Hamman's syndrome: pneumomediastinum and subcutaneous emphysema occurring in labour.

The syndrome of pneumomediastinum and subcutaneous emphysema is a rare and interesting complication of labour. The first case was recorded in 1784 and since that time some 200 other cases have been published. However, very little has appeared in the anaesthetic journals. This case concerns a patient who required general anaesthesia for manual removal of the placenta following a seemingly normal labour and delivery. The procedure was carried out without incident. However, as anaesthesia was being terminated it was noted that there was extensive subcutaneous emphysema over the head and neck. Chest X-ray showed a pneumomediastinum. It is postulated that the use of nitrous oxide may have exacerbated and so highlighted a pre-existing pneumomediastinum since there were no other features of the anaesthetic to account for this pathology. The pathophysiology, diagnosis and management of this condition are discussed together with a historical literature review.