Respiratory Flashcards
What does the upper respiratory tract consist of?
Nose, paranasal sinuses, pharynx and larynx
What is the function of the respiratory system?
Ensure all tissues receive the O2 they need and to dispose of the CO2 they produce
What does the lower respiratory tract consist of?
Trachea, bronchioles and lungs (alveoli)
What are the functions of the upper respiratory tract?
Conduct air, condition air, smell, speech, swallow and protect the airway from inhaling food particles
Outline the structure of the nose
External nose
Nasal cavity which is divided by median nasal septum.
Lateral wall has 3 conchae and the spaces between them are meatus
What are the paranasal sinuses?
Frontal, ethmoidal, maxillary and spheroidal
What are the components of the pharynx? How does one of these parts connect to the middle ear?
Nasopharynx - behind the nose - connect via eustachian tube
Oropharynx - mouth
Laryngopharynx - larynx
What is the epithelium in most of the conducting system of the respiratory tract?
Pseudostratified ciliated epithelium with goblet cells
How does the epithelium of olfactory cells differ?
Thicker pseudostratified without goblet cells containing olfactory dendrites
Boyle’s law?
Pressure inversely proportional to volume
Charles’ law?
Pressure proportional to absolute temperature
Universal gas law?
Pressure x volume = molecules x universal gas constant x temperature
Partial pressure?
Hypothetical pressure of lone gas
Vapour pressure?
Pressure exerted by a vapour
Saturated vapour pressure?
Gas mixture is in equilibrium with water
Tension?
How readily gas will leave liquid
Tidal volume?
Normal volume of air displaced between inhalation and exhalation
Respiratory rate?
Rate of breathing
What is the sternal angle composed of?
Manubrium
Sternal body
Where do ribs 1-7, 8-10 and 11-12 attach?
Via costal cartilage to sternum
To the above costal cartilage
End free in the muscles
What are the bony features of a rib?
Head, neck shaft, costal groove, tubercle
What are the 3 intercostal muscles?
External
Internal
Innermost
Where is the neurovascular bundle supplying the intercostal muscles found?
In the costal groove
Where do the intercostal arteries come from and where do the veins drain to?
Posterior intercostal artery - thoracic aorta
Anterior intercostal artery - internal thoracic artery
Veins - into superior vena cava or the internal thoracic vein
How much does the diaphragm contribute to chest expansion when breathing at rest?
70%
What are the 3 openings of the diaphragm, where are they found and what goes through them?
T8 vena cava
T10 oesophagus
T12 - aorta (aortic hiatus)
What nerve supplies the diaphragm and what is its nerve roots?
Phrenic - C3, 4 and 5
What muscles contribute to inspiration?
External intercostal
Diaphragm
What are the muscles for passive and force expiration?
Passive - elastic recoil
Forced - internal and innermost intercostal
Abdominals
What is significant about the costodiaphragmatic recess?
The lung never fills it
Outline the role of the visceral and parietal pleura
Visceral covers lung. Parietal lines cavity. Separated by fluid which allows friction free movement and also stops them being pulled apart
What 3 factors affect diffusion rate?
Area, gradient and diffusion resistance
What is the inspiratory and expiratory reserve?
The extra volume that can be breathed in/out when compared to rest
What is the residual volume?
The amount of air that’s always left in the lungs. Measured using helium
What is the alveolar ventilation rate and how is it calculated?
The air that is wasted by being left in the airways
Pulmonary ventilation rate - (dead space volume x rate)
What is a pneumothorax?
Air in the pleural cavity causing loss of fluid surface tension and lung collapse
What is compliance?
A measure of lung stretchiness with higher being easier to stretch. Volume change/pressure change
What factors affect compliance?
Surface tension - higher being harder to stretch
Surfactant - disrupts surface tension. More so for small lungs
Why is the resistance of the smaller airways comparatively low?
They are connected in parallel
What is FVC and FEV1?
Forced vital capacity is the maximum expiratory volume
Forced expiratory volume in one second
What is a restrictive deficit and how could you tell if a patient has one?
Lungs difficult to fill but air leaves normally. FVC is reduced but FEV1 is still approximately 70%. Due to muscle weakness
What is an obstructive deficit and how could you tell a patient has one?
Lungs are easy to fill but hard to exit. Usually due to compressed small airways. FEV1 is reduced but FVC is relatively normal
How could you measure functional residual capacity?
Helium dilution test - breathe in known concentration of helium and see how much the concentration changes
What is a transfer factor test?
Test to measure diffusion capacity. Breathe in a small amount of CO and see how much ends up in the blood
What is a nitrogen washout test?
Used to measure dead space. Breathe in 100% oxygen and then measure the volume breathed out before nitrogen appears
How soluble is oxygen in blood in mmol/L?
Not very - 0.13
What are the axes labels for an oxygen dissociation curve? What are the normal values for tissue and lung pO2?
Y - oxygen bound (mmol) or saturation (%)
X - pO2
Lung - 13.3
Tissue - 5
What properties does haemoglobin have that enable it to be a good transporter of oxygen?
Has a tense and relaxed state that allow lots of oxygen to bind in the lungs and allows it to be readily given up in the tissues.
What happens to the oxygen dissociation curve if there is a fall in pH or a rise in temperature?
Shift to the right “Bohr shift”
What affects the diffusion of gases across the alveolar membrane?
Area
Gradient
Resistance
How can you calculate transfer factor/diffusion capacity?
Carbon monoxide
What is the reaction CO2 undergoes in blood?
CO2 + H2O HCO3- + H+
Can also bind to proteins and dissolve in water
What is the Henderson Hasselbalch equation?
pH=pK+log([HCO3-]/(pCO2x0.23))
What influences the hydrogen carbonate concentration in plasma?
Ratio of CO2 reacting in the plasma and the red blood cell.
Primarily dependent on how much CO2 reacts in the RBC which is in turn dependent on how much H+ binds to haemoglobin
How does haemoglobin buffer acids?
If acid is produced it can bind to haemoglobin or react with HCO3- to form CO2 which is breathed out.
What is the function of car amino compounds?
Proteins which bind to CO2. This affects transport but not acid base balance
What is the normal content of CO2 in arterial and venous blood?
Arterial 21.5mmol/L
Venous 23.5mmol/L
What are the ratios of the forms CO2 is transported in?
80% HCO3-
11% carbamino
8% dissolved
Why is acidaemia and alkalaemia dangerous?
Denature enzymes
Tetany due to lower Ca2+
Where are peripheral chemoreceptors located, what do they detect and what do they stimulate?
Carotid and aortic bodies
Hypoxia
Increase breathing, heart rate and blood to brain
What detects changes in CO2? What happens with long term changes?
Central chemoreceptors in the medulla
Choroid plexus cells change “normal” HCO3- levels in CSF
What can cause diffusion impairment?
Fibrotic lung disease - thicken
Emphysema - destroy alveoli
Oedema - fluid increases distance
What is the difference between type 1 and 2 respiratory failure?
Type 1 has normal CO2, type 2 has high
What are some symptoms and causes of type 1 resp failure?
Breathless, exercise intolerant, central cyanosis
Poor perfusion - embolism
Poor ventilation - pneumonia, consolidation, early asthma
Diffusion impairment - oedema, fibrosis
What are some causes of type 2 resp failure?
Ineffective breathing - respiratory depression, muscle weakness, chest wall problems
Ventilation problems - emphysema, COPD, asthma
What defines asthma?
Airway inflammation and remodelling
Reversible obstruction
Outline the inflammatory and remodelling changes in asthma
Smooth muscle - contract/hypertrophy and hyperplasia
Goblet cells - hyper secrete/hyperplasia
Blood vessels - vasodilate and leak/angiogenesis
Epithelium - shed/thicken
What are signs and symptoms indicative of asthma?
Wheeze, cough (worse at night and on exercise), breathless, tight chest
Barrel chest, hyper resonant chest
What tests can be done for asthma?
FEV1 increases after given salbutamol
Allergy testing
X ray to rule out other conditions
How is asthma managed?
Relax airway - B2 agonist - salbutamol
Prevention - steroids
Ventilate
Define COPD
Airflow obstruction that is progressive, irreversible and doesn’t change markedly over a period of months
Emphysema and chronic bronchitis
Explain emphysema
Destroy terminal bronchioles and distal air spaces which reduces surface area. Supporting tissue destroyed closing small airways and elastic tissue is destroyed leading to hyperinflation
Explain chronic bronchitis
Mucus hyper secretion due to inflammation. Chronic productive cough and frequent infections
What causes COPD
Smoking
Alpha 1 antitrypsin deficiency
Occupational exposure
Pollution
What are the symptoms of COPD
Cough and sputum
Breathless
Explain the MRC dyspnoea score
1 - strenuous exercise 2 - hurrying/hill 3 - walk slower or have to stop 4 - can't walk 100m 5 - struggle to dress or leave house
What are some signs of COPD?
Purse lip Tachypnoea Accessory muscle Hyperinflation - barrel chest Wheeze Cyanosis
What would Spirometery show for COPD?
FEV1 < 80%
FEV1/FVC < 70%
Compare COPD and asthma
COPD - smoker, over 65, productive cough and persistent breathlessness
Asthma - under 65, unproductive cough, variable breathlessness, wake at night and changes day to day
What investigations are done for COPD?
X-ray to exclude others
Hi res CT
ABG
Alpha 1 antitrypsin
How is COPD managed?
Stop smoking, bronchodilators, steroids, antimuscarinics
Pulmonary rehab - exercise
Surgery to reduce hyperinflation or a transplant
Explain the pathology of TB
Aerosol
Primary infection resolves with few symptoms
Post primary - persist beyond first few weeks usually re-exposure
Ingest by macrophage but escape and multiply resulting in tissue destruction and cytokines production
Symptoms of TB?
Weight loss
Night fever
Cough
How is TB treated?
Rifampicin, isoniazid - 4 months
Pyrazinamide, ethambutol - 2 months
What are some risk factors for TB?
HIV, crowding, Asian, homeless
What are some common fauna in the respiratory tract?
Viridans streptococci
Neiserria spp
Candida
What defences does the respiratory tract have?
Muco-ciliary clearance
Cough/sneeze
Lymphatic follicles
IgA/G and macrophages
What is pneumonia?
Pulmonary parenchyma infected with consolidation
The distal air spaces become fluid filled and stiff impairing gas exchange
How is pneumonia classified?
Clinical setting - hospital/community acquired
Presentation - acute/sub acute/chronic
Organism - bacterial/fungal/viral
Lung - lobar/broncho/interstitial
What are some causes of pneumonia?
Streptococcus pneumonia - elderly, acute, fever, pain Haemophilus influenza - COPD Chlamydia - bird contact Influenza Hospital - MRSA Aspiration - anaerobes and oral flora
Explain lobar pneumonia
Complete lung lobe consolidation
Usually due to pneumococcus
Community and acute onset
Explain bronchopneumonia
Start in airways and spread to alveoli and lung tissue
Pre-existing disease - influenza/COPD/aspiration
Patchy consolidation
Can be caused by pneumococcus, H influenza, S aureus
Treat with amoxicillin or co-amoxiclav
What are the potential outcomes of pneumonia?
Resolution - organisation with fibrous scarring
Complications - abscess, bronchiectasis, empyema
What makes aspiratory pneumonia more likely? What organisms causes it?
Neurological dysphasia, epilepsy, alcoholics, drowning
Viridans strep, anaerobes
What are the symptoms of pneumonia?
Fever, chills, sweats
Cough sputum - sputum can be clear/purulent/rust coloured
Dyspnoea
Chest pain, malaise, anorexia, vomiting, headache, myalgia, diarrhoea
What are signs of pneumonia?
Bronchial breath sounds Crackles Wheeze Dull percussion Reduced vocal resonance
What investigations are done for pneumonia?
Chest x-ray O2 sat Arterial blood gas FBC, platelets, WCC (>20 or <4 is severe) LFT, urea, CRP (response to treatment) Samples and microbiology
What score is used to determine if a pneumonia patient should be hospitalised?
C - confusion AMT 7
R - respiratory rate >30
B - blood pressure < 90/60
65 - over 65 years old
How is pneumonia treated?
Antibiotics - amoxicillin or co-amoxiclav
How is pneumonia prevented?
Immunise - flu vaccine and pneumococcal vaccine
Chemo prophylaxis - for asplenic/immunocompromised patients
What factors can cause lung cancer?
SMOKING
asbestos, radon, genetics
What are some symptoms of lung cancer?
Primary tumour - cough, dyspnoea, wheeze, haemoptysis, chest pain, weight loss, lethargy, malaise
Metastases - SVC obstruction, hoarseness (left laryngeal nerve palsy), dyspnoea (phrenic nerve palsy), dysphagia, bone pain, CNS symptoms
What is para neoplastic syndrome?
Presence of symptoms or disease due to cancer but not the cancerous cells themselves. Cytokines, hormones and immune system
What are some paraneoplastic symptoms?
Hypercalcaemia, cushings, clubbing, anaemia, DIC, nephrotic syndrome
What imaging is used for lung cancer?
X - ray when suspected
CT, PET, bone scan to diagnose and stage
Explain the TNM staging for lung cancer
T - 1: lung 4: heart and mediastinum
N - 0: no involvement 3:lymph involvement on other side of mediastinum
M - 1: distant metastasis
What are the two types of lung cancer? Which has the worse prognosis?
Non small cell
Small cell - worse
How is lung cancer treated?
Surgery, radiotherapy, chemotherapy, combined chemo and radio, biological targeting
What is the interstitial space?
Potential space between alveolar cells and the capillary basement membrane. Only apparent in disease states
What is interstitial lung disease?
Development of fibrous tissue in the interstitium. This makes the lungs less compliant. The FEV1/FVC ratio is not affected as it is a restrictive deficit. Longer diffusion pathway impairs has exchange
What are the signs and symptoms of interstitial lung disease?
Shortness of breath, reduced exercise tolerance, dry cough, tachypnoea, tachycardia, crackles, cyanosis
What are some types of interstitial lung disease?
Occupational - asbestosis Treatment - chemo Connective tissue - arthritis Immunological - sarcoidosis Idiopathic
Explain the cellular actions that occur in fibrosing alveolitis
Macrophages attract neutrophils and eosinophils which damage the lungs via proteases and ROS
What are some possible pleural effusions?
Haemothorax, chylothorax, empyema, simple effusion
What is the difference between transudate and exudate and suggest causes of each
Transudate fluid has low protein - increased hydrostatic pressure, decreased oncotic pressure, increased permeability
Exudate fluid has high protein - neoplasm, infections
What are the signs and symptoms of pleuritis?
Sharp pain on inspiration - worse when coughing, sneezing, laughing
Small breaths
Hear pleural rub
