Critically evaluate the role of open lung biopsy in the critically ill patient with a diffuse infiltrate on chest radiograph.
There are a myriad of potential causes of a diffuse infiltrate. These include high pressure pulmonary oedema, low pressure pulmonary oedema, diffuse pneumonia, malignancy (eg. lung, haemopoetic), pulmonary haemorrhage or auto-immune/vasculitic. Most patients are able to be managed without invasive investigations.
Open lung biopsy is reserved for those situations where:
• The cause is not apparent
• The patient is not responding to management, or
• There is a suspicion of another specific disease state which would require different management (eg. disseminated malignancy, alveolar haemorrhage, Bronchiolitis Obliterans Organising Pneumonia [BOOP] etc.), and
• The diagnosis has not been able to be made on less invasive tests (eg. Broncho- Alveolar Lavage or even Video Assisted Thoracoscopic Surgery), or
• Determination of prognosis is essential for management.
Open lung biopsy is associated with risks, especially in the critically ill patient, which include death, air-leak and even a sampling error (as limited tissue removed). These potential risks must be balanced against the information to be obtained. The expectation is that, with further information some potentially harmful/expensive/un-necessary medications would be able to be stopped, and more specific management introduced (eg. high dose corticosteroids).
The biopsy needs to be taken from an area likely to be representative, not one with a high likelihood of non-specific fibrosis (eg. dependent segments of RML), and not too late in the disease process.(Patel 2004 Chest)
So, you cannot arrive at a diagnosis of a diffuse interstitial infiltrate.
Lung biopsy is also asked about in Question 4 from the second paper of 2014; there the college answer is mroe comprehensive, as is the discussion.
In brief, lung biopsy is not without its risks, and is indicated only in specific situations.
Indications for lung biopsy
Complications of lung biopsy
The biopsy must be performed in several regions of the lung, and must yield specimens which offer a representative sample, without sampling any areas of irreversible fibrosis.
It cannot be performed in patients who cannot be ventilated on one lung for prolonged periods. Risks and contraindications of of thoracotomy apply.
UpToDate has a nice article about lung bippsy.
Bensard, Denis D., et al. "Comparison of video thoracoscopic lung biopsy to open lung biopsy in the diagnosis of interstitial lung disease." CHEST Journal103.3 (1993): 765-770.