[Is helium beneficial in a pulmonary rehabilitation program for severe COPD?]

Helium is known to reduce airflow limitation. Our hypothesis was that severe COPD patients undertaking exercise would show greater improvement in endurance under a heliox mixture (80/20%) than under air alone. This hypothesis was tested in a double-blinded, randomized study.

METHODS: Out of the 53 patients included, 45 were randomly assigned to two groups : Heliox (n= 23) and Air (n= 22). Patients were assessed with spirometry under air and heliox, incremental exercise test, constant workload (80% Wmax) exercise test and weekly 6-minute walk test. The two groups went through fifteen 30-minute retraining sessions in the overall framework of an identical pulmonary rehabilitation program.

RESULTS: There was no significant difference in endurance improvement (Heliox : +52.5 sec, Air:+114sec, median value). FEV1 improvement under heliox exceeding 10% identified a group of 20 patients as "helium responders", who improved their endurance time by a median of 135sec compared to 50sec for the "non-responders" (non-significant difference).

CONCLUSION: In patients with severe COPD, use of Heliox in exercise retraining did not produce significantly improved endurance. On the other hand, "helium responders" showed more FEV1 improvement than non-responders. Improved FEV1 under heliox should therefore be used in future studies as an inclusion criterion.