Establishment of Ultrasound Evaluation of Bubble Load in Rabbit Model with Decompression Sickness

IntroductionTo establish a decompression sickness (DCS) model in New Zealand white rabbits and a quantitative method for assessing bubble load in DCS by ultrasound.MethodsFifteen male New Zealand white rabbits were exposed in a hyperbaric chamber for 60 min with air compressed to 500 kPa (absolute pressure) at 100 kPa/min, followed by decompression at a rate of 200 kPa/min back to normal pressure. Behavioral changes were observed 10 min after removing the rabbits from the chamber to assess whether a model with DCS was successfully established. Bubbles in the inferior vena cava (IVC) and right ventricle (RV) were detected by ultrasound and semi-quantitatively graded using the Eftedal-Brubakk (EB) grade. One hour after exiting the chamber, the rabbits underwent autopsy to observe macroscopic bubbles in vessels and tissues for postmortem (PM) scoring. Correlations between EB grading by ultrasound and PM bubble scores were analyzed.ResultsThe decompression protocol yielded a 100% DCS incidence (15/15) with 13.3% mortality (2/15) within 1 h after the rabbits were removed from the chamber. Ultrasound revealed bubble-like hyperechoic foci in the IVC and RV after decompression, with significantly higher EB grades in the IVC (p < 0.05). IVC's EB grades exhibited a stronger correlation with its PM bubble scores (r = 0.921, p < 0.01) compared to RV grades (r = 0.573, p < 0.05).ConclusionA reliable DCS model was established in New Zealand white rabbits. EB grading of the IVC and RV by ultrasound demonstrated a robust correlation with their PM bubble scores, suggesting potential for clinical translation in assessing bubble loads in DCS.