Here are some key
points from a review in the Journal of Hospital Medicine:
What is the
classification?
Categories are exposure related (eg hypersensitivity pneumonitis,
drugs, occupational), connective tissue disease related, idiopathic
and miscellaneous (including sarcoid, Langerhans cell histiocytosis,
eosiniphilic pneumonia and vasculitis (including diffuse alveolar
hemorrhage).
What labs should
be ordered initially on a patient suspected for the first time to
have ILD?
According to the review, ANA, RA, anti cyclic citrullinated peptide,
CK and aldolase. (Aldolase may be elevated while the CK is normal in some cases of inflammatory myopathy). (I would wonder
if synthetase antibody testing should be added to this list). After
this round of testing, subsequent tests can be added based on initial
results and the ensuing clinical course.
What imaging
studies should initially be done?
CXR and HRCT according to the article, which also mentioned that if
clinical conditions warrant, instead of just doing a HRCT, get a CT
PA gram with simultaneous high resolution images of the lung
parenchyma.
What about
bronchoscopy?
This is not considered routine and what I get from the review is that
the diagnostic confidence derived from HRCT and the anticipation of
how the results might change treatment will influence this decision.
Circumstances that might favor doing bronchoscopy include suspected
acute eosinophilic pneumonia (AEP), suspected acute hypersensitivity
pneumonitis, suspected sarcoid and suspected unusual infection.
When should
antibiotics be given?
According to the review, onset or exacerbation of ILD can be
difficult to distinguish from infection, so always at least consider
them. (Given the all too often undifferentiated nature of the
presentation in critically ill patients, I suspect the threshold
would be low). The review did not comment on the specific type of
coverage. However, many such patients are immunosuppressed, have had
frequent hospitalizations, or are critically ill and those factors
would guide antibiotic choices.
Should
corticosteroids be used?
In cases of clinical deterioration or respiratory failure, which is
the case with most patients who require hospitalization, yes. The
etiology is often unknown, and it must be kept in mind that some
etiologies are known to be highly steroid responsive, particularly
AEP and COP. Recommendations also support the use of steroids for
CTD related ILD, acute HP and drug induced ILD. IPF by comparison is
poorly steroid responsive but current guidelines conditionally
recommend their use.
Cautions that would apply include the ever present risk of unusual
infection and the potential for steroids to increase the risk of
renal crisis in patients with systemic sclerosis.
Lung
transplantation is a consideration for certain non responding
patients
Form the article:
In these cases, lung transplantation may be the only remaining treatment option. This is particularly true for patients presenting with IPF, and it is 1 of the most common indications for lung transplantation. Patients with respiratory failure and ILD should be evaluated early in the hospital course for transplantation or considered for transfer to a transplant center. General contraindications to transplant are age older than 70 years, underweight or elevated BMI (generally higher than 30), malignancy within the last 2 years (with the exception of cutaneous squamous and basal cell tumors), untreatable major organ dysfunction other than the lung, noncurable chronic extrapulmonary infection (chronic active viral hepatitis B, hepatitis C, human immunodeficiency virus), significant chest wall deformity, untreatable psychiatric or psychologic disease, substance addiction within the last 6 months, or lack of dependable social support.4
Another excellent review, free full text, is here. Though a
couple of years old it is still relevant and has lots of pearls.
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