Thorax 1987;42:801-808 Respiration during sleep in kyphoscoliosis

Eleven subjects with non-paralytic and 10 with paralytic kyphoscoliosis and nine normal control subjects were studied during sleep. The Cobb angle of those with kyphoscoliosis varied from 600 to 1400 (median 100°) and the vital capacity varied from 17% to 56% (median 28%) of the value predicted on the basis of span. Recordings made during sleep included expired carbon dioxide tension at the nose, gas flow at the mouth, arterial oxygen saturation, chest wall movement, and the electroencephalogram, electro-oculogram, and electrocardiogram. In three subjects transcutaneous carbon dioxide tension was measured simultaneously. Patients with kyphoscoliosis hypoventilated during sleep, particularly in rapid eye movement sleep, resulting in a rise in end tidal and transcutaneous carbon dioxide tension, and a reduction in oxygen saturation to a degree not observed in normal subjects. Reduced chest wall movement was the major cause of these episodes, which were more frequent and occupied a greater proportion of sleep time in those with kyphoscoliosis than in normal subjects. Serious cardiac arrhythmias were rarely associated. It is concluded that disturbances of respiration during sleep occur in patients with kyphoscoliosis and that these may be important in the pathogenesis of cardiorespiratory failure. Severe kyphoscoliosis may lead to cardiorespiratory failure and premature death.1 Factors contributing to the onset of respiratory failure are thought to include reduced surface area for diffusion, ventilationperfusion inequality, alveolar hypoventilation, increased respiratory work, and an abnormal increase in pulmonary artery pressure during exercise.2 3 Recent work by Mezon et al4 and Guilleminault et al! has suggested that sleep related disturbances of respiration may also contribute. Discrepancies between their findings, which were based on only a few subjects, prompted this larger study to identify the major abnormality and mechanism of disturbances of respiration during sleep in patients with kyphoscoliosis, to distinguish any differences between non-paralysed and paralysed subjects, and to try to assess the importance of these abnormalities in the pathogenesis of cor pumonale.