Session 6 Flashcards
What is ‘Spirometry’
- ‘Spirometry’ (Latin) = the measuring of breath
- The spirometer records the volume of air that is breathed in and out
- and generates tracings of air flow (i.e. pneumotachographs)
- Tracings used to calculate: – vital capacity, tidal volume – the flow rate of air movement
Reasons for Pulmonary Function Tests
- Diagnosis -Tests are rarely diagnostic on their own – Results taken together with history and examination
- Patient assessment -Most usual reason for tests – Serial changes – Response to therapy – Assessment for compensation – Pre-surgical assessment
- Research purposes – Epidemiology – Study of growth and development – Investigation of disease processes
Do we take spirometry readings standing or seated?
• FVC standing> FVC seated
– BUT high intrathoracic pressure can result in reduced cardiac output and cerebral blood flow
3 types of graph produced using spirometry?
Tracings, Graphs Flow, Volume Loops
insert slide 6 lec 1
Movements of the TRACE
- The classic presentation of the traces from these recordings is therefore:
- INSPIRATION as an upward deflection
- EXPIRATION as a downward deflection
Draw a spirogram trace and label it. How are the values calculated?
insert slide 10 lec 1
- Lung Capacities – Inspiratory capacity =
- VT + IRV – FRC – VT – VC
- Inspirational capacity = – VT + IRV
- Functional Residual Capacity = – ERV + RV
How do we get from a spirogram (volume-time trace) to a volume-time graph?
panopto
Forced flow-volume measurements show us?
• How much air can the subject blow out? – can be reduced in restrictive disorders, – or if there is airway narrowing precipitating early airway closure (e.g. asthma or CF) • How fast is the air expelled? – can be reduced with airway narrowing. • Pattern of change in flow-volume curve (insp& exp) can indicate site of obstruction • Response to treatment (e.g. β2agonist) • Change with age or growth • Progression of disease
What is FVC, FEV1, PEF and why is FEV1 useful
FVC: Maximal amount of air that the patient can forcibly exhale after taking a maximal inhalation
FEV1: Volume exhaled in the first second
Peak expiratory flow (PEF): Maximal speed of airflow as the patient exhales
FEV1 is the most reproducible flow parameter and is especially useful in diagnosing and monitoring patients with obstructive pulmonary disorders (eg, asthma, COPD).
picture from slide 14
Nomogram for predicting FVC
Forced vital capacity (FVC) – The measured value is compared to that of healthy people of the same • gender, • age and • height slide 15 lec 1
The time- volume graph
Patient inspires to vital capacity Rapid forced expiration • Convention shows expiration as a downward defection on a spirometry trace: • This is a graph volume (L) expired against time • Follows normal graph conventions inser pic from slide 16 lec 1
Volume-time plot of maximal forced expiration
ue panopto slide 17 lec 1
Volume-Time graphs in obstructive disease (Asthma, COPD)
- FVC is not markedly reduced
- (if given sufficient time to completely breathe out)
- Narrowed airways reduces the speed at which air can be breathed out.
- Fraction of air expelled during 1st second (FEV1 /FVC) is markedly reduced.
- Typical pattern in obstructive airways disease: – FVC nearly normal – FEV1 markedly reduced – The FEV1 /FVC ratio < 70%
slide 18 lec 1
Volume-Time graphs in restrictive disease (lung fibrosis)
Volume-Time graphs in restrictive disease (lung fibrosis) • FVC is markedly reduced (lungs stiff, cannot be expanded adequately) • However, the speed at which air can be breathed out is normal (because no narrowing of airways) • the fraction of air expelled during 1st second is normal or even greater than normal • The typical pattern in restrictive airways disease: – A Low FVC – Low FEV1 – But FEV1 /FVC ratio ≥ 70% slide 19 lec 1
How do we get from a spirogram (volume-time trace) to a flow-volume loop?
use panopto slide 21 lec 1
Ho might the flow volume look normally compared to COPD, Fixed-extra thoracic obstruction, during a cough, restrictive lung disease and upper airway obstruction? and why?
slide 23 lec 1
How do obstructive diseases differ on a flow volume loop compared to restrictive disease and then mixed disease
slide 30 lec 1
What is bronchiectasis?
DEFINITION: Chronic IRREVERSIBLE dilatation of one or more bronchi – it is a pathological condition that can be caused by many diseases or be idiopathic- resulting in abnormally enlarged bronchi – These deformed bronchi exhibit poor mucus clearance and there is predisposition to recurrent or chronic bacterial infection
- AETIOLOGY: variety of underlying causes, with a common underlying mechanism of of chronic inflammation • Inflammation causes destruction of the elastic and muscular components of the bronchial wall and peribronchial fibrosis
- RADIOLOGICAL FINDINGS • CXR - usually abnormal but inadequate in the diagnosis or quantification of bronchiectasis/ bronchial dilatation – Gold standard diagnostic investigation = CT - specifically High Resolution CT
- We find -bronchial dilatation bigger than the adjacent blood vessel, bronchial wall thickening
How is bronchiectasis signified on a CT?
Signet Ring Signdilated bronchus and accompanying pulmonary artery branch are seen in cross-section. healthy lung bronchus slightly Smaller than artery whereas in bronchiectasis, the bronchus is markedly dilated > artery slide 3 lec 2
What do you notice about this pitients lungs insert diagram from slide 4 lec 2
Gross pathologic lung specimen from a patient with bronchiectasis. Notice the small pulmonary artery abutting the much larger dilated bronchus (arrow), both of which are seen on cross- section
Clinical symptoms of bronchiectasis?
Very Common: • Chronic cough • Daily sputum production – can vary in quantity, colour and consistency Common: • Breathlessness on exertion • Intermittent haemoptysis • Nasal symptoms • Chest Pain • Fatigue Less Common: • Wheeze Symptoms not very specific – history and risk factors key to Dx
Bronchiectasis – what are the clinical signs?
• Pulse oximetry may reveal hypoxaemia in advanced cases of bronchiectasis • Fever relatively common - More than half of patients with bronchiectasis will have recurrent episodes of fever • Haemoptysis - present in about 50% of patients - usually mild • Fine crackles (rales) • High-pitched inspiratory squeaks • Rhonchi • Sometimes can hear both crackles & wheezing - Lungs sounds from CF patient w/ bronchiectasis • Systemic signs - a history of weight loss common • Clubbing of the digits is less common
Causes of bronchiectasis?
• Post infective– whooping cough (pertussis), TB • Immune deficiency– Hypogammaglobulinaemia • Mucociliaryclearance defects– Cystic fibrosis, primary ciliary dyskinesia, Young’s syndrome (triad of bronchiectasis, sinusitis, and reduced fertility), Kartagener syndrome (triad of bronchiectasis, sinusitits, and situs inversus) • Idiopathic • Alpha-1-antitrypsin deficiency • Obstruction – foreign body, tumour, extrinsic lymph node • Toxic insult – gastric aspiration (particularly post lung transplant), inhalation of toxic chemicals/gases • Allergic bronchopulmonary aspergillosis • Secondary immune deficiency – HIV, malignancy • Rheumatoid arthritis • Associations – inflammatory bowel disease; yellow nail syndrome
Bronchiectasis Common Organisms - How is it a vicious cycle?
• Haemophilus influenzae • Pseudomonas aeruginosa • Moraxella catarrhalis • Stenotrophomonas maltophilia • Streptococcus pneumoniae • Fungi – aspergillus, candida • Mycobacteria tuberculosis • Nontuberculous mycobacteria (NTM) • Less common - Staphylococcus aureus Bronchial dilation leads to mucous accumulation, impaired ciliary function and increased risk infection; Infection leads to inflammation and loss bronchial elastic fibres and smooth muscle –leads to more dilatation!
How might a patient with possible bronchiectasis present?
• History of “asthma” (particularly lifelong )without any great objective evidence – such as reversible airway obstruction on spirometry– also in asthma no inspiratory squeaks and crackles • History of “COPD” but diminished breath sounds, characterising COPD, are not found & different risk factors • BUTif they do have a history of – Severe chest infection earlier in life (bacterial, viral or atypical) – Lifelong chest infections ? genetic cause – Recurrent chest infections ?immunodeficiency – Recurrent sinus infections since childhood? ? Ciliary dysfunc, • Sputum culture positive for common organisms such as haemophilus or pseudomonas or atypical mycobacterium • Inflammatory bowel disease, rheumatoid arthritis – also associated with bronchiectasis
Why is early diagnosis of bronchiectasis important?
early diagnosis and treatment of predisposing underlying disorders may impede disease progression
How are Pulmonary function tests used to diagnose bronchiectasis?
• Initial and follow up spirometry is recommended with most surgery visits – diagnosis and follow up lung function • Obstructive airways disease component may be evidenced by reduced forced expiratory volume (FEV1) or an FEV1/forced vital capacity (FVC) ratio of <70% • Full pulmonary function testing may show an elevation of RV/TLC ratio consistent with air trapping. • Diffusing capacity for carbon monoxide (DLCO) may be reduced in severe disease • Question: We all remember diffusing capacity is inversely related to the distance the gas has to travel – so, since there is marked thickening of the bronchial walls why isn’t diffusing capacity reduced in early disease?
