Mediastinal emphysema

Intense toxic inhalant exposures may cause pulmonary edema within 30 to 60 minutes. Secretions from both the nasopharynx and the tracheobronchial tree are copious, with quantities of up to 1 L/ h reported.12 Severe dyspnea is so prominent that the patient may refuse to move. On physical examination, the chest may be hyperinflated. Mediastinal emphysema secondary to peripheral air trapping may dissect to the skin and present as subcutaneous emphysema. The sudden death that occurs with massive toxic inhalant exposure is thought to be secondary to laryngeal spasm.13... 

FoUowing ingestion of more than 20 mg of colchicine in adults, a severe toxic syndrome develops (SED Vlll). Recently reported additional complications include mediastinal emphysema (201 ), respiratory distress syndrome (200 ) and inappropriate antidiuresis (199 ). 

An 18-year-old male was given 2 mg of colchicine intravenously by a Triend under the false impression that it would induce euphoria. In addition to the recognized complications of colchicine poisoning the patient developed mediastinal emphysema (201 ). 

After intratracheal instillation of nickel chloride or nickel sulphate in rats, a modest inflammatory response with increased number of macrophages and polynuclear leucocytes was obtained, together with increased activities of lactate dehydrogenase and -glucuronidase in bronchoalveolar fluid [351]. More severe lesions were characterized by type II cell hyperplasia with epithelialization of alveoli, and in some animals, fibroplasia of the pulmonary interstitium. By inhalation in rats, the nickel salts produced chronic inflammation and degeneration of the bronchiolar epithelium [352, 353]. There was also atrophy of the olfactory epithelium and hyperplasia of the bronchial and mediastinal lymph nodes. Nickel sulphate also produced a low incidence of emphysema and fibrosis [353]. 

Table 2 (2,13,14) (Hgs. 2 and 3). Ground glass opacities (GGO) may be present in UIP, but are nevCT the dominant feature (2,13). Extensive GGO suggest an alternative diagnosis [e.g., DIP, NSIP, or hypersensitivity pneumonitis (HP)] (13). Honeycomb change (HC) is often a prominent feature in UIP, but is uncommon in other HPs (2,9,14). Zones of emphysema (typically in the upper lobes) may be present in smokers (15,16). Mediastinal lymphadenopathy occurs in 55% to 71% of patients with UIP, but is nonspecific (17-19).

Thin-section CT delineates the changes of the thorax in kaolinosis more than chest radiography. Small nodules distributed mainly in centrilobular regions. The appearance of large opacity resembles that of complicated coal workers pneumoconiosis or complicated silicosis (Fig. 12.10c). Peripheral emphysema typically occurs with such masses. Unlike with silicosis, hilar and mediastinal lymph node enlargement more than 1 cm in diameter is not usually seen. 

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