(Originally presented by Dr Andrea Jayendra and Dr Jiaqi Cai)

Pulmonary aspiration of gastric content is a serious complication of anaesthesia.

Ultrasound has been validated by numerous studies to detect the presence of gastric contents.

Scanning Technique

  • Patient position: right lateral
  • Probe: curved array
  • Scanning plane: sagittal or parasagittal
  • Probe position: epigastrium (standardise by identifying aorta/IVC/SMA/SMV)
  • Targets: gastric antrum with left lobe of liver anteriorly and pancreas posteriorly

EMPTY

  • Flat, collapsed, round (Bull’s eye)
  • No hypoechoic contents (or only small amounts)
  • Thick, prominent muscularis propiae

Clear Fluid

  • Round, distended antrum
  • Thin wall
  • Hypoechoic (milk or suspensions will be hypoechoic)
  • Fast wave peristalsis

Solid Food

  • Round, distended antrum
  • Thin wall
  • Hyper-echoic with heterogenous content (mixed with air)
  • Slow wave peristalsis

Proposed Algorithm

Calculating Estimated Gastric Volume 

  • Adults: Gastric Volume (mL) = 27.0 + 14.6 x CSA -1.28 x age 
  • Paediatrics: Volume (mL)  = -7.8 + (3.5 x CSA) + (0.127) x Age (in months) [upper limit normal fasting volume for children is 1.1-1.2mL/kg] 

Note: CSA is the cross sectional area in the right lateral position 

Useful Link:

Van de Putt & Perlas (2014) Ultrasound assessment of gastric content and volume. BJA 113(1): 12-22.

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