Antonelli M, Pennisi MA, Pelosi P, Gregoretti C, Squadrone V, Rocco M, Cecchini L, Chiumello D, Severgnini P, Proietti R, Navalesi P, Conti G. Anesthesiology. 2004 Jan;100(1):16-24
Study of 33 patients with COPD treated with helmet NPPV, compared with 33 historical controls treated with face mask NPPV. In the helmet group, no patients were unable to tolerate NPPV, whereas five of the control group required intubation. Authors conclude that helmet NPPV 'can be used to treat chronic COPD with acute exacerbation'.
Link to abstract.