Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterised by progressive airflow limitation resulting in breathlessness and other associated symptoms. Worldwide, it is a significant cause of morbidity and it is estimated it will be the fourth leading cause of death by 2030.¹ In Ireland, the exact prevalence of COPD is unknown, but is estimated to be over 400,000 with significant levels of underdiagnosis.²

COPD results from interactions between genes and the environment, with smoking being the most encountered environmental risk factor. Exposure to both inorganic and organic dusts and chemical agents is also a recognised risk factor for the development of COPD. The most clearly documented genetic risk factor is a severe deficiency in alpha-1-antitrypsin, a serine protease inhibitor.³

The pathophysiology of COPD involves a chronic inflammatory process where inflammation and narrowing of peripheral airways leads to a reduction in the forced expiratory volume in one second (FEV1). Inflammation also results in destruction of the lung parenchyma, which further diminishes the ability of the airways to remain open during expiration. It should be noted that the terms ‘emphysema’, and ‘chronic bronchitis’ are no longer used in the definition of COPD.⁴

When should a diagnosis of COPD be considered?

A diagnosis of COPD should be considered in any patient who presents with progressive, persistent shortness of breath, chronic cough and/or sputum production with a history of exposure to risk factors. Whether or not there is a family history of COPD should also be determined.

The importance of good history taking cannot be over-emphasised. This is particularly important to distinguish COPD from other differentials, especially asthma, with which it may co-exist (‘overlap syndrome’).

COPD typically develops in adulthood and a careful history can identify symptoms of chronic cough, followed by increased breathlessness and prolonged ‘colds’ over a period of many years. Additional features of severe disease include fatigue, weight loss and anorexia. Asthma typically presents early in life and symptoms can vary widely from day to day and may show a diurnal variation. A past history or family history of asthma should be explored, along with a history of atopic disease or upper respiratory tract symptoms/nasal polyps. Symptoms of congestive cardiac failure, bronchiectasis and TB should also be explored.

The importance of spirometry in diagnosis

Spirometry is required to confirm a diagnosis of COPD. In the correct clinical context, a post-bronchodilator fixed ratio of FEV1/FVC < 0.7 confirms the diagnosis of COPD. Spirometry should be performed on all patients in whom COPD is suspected. It is currently the most reproducible and objective measurement of airflow limitation available, according to the current 2014 GOLD guidelines. Peak expiratory flow measurement alone is not reliable enough. Although it offers good sensitivity, its specificity is weak.

GOLD guidelines recommend that all healthcare providers involved in the care of patients with COPD should have access to spirometry. Spirometry allows assessment of lung function and allows clinicians to reliably differentiate between obstructive lung disease (eg. COPD, asthma) versus restrictive lung diseases (eg. fibrotic lung disease).⁵

While most major hospitals have pulmonary function labs which offer a service to local GPs, these services are often over-subscribed resulting in long waiting lists. Basic spirometry by properly trained personnel is certainly possible in primary care. However, a national survey reported in the National Respiratory (COPD) Framework in 2008 found that only 53.7% of GPs had access to spirometry in their own practice.⁶

How to perform spirometry 

Spirometry should measure the forced vital capacity (FVC), which is the volume of air forcibly exhaled from the point of maximal inspiration, and the forced expiratory volume in one second (FEV1), which is the volume of air exhaled in the first second of this manoeuvre. The ratio of FEV1/FVC can then be calculated. Most spirometers will calculate the percentage of the predicted normal value achieved for any particular patient. Many spirometers also display a flow volume curve.

Preparation

A brief history including smoking history should be taken and documented as well as current medications, dose and time last taken. Patients should not take inhalers for their duration of action when measuring baseline spirometry. If assessing response to therapy, then patients should continue with their regular inhaler regimen. Patients should not smoke or do strenuous activity for one hour before spirometry. The patient’s height, weight, age, sex and race must all be inputted in order to provide adjusted reference ranges.

An important point is that spirometers should be calibrated.

Bronchodilation

Possible protocols are 400µg of beta2-agonist, eg. salbutamol, or 160µg anticholinergic, eg. atrovent. FEV1 should be measured 10-15 minutes post short-acting beta2 agonist, or 30-45 minutes post short-acting anticholinergic. 

Practical aspects

• The patient should be sitting comfortably with both feet on the floor, and arms uncrossed. Use of a nose clip is recommended. 
• Attach a clean, single-use, one-way mouthpiece to the spirometer
• Ask the patient to breathe in as deeply as possible (full inspiration)
• The patient should seal their lips around the mouthpiece (without pursing lips). 
• The patient should blow out forcibly as hard and as fast as possible until there remains no air left to expel. Encouragement should be given to continue to blow out and this process can take up to 15 seconds. Some spirometers give a bleep to confirm that expiration is complete. Early termination of the blow may result in a false restricted diagnosis 
• These steps should be repeated three times with adequate rest in between 
• The spirometer will then display the results on a screen, or may allow results to be printed. 

Common problems affecting spirometry readings

According to Irish Thoracic Society spirometry guidelines for general practitioners (2005), the most common reason for inconsistent readings is patient technique. Common problems which can arise include:

• Lips not tight enough around the mouthpiece
• Inadequate or incomplete inhalation
• A slow start to the forced inhalation
• Exhalation stops before complete expiration
• Some inhalation through the nose
• Additional breath taken
• Coughing.

How do you assess disease severity?

Updated GOLD guidelines from 2011 recommend a combined approach to disease assessment using both degree of symptoms and exacerbation risk to assign patients into one of four groups.

In the past, the severity of COPD was classified using the single factor of airflow limitation, with patients being divided into mild (FEV1 ≥ 80% predicted), moderate (50% ≤⊇FEV1<80% predicted), severe (30% ≤ FEV1 < 50% predicted) or very severe (FEV1 < 30% predicted) COPD stages based on their post bronchodilator FEV1 values. It was believed that most patients would follow a disease course where disease severity would track the severity of their airflow limitation.⁷

Updated GOLD guidelines from 2011 reflect that assessment of COPD is complex and that FEV1 alone is an unreliable marker of overall disease severity. A combined approach to COPD assessment is now recommended as below.

Assessment of symptoms

Symptoms can be assessed using either the Modified British Medical Research Council (mMRC) Questionnaire for assessing the severity of breathlessness or by using a more comprehensive symptoms assessment tool such as the COPD Assessment Test (CAT). An mMRC of ≥ 2 eg. a patient who stops after 15 minutes of walking on the level is still used as a crude cut-off point for separating patients from ‘less breathlessness’ (Grade A), and ‘more breathlessness’ (Grade B).

Assessment of risk

Several methods exist for assessing exacerbation risk. Firstly, using GOLD spirometric classification of airflow limitation as previously outlined. The second, and more practical method in primary care, is to examine the patient’s exacerbation history with a history of ≥ 2 exacerbations in the preceding year indicating a high risk patient. If there is a discrepancy between the two, then the higher risk indicator should be used. 

Another method outlined in the current GOLD guidelines is if there is a history of hospitalisation due to an exacerbation in the previous year.

The combined COPD assessment places patients in one of four groups which can be summarised as follows:

• Group A – Low risk, fewer symptoms
• Group B – Low risk, more symptoms
• Group C – High risk, fewer symptoms
• Group D – High risk, more symptoms.

This also forms the basis for individualised management of COPD with Grade A and B management based primarily on bronchodilation, and grades C and D on bronchodilation with anti-inflammation. 

GOLD has launched a mobile app which is available from the iTunes app store which allows quick and easy assessment, grading and management options for COPD. 

What additional investigations should be ordered?

Chest x-ray

While not diagnostic, certain radiological changes are associated with COPD including signs of lung hyperinflation such as a flattened diaphragm, hyperlucency of the lungs, and rapid tapering of the vascular markings. A chest x-ray can be very useful in excluding other differential diagnoses, and also identifying any comorbid disease or complications. 

Lung volumes and diffusing capacity

Formal pulmonary function tests (PFTs) use body plethysmography, or helium dilution to measure lung volumes. COPD is associated with an increase in residual volume due to gas trapping and hyperinflation resulting in an increased total lung capacity. Measurement of the diffusing capacity allows investigation of the functional impact of emphysema in COPD. 

While formal PFTs are not required in order to diagnose COPD, they may be helpful when a diagnosis is in doubt, or if a patient’s breathlessness seems out of proportion with the degree of airflow limitation.  

Oximetry and ABG measurement

Pulse oximetry is indicated in stable patients with an FEV1 < 35% predicted or with signs of right heart failure. If peripheral oxygen saturations are below 92% on room air, an ABG (arterial blood gas) is indicated.⁹

Alpha 1 anti-trypsin deficiency 

Ireland has a high prevalence of alpha 1 anti-trypsin deficiency (AATD) and therefore doctors should have a low threshold for screening patients.¹⁰ Typically, AATD patients present at a younger age (eg. < 45) with lower lobe emphysema, and may have a family history of COPD. 

Exercise testing

Exercise testing, eg. the six-minute walk test, can help to identify patients who desaturate significantly. These patients may benefit from supplemental oxygen (portable oxygen therapy).¹¹

Management of stable COPD

The major goals of therapy include smoking cessation, symptom relief, improvement in physiological function and limitation of complications such as abnormal gas exchange and exacerbations of the disease.

Smoking cessation

Smoking cessation is the only intervention known to be effective in modifying disease progression, and abstinence results in a 50% reduction in the rate of lung function decline in patients with COPD.¹² All patients should be encouraged to stop smoking and appropriate pharmacological and behavioural support should be made available. At each GP visit, current smoking status should be ascertained and the importance of smoking cessation emphasised.

Pulmonary rehabilitation

Pulmonary rehabilitation involves a multidisciplinary approach for a minimum of six weeks and includes a personalised aerobic programme, disease education, psychosocial counselling and nutritional support. 

A large number of clinical trials have shown pulmonary rehabilitation to be effective in improving quality of life and exercise tolerance, while decreasing the number of hospitalisations related to COPD.^13,14 It should be considered for patients with functionally limiting dyspnoea and can be initiated as early as possible after an exacerbation with home rehabilitation if appropriate. 

Unfortunately, the 2008 National Respiratory (COPD) framework identified significant gaps in the provision of rehabilitation services with only 8% of GPs reporting that they were able to access rehabilitation services.¹⁵

Vaccination

Annual influenza vaccination and pneumococcal vaccination should be offered to all patients in an attempt to reduce both disease-specific mortality and mortality from all causes.¹⁶

Pharmacological therapy

The classes of medication include inhaled bronchodilators, theophylline, oral corticosteroids and other medications. These will be covered in more detail in a future module. The combined COPD assessment places patients in one of four grades and forms the basis for individualised management of COPD. Grade A and B management is based primarily on bronchodilation, with grades C and D on bronchodilation with anti-inflammation.

When should specialist referral be considered? 

Other therapies including supplementary oxygen therapy, non-invasive positive-pressure ventilation, and surgery may be appropriate for patients with severe disease. Practically speaking, this is best managed by a specialist respiratory service. 

Supplementary oxygen 

Clinical trials have shown that supplementary oxygen for 15 or more hours a day (long-term oxygen therapy or LTOT) improves survival and quality of life in hypoxic patients with COPD.¹⁷  There are clear guidelines regarding the prescription of LTOT. 

Surgery

Both lung volume reduction surgery and single lung transplantation could be considered in select patient groups with severe disease. 

Conclusion

COPD is a prevalent and preventable inflammatory disease associated with significant morbidity and mortality. Primary care physicians should have a low threshold to perform spirometry on patients who display symptoms consistent with COPD with a history of exposure to risk factors. 

Current GOLD guidelines recommend that spirometry is required to make a diagnosis of COPD. The presence of a post-bronchodilator FEV1/FVC < 0.70 confirms the presence of persistent airflow limitation and thus of COPD. It allows early identification of patients at risk, and allows early intervention, particularly targeting smoking cessation. 

GOLD guidelines now recommend a combined assessment of disease severity which assigns patients into one of four groups. This forms the basis of individualised management of COPD. Referral to specialist respiratory services may be required with severe disease or to access rehabilitation services. 

The GOLD guidelines recommend that comorbidities be actively looked for and treated, given that they frequently occur in patients with mild, moderate and severe airflow limitation. In addition, they can influence both hospitalisation and mortality independently. 

References

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