Post-dive ultrasound detection of gas in the liver of rats and scuba divers

Abstract

In a previous study, we obtained histologic documentation of liver gas embolism in the rat model of rapid decompression. The aim of the study was to assess in the same model occurrence and time course of liver embolism using 2-D ultrasound imaging, and to explore by this means putative liver gas embolism in recreational scuba divers. Following 42 min compression at 7 ATA breathing air and 12 min decompression, eight surviving female rats were anesthetized and the liver imaged by ultrasound at 20 min intervals up to 120 min. A significant enhancement of echo signal was recorded from 60 to 120 min as compared to earlier post-decompression times. Enzymatic markers of liver damage (AST, ALT, and GGT) increased significantly at 24 h upon decompression. Twelve healthy experienced divers were studied basally and at 15-min intervals up to 60 min following a 30-min scuba dive at 30 msw depth. At 30 min upon surfacing echo images showed significant signal enhancement that progressed and reached plateau at 45 and 60 min. Total bilirubin at 24 h increased significantly (p = 0.02) with respect to basal values although within the reference range. In conclusion, 2-D ultrasound liver imaging allowed detection of gas embolism in the rat and defined the time course of gas accumulation. Its application to scuba divers revealed liver gas accumulation in all subjects in the absence of clear-cut evidence of liver damage or of any symptom. The clinical significance of our findings remains to be investigated.

Cecal metabolome fingerprint in a rat model of decompression sickness with neurological disorders

“…This observation poses the problem of the integrity of digestive function in the context of DCS. As it happens, liver disorders have already been mentioned in DCS in humans 27,28 and animals 19,29,30 .…”

Hyperbaric exposure in rodents with non-invasive imaging assessment of decompression bubbles: A scoping review protocol

“…VGE detection has been applied to various animal models including rats and mice [4]. The presence of VGE can be described using one of several grading scales that have been previously developed (Kisman-Masurel or Spencer for Doppler, Eftedal-Brubakk for echocardiography) [7][8][9].…”

“…Previous work has shown that higher VGE grades correlate with an increased risk of DCS, and a VGE grade of zero corresponds with low risk for DCS [10,11]. However, these VGE grades cannot be directly used as a surrogate endpoint for DCS outcome in dive trial studies aiming to test new decompression procedures [4]. Previous publications have used these scales to assess the risk associated with a certain dive profile, describe the impact of a certain treatment, and aid in tracking the onset of DCS in rats or mice [12][13][14].…”

“…Impacts of decompression-induced VGE can vary from skin irritation to central nervous system impairment or stroke-like symptoms [1]. Post decompression VGE and subsequent DCS injury can be seen in small animal models subjected to extreme dive profiles [4][5][6][7]. Rodent models allow for translational experimentation that provides valuable information to the nature of these bubbles without requiring human subjects to conduct high risk dives.…”