--- **Patient details:** - Age: 68 years old - Gender: Male - Smoking status: Non-smoker - BMI: 23 - Examination (if not performed): Fine, bi-basal crepitations. Nail clubbing. >[!question]- How would you investigate this patient? > - **Blood tests:** FBE (raised WCC for infection, raised Hb in secondary polycythaemia), UEC (low K; can get worse with bronchodilators), A1AT assay and LFTs (A1AT deficiency) > - **Lung function:** Spirometry with BD response and DLCO (to assess for an obstructive ventilatory defect) > - **Imaging:** Chest X-ray (assess for hyper-inflation, narrow heart shadow, bullae, increased retrosternal airspace, prominent pulmonary vasculature). CT Chest could be used (if needed) to clarify any abnormalities seen on CXR, or evaluate for other pathologies as indicated (e.g. lung mass/nodule, interstitial lung disease, plan towards surgical intervention(s)) --- **Respiratory function tests** >[!example]- Flow-volume loop >![[R-FC.png|center]] **Spirometry:** | Parameter | LLN | Pre-BD | % Pred | Post-BD | | --------- | ---- | ------ | ------ | ------- | | FEV1 (L) | 1.82 | 1.85 | 74% | 1.88 | | FVC (L) | 2.50 | 2.20 | 67% | 2.22 | | FEV1/FVC | 0.82 | 0.75 | 91% | 0.76 | **Lung Volumes:** | Parameter | LLN | Pre-BD | % Pred | | --------- | ---- | ------ | ------ | | TLC (L) | 4.80 | 3.30 | 55% | | RV (L) | 1.50 | 1.10 | 45% | | FRC (L) | 2.20 | 2.20 | 69% | | RV/TLC | | 0.33 | | **Gas Transfer:** | Parameter | LLN | Value | % Predicted | | ------------------------ | ---- | ----- | ----------- | | DLCO (Hb) (mL/min/mmHg) | 14.5 | 8.5 | 39% | | VA (L) | 4.40 | 3.80 | 68% | | KCO (Hb) (mL/min/mmHg/L) | 2.80 | 2.24 | 57% | > [!question]- Describe the findings of these respiratory function tests > - The FER is greater than 0.7 is **no** obstructive component. > - The FEV1 and FVC are both reduced; as the FVC is 67% predicted, this is suggestive of a moderate restrictive ventilatory defect *(ATS/ERS 2005)*. There is **no** acute bronchodilator response. > - Static lung volumes demonstrate a reduced TLC and RV, with a normal RV/TLC ratio (<0.35). This confirms the presence of a moderate-severe restrictive defect. > - Diffusion capacity is severely reduced (39% pred), and remains low despite correction for alveolar volume (KCO 57% pred), which is suggestive of pulmonary parenchymal and/or pulmonary vascular disease. > - The flow-volume loop demonstrates a tall and narrow shape with reduced lung volumes, consistent with restrictive lung disease. > - **Summary:** Respiratory function tests demonstrate a moderate-severe restrictive ventilatory defect. There is no bronchodilator response. Diffusion capacity is reduced, and does not correct for alveolar volume, suggestive of underlying pulmonary parenchymal and/or vascular disease. **These results are/are not consistent with my provisional diagnosis of (XYZ)** >[!info] Scroll down for chest imaging when ready --- **Chest imaging** *Chest X-ray*: ![[Case JH CXR.png]] >[!example]- Please comment on the relevant findings of this X-ray > The most prominent finding on this chest X-ray is that of <<>>. > > Other findings on chest X-ray imaging include: > - <<>> > - <<>> > > **These findings reinforce/go against my differential diagnosis of (XYZ)** **CT Chest** ![[Case JH CT1.png]] ![[Case JH CT2.png]] >[!example]- Please comment on the relevant findings of this these CT slices > The most prominent finding on this CT scan is <<>>. > > Other findings on these CT Chest slices include: > - <<>> > - <<>> > > **These findings reinforce/go against my differential diagnosis of (XYZ)** >[!info] Scroll down for discussion when ready --- **Discussion questions** >[!question]- What are the causes of chronic interstitial lung disease? > >The causes of interstitial lung disease include: > >- **Idiopathic**: Idiopathic pulmonary fibrosis (IPF) >- **Connective tissue diseases:** Rheumatoid arthritis, SLE, scleroderma, ANCA, myositis >- **Inhalational exposure:** Asbestosis, silicosis, hypersensitivity pneumonitis >- **Medication exposure:** Amiodarone, Methotrexate, Bleomycin, Nitrofurantoin > > > [!tip] > > - In answering this question, suggest focusing on the general categories and citing 1-2 examples each, rather than rattling off an unstructured list of differentials. > > - Demonstrating a structured, logical approach to your thinking is more valuable than how many differentials you can name. As long as you can remember the general categories, it is typically straightforward to provide 1-2 examples for each. > > - It is also important to **link** this discussion to your patient. For example, are there signs on clinical examination (e.g. stigmata of CTD, pacemaker/valve disease) that suggest one of these aetiologies? >[!question]- What are the respiratory causes of nail clubbing? > >The respiratory causes of nail clubbing include: >- Lung malignancy >- Interstitial lung disease >- Bronchiectasis >- Chronic suppurative infection (e.g. lung abscess, empyema, cavitating infection) >[!question]- How would you investigate a patient with interstitial lung disease? >> [!tip] > > *The response to this question is somewhat dependent on what has already been discussed (e.g. if you have already discussed RFTs/HRCT, there is no need to re-cite these and it may be that you start discussion from 'blood tests' onwards). It is also important to cite what you are looking for on these investigations in a concise way.* > - **Imaging:** > - **CXR:** Evaluate for reticular or nodular infiltrates suggestive of interstitial lung disease, and features suggestive of the underlying aetiology, such as lymphadenopathy (sarcoidosis) or pleural plaques (asbestosis). > - **HRCT Chest:** To evaluate pattern, distribution, and extent of any interstitial changes, such as reticular changes, ground-glass opacity, honeycombing, or traction bronchiectasis >- **Respiratory function tests:** > - **Spirometry and gas transfer:** May see restrictive pattern and reduced DLCO. > - **Static lung volumes**: Confirm true restriction (if suggested on spirometry). Expect to see reduced TLC and RV. >- **Blood tests:** > - **FBE/CRP:** Evidence of an acute inflammatory process and/or polycythaemia > - **Autoimmune screen** (e.g. RF, anti-CCP, ANA, dsDNA, ANCA, myositis panel etc.): Evaluate for an underlying CTD > - **Other tests** to evaluate for an underlying aetiology (e.g. ACE, avian precipitins) > - **Arterial blood gas**, to evaluate for chronic type 1 respiratory failure >- **Other tests:** > - **TTE:** Evaluate for pulmonary hypertension and/or cor pulmonale > >[!question]- What are the complications of interstitial lung disease? >The complications of interstitial lung disease include those related to: > >- **Chronic hypoxaemia:** Hypoxaemic respiratory failure, which can lead to pulmonary hypertension and right heart failure (cor pulmonale) >- **Chronic inflammatory state:** Increased risk of lung malignancy >- **Complications of therapy**: Increased risk of infection with immunosuppression --- **References:** - CXR: [Case courtesy of Bruno Di Muzio, Radiopaedia.org, rID: 28155.](https://radiopaedia.org/cases/idiopathic-pulmonary-fibrosis-7?lang=gb) - Flow-volume loop: [Deranged Physiology](https://derangedphysiology.com/main/cicm-primary-exam/respiratory-system/Chapter-556/interpreting-shape-flow-volume-loop) - RFTs: Randomly generated to fit the case.