01 Sep

Canadian Health and Care Mall: Lung Injury

ARDSHRCT scanning was used to evaluate the structural changes caused in the lung by smoke inhalation injury because it has become a major imaging method in the assessment of infiltrative lung dis-ease.” GGO usually reflects avariety of pathologic processes such as mild airspace disease, interstitial lung disease, or both. In patients with ZCSII, the histologic features include pulmonary edema, alveolitis, interstitial and intraalveolar fibrosis, and diffuse alveolar damage, which may be detected as GGOs on HRCT scans.

There have been reports describing ARDS soon after a significant exposure to zinc chloride (smoke bomb) fumes. In contrast, others have reported> some type of delayed ARDS with a slowly progressive clinical course over the ensuing 2 weeks. A discrepancy in the progression to ARDS over time or severity among different investigations may be attributed to the amount of smoke inhalation, to the duration of exposure, and to whether exposure occurred in an open or confined space. In this study, ARDS developed in five of our patients (25%) within 72 h after inhalation. In general, these patients had higher HRCT scan scores, suggesting that they had more severe lung injury soon after inhalation. The exact mechanism by which ARDS is triggered remains unclear, although there is evidence of involvement of the release of proinflammatory cytokines.

Pneumomediastinum and/or pneumothorax have been reported in patients with ZCSII. These conditions may follow severe strain or cough induced by exposure to a variety of toxic agents such as chlorine gas and oxides of nitrogen. The mechanism involved in pneumothorax or pneumomediastinum is probably the result of alveolar rupture caused by the direct injury of the alveoli or secondarily by barotrauma from mechanical ventilation. In our 20 patients, 2 patients had pneumothorax, and pneumomediastinum developed in 3 patients, with 1 and 2 patients, respectively, who required mechanical ventilation because of ARDS. Our observations therefore support previously proposed possible mechanisms, as described above. Five patients had minimal pleural effusions initially after injury, all of which resolved spontaneously as clinical conditions improved. We speculated that the effusion was reactive secondary to the inhalation injury, as none of the patients presented with clinical signs of infection. Infections are agents which enter our organism to damage it. But why they operte in such a way? Maybe the answer is given here https://healthandcaremallcanada.wordpress.com or you will find some other interesting facts about medical science or ordering online.

In general, follow-up HRCT scans of our patients showed a considerable improvement in lung abnormalities over a relatively short period of time in less severely injured patients as compared with those in whom ARDS developed (Table 2). Consistent with observations from previous reports, severe ZCSII may cause extensive interstitial and intraalveolar fibrosis. Similarly, it was noted that our five severely injured patients presented with reticular opacities and traction bronchiectasis consistent with lung fibrosis at follow-up,’ thus supporting the view that fibrosis is more likely to develop in patients with more severe injury.

Lung fibrosisTo our best knowledge, this is the first report of initial and follow-up studies of pulmonary function and CT scan changes in a relatively large series of patients with ZCSII. Significant declines were observed in FVC, FEV1, TLC, and Dlco, but not in FEV1/FVC ratio, early after smoke inhalation, with a good correlation noted between HRCT scan scores and functional parameters, suggesting that this combined modality may predict reliably the severity of the ZCSII. Although remaining lower than normal, all functional parameters improved significantly in a follow-up period ranging from 1 to 2 months after exposure. Similarly, Zerahn et al also showed a decrease in TLC and Dlco that was observed during a short-term follow-up (4 weeks after exposure) in 13 patients who had experienced a modest exposure to zinc chloride smoke. Both studies suggested that flow conduction appeared to be fairly preserved with damage confined to the lung parenchyma. Of these 20 patients, obstructive ventilatory impairment was identified in only 2 patients with the highest HRCT scan scores who had abnormal FEVj values and reduced FEV1/FVC ratios. Taken together, these results further suggest that, in general, ZCSII causes insignificant airway injury except in the context of a more severe alveolar injury that might be associated airway obstruction. A significant correlation between the initial HRCT scan scores and lengths of hospital stay that were observed in this study suggested that the HRCT scan score might reflect reliably the severity of the inhalation injury. Intriguingly, changes in HRCT scan scores correlated well only with changes in FVC in the follow-up period, suggesting that FVC may be the only significant functional predictor of long-term outcome for patients with ZCSII. However, this assumption needs to be tested in a larger number of patients.

In conclusion, the CT scan features of ZCSII are predominantly GGOs with or without associated consolidation, no zonal predominance, and both central and peripheral distribution. A good correlation was observed between HRCT scan findings and pulmonary function in our study, and our results suggest that ZCSII causes predominantly parenchymal damage of the lung and a restrictive type of functional impairment in general.

Categories: Injury
Tags: , , ,

© 2008 HIV/AIDS News & Information