Gastric Point-of-care Ultrasound (POCUS)

Reviewed and revised 16 February 2020; peer reviewed by Dr Chris Nickson

OVERVIEW

Gastric POCUS has an emerging and controversial role in assessing peri-procedural aspiration risk prior to the induction of anaesthesia

• Aspiration was responsible for 50% of anaesthesia related deaths (8 of the 16 total reported deaths) in the Royal College of Anaesthetists The Difficult Airway Society 4th National Audit Project (NAP4) (Cook, Woodall, and Frerk, 2011). In addition, 23% of all cases reported to NAP4 involved aspiration as a primary or secondary contributor to morbidity.
• Reliable methods for assessing gastric contents are currently lacking

INDICATIONS

Objective assessment of pre-operative gastric contents in the setting of

• Unreliable fasting history (eg: trauma, poor historian)
• Potential for delayed gastric emptying (eg: opioid therapy, pregnancy, trauma, underlying gastrointestinal disease, diabetes mellitus)

TECHNIQUE

Technique for risk stratification:

• Stomach Contents
  • Gastric antrum is most sensitive location for identification of stomach contents
  • Supine patient
  • Scan epigastrium in sagittal plane using curved low frequency (2-5 mHz) probe for adults or linear high frequency (5-12 mHz) probe for paediatric patients
  • Roll patient to right lateral position and repeat imaging 
• Stomach Volume
  • While in right lateral position, estimate antral cross-sectional area and refer to predictive table, or alternatively use mathematical model below to determine volume. 
    • Estimated Volume = 27 + 14.6 x right lateral decubitus cross-sectional area – 1.28 x age (in years) 
  • Acceptable volume is ≤1.5ml/kg in non-pregnant adult

EVIDENCE

Current evidence is limited

• A systematic review by Van de Putte and Perlas (2014) identified 17 studies of gastric ultrasound for the assessment of gastric contents and volume

Kruisselbrink et al, 2019

• 80 ultrasound study sessions performed by blinded sonographers, with 40 healthy volunteers, randomised to either fasting or ingesting a standardised volume of clear liquid or solid food
• For identification of a full stomach (defined as presence of solid food or >1.5mL/kg of clear fluid), sensitivity was 100% (95% CI 93-100 percent) and specificity was 98% (95% CI 95-100 percent)

References and Links

LITFL

• CCC — Peri-procedural fasting

Journal articles

• Cook T,  Woodall N, Frerk C. 4th National Audit Project (NAP 4): Major Complications of Airway Management in the United Kingdom Report and Findings—Chapter 19. Aspiration of gastric contents and of blood. 2011 The Royal College of Anaesthetists and The Difficult Airway Society. [report downloads]
• Zimmerman J, Birgenheier N. Overview of perioperative uses of ultrasound. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed December 2019.) [website]
• Kruisselbrink R, Gharapetian A, Chaparro LE, Ami N, Richler D, Chan VWS et al. Diagnostic accuracy of point-of-care gastric ultrasound. Anesth Analg 2019; 128(1):88-95. [article]
• Van de Putte P, Perlas A. Ultrasound assessment of gastric content and volume. Br J Anaesth 2014; 113(1):12. [article]
• Robinson M, Davidson A. Aspiration under anaesthesia: risk assessment and decision-making. Continuing Education in Anaesthesia Critical Care & Pain 2014; 14(4):171-175. [article]

FOAM and web resources

• Gastricultrasound.org