Extended Focused Assessment with Sonography for Trauma – eFAST
Author: Lynette Hassall DMU AMS MLI.
According to the Australasian College for Emergency Medicine (ACEM), clinician performed bedside ultrasound is a ‘limited, goal directed examination’, designed and used to answer ‘specific clinical questions’. (1)
The indications for performing a FAST or eFAST include:
It is quick to perform, and should not be used as a ‘stand-alone’ examination – it should be repeated at regular intervals to check the status of the patient.
The clinician performed eFAST scan is not intended to replace formal diagnostic ultrasound tests, nor is it designed to diagnose solid organ injury or other pathology.
The FAST scan should be documented, by saving images of the standard views, plus any additional images to document pathology.
If you cannot see an area clearly, you cannot comment on this part of the examination. The decision on treatment path for the patient is then made on your physical examination, whether the patient is stable or not, the results of other tests, and your clinical opinion. It does not rest alone on what the ultrasound shows.
The ACEM also recommend practical training courses, mentoring and a process of accreditation to ensure that the scans are being performed by clinicians who are competent in this technique.
Benefits of Performing eFAST:
The eFAST answers very simple clinical questions:
What constitutes a positive eFAST?
What next? – your clinical skills dictate course of action
The four abdominal views comprise:
|The ACEM recommends FOUR views of the abdomen, and then an extension of the examination to the pleura for the fifth.||
1. Choose an appropriate Transducer - To begin, choose either a Curved array or a Phased array.
The curved array will produce a wider near field of view, the phased array will produce a ‘pizza slice’ shaped image with a narrower near field, and wider far field of view
(also called curvilinear)
(particularly useful for intercostal views)
2. Enter the Patient Details in the machine
3. Choose an ‘Abdominal’ Preset
4. Choose the appropriate Frequency setting:
5. Choose the appropriate DEPTH setting – the area you are assessing should fill the screen.
6. Adjust the GAIN settings so that you do not obscure small pockets of fluid with a setting that is too bright – remember in Ultrasound you want to take a walk on the ‘Dark side’ of the Force and turn the gain down. 9if available, try using the AUTOGAIN function, but remember that you may still need to adjust the settings if the image on the screen requires it).
|The 'toe' of the transducer should be approximately at the level of the xiphoid process.
||Right side: Morrison's pouch|
a. The transducer is placed at approximately the mid axillary line.
b. Change your grip so that the transducer is held comfortably, close to the face of the transducer.
c. The marker end (top) of the transducer is placed at the level of the xiphisternum
d. The transducer is rotated so Xyphisternum that the non marker end is slightly anterior, parallel to the ribs, in the intercostal space.
e. From this position the beam is directed posteriorly toward the bed.
f. Optimize the image – appropriate depth and gain for best resolution
g. Slide the probe cephalad or caudal to obtain a window between the ribs to view Morisons Pouch
h. Note should be made of the normal mirror image artifact above the diaphragm – if this is absent a pleural effusion, or collapse and consolidation, is present in the lung Remember that we are interrogating a volume of tissue so the transducer should be held in place and the beam should be fanned from anterior to posterior.
i. Fluid may sit in the anterior recess of the subphrenic space so observe the potential space between anterior surface of the liver and anterior abdominal wall
j. This view is completed by sliding the transducer caudally to observe the lower pole of the right Kidney and the paracolic gutter.
The transducer is again placed at approximately the left mid axillary line, however, for this view the middle of the transducer should be placed at the level of the xiphisternum.
|The middle of the transducer should be approximately at the level of the xiphoid process.||Left side - Splenorenal angle
The transducer is next placed in midline in longitudinal (Sagittal) to view the suprapubic region.
Rotate transducer 90° to a transverse position.
||The resultant image|
||The resultant image
A subcostal (or subxiphoid) view of the heart is obtained next. Probe grip is important –hold the transducer close to the face so that you have control over the probe and it is less likely to slip.
Change to an ‘overhand’ grip on the transducer
Place the transducer in transverse position just below the xiphisternum.
|Subcostal pericardial probe placement.
|1. Pressure down toward the bed is used...||
2. and then the transducer is angled up towards the heart. Downward pressure on the probe is maintained.
This will result, sometimes, in the transducer being almost flat on the patients belly to obtain this view.
The transducer is angled toward the toward the patient's left shoulder in a ‘scooping’ motion.
We are attempting to look beneath the xiphisternum and view the subcostal window to the heart.
If you cannot obtain a view of the 4 chamber heart using the subcostal view you can try to obtain an intercostal, parasternal long axis view (see below) to identify pericardial fluid or tamponade.
|An intercostal, parasternal long axis view|
To complete the extended FAST, we assess the lung for pneumothorax.
Clinical Question? Is there normal movement of the pleura between the rib spaces?
What is a positive result? The lung is not seen to slide, and there are no comet tail artifacts seen, at one intercostal space OR at all intercostal spaces.
LINEAR ARRAY PROBE
|*In the presence of a pneumothorax, you will still see the white line, representing the interface between air and the pleura – you will not see the sliding movement, or the twinkling artifacts that occur with a normal lung.|
An image of each of the standard views should be documented, plus any extra images showing pathology.
As a minimum the images should be:
If performing the EFAST, also consider -
6. Lung Edge at the same position on both sides of the patient or with M-Mode showing Seashore sign (if available).
7. Video Clip of sliding lung edge may also be obtained.
8. ANY ADDITIONAL IMAGES NECESSARY TO SHOW PATHOLOGY
Is the patient stable or unstable? If the patient is positive and stable – consider other sources of the fluid – is the patient on Peritoneal Dialysis? Do they have Cirrhosis? Is the patient negative and stable? Repeat the scan at regular intervals. This technique is fast and repeatable – check again to see if you missed a small collection, or if a small collection is getting larger.
Remember this examination only allows you to state whether there is fluid or not – You cannot define whether there is solid organ injury using the protocol for eFAST. This is not what the test is for. If you are querying any solid injury the patient should be transported to the X-ray Dept for CT Scan or a formal diagnostic Ultrasound.
There are decision trees available which provide suggested logical steps for patient care, however any decision made regarding treatment or further testing is at the discretion of the treating physician, using all information available. One such algorithm is provided below, (adapted from Nevit Dilmen 2011)
1. ‘POLICY ON CREDENTIALLING FOR ED ULTRASONOGRAPHY: TRAUMA EXAMINATION AND SUSPECTED AAA’ http://www.acem.org.au/media/policies_and_guidelines/P22_Credentialling_for_E D_Ultrasonography.pdf Accessed 21 January 2009
2. Leech S ‘Life-saving Point-of-Care Ultrasound Applications’ Sonosite, Inc, Sonosite Institute for Training and Education, available from www.sonosite.com
3. Bedside Ultrasonography, Trauma Evaluation http://emedicine.medscape.com/article/104363-overview accessed 22 Jan 09
4. http://www.emedicine.com/med/topic1786.htm accessed 22 Jan 09
5. http://www.webmd.com/heart-disease/guide/pericardial-effusion accessed 22 Jan 09
6. ‘Practical Applications’ Sonosite Global Learning website http://sonosite.articulateglobal.com/Portal/Workspaces
7. Goudie, A ‘Ultrasound in Trauma – foolish fad or standard of care?’ Soundeffects Issue 4 2008 pp16-18
8. Gent, R; ‘Applied Physics and Technology of Diagnostic Ultrasound’ 1997 Milner Publishing ISBN 0 646 27601 8
9. Sanders, R; Winter, T; ‘Clinical Sonography A Practical Guide’ 2006 Lippincott Williams & Wilkins ISBN-10; 0781748690