Pulmonary Function Tests

Background

• These can be useful in evaluating the nature and severity of respiratory disease BUT must always be interpreted in context of the patient history and examination

Indications

• To evaluate presentations of lung disease (most commonly dyspnoea and hypoxia, but also for others e.g. hypercapnia, cyanosis, wheezing etc)
• To assess progression of lung disease (NB more commonly this is done using peak flow monitoring but PFTs can also be a more formal measure, particularly if you suspect more than one underlying cause)
• To evaluate patients pre-operatively

Components

• Spirometry
  • Measures the air movement in and out of the lungs during respiratory maneouvres e.g. forced inspiration and expiration
    • It can measure volumes and speeds of air movement (i.e. FEV1)
    • Most useful at measuring the FVC, FEV1 and FEV1/FVC ratio

 

• Spirometry can also be used to produce a flow-volume loop (showing the same thing but volume is plotted on the x-axis and flow is plotted on the y-axis.  These can be useful in estimating the kind of obstruction.

Note that volume is plotted backwards on this volume loop

 

• Diffusing capacity
  • A further PFT which uses labelled Carbon monoxide to measure the ability of the lungs to diffuse and transfer gases- which can subsequently be used as a measure of functional lung surface area and thus total lung volume.
  • It is most commonly used to evaluate restrictive pattern diseases or spirometry results that have not been responsive to bronchodilators.
  • Common causes of reduced capacity include
    • **Anaemia (remember non-respiratory causes- take into context)
    • Emphysema, ILD, Po Oedema, Po vascular disease

Interpretation

1. Is the FEV1/FVC ratio less than the lower limit of normal (0.70 is the normal cut off for obstructive disease; >0.75 is regarded normal)?
   1. Obstructive or not?
2. Is the FVC less than the lower limit of normal? (NB Normal FVC is calculated based on age, size/weight/height etc)
   1. Any restrictive component or not?
3. Is the total lung capacity known?
   1. Reduced in true restriction and normal in pseudo-restriction

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Chest X-ray Interpretation

DRS ABCDE

• Details
  • Patient name, age/DOB, sex
  • Type of film (most PA erect, but some will be AP, supine, expiratory etc. Check also L/R marker is correct for PA/AP view)
  • Date and time of CXR (in relation to patient history/condition if available)
    • Compare to previous films if possible
• RIPE
  • Rotation- medial clavicles are equidistant from the spinous process
  • Inspiration- should be able to visualise 5-6 anterior ribs in mid-clavicular line and 8-10 posterior ribs above the diaphragm (?poor inspiration if less; hyperexpansion if more)
  • Picture- straight vs oblique, entire lung fields, scapulae out of lung fields, angulation (excess lordosis/kyphosis)
  • Exposure (penetration)- IV disc spaces, spinous processes to T4 and L hemidiaphragm (through cardiac shadow) should all be visible
• Soft tissues and Bones (in reality, this is commonly left until the end- but DON’T FORGET if you do leave it til later)
  • Ribs, sternum, spine, clavicles (look for symmetry, fractures, dislocations, lytic lesions, density)
  • Soft tissues (symmetry, masses, subcutaneous air/swellings
  • Breast shadows
  • Calcification e.g. of the great vessels, carotids, masses
• Airway (& mediastinum)
  • Trachea – should be central or slightly rightly deviated as it crosses the aortic arch
  • Paratracheal/mediastinal masses/lymphadenopathy
  • Carina, right and left main bronchi
  • Mediastinal width <8cm on PA film
  • Aortic knob and Hilum (T6/7, left side usually higher and squarer than right (triangular))
• Breathing
  • Lung fields
    • Vascularity normally extends to ~2cm of pleural space
    • Look for any pneumothorax (don’t forget apices)
    • Look for any lesions, opacities, atelectasis (collapse), consolidation, bullae
    • Remember the apices, the bases/angles
  • Pleura
  • Effusions
• Circulation
  • Heart position and size (2/3 left and 1/3 right; total <1/2 of chest diameter)
  • Heart borders (right atrium and left atrium/ventricle)
  • Heart shape
• Diaphragm
  • Hemidiaphragm levels (Right higher than left)
  • Shape/contour
  • Cardio/costophrenic angles (clear/sharp)
  • Gastric bubble/colonic air
  • SUBDIAPHRAGMATIC AIR
• Extras
  • E.g. lines, tubes, catheters, electrodes, metalwork, stents etc

Some tips

• Collapse is uniform, consolidation is non-uniform (consolidation will also have air bronchograms (visible air in the bronchial tree))
• In an effusion, look for a meniscus sign (fluid level)
• Structures are pulled towards a collapse and away from an effusion
• A sail sign is suggestive of left lower lobe collapse
• Loss of the silhouette of the heart on the right border of the heart suggests right middle lobe disease (NB If the R heart border is still visible but there is an opacity adjacent to it, this may be lower lobe disease)
• Some features of
  • COPD
    • Hyperinflation; flat hemidiaphragms; decreased lung markings; black lesions (bullae); prominent hila
  • Heart failure (ABCDE)
    • Alveolar shadowing; B-lines (interstitial oedema); Cardiomegaly; Diversion of blood to upper lobe; Effusion

Peak Flow Meter and Inhaler Explanation/Technique

Intro

• Wash hands, introduce self to patient, check patient name and DOB, explain reason and gain consent

Before starting

• It is a good idea to check the patient’s own understanding of asthma and their condition, PEFR and why it is used, and the importance of inhaler technique
  • Explain the use of PEFR/inhaler and any gaps in knowledge where necessary
    • Use first thing in the morning and during an exacerbation; or more regularly when their asthma is bad
• Ask how regularly they are using their inhalers, whether they are having an effect, whether they have any side effects etc

PEFR Explanation 

NB Good idea to explain and demonstrate (either one after the other or simultaneously) before asking the patient to explain and demonstrate.

• Attach a clean mouthpiece
• Ensure the marker is set to 0
• Stand up or sit upright
• Hold the peak flow meter horizontal, keeping your fingers clear of the marker
• Take as deep a breath in as you can and hold it
• Place the mouthpiece in your mouth and form a tight a seal as possible around it with your lips
• Breathe out as hard as you can
• Observe and record the reading
• Repeat the process 3-6 times, recording only the highest reading
  • Compare this with previous readings and/or with norm for age, sex and height
  • 

Explanation of Inhaler technique

• Vigorously shake the inhaler and remove the cap
• Hold the inhaler upright and close to your mouth between the index finger (top) and thumb (base)
• Breathe out completely
• Put the mouthpiece in your mouth, breathe in deeply whilst activating the inhaler canister at the same time
• Hold you breath for 10 secs before breathing out
• If necessary, repeat after 1 minute
• Check patient understanding and ask them to explain/demonstrate

End

• Reassess understanding
• Thank patient
• (Wash hands)

Respiratory Examination

Intro

• Wash hands, introduce self, check patient name and DOB/CHI, explain procedure and gain consent

General

• Look from the end of the bed for
  • any signs of respiratory distress (consider an ABCDE approach)
  • general patient appearance and well being
  • any audible breathing sounds
  • any obvious abnormalities
  • any oxygen; any inhalers/nebulisers, any drugs etc
• Look at the hands for
  • Peripheral cyanosis
  • Finger clubbing
  • Tar staining
  • CO2 flap (coarse)- ask the patient to extend their arms and wrists/fingers
• You may want to take the patient’s pulse +/- respiratory rate now (or later in the examination)
• Examine the JVP (may be raised in pulmonary hypertension)
• Look at the face for
  • Eyes
    • Ptosis/meiosis (constriction) + anhydrosis + enophthalmos may suggest a Horner’s syndrome
    • Pallor of anaemia
  • Central cyanosis (blue under the tongue)
• Palpate the trachea to check it is central 

Inspection

• Look at the chest for any deformity (including hyperinflated chest/barrel chest), scars/wounds, any asymmetry; note the use of any accessory muscles
  • Check respiratory rate if not already done so

NB It is often easier to perform the rest of the examination on the front of the chest first then move to the back and repeat all the steps there

Palpation

• Check for tracheal deviation if not already done so
• Palpate for chest expansion at the front (upper and lower zones) and the back
  • Take a tight hold of the chest, letting your thumbs just meet in the centre- they should move with breathing

Percussion

• Percuss the chest at the apex, compare sides and repeat down the chest (include the clavicle)
• Make sure to percuss at least each lobe (on the back it is good practice to percuss the lower lobes at least twice (superiorly and inferiorly (bases))

Tactile Vocal Fremitus

• With the ulnar border of your hand at each percussion site (again comparing sides), ask the patient to say ‘ninety-nine’

Auscultation

• Auscultate each site (comparing sides), asking the patient to inhale and exhale slowly and deeply through their mouth
  • NB For a good collection of normal/abnormal breath sounds, see here
• Vocal resonance
  • As with TVF, ask the patient to say (or whisper) ‘ninety-nine’ whilst you auscultate the sites

End

• You may also want to examine the patients legs for oedema or signs of DVT
• Wash hands and thank patient
• You may also want to look at patient’s notes/chart, arrange further testing etc

Whooping cough

Background

• Also known as pertussis
• Highly infectious disease caused by Bordatella pertussis
  • Produces pertussis toxin
  • Incubation usually around 7 days; spread via aerosol droplets; infectious for 3 weeks after initial symptoms
• Fortunately infrequent (1 in 1000 per year during ‘peak year’ which recur every 3-5 years) in the UK due to vaccination (DTaP at 2, 3, 4 months)
  • More common in infants who have not yet received full vaccination (or unvaccinated)

Presentation

• 3 phases of infection
  • catarrhal phase
    • dry, unproductive cough; may be preceded by prodromal symptoms typical of URTI (up to 7 days)
  • Paroxysmal phase
    • whooping (inspiratory gasp- may not be seen in adults), post-tussive (cough) vomiting is common in infants, generalised symptoms (can last a month or more)
    • between coughing fits, the patient is generally well
    • coughing fits are more common at night, can be triggered by cold/noise
      • in adults there may be associated autonomic features e.g. sweating, flushing; in children, it can cause cyanosis
  • Convalescent phase
    • Gradual improvement (can take 2+ months)

• NB Pertussis is a notifiable disease

Investigations

• Most cases are clinical diagnoses; but health protection may request laboratory confirmation via
  • nasopharygeal aspirate/swab
  • antipertussis toxin IgG
  • PCR positive

Management

• Consider admission to those who are seriously unwell e.g. cyanotic, apnoea, trouble breathing
  • Low threshold in infants <6 months
  • Particularly in cases with complications e.g. pneumonia
• Consider antibiotic treatment (macrolide- clarithromycin in <1 month; azithromycin + clarithromycin in older infants/children/adults; erythromycin in pregnancy) if symptoms started within 21 days
  • Important to treat in pregnancy to prevent transmission
• Health protection can consider offering antibiotic prophylaxis to those at risk (priority group) contacts e.g. those with pregnant women or baby in household.  Also offer immunisation

Common Cold

Background

• Mild and self limited URTI characterised by nasal stuffiness and discharge, sneezing, sore throat and cough
  • Most common in young children (3-8 per child per year), but still incredibly common in adults (~2-4 per person per year); more common in winter months
• Caused by a wide range of pathogens
  • Rhinovirus most common (50-80%)- huge variety (over 100 subtypes)
  • Coronavirus (10-15%)- can be a cause of SARS
  • Respiratory Syncytial Virus (RSV) (5%)- more common in children
  • Parainfluenza viruses; adenoviruses; enteroviruses; metapneumovirus
  • Unknown (~20%)
• Transmitted via direct contact, small particle aerosols and large particle aerosols.

Presentation

• Sore/irritated throat (often first)
• Nasal irritation, congestion, discharge and sneezing
  • Often profuse and clear initially, then becomes thicker and more purulent later on
• Hoarseness
• Cough typically develops after nasal symptoms
• Malaise/feeling unwell
• NB Fever is unusual, headache and myalgia may be present but are usually mild
  • Features of complications e.g. sinusitis (frontal head pain) or conjunctivitis may be present

Examination and Investigations are often not required

In Children

• Restlessness/Irritability; Fever (more common in children)
• Severe nasal congestion may interfere with feeding, breathing and sleep
• Occasionally vomiting can follow coughing fits
• There may also be lymphadenopathy but examination of the throat is classically normal (examine also for acute otitis media/ear infection)

Management

• Antipyrexials and analgesia (paracetamol and/or ibuprofen) may or may not be required
• Otherwise, the common cold is self-limiting- symptoms tend to peak after 2-3 days then improve, although can take a while (>2 weeks) to resolve

Complications

• Sinusitis
• CAP
• Acute otitis media in young children
• Bronchiolitis, pneumonia and croup in very young infants/babies
• Asthma exacerbation

Pleural Effusion

Background

• Principally a radiological diagnosis
• Accumulation of serous fluid within the pleural space
  • Can appear similar to empyema or haemothorax (pus or blood, respectively in the pleural space- see below for differences)

Pathophysiology/Aetiology

• Transudates
  • Transudates are usually bilateral on CXR
  • Usually resulting from increased hydrostatic or decreased osmotic pressures
  • Causes of transudate (protein <30g/l; LDH typically <200IU/l) include organ failures
    • Heart failure
    • Nephrotic syndrome
    • Liver failure
    • Other causes include hypothyroidism and Meig’s syndrome (ovarian tumours causing right sided pleural effusion)
• Exudates
  • exudates are typically unilateral
  • usually a result of increased microvascular pressure due to disease of the pleura or adjacent lung
  • Causes of exudates (protein >30g/l; LDH usually >200IU/l) include
    • Infection (pneumonia; TB)
    • Inflammation (Rheumatoid/SLE)
    • Infarction
    • Malignancy
    • Pancreatitis

Clinical Presentation/Assessment

• Try and determine an underlying cause i.e.
  • Infection- SOB, cough, sputum, chest pain, fever
  • Malignancy- SOB, cough, weight loss, night sweats, smoking history
  • Heart Failure- SOB, chest pain, oedema,
• The side of a unilateral effusion may give a clue
  • Left
    • Pancreatitis; Dressler’s syndrome (transudative); distal thoracic duct obstruction
  • Right
    • Heart or liver failure; ovarian malignancy; proximal thoracic duct obstruction
• Symptoms/signs specifically of pleural effusion include
  • Chest pain (pleuritic)
  • Cough
  • Occasionally SOB
  • Dullness to percuss (and decreased vocal resonance/whispering pectoriloquy)
  • Pleural rub, decreased air entry (possible crackles above the effusion)

Investigation

• CXR
  • Classical appearance is a curved shadow at the lung base (meniscus sign), blunting of the costophrenic angle and ascending towards the axilla (tracking up the chest wall)
  • Other signs may include
    • blunting of the cardiophrenic angle
    • fluid within the horizontal or oblique fissures
    • mediastinal shift can occur with large effusions
  • NB Lateral and (moreso) lateral decubitus films may show fluid more clearly and earlier than PA view
• USS (greater sensitivity for effusion)

Suspect an empyema if the shadow forms an obtuse angle with the chest wall; markedly asymmetrical bilateral shadows; lenticular (lens) shaped rather than crescent shape.  There is also more likely to be associated consolidation and features of infection.
NB It is almost impossible to differentiate effusion from haemothorax.

• From radiological diagnosis, further investigation depends on whether the effusion is unilateral and whether an underlying cause (or suspicion of transudate/exudate) is present
  • A transudative unilateral effusion with a clinically apparent underlying cause e.g. organ failure, requires no further investigation and should be treated
  • A unilateral effusion with no apparent cause:
    • USS-guided pleural aspiration for cytology, protein, LDH, pH (acidity suggests infection), microscopy, culture and sensitivity; AAFB stains and culture
      • + haematocrit for haemothorax; cholestrol for chylothorax; glucose and complement if rheumatoid suspected; amylase if pancreatitis
  • A unilateral effusion with underlying infective cause requires pleural tap (USS guided)
  • NB A bilateral effusion (presumably transudative) does not require aspiration unless it fails to respond to treatment
• Fluid analysis (and Light’s criteria)
  • In general >30g protein/l suggests exudate and <30g/l suggests transudate
  • If 25-35g/l, use Light’s criteria for accuracy
    • For exudate- one or more of
      • Pleural fluid protein / serum protein >0.5
      • Pleural fluid LDH / serum LDH >0.6
      • Pleural fluid LDH > two thirds the upper limit normal serum LDH
  • + other tests
    • Blood suggests malignancy (as can cytology- although this can be negative and requires repeating in ~40% of malignant effusions) or infarction
    • Low pH suggests
      • Pleural infection and empyema (also low glucose)
      • Rheumatoid/SLE effusion
      • TB
      • Malignancy
      • Oesophageal rupture
      • NB A low pH is an indication for tube drainage
    • Low glucose- rheumatoid and tuberculosis
    • Raised amylase- pancreatitis; oesophageal perforation
    • Heavy blood staining- mesothelioma; PE; TB
• If other tests do not suggest a diagnosis, CT thorax +/- biopsy (USS/CT guided or thoracoscopy)

Cystic Fibrosis

Background/Epidemiology

• Most common fatal genetic disease in caucasians
• Incidence of ~1 in 2500 live births
• NB It can be associated with atopy/asthma in up to 88%

Genetics and Pathophysiology

• Result of mutations (most commonly ΔF508) affecting a gene on chromosome 7 encoding a subunit of a chloride channel (cystic fibrosis transmembrane conductance regulator- CFTR)
  • Results in increased sodium and chloride (salt) in sweat and increased resorption of sodium and water from respiratory epithelium.
  • The main pathology seen in CF is a relative dehydration of the airways which can predispose to bacterial infections and ciliary dysfunction
    • Chronic infections/dysfunction can result in bronchiectasis
  • There are other organs affected
    • e.g. pancreas, GI tract and reproductive system
• Most patients are identified through screening either antenatally (at risk) or at birth (screening)

Diagnosis

• The majority will be diagnosed by immunoreactive trypsinogen (IRT) on the blood spot (Guthrie) test 6 days post-natally

Complications/Clinical Features

• Most patients will develop bronchiectasis during childhood.
  • Lungs are ‘fragile’
    • Frequent exacerbations of bronchiectasis
    • Spontaneous pneumothorax (20%)
    • Haemoptysis
    • Nasal polyps
    • Respiratory failure
    • Cor pulmonale
    • Lobar collapse
• Extra-respiratory features include
  • GI
    • Malabsorption (including failure to thrive) and steatorrhoea
    • Biliary cirrhosis and portal hypertension
    • Gallstones
    • Acute pancreatitis
    • Heartburn and peptic ulcers (often secondary to pancreatic failure)
  • Diabetes (25%)
  • Delayed puberty
  • Male infertility
  • Stress incontinence
  • Osteoporosis
  • Arthropathy
  • Cutaneous vasculitis
  • Rectal prolapse (up to 10%)
    • NB ALL children who present with rectal prolapse in the absence of other symptoms should be investigated for CF

Management

• Patients require intense physiotherapy to help clear secretions from the lungs
• Regular nebulised tobramycin is used between acute exacerbations to help prevent/suppress chronic pseudomonas infection
• Patients will usually require intense (and possibly unusual) antibiotic treatments to tackle all infections (initially normal specific antibiotics for infections but later more specialised anti-pseudomonas antibiotics)

Pneumoconiosis

Background

• Permanent alteration of lung structure due to inhalation of (inorganic) mineral dust, excluding bronchitis and emphysema.
• Can be classified by the type of particle causing disease:

Asbestosis

Coal workers pneumoconiosis

• caused by prolonged exposure/inhalation of coal dust
• dust-laden macrophages group to form macules around the pulmonary lobule; fibrosis occurs resulting in discreet fibrotic lesions scattered throughout the lobule
• can be classified as
  • simple (small nodules in asymptomatic patients; no impairment of lung function; rarely deteriorates once exposure has ceased)
  • progressive massive fibrosis (PMF) (larger masses of dust lesions usually in the upper lobe, which can cavitate; usually associated with cough and sputum (can be black), and breathlessness; can be mistaken for cancer/TB by appearance on X-ray; can progress even after exposure cessation)

Silicosis

• Quite rare- found in people exposed to silica/quartz dust e.g. stone workers; usually 10-20 years after but accelerated may appear much more quickly
• Radiological features include multiple well-circumscribed nodular opacities (similar to CWP), predominantly in mid- and upper lobes; also classical hilar lymphadenopathy with ‘egg-shell’ pattern of calcification
• Silicosis is highly fibrogenic and PMF may occur later in disease

Caplan’s syndrome

• Concomitant rheumatoid arthritis and CWP.

Rarer diseases

• Siderosis (iron exposure e.g. welding/iron foundry workers); Berylliosis (beryllium exposure e.g. air fuel, dentistry); Baritosis (barium exposure); Stannosis (tin exposure)

Management

• Most management is symptomatic and prophylactic e.g. oxygen for chronic hypoxia; vaccinations; smoking cessation to reduce risk of cancer

Pulmonary Hypertension

Background/Epidemiology

• Mean pulmonary artery pressure of ≥25mmHg at rest (measured by right heart catheterisation)
  • Usually with a normal pulmonary artery occlusion (or wedge) pressure (>15mmHg excludes raised pulmonary pressure due to left ventricular failure (a common cause of pulmonary hypertension)
  • Other measurements include the transpulmonary pressure gradient (TPG= PAP-PWP; if >12mmHg, this is suggestive of intrinsic pulmonary disease regardless of a raised PWP)
• Pulmonary Hypertension can be classified as
  • Arterial hypertension
    • Primary (sporadic and familial)- see below
    • Secondary
      • e.g. in connective tissue disease (e.g. limited cutaneous systemic sclerosis; CREST)
      • Congenital (pulmonary shunt systems)
      • Portal hypertension
      • Infection e.g. HIV
      • Drug/toxins
  • Venous
    • Left sided heart disease/failure (including valvular disease)
    • Pulmonary veno-occlusive disease (e.g. chronic/recurrent PE)
  • PH due to lung disease (most common)
    • e.g. COPD, diffuse parenchymal lung disease etc

Primary Pulmonary Hypertension

Epidemiology

• Very rare (2-6/1000,000); predominantly young females (20-30 years old)
  • Most cases seem to be sporadic but (even rarer) familial forms occur (mutations of TGFβ receptor)

Pathology

• Hypertrophy of the vessel wall media/intima, with hyperplasia of endothelial cells (appear as ‘plexiform’ lesions)
  • causes narrowing of the vessel lumen and predisposition to thrombosis; increased vascular resistance and pulmonary hypertension

Presentation

• Often presents with insidious onset breathlessness, chest pain, fatigue, palpitation and syncope
  • Can present very late
• Signs include elevated JVP (may also have a prominent a-wave); parasternal heave (right ventricular hypertrophy); loud pulmonary component of the second heart sound and/or third heart sound
  • It is important to look for signs of an underlying cause (secondary PH) e.g. interstitial lung disease; liver failure; connective tissue disease etc

Investigations

• ECG can show right heart strain pattern (ST depression/T wave inversion in the right leads (V1-3/4 and II, III and avF))
• CXR may show enlarged pulmonary arteries and right ventricular enlargement
• Doppler Echocardiography can provide an estimate of pulmonary pressures although further assessment with right heart catheterisation is often required to guide further therapy.

Management

• Symptomatic/Prophylaxis
  • Diuretic therapy (for right heart failure)
  • Oxygen therapy for patients with chronic hypoxaemia
  • Anticoagulation (warfarin or oral anticoagulation) unless there is a risk of bleeding
  • Vaccination against pneumococcus/influenza
• Treatments
  • Pharmacological
    • High dose calcium channel blockers
    • Prostaglandins e.g. epoprostenol (prostacyclin) or iloprost
    • PDE5 inhibitors e.g. sildenafil
  • Heart-lung transplantation/pulmonary thrombo-endarterectomy in patients with chronic proximal thromboembolic disease