(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.