The RUSH exam can be thought of as the medical equivalent of the trauma FAST exam. RUSH stands for Rapid Ultrasound in Shock or Hypotension. Synthesizing the RUSH exam findings, can point to both a general classification of shock as well as specific causes of shock.
INDICATIONS
- Type of Shock
- Etiology of Shock / Hypotension
PREPARATION
The RUSH exam can be performed with a single probe. The phased array or cardiac probe is the most versatile. However, if needed a better view of the pleura can be obtained with the higher frequency linear probe. The large curvilnear probe will provide better imaging of abdominal structures – the aorta, upper quadrants and suprapubic views.
PROCEDURE / VIEWS
The following sequence will efficiently guide you through all of the RUSH views. You can use the HI MAP mnemonic to remember to look through the Heart, IVC, Morison’s (and the FAST exam views), the Aorta and then Pulmonary (pleura, lung consolidation, pleural effusions)
PATHOLOGY
Hypodynamic Heart
The hypodynamic heart in this parasternal long axis view, has a dilated LV with poor contractility. The aortic valve opening time is quite short. Clip courtesy of Danny Duque, MD.
Hyperdynamic Heart
This hyperdynamic heart is not fast but has a very high cardiac output with the LV walls slapping together with each beat. Clip courtesy of Rob Arntfield, MD.
Tamponade
Note the right ventricular diastolic collapse in this clip of a pericardial effusion. In the hypotensive patient, this is consistent with cardiac tamponade.
RV Strain
This parasternal short axis view demonstrates a very dilated right ventricle and a collapsed, d-shaped left ventricle. Another view that might be used to assess right ventricular function further is the apical 4 chamber view to assess for TAPSE. See the cardiac page for more.
Collapsing IVC
A small or dynamic IVC once thought to correlate with right heart pressures as a surrogate of a surrogate for fluid responsiveness, has better value in determining that there is no back pressure from an obstructive process like cardiac tamponade, pneumothorax or pulmonary embolism.
Intraperitoneal Free Fluid
The “M” in the HI MAP mnemonic reminds us to look through the abdomen for free fluid. If more than physiologic fluid is seen in the right upper quadrant, left upper quadrant or the pelvis, this suggest bleeding into the abdomen may be the etiology of hypotension. Further search for the source is indicated. Is there an ectopic pregnancy? Is there an aortic aneurysm rupture? Is there bowel injury after recent surgery or trauma?
Pelvic Free Fluid
Aortic Aneurysm
Aortic Dissection
If thoracic aortic dissection is present it can be seen in the descending thoracic aorta in the parasternal long axis view as seen here.
Dissection may be seen in the abdominal aorta as well – seen here in long axis.
Pneumothorax
Pneumonia
If the patient is in septic shock, the lung exam may reveal subpleural consolidations as seen here. Frequently there is also pleural effusion at the lung bases which is more easily seen on ultrasound than on chest x-ray.
Lung B-Lines (Acute Interstitial Syndrome)
Along with poor LV function on teh cardiac exam, multiple b-lines in multiple lung fields suggests acute interstitial syndrome. In the ED setting this is usually pulmonary edema due to acute decompensated heart failure and in the patient in extremis with Sympathetic Crashing Acute Pulmonary Edema (SCAPE).
TYPES OF SHOCK
Even when the RUSH exam does not uncover a specific diagnosis, putting together the findings of the exam can point to a specific classification of shock. For example the patient with a dilated hypocontractile LV, wtih b-lines and lung rockets in multiple lung fields and a dilated IVC, you might suspect cardiogenic shock and treat appropriately.
DOES MY PATIENT NEED MORE IV FLUID?
For a long time the IVC has been taught to be the arbiter of volume responsiveness. We know this is not a reliable marker and that a more important point may be volume tolerance. The FALLS protocol by Dr. Lichtenstein, suggest repeated lung sonography during fluid administration with the goal of stopping as soon as the first b-lines appear.
Phillippe Rola, an intensivist from Montreal who is a well recognized expert on venous congestion and volume assessment in the critically ill patient, suggests that in many critically ill paitents volume tolerance may be exceeded before volume responsiveness. Sometimes early pressor support is more important than the 8th liter of Lactated Ringer’s.
REFERENCES AND RESOURCES
- The RUSH Exam. Scott Weingart at emcrit.com
- SCAPE. emcrit.com
- Volume. Phil Rola at thinkingcriticalcare.com
- Sonoguide RUSH exam
- Core Ultrasound – 5 Min Sono on RUSH exam