In-water recompression for severe decompression illness in competitive freediving: a case report

Introduction: Decompression illness (DCI) is a recognised risk of freediving. When timely hyperbaric oxygen therapy (HBOT) is unavailable, oxygen-based in-water recompression (IWR) may be considered. Methods: A 49-year-old competitive freediver developed severe neurological DCI within minutes of surfacing from a dive to 117 metres of seawater at a sanctioned competition, with altered mental status, right facial droop, right hemiparesis and aphasia. With an anticipated 24-48 h delay to HBOT, emergency IWR was initiated with a full-face mask and 100% oxygen. Incremental ascent from 18 msw over 14.5 min produced substantial recovery. Residual gait instability and pronator drift prompted a second oxygen-IWR 5.5 h later from 15 msw over 41 min, achieving complete resolution. Results: While this case had an excellent outcome, IWR carries significant risks including oxygen toxicity and drowning, and review identified serious safety and ethical failures. Patient selection is key; perceived benefit must be weighed carefully against risk. Conclusions: IWR may be considered for DCI when HBOT is not promptly accessible. No IWR guidelines exist specifically for freedivers. The success of this case does not establish that deeper exposures were necessary or superior to shallower protocols. IWR is high-risk, requiring proper selection, trained personnel and favorable conditions.