Assessment of chest movements in tetraplegic patients using a three-dimensional motion analysis system
We used optoelectronic plethysmography (OEP) to evaluate the effects of posture on chest and abdominal movements during respiration in patients with chronic-stage complete spinal cord injuries. The subjects were five cervical injury patients (male, C4-C8 injury, American Spinal Injury Association Impairment Scale grade A) and five healthy people matched to each of the cervical injury patients for age, height, and weight. The chest wall movement each of the subjects was recorded using OEP during six quiet breathing and three deep breathing periods in each of the following positions: supine, with the trunk elevated to 30°, and with the trunk elevated to 60°. Data on the chest wall volume and compartment volumes (upper thorax, lower thorax, abdomen) were then compared among the postures. During quiet breathing in the tetraplegic patients, the change in upper thorax volume was smaller at the end of inhalation than at the end of exhalation, presenting as a paradoxical breathing pattern. During deep breathing in the tetraplegic patients, abdominal volume accounted for a large portion of the change in total chest wall volume. Posture affected the recorded abdominal volume; volume was greatest in the supine position and decreased as the posture became more upright.