Gas Embolism on a Chip: Mimicking Iatrogenicity at the Microscale

Gas embolism (GE) is a potentially life-threatening condition with difficult in vivo investigation. The physical nature of the initial stages of GE makes in vitro abiotic microfluidics valuable for phenomenological studies. A versatile microfluidic system was used to mimic the microscale iatrogenic GE during gastroscopy, laparoscopy, and hyperbaric therapy under three scenarios: gas transfer through perforated or non-perforated microvasculature, and via tissue supersaturation.

Polydimethylsiloxane devices mimicking microvascular geometries, with, or without injuries, hosted the flow of artificial blood. Localized gas pressures comparable to those used in gastroscopy, laparoscopy, and hyperbaric therapy were applied on microvasculature using air, carbon dioxide or /nitrogen to mimic microscale GE.

Air and carbon dioxide produced markedly different GE patterns. Air generated numerous small bubbles across the entire pressure range, and a distinct population of larger emboli at lower pressures. Conversely, carbon dioxide embolism occurred beyond a threshold pressure (23-58 mm Hg), but once initiated, complete blockage or continuous gas injection lasting tens of seconds occurred.

Air embolism may occur in injured microvasculature at pressures within the lower range encountered during gastroscopy. Carbon dioxide embolism requires higher pressures, but once triggered, it can result in high-volume gas entry during laparoscopy. High pressure gas-supersaturated tissues can act as gas 'reservoirs' prolonging GE therapy.

These findings underscore the risk of air GE in gastroscopy and the need for pressure and flowrate control; possible carbon dioxide GE during laparoscopy warrants further assessment; and the duration of gas clearance during GE therapy needs to be considered.