Diaphragmatic paradox or paradoxical diaphragm phenomenon is an abnormal medical sign observed during respiration, in which the diaphragm moves opposite to the normal directions of its movements. The diaphragm normally moves downwards during inspiration and upwards during expiration. But in diaphragmatic paradox, it moves upwards during inspiration and downwards during expiration.
Causes and associated conditions
Diaphragmatic paradox may be caused by weakening of inspiratory muscles due to injury, pyopneumothorax (collection of pus and excess air inside pleural cavity) or hydropneumothorax (collection of watery fluid and excess air inside pleural cavity).
References
Diaphragmatic paradox Wikipedia(Text) CC BY-SA