Respiratory
Question 84 of 180
A 67 year old man is brought to the Emergency Department by his wife. She describes his breathing getting progressively worse over the last week, to the point where he is unable to speak in full sentences. He recently underwent spirometry investigation for suspected COPD. What spirometry result would be expected in a patient with COPD?
Answer:
Patients with COPD have increased lung capacity and residual volumes. They have a reduced FEV1/FVC ratio, as their FEV1 is reduced.Chronic Obstructive Pulmonary Disease
Respiratory
Last Updated: 12th February 2021
Chronic obstructive pulmonary disease (COPD) is characterised by persistent respiratory symptoms (such as breathlessness, cough, and sputum) and airflow obstruction (usually progressive and not fully reversible). Airflow obstruction results from chronic inflammation caused by exposure to noxious particles or gases (usually tobacco smoke but also from environmental and occupational exposures). Exacerbations are acute episodes of worsening COPD symptoms (such as increased breathlessness, cough and sputum) which are beyond normal day-to-day variations.
Risk factors
- Smoking
- Cigarette smoking is the most common risk factor for COPD - About 90% of cases are associated with cigarette smoking.
- Occupational exposure
- Occupational exposures to dusts (such as coal, grains and silica), and certain fumes or chemicals (such as welding fume, isocyanates, and polycyclic aromatic hydrocarbons) have been associated with development of COPD.
- Air pollution
- Exposure to high levels of indoor air pollutants from burning wood and other biomass materials (such as coal) have been associated with increased risk of COPD.
- Genetics
- Less common risk factors for development of COPD include genetic abnormalities such as alpha1-antitrypsin deficiency. Severe alpha1-antitrypsin deficiency is linked with premature and accelerated development of COPD in smokers and non-smokers.
- Lung development
- Asthma
Diagnosis of COPD
Suspect COPD in people aged over 35 years with a risk factor (such as smoking, occupational or environmental exposure) and one or more of the following symptoms:
- Breathlessness — typically persistent, progressive over time, and worse on exertion.
- Chronic/recurrent cough.
- Regular sputum production.
- Frequent lower respiratory tract infections.
- Wheeze.
Examination may be normal. Signs on examination may include:
- Cyanosis.
- Raised jugular venous pressure and/or peripheral oedema (may indicate cor pulmonale).
- Cachexia.
- Hyperinflation of the chest.
- Use of accessory muscles and/or pursed lip breathing.
- Wheeze and/or crackles on auscultation of the chest.
Spirometry is required for confirmation of diagnosis:
- A post bronchodilator FEV1/FVC less than 0.7 confirms persistent airflow obstruction.
- Consider other causes in older people without typical symptoms of COPD who have an FEV1/FVC ratio less than 0.7.
- Consider COPD in younger people who have symptoms of COPD, even when their FEV1/FVC ratio is above 0.7.
- Severity of airflow is graded according to reduction in FEV1 compared to appropriate reference values (based on age, sex, height and ethnicity):
- Stage 1, mild — FEV1 80% of predicted value or higher.
- Stage 2, moderate — FEV1 50–79% of predicted value.
- Stage 3, severe — FEV1 30–49% of predicted value.
- Stage 4, very severe — FEV1 less than 30% of predicted value or FEV1 less than 50% with respiratory failure.
Other investigations may include:
- Chest x-ray - to help exclude other causes
- FBC - to identify anaemia or polycythaemia
- Sputum culture - if sputum is purulent and persistent (to identify organisms)
- Serial home peak flow measurements – to exclude asthma if diagnosis is in doubt
- ECG and serum natriuretic peptides – if cardiac disease or pulmonary hypertension are suspected
- Echocardiogram may also be indicated to look for right sided heart failure
- CT thorax – if symptoms seem disproportionate to spirometry measurements; another diagnosis (such as fibrosis or bronchiectasis) is suspected, or an abnormality on chest x-ray requires further investigation
- Serum alpha-1 antitrypsin - in people with early onset of symptoms, minimal smoking history or a positive family history
Acute exacerbation of COPD
An acute exacerbation of chronic obstructive pulmonary disease (COPD) is a sustained worsening of a person's symptoms from their usual stable state (beyond normal day-to-day variations) which is acute in onset. Acute exacerbations of COPD can be triggered by a range of factors including respiratory tract infections (most commonly rhinovirus), smoking, and environmental pollutants.
Symptoms may include:
- Increased breathlessness
- Increased cough
- Increased sputum production and change in sputum colour
- Increased wheeze and chest tightness
- Upper respiratory tract symptoms (for example cold or sore throat)
- Reduced exercise tolerance
- Ankle swelling
- Increased fatigue
- Acute confusion
- Fever without an obvious source
Differential diagnosis includes:
- Pneumonia
- Pulmonary embolism
- Pneumothorax
- Acute heart failure
- Pleural effusion
- Cardiac ischaemia or arrhythmia
- Lung cancer
- Upper airway obstruction
A severe COPD exacerbation is suggested by:
- Marked breathlessness and tachypnoea
- Pursed-lip breathing and/or use of accessory muscles at rest
- New-onset cyanosis or peripheral oedema
- Acute confusion or drowsiness
- Marked reduction in activities of daily living
In all people presenting to hospital with an acute exacerbation:
- Obtain a chest X-ray
- Measure arterial blood gas tensions and record the inspired oxygen concentration
- Record an ECG (to exclude comorbidities)
- Perform a full blood count and measure urea and electrolyte concentrations
- Measure a theophylline level on admission in people who are taking theophylline therapy
- Send a sputum sample for microscopy and culture if the sputum is purulent
- Take blood cultures if the person has pyrexia
Management:
- Short-acting bronchodilators
- If a person with COPD is hypercapnic or acidotic the nebuliser should be driven by compressed air rather than oxygen (to avoid worsening hypercapnia). If oxygen therapy is needed, administer it simultaneously by nasal cannulae.
- Systemic corticosteroids
- In the absence of significant contraindications, use oral corticosteroids, in conjunction with other therapies, in all people admitted to hospital with a COPD exacerbation.
- In the absence of significant contraindications, consider oral corticosteroids for people in the community who have an exacerbation with a significant increase in breathlessness that interferes with daily activities.
- Offer 30 mg oral prednisolone daily for 5 days.
- Antibiotics
- Consider an antibiotic for people with an acute exacerbation of COPD, but only after taking into account:
- the severity of symptoms, particularly sputum colour changes and increases in volume or thickness beyond the person's normal day-to-day variation
- whether they may need to go into hospital for treatment
- previous exacerbation and hospital admission history, and the risk of developing complications
- previous sputum culture and susceptibility results
- the risk of antimicrobial resistance with repeated courses of antibiotics.
- When prescribing an antibiotic for an acute exacerbation of COPD:
- Give oral antibiotics first line if the person can take oral medicines, and the severity of their exacerbation does not require intravenous antibiotics.
- Review intravenous antibiotics by 48 hours and consider stepping down to oral antibiotics where possible.
- Choice of antibiotic:
- First-choice oral antibiotic: amoxicillin, doxycycline or clarithromycin
- First-choice intravenous antibiotic: amoxicillin, co-amoxiclav, clarithromycin, co-trimoxazole or tazocin
- Consider an antibiotic for people with an acute exacerbation of COPD, but only after taking into account:
- Theophylline and other methylxanthines
- Only use intravenous theophylline as an adjunct to exacerbation management if there is an inadequate response to nebulised bronchodilators.
- Take care when using intravenous theophylline, because of its interactions with other drugs and potential toxicity if the person has been taking oral theophylline.
- Monitor theophylline levels within 24 hours of starting treatment, and as frequently as indicated by the clinical circumstances after this.
- Oxygen therapy
- Measure arterial blood gases and note the inspired oxygen concentration in all people who arrive at hospital with an exacerbation of COPD. Repeat arterial blood gas measurements regularly, according to the response to treatment.
- If necessary, prescribe oxygen to keep the oxygen saturation of arterial blood (SaO2) within the individualised target range.
- Non-invasive ventilation (NIV)
- Use NIV as the treatment of choice for persistent hypercapnic ventilatory failure during exacerbations despite optimal medical therapy.
- When people are started on NIV there should be a clear plan covering what to do in the event of deterioration, and ceilings of therapy should be agreed.
- Invasive ventilation and intensive care
- Treat hospitalised exacerbations of COPD on intensive care units, including invasive ventilation when this is thought to be necessary.
- When assessing suitability for intubation and ventilation during exacerbations, think about functional status, BMI, need for oxygen when stable, comorbidities and previous admissions to intensive care units, in addition to age and FEV1.
- Respiratory physiotherapy
- Consider physiotherapy using positive expiratory pressure devices for selected people with exacerbations of COPD, to help with clearing sputum.
Complications of COPD
- Pulmonary hypertension
- Cor pulmonale (right heart failure secondary to lung disease caused by pulmonary hypertension)
- Peripheral oedema
- Raised jugular venous pressure (JVP)
- Systolic parasternal heave
- Loud pulmonary second heart sound (over the second left intercostal space)
- Hepatomegaly
- Widening of the descending pulmonary artery on chest x-ray
- Right ventricular hypertrophy on ECG
- Frequent chest infection
- Secondary polycythaemia
- Type two respiratory failure
- Pneumothorax
- Lung malignancy
- Muscle wasting and cachexia
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
