6 Flashcards
(48 cards)
1
Q
What is spirometry?
A
- measurement of the movement of air during breathing
- records the volume of air that is breathed in and out
- generates tracings of air flow
2
Q
What are the tracings from a spirometry used to calculate?
A
- vital capacity, tidal volume
- flow rate of air movement
3
Q
What are the reasons for pulmonary function tests?
A
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
4
Q
Why is vital capacity useful in spirometry?
A
-measured value can be compared to the predicted vital capacity of an individual of the same age, height and sex to determine the status of patient
5
Q
Why might vital capacity be reduced?
A
- filled normally in inspiration
- emptied normally in expiration
- or both
6
Q
What is “restrictive” deficit?
A
- maximal filling of lungs usually determined by the balance between maximum inspiratory effect and force of recoil of the lungs
- so if lungs are unusually stiff, or inspiratory effort is compromised by muscle weakness, injury or deformity, then this deficits is produced
7
Q
What is an “obstructive” deficit?
A
When airways are narrowed so expiratory flow is compromised much earlier in expiration
8
Q
How do modern spirometers work?
A
- use electronic method of measuring the volume of gas inhaled/exhaled through a mouthpiece
- recorded on a vitalograph which shows the volume expired during a vital capacity breath
- FVCstanding > FVCseated but high intrathoracic pressure can result in reduced cardiac output and cerebral blood flow so pt. May faint
- preferable to put nose clip on pt. So that air isnt lost through nose
- must observe the subject
9
Q
What is a Collins water seal spirometer?
A
- old spirometer
- if pen records an upward deflection and the silver sinks, that means pt. Is breathing IN air
- if pen shows downward curve and the silver rises then pt. Is breathing air OUT
- floating bell-jar is inversely proportional to breathing
- expired gas passes into water seal
- increased pressure causes jar to rise
- movement transmitted to pen
- pen movement proportional to volume breathed in/out
- see lecture 6.1 slides 5-7
10
Q
Explain what the movements of the TRACE mean?
A
- INSPIRATION as an upward deflection
- EXPIRATION as a downward deflection
11
Q
What lung capacities are shown on a Spirograph?
A
- Vt= tidal volume
- FRC= functional reserve volume
- VC= vital capacity
- inspiratory capacity
12
Q
How do we calculate inspiratory capacity?
A
Vt + IRV
13
Q
How do we calculate functional residual capacity?
A
-ERV + RV
14
Q
How can we distinguish between restrictive and obstructive deficits on paper?
A
- through time-volume graph
- convention shows expiration as a downward deflection on spirometry trace
- graph of volume (L) expired against time
- follow normal graph conventions
- pt. Inspires to vital capacity
- rapid forced expiration
- see session 6.1 slides 16-17
15
Q
What do forced flow-volume measurements show us?
A
- how much air can the subject blow out?
- could be reduced in restrictive disorders
- may be airway narrowing precipitating early airway closure (ex. Asthma or CF)
- how fast is the air expelled? (Could be reduced with airway narrowing)
- pattern of change in flow-volume curve (insp and exp) can indicate site of obstruction
- response to treatment (ex. B2 agonist)
- change with age or growth
- progression of disease
16
Q
Define FVC, FEV1 and PEF on a time-volume graph
A
- FVC: maximal amount of air that the pt. Can forcibly exhale after taking a maximal inhalation
- FEV1: volume exhaled in the first second
- PEF (peak expiratory flow): maximal only 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 (ex. Asthma, COPD)
17
Q
How will a volume-time graph look in obstructive disease (asthma, COPD)
A
- FVC is nearly normal if given sufficient time to completely breathe out
- narrowed airways reduces the speed at which air can be breathed out
- FEV1 is markedly reduced
- fraction or air expelled during first second (FEV1/FVC) is markedly reduced; ratio <70%
- see graph on session 6.1 slide 18
18
Q
How will a volume-time graph look in restrictive disease? (Lung fibrosis)
A
- FVC is markedly reduced (lungs stiff, cant be expanded adequately)
- lungs not as stretchy anymore
- however the speed at which air can be breathed out is normal (because no narrowing of airways)
- FEV1 is reduced proportionately
- fraction of air expelled during first second is normal or even greater than normal
- FEV1/FVC ratio is greater or equal to 70%
- see graph on session 6.1 slide 19
19
Q
What is a flow volume curve/loop?
A
- when expiratory flow rate is plotted against lung volume
- obstructive deficient may be more revealed through this loop
20
Q
Explain how to read a flow-volume loop
A
- look at it like a clock, goes in clockwise direction
- at the start of expiration, line goes up to produce peak expiratory flow
- as expiration continues, there is a fall in expiratory flow rate since airways are narrowing
- then residual volume is empty
- inspiration begins, so producing a vital capacity
- inspiration continues until total lung capacity produced
- then cycle starts again
21
Q
What cheap device can patients use at home to produce a peak expiratory flow rate?
A
-Peak Flow Meter
22
Q
What is scolloping?
A
- when the flow-volume loop produces a concave shape
- means the small airways are narrower than expected; they are contracting abnormally
- see session 6.1 slide 22
23
Q
Why do COPD and asthma produce the same flow-volume loop but COPD is worse than asthma?
A
-asthma loop can be fixed after taking bronchodilators but COPD loop cannot be fixed
24
Q
How would a flow-volume loop look like in obstructive airways disease?
A
- mild obstruction of the small airways produces scalloping of the flow volume curve
- more severe obstruction also reduces PEFR
25
How would a flow volume loop look in restrictive disease?
- characterized by a reduction in FVC
- results in narrow flow volume loop
- but PEFR is not significantly reduced as there is no airways obstruction
- results in a narrow and tall flow volume loop
26
How can we measure residual volume?
- volumes of air remaining in the lungs after expiration
| - may be measured by the helium dilution test
27
How can we measure dead space?
-measured by the nitrogen washout method
28
How can we measure diffusion capacity?
- “diffusion conductance”: resistance to diffusion across the alveolar membrane
- estimated by the carbon monoxide transfer factor (TLCO)
29
What is bronchiectasis?
- chronic irreversible dilation of one or more bronchi
- bronchi exhibit poor mucus clearance
- predisposition to recurrent or chronic bacterial infection
- results in abnormally enlarged bronchi
- pathological condition that can be caused by many diseases or is idiopathic
30
What is the aetiology (causes) of bronchiectasis?
- common underlying mechanism of chronic inflammation
- inflammation causes destruction of the elastic and muscular components of the bronchial wall and peribronchial fibrosis
- post-infective: whooping cough, TB
- immune deficiency: hypogammaglobulinaemia
- genetic/mucociliary clearance defects: CF, primary ciliary dyskinesia, Young’s syndrome (triad of bronchiectasis, sinusitis and reduced fertility), Kartagener syndrome (triad of bronchiectasis, sinusitis and situs inversus)
- obstruction: foreign body, tumour, extrinsic lymph node
31
What diagnostic tests will be done for bronchiectasis? What will you see?
- CXR: usually abnormal but inadequate in the diagnosis or quantification of bronchiectasis/bronchial dilation
- Gold standard is a high resolution CT: willl see bronchial dilation bigger than the adjacent pulmonary arteriole and bronchial wall thickening
32
What is the signet ring sign?
- seen in CT-dilated bronchus and accompanying pulmonary artery branch are seen in cross-section
- in healthy lung the bronchus is slightly smaller than the artery
33
What are the 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
34
What are the clinical signs of bronchiectasis?
- pulse oximetry (measures o2 sat of blood) may reveal hypoxaemia in advanced cases of bronchiectasis
- fever relatively common: more than half of bronchiectasis patients will have recurrent fever episodes
- haemoptysis: present in about 50% of patients but usually mild
- fine crackles (rales) due to the collapsed airways popping
- high-pitched inspiratory squeaks
- rhonchi: sounds that are lower in pitch, sounds like rumbling
- sometimes can hear both crackles and wheezing
- systemic signs: history of weight loss (common) and clubbing of digits (less common)
35
What are some common organisms that cause bronchiectasis?
- haemophilus influenzae
- pseudomonas aeruginosa
- moraxella catarrhalis
- strenotrophomonas maltophilia
- fungi: aspergillus, candida
- non-tuberculous mycobacteria (NTM)
- staph aureus (less common)
36
Why is it important to consider whether a patient may have bronchiectasis?
- early diagnosis and treatment may impede disease progression
- see if they have history of asthma or COPD
- see if they have history of chest infections
- see if sputum culture is positive for common organisms such as haemophilus, pseudomonas or atypical mycobacterium
- check if they have IBD or rheumatoid arthritis
37
How would you manage bronchiectasis?
- treat underlying cause
- physio/airways clearance: daily airway clearance is essential for treatment success
- sputum sampling: routine culture and NTM
- exclude immunodeficiency
- consider long-term therapies at future visits
- supportive: flu and routine vaccine
- management plan for infective exacerbations
38
How can we define an exacerbation in bronchiectasis?
Has deterioration in 3 or more key symptoms for at least 48 hours:
- cough
- sputum volume and/or consistency
- sputum purulence
- breathlessness and/or exercise tolerance
- fatigue
- haemoptysis
39
What is the most common identifiable cause of bronchiectasis?
Cystic fibrosis
40
Define cystic fibrosis
- autosomal recessive disorder leading to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)
- can lead to multisystem disease (i.e. respiratory and GI) which is characterized by thickened secretions
41
How is cystic fibrosis diagnosed?
- one or more of the characteristic phenotypic features
- or a history of CF in a sibling
- or a positive newborn screening test result
AND
- increased sweat chloride concentration (>60mmol/L) SWEAT TEST
- Or identification of 2 CF mutations (genotyping)
- or demonstration of abnormal nasal epithelial ion transport (nasal potential difference)
42
What are the classic CF clinical presentations?
Meconium ileus
- 15-20% newborn CF infants have bowel blocked by sticky secretions
- signs of intestinal obstruction soon after birth with bilious vomiting, abd distension and delay in passing meconium
Intestinal malabsorption
- over 90% of CF individuals have intestinal malabsorption
- most is evident in infancy
- main cause is sever deficiency of pancreatic enzymes, potentially leading to type 3 diabetes
Recurrent chest infections
Newborn screening
43
What are some complications of CF?
Lungs
- bronchiectasis
- pneumothorax
- haemoptysis
- resp failure
Nasal/upper resp tract
- chronic sinusitis
- nasal polyposis
Pancrease
- pancreatic insufficiency
- diabetes mellitus
Gut
- distal intestinal obstruction syndrome (DIOS)
- oesophageal reflux/oesophagitis
Liver
- chronic liver disease
- portal hypertension
Biliary tree
-gallstones
Heart
-cardiac failure to right side of heart because pumping into a diseased lung
Joints and bones
- arthritis
- osteoporosis
Reproductive tract
- male infertility
- congenital bilateral absence of vas deferens (CBAVD)
44
What lifestyle advice should CF patients follow?
- no smoking
- avoid other CF patients
- avoid friends/relatives with colds/infections
- avoid jacuzzies (pseudomonas)
- clean and dry nebulisers thoroughly
- avoid stables, compost or rotting vegetation (risk of aspergillus fumigatus inhalation)
- annual influenza immunization
- NaCl tablets in hot weather/vigorous exercise
45
What are the categories of defects due to CFTR mutation?
- no protein production
- protein made but never gets to cell membrane
- protein gets to membrane but DOESNT work at all
- protein made but only partially active
- protein expressed at gene level but substantial reduction in mRNA or protein, or both, synthesis
- protein gets to membrane but partially unstable
46
What drug has been made to treat CF?
Orkambi (trade name for two drugs)
Lumacaftor
- CFTR chaperone during protein folding which increases the number of CFTR proteins that are trafficked to the cell surface
- helps in people with Phe508del (most common mutation)
Ivacaftor
- CFTR potenitator which improves the transport of chloride through the ion channel by binding to the channels directly and increasing the probability that the channel is open
- helps people with G551D mutation (in 4-5% cases of CF)
47
What is V/Q?
Ventilation/perfusion ratio
48
What will happen to v/Q if there is reduced ventilation of parts of the lung?
- occurs in pneumonia, asthma, COPD, and respiratory distress syndrome in newborns
- V/Q < 1 since ventilation is low relative to perfusion
