Respiratory Flashcards
Define inspiratory reserve volume (IRV).
The additional volume of air that can be forcibly inhaled after a tidal volume inspiration.
Define expiratory reserve volume (ERV).
The additional volume of air that can be forcibly exhaled after a tidal volume expiration.
Define forced vital capacity (FVC).
The maximum volume of air that can be forcibly exhaled after maximal inhalation.
Define total lung capacity.
The vital capacity plus the residual volume. It is the maximum amount the lungs can hold.
Define residual volume (RV).
The volume of air remaining in the lungs after a maximal exhalation.
Define functional residual capacity (FRC).
The volume of air remaining in the lungs after a tidal volume exhalation.
Define tidal volume (TV).
The volume of air moved in and out of the lungs during a normal breath.
Define FEV1.
The volume of air that can be forcibly exhaled in 1 second.
When is FEV1 abnormal
When FEV1 is less than 80% if the predicted value = obstruction
Define forced vital capacity
Total amount of air a person can exhale after full exhalation
When is FVC abnormal
When is is less than 80% of the predicted value
When is obstructive lung disease diagnosed in terms of lung function tests
FEV1/FVC <0.7
FEV1 lower than FVC
Suggests that there is some obstruction slowing the passage of air getting out of the lungs
What are the two main obstructive lung diseases
Asthma - narrowed airway due to bronchoconstriction
COPD - Chronic airway and lung damage causing obstruction
Describe the lung function test results for restrictive lung diseases
FEV1/FVC above 0.7
FVC and FEV1 equally reduced below 80% predicted volume
Restriction to the ability of the lungs to expand and take in air
Define peak expiratory flow (PEF).
The greatest rate of airflow that can be obtained during forced expiration. Age, sex and height can all affect PEF.
What is the transfer coefficient?
The ability of O2 to diffuse across the alveolar membrane.
How can you find the transfer coefficient?
Low dose CO is inspired, the patient is asked to hold their breath for 10s at TLC, the amount of gas transferred is measured.
Name 3 diseases that might have a low transfer coefficient.
- Emphysema.
- Anaemia.
- Fibrosing alveolitis.
- Pulmonary hypertension
- Idiopathic pulmonary fibrosis
- COPD
Name a disease that might have a high transfer coefficient.
- Pulmonary haemorrhage.
What happens in respiratory acidosis
Fail to get rid of CO2 resulting in a decrease in pH
What are the causes of respiratory acidosis
Hyperventilation COPD Any cause of respiratory failure - Type 1 = PE - Type 2 = hypoventilation
Describe the renal compensation to respiratory acidosis
Kidneys increase H+ secretion in form of NH4+ and will release more HCO3- into the plasma which increases pH
Define respiratory alkalosis
Too much CO2 lost resulting in an increased pH as CO2 is lost
What are the causes of respiratory alkalosis
CO2 depletion due to hyperventilation
Hypoxia
T1 respiratory failure due to PE
What is the renal compensation for respiratory alkalosis
Kidneys decrease H+ secretion thereby retaining H+ and helping the pH return to normal
Decrease in H+ secretion will result in a decrease in HCO3- reabsorption resulting in HCO3- excretion and thus a fall in plasma HCO3-
What is metabolic acidosis
Excess acid production resulting in a decrease in pH
What are the causes of metabolic acidosis
Renal failure
GI HCO3- loss
Dilution of the blood
Failure of H+ excretion - hypoaldosteornism
What is the respiratory compensation to metabolic acidosis
Decrease in pH will stimulate chemoreceptors of the lung resulting in enhanced respiration resulting in a fall in CO2 resulting in a increase in pH
What are the causes of a metabolic alkalosis
Increase in pH Vomiting (Due to loss of gastric secretions) Volume depletion Alkali ingestion Hyperaldosteronism Hyperkalaemia
What is the respiratory compensation for metabolic alkalosis
Increase in pH inhibits chemoreceptors of the lung thereby reducing respiration thereby increasing CO2 resulting in a decrease in pH
What are the natural defences of the upper respiratory tract against pathogens
Mucosal defences
- Cough reflex
- Mucus barrier and respiratory cilia
- Surface secretions (Defensins and complement)
Innate immunity
- macrophages
- neutrophils
Adaptive immunity
- B-cells
- T cells
Name 2 upper respiratory tract infections.
Rhinovirus = cold, bronchitis, sinusitis Influenza = flu Coronavirus = colds but sometimes severe respiratory illness Adenovirus = URTI, pharyngitis, bronchitis, pneumonia
Name some emergency respiratory infections
Severe acute respiratory distress syndromes (SARS)
Middle East respiratory syndrome novel coronavirus
Avian influenza
What viruses can cause pneumonia?
Adenoviruses, influenza A and B, measles, VZV.
What are the causative agents of the common cold
Rhinovirus and coronavirus
What are the symptoms of rhinitis or sinusitis
Blocked/runny nose Sore throat Cough Sneezing Pain, swelling and tendernesss around sinuses Facial pain Fever
What is the management of rhinitis and sinusitis
Nasal decongestants = xylometazoline
Broad spectrum antibiotics = Co-amoxiclav
Is sinusitis usually bacterial or viral?
Viral.
What are the causative agents of bacterial sinusitis
Streptococcus pneumoniae
Haemophilus influenzae
What are the symptoms of bacterial sinusitis
Unilateral pain
Purulent discharge
Fever
What are the complications of sinusitis
Brain abscess, sinus vein thrombosis, orbital cellulitis
Is pharyngitis normally caused by bacterial or viral infection?
Viral e.g. rhinovirus, adenovirus etc.
Rarer causes = EBV and acute HIV
What bacteria might sometimes cause pharyngitis?
Streptococcus pyogenes.
Rare = mycoplasma pneumoniae, N. gonorrhoea, C.diptheriae
What are the symptoms of pharyngitis
Painful throat Dry/scratchy throat Pharyngeal erythema Dry cough lymphadenopathy Fever Tonsils inflamed and swollen
What is the Centor criteria used for?
It determines the likelihood that a sore throat is bacterial or viral
What signs make up the Centor criteria?
- Tonsillar exudate.
- Tender/enlarged anterior cervical lymph nodes.
- Fever (>38°C).
- Absence of cough.
(3 or 4 of these = 50% chance of bacterial infection).
(0-2 = viral infection)
What is the management of pharyngitis
Self limiting disease
Symptomatic treatment
No antibiotics
Persistent and severe tonsillitis treated with phenoxylmethylpenicillin
What is the causative agent of acute epiglottis
Haemophilus Influenza B
What are the symptoms of acute epiglottis
Odynophagia (Pain on swallowing)
Sore throat
Inspiratory stridor (High pitched wheezing noise when she breathes it in)
Febrile
What is the management of acute epiglottis
Prevention = HiB vaccine Treatment = amoxicillin --> Doxycycline or co-amoxiclav
What is the causative agent of whooping cough
Bordatella pertussis - childhood disease with 90% cases below the age of 5
What type of bacteria is Bordetella pertussis?
Gram negative bacilli.
What is the disease course of whooping cough
7-10 day incubation
1-2 wk catarrhal stage
1-6wk paroxysmal stage
What are the symptoms of whooping cough in adults?
- Chronic paroxysmal cough = sudden and severe
- Inspiratory ‘whoop’ posttussive vomiting (Vomiting after cough)
What are the complications of whooping cough
Pneumonia
Encephalopathy
Sub-conjunctival haemorrhage
What antibiotics might you use in someone with bordetella pertussis infection?
Clarithromyocin.
What agar would you culture bordetella pertussis on?
Bordet Gengou agar.
When is someone vaccinated against bordatella pertussis?
A child is vaccinated at 8, 12 and 16 weeks and at 3 years 4 months with dTaP vaccine.
What is the causative agent in influenza
Influenza A (Severe outbreaks) Influenza B and C
What are the main antigens on influenza A?
- Hemagglutinin (H).
- Neuraminidase (N).
What is the function of hemagglutinin?
‘Grappling hook’; grabs onto cells.
What is the function of neuraminidase?
‘Bolt cutters’; cuts newly formed virus loose from infected cells.
Which influenza pathogen is commonly behind severe and extensive outbreaks? Why?
Influenza A; it replicates a lot and mutations are common.
What are the two types of genetic variability in influenza
Antigenic drift
Antigenic shift
Define antigenic drift.
When there are small mutations and minor antigenic variation. Antigenic drift can cause seasonal epidemics.
Define antigenic shift.
When there are larger mutations and major antigenic variation. Antigenic shift can cause pandemics!
How can influenza virus be transmitted?
- Aerosol: coughing and sneezing, inhale particles.
- Droplet: hand to hand.
What is the reproduction number?
The average number of secondary cases generated from a primary case.
What are the symptoms of influenza
URT infections = cough, sore throat, runny nose
Systemic symptoms = fever, headache and myalgia
What are the complications of influenza
Bacterial pneumonia
What is the treatment for influenza?
Supportive care! Antiviral medications might be used to reduce the risk of transmission.
Define outbreak.
> 2 linked cases.
Define epidemic.
More cases in a region/country.
Define pandemic.
Epidemics that span international boundaries.
What are the possible consequences of pandemics?
- High morbidity.
- Excess mortality.
- Social disruption.
- Economic disruption.
What factors are there to suggest that future pandemics may be likely?
- More travel.
- Increasing world population.
- Rise in intensive farming.
What factors are there to suggest that future pandemics may be unlikely?
- Healthier population due to medical advances.
- Better healthcare.
- Vaccination.
- Antivirals.
Where are a high proportion of cases of TB found?
The indian sub continent e.g. India, Bangladesh, Pakistan etc.
What are the 4 main mycobacterial species
Mycobacterium tuberculosis
Mycobacterium bovis
Mycobacterium africanum
Mycobacterium microti
Describe mycobacterium tuberculosis.
- Acid fast bacilli.
- Has a waxy capsule.
- It grows slowly and therefore is hard to culture in a lab.
- It can resist phagolysosomal killing resulting in granulomatous disease.
What mycobacterium can cause abdominal tuberculosis?
Mycobacterium bovis.
- Can be found in unpasteurised milk.
Give 5 risk factors for TB.
- If you live in a high prevalence area.
- IVDU.
- Homeless.
- Alcoholic.
- HIV+.
- smoking
- Prisons and malnutrition
How is TB transmitted?
Aerosol transmission - mycobacterium TB bacilli are inhaled and enter the lung.
Describe pulmonary infection of TB.
Bacilli settle in lung apex. Macrophages and lymphocytes mount an effective immune response that encapsulates and contains the organism forever.
Describe the pathogenesis of pulmonary TB disease.
- Bacilli and macrophages form primary focus.
- Mediastinal lymph nodes enlarge.
- Primary focus and enlarged lymph nodes = primary complex.
- Granuloma develops into a cavity.
- The cavity is filled with TB bacilli - these are expelled when the patient coughs.
TB disease: Where in the lung is a granuloma cavity most likely to develop?
Most likely to develop in the apex of the lung as there is more air and less blood supply/immune cells.
Presentation of TB: what systemic symptoms might you see?
- Weight loss.
- Night sweats.
- Anorexia.
- Malaise.
- Fever
Presentation of TB: what pulmonary TB symptoms might you see?
- Cough for more than 3 weeks in a year
- Chest pain.
- Breathlessness.
- Haemoptysis.
What are the extra pulmonary symptoms of TB
Lymph node TB with swelling and discharge
Bone pain and swelling in the joint
Abdominal TB = ascites and abdominal lymph nodes
What tests might you do in someone with suspected TB
Inflammatory markers = raised CRP, hyperalbuminaemia, thrombocytosis
Microbiology = Ziehl neelsen on sputum/biopsy
Tuberculin skin test (Mantoux test for latent TB) = stimulates T4 hypersensitivity reaction
CXR
What might you see on a CXR taken from someone with TB?
- Consolidation.
- Collapse.
- Pleural effusion.
Name 6 places where TB might spread to?
- Bone and joints - pain and swelling.
- Lymph nodes - swelling and discharge.
- CNS - TB meningitis.
- Miliary TB - disseminated.
- Abdominal TB - ascites, malabsorption.
- GU TB - sterile pyuria, WBC in GU tract.
What test might you do to diagnose latent TB?
Mantoux test - stimulates type 4 hypersensitivity reaction.
What drugs are given in the treatment of TB?
Rifampicin (6 months).
Isoniazid (6 months).
Pyrazinamide (2 months).
Ethambutol (2 months).
TB treatment: which 2 drugs are taken for the entire 6 months in active TB?
- Rifampicin.
2. Isoniazid.
TB treatment: which 2 drugs are taken for only the first 2 months for active TB?
- Pyrazinamide.
2. Ethambutol.
Which drug is taken for 6 months for latent TB
Isoniazid
Which drug is taken for 3 months for latent TB
Rifampicin
Give 3 potential side effects of Rifampicin.
- Red urine.
- Hepatitis.
- Drug interactions; rifampicin is an enzyme inducer.
Give 2 potential side effects of Isoniazid.
- Hepatitis.
2. Neuropathy.
Give 3 potential side effects of Pyrazinamide.
- Hepatitis.
- Gout.
- Rash.
Give 1 potential side effect of Ethambutol.
- Optic neuritis.
Compliance in taking TB medication is critical. Why?
Resistance and relapse may be likely if the patient is non-compliant.
Why does TB treatment need to last for 6 months?
TB treatment lasts for at least 6 months to ensure all the dormant bacteria have ‘woken up’ and been killed.
What is the acronym commonly used for the drugs taken in TB treatment?
HRZE.
HR = 6 months. ZE = 2 months. - H - isoniazid. - R - rifampicin. - Z - pyrazinamide. - E - ethambutol.
TB treatment: Give 4 factors that can increase the risk of drug resistance?
- If the patient has had previous treatment.
- If they live in a high risk area.
- If they have contact with resistant TB.
- If they have a poor response to therapy.
What are the problems associated with drug resistance in TB treatment?
- TB becomes more difficult to treat.
- Medication course > 20 months.
- Increased risk of side effects.
- Increased relapse rate.
How can TB be prevented?
- Active case finding - reduce infectivity.
- Detect and treat latent TB.
- Vaccination - BCG.
A special culture medium is needed to grow TB. What is the medium called?
Lowenstein Jensen Slope.
Lowenstein Jensen Slope is a medium used to grow TB. What is special about this medium?
- It contains growth factors that promote mycobacterial growth.
- It contains small amounts of penicillin that prevent pyogenic bacteria growth.
What might a lymph node biopsy from someone with TB show?
Caseating granuloma.
Why does TB cause hypercalcaemia?
Granulomatous diseases -> increased vitamin D production and so increased bone resorption, increased absorption from gut and increased re-absorption from kidney.
This is also seen in sarcoidosis.
State the name of the pathological lesion that characterises primary tuberculosis?
Ghon complex.
State two socioeconomic factors that are associated with an increased prevalence of tuberculosis.
- Overcrowding.
- Poverty.
- Lower socio-economic class.
Define pneumonia
Infection of the lung tissue
= acute lower respiratory chest infection
Name 5 groups of people who might be at increased risk on pneumonia.
- The elderly.
- Children.
- People with COPD.
- Immunocompromised people.
- Nursing home residents.
What are the two anatomical classifications of pneumonia
Bronchopneumonia = patchy consolidation of different lobes
Lobar pneumonia = Fibrosuppurative consolidation of a single lobe
Describe in 3 steps the pathogenesis of pneumonia.
- Bacteria translocate to normally sterile distal airway - alveolar macrophage response
- Resident host defence is overwhelmed.
- Macrophages, chemokines and neutrophils produce an inflammatory response leading to airway exudate and parenchyma damage
What intrinsic factors can affect pneumonia?
Cold temperature, infection, stress, exercise, various pollutants.
Describe the process of pneumonia resolution?
Bacteria are cleared and inflammatory cells are removed by apoptosis.
What are different etiological classifications of pneumonia
Community acquired pneumonia
Hospital acquired pneumonia
Aspiration pneumonia
Immunocompromised pneumonia
What are the three main causes of community acquired pneumonia
Streptococcus pneumococcus
Mycoplasma pneumoniae
Haemophilus influenzae
What are the atypical causes of community acquired pneumonia
S.aureus
Moraxella cattarrhalis
Chlamydia pneumoniae
Legionella pneumonphilia
What are the main causative agents of hospital acquired pneumonia
> 48 hours since hospital admission
S.aureus
Pseudomonas Aeruginosa
Klebsiella pneumoniae
Which groups are at greater risk of aspiration pneumoniae
Patients with stroke, bulbar palsy, decreased GCS, GORD
What causes of immunocompromised pneumonia
S.pneumococcus
M.pneumoniae
H. Influenza
Rarer causes
- Pneumocystis Jirevecii
- TB
- Aspergillus
- CMV/HSV
What symptoms might you see in someone with pneumonia?
- Productive cough with purulent sputum (Rusty) and haemoptysis
- Sweats and rigor
- Fever.
- Breathlessness.
- Pleuritic chest pain.
- Anorexia, malaise
- Myalgia, headache, arthralgia suggests atypical pneumonia.
What signs might you see in someone with pneumonia?
Tachycardia + Tachypnoea Cyanosis Confusion Consolidation - Dull percussion due to lung collapse - Bronchial breathing (Harsh breathing on insp and exp due to consolidation) - Crackles (Air passing through sputum)
What investigations might you do on someone to determine whether or not they have pneumonia?
- CXR - look for air bronchogram in consolidated area, infiltrates, cavities
- FBC (look at WBC’s).
- U+E.
- ABG
- Liver function tests.
- CRP (marker of inflammation).
- Microbiology: sputum culture, blood culture, serology etc
- Sera Abs for atypicals ie mycoplasma, chlamydia and legionella
How can pneumonia be prevented?
How can pneumonia be prevented?
- Children are given PCV.
- Smoking cessation is encouraged.
- Influenza vaccines are given to children and the elderly.
What is CURB65 used for?
It is a way of assessing the severity of community acquired pneumonia. It predicts mortality.
What does CURB65 stand for?
Confusion. Urea >7mmol/L. RR >30/min. BP reduced - systolic <90mmHg, diastolic <60mmHg. Age >65.
1 point for each
0-1 = home Mx
2 = hospital Mx
>3 = consider ICU
Why is CRB65 often used in the community?
Because facilities to measure urea are often not available.
What is the treatment for pneumonia
Abx
O2
Analgesia if pleurisy
Chest physio
Which antibiotics are used for mild pneumonia
Amoxicillin OR clarithromycin
What antibiotics are used for moderate pneumonia
Amoxicillin AND Clarithromycin
What antibiotics are used for severe pneumonia
Co-amoxiclav/cefuroxime AND clarithromycin
What antibiotics are used for atypical pneumonia
Chlamydia = tetracycline PCP = Co-trimoxazole Legionella = Clarithro + Rifampicin
What groups of people may develop pneumonia caused by klebsiella pneumoniae?
- Homeless people.
- Alcoholics.
- People in hospital.
What are the complications of pneumonia
Respiratory failure Hypotension (Due to dehydration and septic vasodilatation) Atrial fibrillation pleural effusion Empyema Lung abscesses Sepsis Myocarditis/pericarditis Jaundice
What is empyema?
Pockets of pus that have collected in a body cavity e.g. in the pleural cavity
What bacteria can cause empyema
Anaerobes
Staph
Gm -ve
Associated with recurrent aspiration
Give 3 signs of empyema.
- WBC/CRP don’t settle with antibiotics.
- Pain on deep inspiration.
- Pleural collection.
What is the usual treatment for empyema?
Drainage.
What might you see in tap of someone with empyema
Turbid
pH <7.2
Decrease glucose
Yellow
What are lung abscesses
Severe localised suppuration within the lung associated with cavity formation
What are the causes of lung abscesses
Aspiration
Bronchial obstruction by tumour or foreign body
Septic emboli
What are the features of lung abscesses
Swinging fever Cough, foul purulent sputum and haemoptysis Malaise and wt loss Pleuritic pain Clubbing Empyema
What is the management of lung abscesses
Aspiration
Abx
Surgical excision
Name 3 groups of people who might be at risk of hospital acquired pneumonia.
- Elderly.
- Ventilator associated.
- Post operative patients.
A 66 y/o patient presents to you with fever and a productive cough. On examination you notice they are their confused. Their vital signs are: RR - 35; BP - 80/55 and HR: 130. You measure their urea and it comes back at 8mmol/L.
a) What is this patients CURB65 score?
b) Where should they be treated?
c) Describe the treatment for this patient.
a) Their CURB65 score is 5.
b) This patient should be treated in hospital and admitted to critical care.
c) The patient should be given IV clarithromyocin and co-amoxiclav.
How can less common ‘atypical’ pathogens responsible for causing pneumonia be identified?
They are hard to grow in culture and so serology and antigen tests are often used.
What antibiotic might be used against less common ‘atypical’ pathogens responsible for causing pneumonia?
Macrolides like clarithromyocin as they are often resistant to beta lactams.
What can cause acute airway obstruction?
Tumour or foreign bodies with distal collapse of the lung.
If the trachea, bronchi and bronchioles are involved in a disease process, is this likely to be an obstructive or a restrictive disease?
Obstructive.
If the lung parenchyma are involved in a disease process, is this likely to be an obstructive or a restrictive disease?
Restrictive.
If the chest wall is involved in a disease process, is this likely to be an obstructive or a restrictive disease?
Restrictive.
What happens to the FEV1, FVC and FEV1/FVC ratio in an obstructive lung disease?
- FEV1 is < 80% predicted.
- FVC is normal.
- FEV1/FVC ratio < 0.7.
What happens to the FVC and FEV1/FVC ratio in a restrictive lung disease?
- FVC reduced.
- FEV1/FVC ratio normal or increased
Give an example of a reversible obstructive lung disease.
Asthma.
Give an example of an irreversible obstructive lung disease.
COPD.
What is the affect of COPD on residual volume and total lung capacity?
RV and TLC are increased.
Give an example of a restrictive lung disease.
Pulmonary fibrosis.
What is bronchiectasis?
chronic infection of the bronchi/bronchioles leading to Permanent dilation of bronchi leading to a build-up of excess mucus and predisposes someone to chest infections.
Describe the pathogenesis of bronchiectasis.
Failed mucocilliary clearance and impaired immune function mean that a microbe can easily invade and cause infection. This leads to inflammation and therefore progressive lung damage. Bronchitis -> bronchiectasis -> fibrosis.
What can cause bronchiectasis?
- Often post-infective e.g. previous pneumonia, TB or whooping cough, measles
- Congenital causes e.g. primary ciliary dyskinesia/CF/Kartenger’s
- 50% idiopathic.
- Hypogammaglobinaemia
- Bronchial obstruction (Tumour, foreign body)
- Ulcerative colitis and Rheumatoid arthritis
Which bacteria might cause bronchiectasis?
- Haemophilus influenzae.
- Streptococcus Pneumococcus
- Pseudomonas aeruginosa.
- Staphylococcus aureus.
Give 6 symptoms of bronchiectasis.
- Chronic productive cough with purulent sputum
- Recurrent chest infections.
- Fever and wt loss
- Dyspnoea and wheeze.
- Recurrent exacerbations.
- Chest pain.
- Haemoptysis.
What are the signs of Bronchiectasis
Clubbbing
coarse inspiratory wheeze (Crackles)
Wheeze
Purulent sputum
Complications of bronchiectasis
Pneumonia
Pleural effusion
Pneumothorax
Pulmonary HTN
What investigations might you do on someone to determine whether they have bronchiectasis?
- High resolution CT scan showing dilated and thickened airways
- Spirometry - would be obstructive.
- Sputum culture.
- CXR showing thickened bronchial walls (Tramlines and rings)
- Bloods (Serum Abs for aspergillus, RF, a1-AT)
- Bronchoscopy
What is the treatment/management for bronchiectasis?
- Education.
- Smoking cessation.
- Annual influenza and pneumococcal vaccinations.
- Antibiotics.
- Anti-inflammatories.
- Bronchodilators - salbutamol
- Improved mucus clearance e.g. physiotherapy = postural drainage
- Treat underlying cause
- Mucus = DNAse
- Immune deficiency = IVIg - Surgical lung resection
What antibiotic is used for P.aeruginosa
Ciprofloxacin
What antibiotic is used for H.influenza
Amoxicillin
Co-amoxiclav
Cephalosporin
The airways in a person with bronchiectasis often become chronically colonised. What is the airway of a neonate likely to be colonised with?
s.aureus.
The airways in a person with bronchiectasis often become chronically colonised. What is the airway of a child likely to be colonised with?
h.influenzae.
The airways in a person with bronchiectasis often become chronically colonised. What is the airway of an adult likely to be colonised with?
pseudomonas aeruginosa.
A lady who has recently had pneumonia presents to you with SOB and chronic cough. She is producing copious amounts of purulent sputum. What is the likely diagnosis?
Bronchiectasis.
Define CF.
An autosomal recessive disease resulting in abnormal exocrine gland function.