ABSTRACT
Mediastinal emphysema results from multiple etiologies and is associated with a variety of underlying disease entities. Twenty five patients with pneumomediastinum treated on a surgical service over a 6 year period were reviewed. The cause of the mediastinal emphysema was related to trauma in seven patients, attempted central venous access in four patients, cardiopulmonary resuscitation in four patients and some type of Valsalva maneuver in ten patients. Besides the mediastinal emphysema, air may dissect into the peritoneal cavity, the pericardium, and the subcutaneous tissues within the neck and chest wall. Treatment of the mediastinal emphysema, per se, is expectant; success or failure is determined by treatment of the associated underlying problems. Deaths occurred in three patients after cardiopulmonary resuscitation and in one patient after crushing chest injury. One patient with an associated hydrothorax was found to have a perforated distal esophagus which was treated by emergency fundoplication. When associated diseases are absent and there is no evidence of pleural effusion or hydrothorax, no special diagnostic tests are indicated. Sequential chest x-rays are used to follow the pneumomediastinum through resolution, which usually occurs within 72 hours.
Subject(s)
Mediastinal Emphysema/etiology , Adult , Aged , Asthma/complications , Female , Humans , Male , Mediastinal Emphysema/complications , Mediastinal Emphysema/diagnostic imaging , Mediastinal Emphysema/therapy , Medical Records , Middle Aged , Physical Exertion , Radiography , Resuscitation/adverse effects , Thoracic Injuries/complications , Valsalva Maneuver , Wounds and Injuries/complicationsABSTRACT
Most of the small particles (50 to 100 micrometers in diameter) of microcrystalline beta-rhombohedral boron that quickly transit an argon plasma maintained within a radio-frequency induction-coupled torch emerge as better crystallized spheroids of the same crystalline form and nearly the same size as the starting material. A few crystals of each of four distinctive, well-faceted habits are formed along with the general product. Three of these types are monocrystals of the beta-rhombohedral polymorph, of the tetragonal-III modification, and of an unreported cubic form of boron. Specimens of the fourth type are polycrystals of another unreported form of boron, apparently consisting of many hexagonal platelets stacked in an imprecise fashion.
