Head position and its effect on pulmonary function in tetraplegic patients

To test the influence of head position on pulmonary function in tetraplegic individuals 15 subjects with chronic C4-C7 injuries participated in a one group pre-post test comparing the relationship between orthostatic position of the head (OPH) and standard pulmonary function tests (PFTs). Twelve subjects with habitual forward head posture and three with non-forward head posture performed PFTs in (1) their habitual posture, and (2) an experimental posture imposed by placement of thoracic and/or lumbar rolls behind their back. Results showed that changing head posture did not alter mid-forced expiratory flow or forced inspiratory vital capacity, but significantly affected forced vital capacity (t = 2.83; P < 0.05) and 12 s maximum voluntary ventilation (t = 2.07; P < 0.05). In cases where pulmonary function was altered by head position, the resulting performance was best in the subject's habitual posture, although no differences in resting pulmonary tests were observed between subjects with and without forward head position. These data show that temporary postural alterations affecting OPH, if not allowing sufficient time for muscular adaptation, adversely affect pulmonary function in tetraplegic patients.