Interstitial And Fibrotic Lung Disease

Explanation
Diagnosing IPF with certainty requires the fi nding of UIP on pathology in the appropriate clinical setting, namely, the exclusion of other causes of UIP, such as drug toxicities, exposures, and collagen vascular diseases. In the absence of a surgical biopsy, the American Thoracic Society/European Respiratory Society (ATS/ERS), in its consensus statement of 2000, outlined major and minor criteria in diagnosing IPF. In this schema, all major criteria and at least three of the four minor criteria should be present to make a confi -dent diagnosis of IPF in an immunocompetent host. The major criteria are exclusion of other known causes of diffuse parenchymal lung disease, abnormal pulmonary function with evidence of restriction and impaired gas exchange, bibasilar reticular abnormalities with minimal ground-glass opacities on HRCT, and transbronchial lung biopsy or bronchoalveolar lavage showing no features to support an alternative diagnosis. Minor criteria are age greater than 50 years, insidious onset of otherwise unexplaineddyspnea on exertion, duration of illness more than 3 months, and bibasilar, inspiratory crackles (dry or "Velcro"-like in quality).

Explanation
Ostensibly, similar patients may behave quite differently over time, and our ability to distinguish this on initial assessment is relatively poor. Several authors have investigated the predictive power of trends in clinical progression to predict mortality. A number of studies have now pointed to a change in FVC, often set at 10%, as being clinically predictive of further disease progression. Other measures of disease progression, such as measures of oxygenation (A-a gradient, DLCO, amount of desaturation on a 6-minute walk test) and a decrease in 6-minute walk distance, may have prognostic signifi cance. Of all of these, a change in FVC of 10% may be the most reliable end point.

Explanation
Unfortunately, there is no proven therapy for the treatment of IPF. In spite of these limitations, pulmonologists and internists continue to prescribe medications without proven benefi t in the hope that an individual patient might respond. Fortunately, more placebo-controlled trials are in progress or planned for the near future. Lung transplantation remains the only therapy for IPF with proven survival benefi t. Under the previous organ allocation system used in the United States for lung transplantation, time on the waiting list was paramount in a patient being offered a transplant. Under this system, the median time on the waiting list was roughly 2 years. As of May 2006, the allocation system was revised such that a complex, iterative formula comparing anticipated benefi t from transplantation with anticipated clinical course in the absence of transplantation now determines the priority of organ allocation. As a result, the waiting time for patients with IPF has decreased considerably.

Explanation
The onset of AIP is typically abrupt, with several days of a fl ulike illness with headaches, myalgias, malaise, sore throat, and productive cough. Exertional dyspnea ensues, often becoming severe. Patients typically present within 3 weeks of the onset of their symptoms appearing quite ill. Fever is present in half of patients at presentation, but all investigations for infectious etiologies are, by defi nition, negative. Examination may show evidence of widespread consolidation or diffuse crackles. Digital clubbing is typically absent in AIP, and its presence might suggest a diagnosis of acute exacerbation of (undiagnosed) IPF. Pulmonary function testing, when done, shows a restrictive pattern with gas exchange impairments, which are often severe. Hypoxemia is present, and patients commonly require mechanical ventilation. By clinical criteria, patients meet the defi nition of ARDS, namely, an acute onset, a PaO2 to FIO2 ratio of less than 200, diffuse bilateral opacities on chest imaging, and a pulmonary arterial occlusion pressure of less than 18.

Explanation
Unlike many of the idiopathic interstitial pneumonias, cryptogenic organizing pneumonia (COP) can often be treated effectively, at least initially. Corticosteroids are the mainstay of initial therapy, typically at moderate to high doses over several months to a year. No standardized consensus has been reached: some treat with once-daily doses of 1 mg/kg prednisone (60 mg/day) for 1 to 3 months, followed by 40 mg/day for 3 months and then tapering for a total duration of 1 year, whereas others have suggested shorter courses initially. Although shorter courses may be effective in certain individuals, relapses are common, often within 1 to 3 months of discontinuing or even tapering corticosteroids. Parenteral methylprednisoloneat doses of 500 to 1,000 mg/day ("pulse dosing") has been recommended for particularly rapidly progressing forms of COP, and cytotoxic therapy with cyclophosphamideand azathioprine has been used.