Helium and oxygen treatment of severe air-diving-induced neurologic decompression sickness

Background: The use of helium and oxygen recompression treatment of neurologic decompression sickness (DCS) has several theoretical advantages over the traditionally used air and oxygen recompression tables that have been confirmed by findings from recent animal experiments. Objectives: To evaluate the outcome of patients with neurologic DCS who had been treated with a helium-oxygen protocol and to compare it with that of a retrospective control group that was treated with air-oxygen tables. Design: The study and control groups included 16 and 17 diving casualties, respectively. The severity of neurologic DCS was estimated according to a 9-point scale weighting motor, sensory, and sphincter control functions. The study group was treated with a helium-oxygen decompression protocol, and the control group was treated with the US Navy air-oxygen Table 6 or 6A. Persistent residual dysfunction was treated in both groups with daily hyperbaric oxygen sessions, at 2.5 absolute atmospheres for 90 minutes, until no further clinical improvement was noted. Setting: The Israel Naval Medical Institute (Israel's national hyperbaric referral center), Haifa. Results: Significant clinical score increments were found for both the helium-oxygen- and air- oxygen treated groups: 2.8±2.4 (mean±SD) and 7.4±1.1 at presentation vs 7.6±2.1 and 8.1 ± 1.5 at discharge, respectively (P<.001 and P= .005, respectively). Although the score at presentation was significantly lower for the helium-oxygen-treated group (P<.001), no difference was found between the groups' average outcome scores. While most of the improvement in the patients in the study group could be attributed to the helium-oxygen treatment and not to the supplemental hyperbaric oxygen, in the control group, no significant difference could be demonstrated between the scores at presentation and at completion of the air-oxygen recompression table. In 5 patients who were treated with the use of the air-oxygen tables, deterioration was observed after recompression. No deterioration or neurologic DCS relapse occurred in the helium-oxygen-treated group. Conclusion: The results suggest an advantage of helium-oxygen recompression therapy over air-oxygen tables in the treatment of neurologic DCS.