Week 8 - Respiratory Flashcards
What is spirometry?
Forced expiratory manoeuvre from total lung capacity followed by a full inspiration .
How might you instruct a patient who is doing a spirometry test?
“Take a deep breath in as far as you can then blow out as hard as you can for as long as you can and then take a deep breath all the way in.”
What are some of the pitfalls of spirometry?
Result depends on patient technique and effort, requires a trained technician, patients may be too ill or in pain to do the test.
What would a normal FEV1/FVC ratio be?
> 70%
What type of lung disease is asthma and COPD? What would you expect the FEV1/FVC ratio to be?
Obstructive lung disease
<70%
Severity of COPD is stratified by % of predicted FEV1. What % corresponds to mild, moderate, severe and very severe COPD?
Mild >80%
Moderate 50-80%
Severe 30-50%
Very severe <30%
How is reversibility testing done? What result would be suggestive of asthma?
Nebulised or inhaled salbutamol given, spirometry done before and 15 minutes after salbutamol.
15% and 400ml reversibility in FEV1 suggestive of asthma.
What effect would a restrictive lung disease have on the FVC and the FEV1? What would the expected FVC/FEV1 ratio be?
FEV1 and FVC reduced.
FEV1/FVC ratio >70%.
What are some of the causes of a restrictive spirometry?
Interstitial lung disease, kyphoscoliosis, previous pneumonectomy, neuromuscular disease, obesity, poor effort/technique.
How is transfer factor measured? What conditions is it reduced in?
Single breath of very small concentration of carbon monoxide inhaled, then the concentration in expired gas measured to derive uptake in the lungs. (CO has a very high affinity for haemoglobin).
Emphysema
Anaemia
Interstitial lung disease
Pulmonary vascular disease.
What effect does restrictive and obstructive lung diseases have on lung volumes?
Restrictive - lung volume reduced
Obstructive - lung volume can increase.
What equation allows you to measure the alveolar oxygen partial pressure?
PAO2 = FiO2 - (1.25 x PaCO2)
FiO2 - inspired oxygen concentration
PaCO2 - arterial CO2 concentration
What is the difference in arterial gas results in type 1 and type 2 respiratory failure?
Type 1 - low oxygen without increased CO2
Type 2 - low oxygen and elevated CO2.
Describe COPD, including its aetiology.
COPD is a disease characterised by airflow obstruction which is normally progressive and not fully reversible.
Commonly caused by smoking but also pollution, occupational dusts and alpha 1 antitrypsin deficiency.
What are some of the effects of cigarette smoking on the respiratory system?
- cilial motility reduced
- airway inflammation
- goblet cell and mucous hypertrophy
- increased protease activity
- oxidative stress
- squamous metaplasia - higher risk of lung cancer.
What is the function of alpha 1 anti-trypsin and how does it contribute to lung disease?
There to counterbalance destructive enzymes in the lung, if you are deficient you get destruction of lung tissue and COPD much earlier.
What are the two clinical syndromes of COPD? Describe them.
Chronic bronchitis - production of sputum on most days for 3 months for at least 2 years in a row.
Emphysema - abnormal, permanent enlargement of the airspaces distal to the terminal bronchioles due to destruction of lung parenchyma.
Chemoattractant substances in cigarette smoke attract inflammatory cells to the alveoli. What cells types are involved? What inflammatory mediators are involved?
Macrophages, T lymphocytes, neutrophils.
TNF, IL-8, MMPs, reactive oxygen species.
What is the difference in pathology and aetiology between centri-acinar and pan-acinar emphysema?
Centri-acinar - damage around the respiratory bronchioles, more in the upper lobes. Caused by smoking and inhaling fumes.
Pan-acinar - uniformly damaged from the level of the terminal bronchiole distally, associated with alpha 1 antitrypsin deficiency.
What treatment is available for COPD?
Inhaled bronchodilators - i.e. LAMAs, LABAs (salmeterol), SAMAs, SABAs (i.e salbutamol).
Inhaled corticosteroids - budesonide, fluticasone.
Oxygen therapy, mucolytics, nebulised therapy.
What percentage of oxygen would you aim to give acute COPD patients? What oxygen saturation are you aiming for? What is the reason for this?
24-28% oxygen
88-92% sats
Too much oxygen and too high sats in COPD patients can reduce respiratory drive and lead to worsening hypercapnia.
Define allergy.
Allergy is an immune system mediated intolerance.
How would you define asthma clinically?
Appropriate symptoms with signs which is episodic, triggered and variable with some response to asthma therapies.
What is asthma?
Inflammation of the airway causing reversible airflow obstruction brought on by a trigger which may be allergic.
Asthma leads to airway remodelling in the long term. What changes may occur in the airway of an asthmatic?
Smooth muscle hypertrophy, angiogenesis, epithelial cell damage, fibrosis and scarring.
What cytokines are increased in asthmatics? Which inflammatory cells are activated as a result?
IL-5, IL-13, TNF-alpha
Mast cells, lymphocytes, macrophages, eosinophils, basophils.
What is the clinical presentation of extrinsic allergic alveolitis (EAA)? What are some of the triggers?
Symptoms of wheeze, cough, fever, chills, headache, myalgia, malaise, fatigue 4-6 hours after exposure to a trigger.
Pigeon dander, aspergillus.
What would be the outcome of chronic EAA? What causes the damage?
Fibrosis and emphysema in the lung.
Immune complexes activating complement in the lung which causes tissue damage.
Which type of hypersensitivity is EAA? What mediators are involved?
Type 3
IL-12 and interferon gamma.
What is a pneumothorax? What are it’s three potential aetiologies?
Air within the pleural cavity.
Traumatic, iatrogenic, spontaneous.
What is the difference between a primary and secondary spontaneous pneumothorax?
Primary - no underlying lung disease.
Secondary - underlying lung disease i.e. COPD, CF
What is the treatment of a tension pneumothorax?
Immediate insertion venflon into the second intercostal space, midclavicular line to relieve the pressure.
Will always require ICD.
What are the risk factors for a spontaneous pneumothorax?
Smoking, male gender, height, underlying lung disease?
How does a primary pneumothorax occur?
A subpleural bleb ruptures and leads to a tear in the visceral pleura.