Critical Care Medicine-Neurologic Disorders>>>>>Respiratory Failure
Question 4#

A 65-year-old man diagnosed with idiopathic pulmonary fibrosis a year ago not on supplemental oxygen therapy presents to the ED with a week and a half of worsening exercise tolerance, increased dry cough, myalgias, and subjective fevers. Over the last day he has been unable to walk across the room without resting. Physical examination is remarkable for SpO2 of 85% on 6 L NC with tachypnea and increased work of breathing, bibasilar crackles. Laboratory test results reveal WBC 10,000/ µL (slightly increased absolute neutrophil count), normal metabolic panel and liver function tests, troponin of 0.1 ng/mL, and BNP of 120 pg/mL. Rapid flu is negative, and PCR panel is pending. CXR shows worsening bilateral opacities, and results of CT scan are shown in the figure below:

The patient is admitted to the ICU and placed on high flow nasal cannula at 40 LPM flow. Overnight FiO2 has ranged between 0.7 and 0.9 to maintain SpO2 in the low 90s, and he was unable to sleep because of dyspnea. On examination he appears to be tiring.

Which of the following statements is true?

A. Intubation and mechanical ventilation in this setting are associated with in-hospital mortality approaching 90%
B. The use of corticosteroids is supported by moderate- to high-quality trial data
C. If metapneumovirus nucleic acid is detected in respiratory secretions, then it is not appropriate to diagnose “Acute exacerbation of IPF” (AE-IPF)
D. Risk factors for AE-IPF include low BMI
E. Lung biopsy would be most likely to show organizing pneumonia

Correct Answer is A

Comment:

Correct Answer: A

This patient is experiencing an acute exacerbation of IPF (AE-IPF). In 2016, an International Working Group Report defined AE-IPF as “an acute, clinically significant respiratory deterioration characterized by evidence of new widespread alveolar abnormality” with the following diagnostic criteria:

  1. Previous or concurrent diagnosis of IPF
  2. Acute worsening or development of dyspnea typically <1-month duration
  3. CT with new bilateral ground-glass opacity and/or consolidation superimposed on a background pattern consistent with usual interstitial pneumonia pattern
  4. Deterioration not fully explained by cardiac failure or fluid overload

This report recommended that AE-IPF be subcategorized as “Triggered Acute Exacerbation” and “Idiopathic Acute Exacerbation.” Thus the detection of a respiratory pathogen does not exclude the diagnosis but rather clarifies it as triggered. International guidelines make a weak recommendation against mechanical ventilation to treat acute respiratory failure in IPF because of estimated in-hospital mortality of nearly 90%. Although corticosteroids are commonly given during AE-IPF, no highquality trial data support this practice, which is driven by anecdotal reports of benefit. Risk factors for AE-IPF include higher BMI. In autopsy series of patients with AE-IPF, the most common acute pathologic finding is diffuse alveolar damage.

References:

  1. Collard HR, Ryerson CJ, Corte TJ, et al. Acute exacerbation of idiopathic pulmonary fibrosis. An International Working Group Report. Am J Respir Crit Care Med. 2016;194:265-275.
  2. Raghu G, Collard HR, Egan JJ, et al. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med. 2011;183:788-824.
  3. Oda K, Ishimoto H, Yamada S, et al. Autopsy analyses in acute exacerbation of idiopathic pulmonary fibrosis. Respir Res. 2014;15:109.