The FAST exam is considered the standard of care when treating a trauma patient in the ED. Ultrasound has the same potential to improve our care of patients with non-traumatic causes of shock and hypotension. However, unlike the trauma ultrasound exam, there is not a clear protocol or way of referring to ultrasound for medical patients in extremis. Recently, a few excellent articles have discussed protocols for sonography during resuscitation. Similarly, we have been using a protocol at our institution that allows the rapid diagnosis of shock patients.

·          Cause Protocol for Cardiac Arrest (Cardiac Arrest UltraSound Exam) (Resuscitation 2008;76, 198-206)

·          Ultrasound for Hypotension (Weekes AJ, Zapata RJ, Napolitano A. Emergency Medicine Practice 2007;9(11):1)

·          Focused echocardiographic evaluation during resuscitation  (Acad Emerg Med Volume 14 Issue 1 Page e1-e16, January 2007)

We refer to this protocol as the RUSH Exam. RUSH stands for Rapid Ultrasound for Shock and Hypotension. It is hoped that choosing this name will allow linking with the existing FAST exam as an additional mnemonic.  It encompasses the areas we feel are most crucial during the evaluation of the patient in shock.

The five components can be remembered by the acronym HI MAP:

Heart

IVC
Morison’s/Splenorenal windows with Hemothorax views

Aorta

Pneumothorax

The heart portion of the exam is to evaluate for pericardial tamponade, right ventricular failure, and a hyperdynamic vs. hypodynamic left ventricle.

Two views should be adequate:

The parasternal long view allows us to get an idea of the left ventricular function as well as evaluating for effusion. The four chamber view allows us to see the relative size of both ventricles.

Effusion/Tamponade

Obviously a moderate or larger effusion raises the possibility of pericardial tamponade. More savvy ultrasonographers can actually look for objective signs of tamponade as well, such as right atrial and ventricular collapse.

Pulmonary Embolism

If the right ventricle is >60% the size of the left, the possibility of right ventricular failure should be entertained. When the right ventricle is the same size or larger than the left, pulmonary embolism might be the cause of the patient’s shock state.

Cardiogenic Shock

A hypodynamic left ventricle (<30% change in size between systole and diastole) indicates some cardiogenic component to the shock state

Hypovolemia

A hyperdynamic  (>90% systolic closure) left ventricle usually indicates hypovolemia in the setting of good cardiac function.

The IVC Portion of the exam allows you to estimate the central venous pressure. While CVP is a poor marker of fluid status in most situations, when it is very low, fluids are probably indicated. Most studies of IVC ultrasound use the sub-xiphoid long axis view (shown in the diagram)

From Weekes et al., Ref. above

Using the IVC size and response to spontaneous inspiration (or to a lesser extent mechanical ventilation expiration), you can obtain an estimate of CVP. If the IVC collapses >50% in a shock patient, I would give fluids.

We are very familiar with these two views. Look at the bilateral diaphragm views as well to screen for hemothorax. If there is intraperitoneal fluid, consider ruptured viscus, bleeding from intraperitoneal organs, mesenteric ischemia, or AAA with intra-peritoneal rupture. Of course if there is fluid in the chest it is most likely pleural effusion or hemothorax.

If the Aorta is > 5 cm in the setting of shock, it is a ruptured AAA until proven otherwise. Remember to image above and below the renal vasculature as most, but not all AAAs are infrarenal.

Though more likely in trauma, tension pneumothorax can be a cause of shock in medical patients as well, especially if this was your first time trying a subclavian line. Scan in the anterior 3^rd intercostal space on both sides.

This entire exam can be completed in less than 2 minutes and it provides a wealth of information. I go in the order of HIMAP.

1.       Parasternal long and then 4 chamber cardiac views, with the general purpose or cardiac probe

2.       IVC view with the same probe

3.       If not already using it, switch to general purpose abdominal probe and scan morison’s and splenorenal views with hemothorax shots.

4.       Increase your depth and find the aorta above and below the renal artery.

5.       Switch to small parts, high frequency transducer and scan both sides of the chest for pneumothorax.

Right ventricular size bigger than left ventricle-consider PE D-Sign is paradoxical septal movement . normally lv is round, if septum flattens romf rv strain, it looks like a “D” instead

Underfilled RV with hypercontractile LV (kissing trabeculae)-hypovolemia

Wall motion abnormalities

Pericardial Effusion

Tamponade

No IVC collapse with sniff test

On PSL view, a real pericardial effusion will be between heart and descending aorta

Pneumothorax, add (seashore picts from ccm supplement article)

Measure ratio between RV and LV at end diastole 0.6-1.0 is moderate

>1.0 is severe

Akinesia of mid-free wall but normal motion at the apex (McConnel)

IVC

Assess if RA press is <10 or >10

IVC > 2cm without normal insp decrease (should decrease by half with gentle sniffing)

Small vena vava reliably excludes high RA

12% variation in IVC diameter with mech vent predicted response to fluid challenge

Max size is end inspiration min size is at end expiration