The study of breathing kinematics in spinal muscle atrophy patients

Through a new method based on the kinematic analysis of chest wall movements a group of 12 SMA (Type II) patients has been studied analysing volume changes of the different compartments of the chest wall (upper and lower thorax, abdomen) in supine position, during both spontaneous quiet and deep breathing. Results show that the respiratory behaviour of SMA subjects is almost fixed, allowing quite a few degrees of freedom, with the abdominal (diaphragmatic) component clearly prevailing on the thoracic ones: this ventilatory pattern shows analogies with diaphragmatic breathing of tetraplegic, spinal cord injured patients. Moreover the lowered, paradoxical thoracic ventilation (particularly in upper thoracic district) causes further functional and prognostic problems with more risks of acute pneumonia episodes, microatelectasic complications and increase of total respiratory resistences. The need to assess and to treat, in these patients, the hypoventilation of thoracic districts is emphatized.