Respiratory Flashcards
Lung volumes.
Describe the components of Vital Capacity (VC), Functional residual capacity (FRC) and Total Lung Capacity (TLC).
VC = IRV + TV + ERV FRC = ERV + RV (the total of the reserve volumes) TLC = IRV + TV + ERV + RV
Bronchial challenge tests in Asthma.
Describe Indirect versus Direct challenges.
What components of airway hyperresponsiveness does each challenge reflect?
INDIRECT challenges (eg mannitol, hypertonic saline, voluntary hyperventilation, exercise challenge) activate mast cells to release histamine and other bronchoconstrictor mediators.
INdirect challenges reflect the INflammatory component of airway hyperresponsiveness.
(Highly specific! = INdirect rules “IN” Asthma)
DIRECT challenges (eg methacholine, histamine) DIRECTLY constrict airway smooth muscle via receptors on smooth muscle. Direct challenges reflect the persistent airway remodelling component of AHR. ie. Muscle function, airway calibre. (Highly sensitive)
What are the causes of Constrictive Bronchoilitis (synonym Bronchiolitis Obliterans)?
What is the clinical presentation and diagnosis?
(PEP lecture)
Causes and associated disorders:
- cryptogenic
- post infectious (adeno, RSV, para/influenza, mycoplasma)
- CT diseases eg RA
- inhalational injury (NO2, SO2, ammonia)
- allograft recipients (heart, lung or BM transplants)
- drugs (penicillamine, lomustine, cocaine, gold)
- other associations: inflam bowel disease, carcinoid
Clinical presentation:
- persistent cough
- worsening dyspnoea
- progressive and poorly responsive to steroids
- PFTs- air trapping, progressive obstructive defect
- CXR- nonspecific
- HRCT- mosaic areas of decreased attenuation and vascularity, air trapping, +/- cylindric bronchiectasis
- Histopath- peribronchiolar fibrosis, cicatrisation (healing/scarring) or bronchiolar lumen, fibrosing inflammatory process surrounding lumen, extrinsic compression and obliteration of the airway
What are the features of COP (Cryptogenic Organising Pneumonia)?
- symptoms
- causes
- PFTs
- CT Chest
- Histopath
Symptoms:
- malaise, fever, chills, weight loss, myalgias (Systemic symptoms!)
- SOB, cough (dry or productive)
- usually steroid responsive
Causes:
- may be idiopathic or nonspecific response to infection or a drug
PFTs:
- mild-mod restriction
- reduced TLCO
CT Chest:
- consolidation in lower/subpleural zones
- ground glass opacities
- pulm nodules
- pleural thickening/tags
Histopath:
- loose granulation tissue in terminal bronchioles/alveoli
- presence of fibrin and collagen
(Because of failure of lung to respond to injury –> persistent inflammatory and loose granulation tissue)
What is the best current standard for measuring deterioration of Idiopathic Pulmonary Fibrosis/ UIP?
Name the biomarkers of poor prognosis in UIP.
(PEP lecture)
Best measure of decline in IPF is by a 10% reduction in FVC.
(Older way is by a decline in DLCO by 15%)
Change in saturation is only seen in advanced disease, hence look for a change in PFTs.
Circulating Fibrocytes = indicator of poor prognosis in IPF
Increased serum CCL-18 levels = predictive of disease progression
What is the diagnostic criteria for IPF/ UIP?
What are the common findings on imaging and histo?
(PEP lecture)
IPF = UIP = FIBROBLASTIC FOCI!!!
New diagnostic criteria for IPF:
- Exclusion of other known causes of interstitial lung disease
- UIP pattern on HRCT (if not biopsied)
- Combination of HRCT and biopsy patterns
(HRCT findings of UIP always trumps Histopathalogy!!! eg. if Histopath is equivocal but CT is suggestive of UIP, then a diagnosis of UIP can be concluded based on imaging alone. Or if there are typical UIP features then there is NO need for biopsy)
HRCT findings:
- HONEYCOMBING in subpleural distribution
- Marked FIBROSIS
- Architectural distortion
- TRACTION BRONCHIECTASIS
- patchy involvement
- usually symmetric and spares the Apices (BASAL predominance)
- reticular changes
Histo:
- FIBROBLASTIC foci pathognomonic
- marked fibrosis
- patchy (some areas of normal lung, not uniform –> temporal HETEROgeneity)
- mostly collagen with minimal inflammatory cells
Radiology findings in Interstitial Lung Disease.
What are the DDx for:
- Upper or mid-lung changes
- Peribronchovascular changes
- Extensive ground glass
- Micronodules
(PEP lecture)
- Upper or mid lung - think sarcoidosis or hypersensitivity pneumonitis
- Peribronchovascular - think sarcoidosis
- GGO’s - think NSIP
- Micronodules - think hypersensitivity pneumonitis, MAC
What are the Radiology and Histopath findings in NSIP?
Radiological findings:
- GROUND GLASS changes
- Absence of honeycombing
(These 2 findings differentiate NSIP from UIP.
Distribution is also basal/subpleural and spares the apices, bilateral, traction bronchiectasis, reticular pattern)
Histopath findings:
- HOMOGENOUS pattern (UNIFORM distribution, not patchy) temporally and spatially
- Inflammatory cells present
- Mixture of interstitial fibrosis and inflammation
- absence of fibroblastic foci
What is the best evidence-based management for a patient with idiopathic pulmonary fibrosis?
(PEP lecture)
1. Refer patient to an IPF centre for enrolment in clinical trial! (“Best current treatment” is participation in a new study)
- Long term oxygen therapy (but no evidence that it influences QoL or survival)
- Lung transplant (strong evidence)
- refer when TLCO is 40%
- *SINGLE lung transplant is preferred over double lung Tx (equivalent outcomes)
- age cut off is 65yo (mean age at Dx is 66yo; most people miss out) - Pulmonary rehab (weak evidence - should offer to all patients)
- Treat uncontrolled GORD (weak evidence)
- Also weak evidence for a role for steroids in acute exacerbations
- MONITORING of PFTs is crucial!
Steroids, immunomodulators, anti fibrotics, NAC, warfarin NOT USEFUL.
What is NSIP?
What therapy is available for NSIP?
(PEP lecture)
Mainly a Connective-tissue related lung fibrosis.
May also be idiopathic.
There is a spectrum of fibrotic lung disease vs predominantly ground glass disease.
There is some response to medical therapy with Prednisolone/ Cyclophosphamide (depends on where patient lies in spectrum –> less responsive if fibrotic disease)
What rare idiopathic interstitial LD is commonly associated with HIV or Sjögren’s syndrome?
What are the CT and Histopath findings in this condition?
- Lymphocytic interstitial pneumonia
(Dense lymphocytic infiltrates may progress to lymphoma) - CT- ground glass, nodular infiltrates –> resolves leaving cysts
Histo- T cells +++, dense lymphocytic infiltrates
Pulmonary Sarcoidosis.
What are the CT findings?
Histopath findings?
Treatment?
CT findings:
Upper zone fibrosis (+/- mid zone)
Bilateral symmetrical mediastinal lymphadenopathy
Histopath:
- NON-caseating granulomas
- Normal lung parenchyma
Treatment:
No treatment unless symptomatic
Steroids +/- Methotrexate for progressive disease
Can recur following lung tx
Combined Pulmonary Fibrosis and Emphysema (CPFE) is a newly described condition.
What are the features (clinically, PFTs, imaging)?
Interstitial LD with the confounding effect of emphysema.
Present in 30-40% of ILD patients.
High incidence of pulmonary HT (Cor pulmonale)
PFTs show NORMAL volumes!! (Because hyperinflation/emphysema and restriction/ILD neutralise the lung volumes)
Major reduction in gas transfer
CT shows UPPER ZONE emphysema and LOWER ZONE fibrosis/IPF.
What interstitial lung disease affects non-smoking postmenopausal women, with renal or ovarian cysts?
What are the CT findings?
What new treatment has been shown to be beneficial?
PLAM = Pulmonary Lymphangio Leiomyomatosis
(Leiomyoma in lungs / proliferation of smooth muscle)
Mainly in postmenopausal women, with angiofibromas in face, renal/ovarian cysts.
CT shows CYSTS, hyperinflation, Chylous (lymph) effusions.
SIROLIMUS changes the disease progression.
What is Lofgen Syndrome?
Sarcoidosis (bilateral hilar lymphadenopathy) \+ Arthralgia \+ Erythema nodosum.
= good prognosis
(“I LAUGHed at his SARCastic Attempt to ENtertain” = LAUGHgren = SARCoid, Arthralgias, Erythema Nodosum)
