Medical use
Hereditary angioedema
Blood-derived C1-inhibitor is effective but does carry the risk associated with the use of any human blood product. Cinryze, a pharmaceutical-grade C1-inhibitor, was approved for the use of HAE in 2008 in the US after having been available in Europe for decades. It is a highly purified, pasteurized and nanofiltered plasma-derived C1 esterase inhibitor product; it has been approved for routine prophylaxis against angioedema attacks in adolescent and adult patients with HAE.A recombinant C1-inhibitor obtained from the milk of transgenic rabbits, conestat alfa (trade name Ruconest), is approved for the treatment of acute HAE attacks in adults.While C1-inhibitor therapy has been used acutely for more than 35 years in Europe in patients with C1-inhibitor deficiency, new methods of treating acute attacks have emerged: a plasma kallikrein inhibitor and the bradykinin receptor antagonist icatibant. Other products also have been introduced including plasma-derived products such as Berinert and Haegarda. For other conditions
The activation of the complement cascade can cause damage to cells, therefore the inhibition of the complement cascade can work as a medicine in certain conditions. When someone has a heart attack, for instance, the lack of oxygen in heart cells causes necrosis in heart cells: Dying heart cells spill their contents in the extracellular environment, which triggers the complement cascade. Activation of the complement cascade attracts phagocytes that leak peroxide and other reagents, which may increase the damage for the surviving heart cells. Inhibition of the complement cascade can decrease this damage.
For example, foreign body aspiration, in which someone inhales an object, can cause pneumomediastinum (and lead to subcutaneous emphysema) by puncturing the airways or by increasing the pressure in the affected lung(s) enough to cause them to burst.Subcutaneous emphysema of the chest wall is commonly among the first indications that barotrauma, damage caused by excessive pressure, has occurred; it suggests that the lung was subjected to significant barotrauma. Thus the phenomenon may occur in diving injuries.Trauma to parts of the respiratory system other than the lungs, such as rupture of a bronchial tube, may also cause subcutaneous emphysema. Air may travel upward to the neck from a pneumomediastinum that results from a bronchial rupture, or downward from a torn trachea or larynx into the soft tissues of the chest. It may also occur with fractures of the facial bones, neoplasms, during asthma attacks, when the Heimlich maneuver is used, and during  childbirth.Injury with pneumatic tools, those that are driven by air, is also known to cause subcutaneous emphysema, even in extremities (the arms and legs). It can also occur as a result of rupture of the esophagus; when it does, it is usually as a late sign. Medical treatment
Subcutaneous emphysema is a common result of certain types of surgery; for example it is not unusual in chest surgery. It may also occur from surgery around the esophagus, and is particularly likely in prolonged surgery. Other potential causes are positive pressure ventilation for any reason and by any technique, in which its occurrence is frequently unexpected.