This 36 year old presented with an isolated blunt head injury sustained whilst on a “big night out“. He required intubation and a FAST was performed to assess for any clinically undetected injury prior to RSI.
This is the LUQ view. What does it show?
Patient 2 – Left upper quadrant FAST
Describe and interpret these scans
Image 1: Left upper quadrant FAST view. A large rounded fluid filled structure is seen in the LUQ, with large amounts of echogenic debris. This is the appearance of a full stomach.
Image 2: Left upper quadrant FAST view: This is a different patient, but the appearance similar. Perhaps this patient had superior masticatory skills.
Full stomach. Big Mac, Fries and a Large Coke.
Free fluid tends to lie between other intra-abdominal organs and so has sharp angles where it fits between rounded structures. Here it lies within the stomach. The large echogenic floaty bits in this case are typical of food, but the appearance does vary.
You occasionally see free fluid with this food like appearance in the abdominal cavity post intestinal perforation (e.g. duodenal ulcer) or in the thoracic cavity when there has been oesophageal rupture into the thoracic cavity.
The risk of aspiration with RSI when there is an extremely full stomach is increased. Measures to reduce this risk as much as possible are warranted. Evidence is sparse but options include using cricoid pressure and intubating with the patient at 30 degrees head up.
Deliberately using ultrasound to assess the stomach volume prior to intubation has been described. Measuring the area of the gastric antrum with the patient supine and in the right lateral decubitus position is described. A cross-sectional view of the antrum is used (a sagittal view as the stomach crosses anterior to the aorta). The theory being that if there is a large amount of gastric content the antrum will be full in both positions, if there is a moderate amount of gastric content it will only be obvious in the right lateral decubitus position, and if the stomach is empty the antrum will be empty in both positions.
My more simplistic approach is to use a single LUQ FAST view, with the probe slightly caudal and angled more anteriorly when compared with the typical splenic view. If the stomach is full you usually see it using this window. I find the anterior approach in the supine patient is less reliable as air fills the anterior part of the stomach and the window to dependent intragastric fluid is obscured.