Respiratory function and respiratory complications in spinal cord injury: protocol for a prospective, multicentre cohort study in high-income countries oleh David J Berlowitz, Maria T E Hopman, Gabi Mueller, Martin W G Brinkhof, Xavier Jordan, Anja M Raab, Karin Postma, David Gobets, Sven Hirschfeld, Burkhart Huber, Margret Hund-Georgiadis, Renate Wildburger