Features of the normal thorax:
(1) normal, stable volume
(2) ability for the lung volume to change during the respiratory cycle (thoracic function)
Features of the thoracic insufficiency syndrome:
(1) A reduction in volume and/or mobility means that the thorax is unable to support normal lung growth or respiration.
(2) The patient experiences reduced oxygenation with features of a restrictive lung disease.
(3) There is a significant reduction in chest wall mobility, as demonstrated by the thumb excursion test. The loss of mobility means that lung volume is unable to change during the respiratory cycle.
(4) Imaging studies to demonstrate the thoracic volume available for ventilation shows a significant reduction from normal.
(5) Pulmonary function tests shows a reduction in vital capacity compared to that predicted.
Complex congenital or acquired deformities can result in the thoracic insufficiency syndrome. The combination of congenital scoliosis and fused ribs can significantly impair thoracic growth and function.
