen in parasternal long axis. You may see an intimal flap if dissecting

“Clogged Pipes” – Deep Vein Thrombosis

  • Compression US of lower extremities using linear probe
  • Should be performed at the level of the common femoral vein to the bifurcation of the deep and superficial femoral veins and at the popliteal vein extending to the trifurcation of the calf veins

The RUSH exam provides a framework for approaching the non-traumatic patient in the emergency department presenting with undifferentiated hypotension.  While the exam generally should start with the cardiac exam, the clinician’s judgment and clinical context should guide the progression through the different components of the exam.

References

  • Weingart SD, Duque D, Nelson B. Rapid ultrasound for shock and hypotension (RUSH-HIMAPP). 2009; http://emedhome.com/.
  • Perera P, Mailhot T, Riley D, Mandavia D. The RUSH exam: rapid ultrasound in shock in the evaluation of the critically ill. Emergency Medicine Clinics of North America. 2010; 28(1): 29–56.
  • Seif D, Perera P, Mailhot T, Riley D, Mandavia D. Bedside ultrasound in resuscitation and the rapid ultrasound in shock protocol. Crit Care Res Pract. 2012; doi: 10.1155/2012/503254.
  • Liteplo A, Noble V, Atkinson P. My patient has no blood pressure: point of care ultrasound in the hypotensive patient-FAST and RELIABLE. Ultrasound. 2012; 20: 64–68.
  • Moore CL, Rose GA, Tayal VS, et al.  Determination of left ventricular function by emergency physician echocardiography of hypotensive patients.  Academic Emergency Medicine. 2002; 9(3): 189-193
Edited by Adaira Landry, MD

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