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Idiopathic pulmonary fibrosis
From WikEM
Contents
Background
- Normal lung parenchyma is interspersed with areas of decrease compliance
- Unlike ARDS, in which lung injury more uniform
- Mechanical ventilation strategies learned from ARDS not completely transferrable
- Median survival time 3 yrs after diagnosis
- Prevalence about 10-20 cases per 100,000 people
- AE-IPF = Acute Exacerbation of IPF
- Acute exacerbations carry mortality up to 80%
- 60% die from idiopathic pulmonary fibrosis, others die from:
Clinical Features
- Diagnosis of exclusion
- Presentations with rapid deterioration without obvious cause common
- May co-exist with pulmonary hypertension and heart failure
Acute exacerbation of IPF
- Diagnosis of IPF
- Unexplained worsening of dyspnea within 30 days
- Hypoxemia deviated from baseline ABG
- No evidence of pulmonary infection
- Exclusion of alternative causes (i.e. VTE)
- CT with bilateral ground-glass abnormalities/consolidation on a background reticular/honeycomb pattern consistent with interstitial pneumonia[1]
- 100% have bilateral ground-glass opacities
- ~70% have consolidation
Differential Diagnosis
Pulmonary Fibrosis
- Interstitial pneumonias (acute, lymphocytic)
- Lung malignancy
- Aspiration pneumonitis
- Aspiration pneumonia
- Bacterial pneumonia
- Viral pneumonia
- Fungal pneumonia
- Cryptogenic organizing pneumonia
- Interstial lung disease associated with collagen-vascular disease
- Drug-induced pulmonary toxicity (amiodarone, bleomycin, amphotericin B, carbamazepine, etc.)
- Eosinophilic granuloma (Histiocytosis X)
- Radiation pneumonitis
- Sarcoidosis
- Pneumoconiosis (Workplace exposure)
- Asbestosis
- Berylliosis
- Chemical worker's lung
- Coal worker's pneumoconiosis
- Silicosis
Evaluation
- CBC, leukocytosis
- CRP elevated
- LDH elevated
- ABG with hypoxemia, hypercapnea
- ECG
- CXR with likely need for CT
- Echo to assess for pulmonary hypertension, rule out CHF
- BAL in ICU to rule out infection
Management
- All treatments controversial and of questionable efficacy
- Methylprednisolone 500-1000mg qd for 3 days[2][3]
- Heparin drip
- Alveolar injury predisposes to prothrombotic state
- Prevents further vascular injury
- Cyclosporine A 1-2mg/kg/day with steroids[4]
Mechanical Ventilation Strategies
- Current strategies controversial, with some contending mechanical ventilation adds insult to AE-IPF
- Non-invasive may be use as a temporizing measure
- Low TVs at 6 cc/kg
- Permissive hypercapnea may be necessary
- Maintaining minute ventilations
- High respiratory rates may be necessary
- Heavy sedation with possible paralysis with cisatricurium
- Deviations from ARDS treatment strategies
- Must restrict PEEP given to AE-IPF
- No place for recruitment maneuver or prone postioning
- Questionable benefit of APRV (BiVent) and high-frequency oscillation ventilation
Disposition
- ICU
- ECMO has been used as a bridge to lung transplant
- Transfer to transplant center if candidate
- Lung transplant is the only proven therapy to increase long term survival
See Also
References
- ↑ Akira M, Kozuka T, Yamamoto S, Sakatani M. Computed tomography findings in acute exacerbation of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med 2008;178:372-8.
- ↑ Rice AJ, Wells AU, Bouros D, Du Bois RM, Hansell DM, Polychronopoulos V, et al. Terminal diffuse alveolar damage in relation to interstitial pneumonias. An autopsy study. Am J Clin Pathol 2003;119:709-14.
- ↑ Saydain G, Islam A, Afessa B, Ryu JH, Scott JP, Peters SG. Outcome of patients with idiopathic pulmonary fibrosis admitted to the intensive care unit. Am J Respir Crit Care Med 2002;166:839-42.
- ↑ Meduri GU, Golden E, Freire AX, Taylor E, Zaman M, Carson SJ, et al. Methylprednisolone infusion in early severe ARDS: Results of a randomized controlled trial. Chest 2007;131:954-63.
