Pulmonary contusion causes long-term respiratory dysfunction with decreased functional residual capacity

To elucidate the mechanism of persistent dyspnea after blunt chest trauma, we prospectively studied the pulmonary function of 18 patients with blunt chest trauma for 6 months. Nine of the patients had flail chest and 12 had pulmonary contusion (PC). Pulmonary function was evaluated using spirometry, arterial blood gas analysis, chest x-ray studies and CT scans. Functional residual capacity (FRC) remained significantly reduced throughout the 6 months in patients with PC. Such patients experienced a fall in Pao2 when changed from a sitting position to a supine position and they had fibrous changes in the contused lung as demonstrated by CT scans at 6 months after injury. These findings were supported in an additional study of another 20 patients who had suffered PC 1 to 4 years previously. This study demonstrated that pulmonary function recovered within 6 months in patients without PC even with a residual deformity of the thoracic wall caused by flail chest, while patients with PC had decreased FRC and a fall in Pao2 when moved to the supine position even several years after injury. This might be related to the persistent dyspnea seen after blunt chest trauma.