Winter can be a worrisome time for individuals with asthma – fuelled by fears of intensified symptoms and insufficient preparation. Dr Peter Kewin, Consultant in Respiratory and General Medicine, Queen Elizabeth University Hospital, investigates the factors which come into play, and how you can help patients cope in the colder months.
Winter is coming! While true, this doom-laden phrase lifted from a recent TV epic does not have to signal a hard time for asthma patients. Asthma itself does not change with the seasons, but winter brings with it a specific set of triggers and problems to consider in any patient.
To put this in context, first let me summarise what asthma actually is.
Asthma is a disease of the lower airways characterised by variable levels of inflammation influenced by both intrinsic and extrinsic factors. This leads to variable narrowing of the airways as a result of inflammatory changes in the epithelium (i.e. swelling), mucous production and smooth muscle contraction. This then results in the typical symptoms of exacerbation:
1. Wheeze – air moving through the narrowed tubes
2. Cough – irritated airway nerve endings and extra mucous to clear
3. Breathlessness – a combination of both
4. Chest tightness – increased effort of breathing due to the above
There are a number of different ‘types’ of asthma (phenotypes) depending on the most important factors present in individual patients, so in asthma clinics we make an attempt to measure these to help guide our advice and treatment. Examples of important factors include the presence or not of eosinophils, the co-existence of allergies, and very specific triggers such as drugs (aspirin / non-steroidal anti-inflammatory drugs especially). Regardless of the type of asthma, ‘non-specific’ (i.e. non-allergic) triggers in the environment also play a key role in driving symptoms.
The cornerstones of treating asthma are controlling the inflammation, and dilating the airways as much as possible. This does not change in winter. ‘Reliever’ medication is aimed at opening up the airways rapidly if narrowing occurs due to smooth muscle contraction after a trigger. This is usually in the form of short-acting beta agonists (SABA).
‘Preventer’ treatments are those taken regularly to damp down any inflammation and keep airways as open as possible. They include inhaled corticosteroid (ICS) and long-acting bronchodilators in the form of beta-agonists (LABA) and muscarinic antagonists (LAMA). ICS and LABA are often used in combination inhalers. If these are insufficient, additional treatments include leukotriene receptor antagonists (LTRA), theophyllines, antihistamines if there are allergies, and in the last resort oral prednisolone.
Treatments are escalated as per British Thoracic Society / SIGN guidelines according to levels of symptoms and frequency of exacerbation (ref). There are newer biological therapies targeting immunoglobulin E (IgE) responsible for allergies, and interleukin-5 (IL-5) that drives eosinophil levels, for those patients with these phenotypes and recurrent or persistent need for prednisolone.
An exacerbation of asthma is regarded as any increase in symptoms necessitating an increase in preventer-type treatment. There is considerable variability in severity (usually based on drop in peak flow rate and severity of breathlessness) and speed of on-set (rarely hours, usually days). Milder exacerbations (e.g. exposure to chemical scents, pollution, allergies) usually result in an increase in SABA use and ICS dose, but more severe exacerbations (usually viral) will require a short course of prednisolone. Only occasionally are antibiotics indicated (for bacterial chest infection).
Hospitalisation is required if rapid onset, or if not responding to initial increase in treatment, and will usually involve the addition of nebulised SABA / SAMA. Very severe exacerbations can lead to intensive care admission or even death. So, exacerbations are inconvenient, debilitating, and the time of most danger to the patient, and expensive for the healthcare system.
The approach to managing asthma during winter then is aimed at ensuring good asthma control in general, and avoiding exacerbation as much as possible.
Ensuring Good Control
This is the same all year-round. The better controlled asthma is, the less likely to exacerbate when provoked.
The key features are:
• Education – patients should understand their own disease and triggers and its variable nature, and the need for preventative treatment even when feeling well
• Avoidance of known triggers (e.g. cats if allergic to cats)
• Adherence to treatment – can be challenging in ‘well’ patients but needs to be frequently encouraged and any barriers removed (e.g. access to medication / prescriptions, allay fears of side-effects)
• Inhaler technique – needs constant vigilance, especially when devices are changed as medications are changed, and especially when changing from metered dose inhaler (MDI) to dry powder or vice versa. An MDI and spacer is often the simplest best option
• A written asthma action plan of usual treatment, when and how to escalate treatment, and any specific issues for that patient
Avoiding Exacerbations in Winter
As mentioned, there are some specific issues with winter:
These are much more common in winter due to crowding together indoors and having more contact with people for longer. Patients with asthma are no more susceptible to viral infection, but tend to have more serious and longer-lasting lower respiratory tract symptoms. They are responsible for 85 per cent of exacerbations in school-age children, with a peak not long after the start of each term, and about 50 per cent of adult exacerbations. The majority are due to rhinoviruses (the common cold) for which there is no treatment.
So, the key is avoiding people who have the cold, and keeping hands scrupulously clean, as most viral spread occurs via droplets on surfaces transferring by hand to the face. Influenza is less common but more severe so the flu vaccine should be considered, especially if other co-morbidities and in older and younger patients.
Cold air tends to be dry air. This can dehydrate the airway epithelium and provokes an inflammatory response and smooth muscle contraction. Simply using a scarf to breathe through, or exclusive nasal breathing, will warm and humidify the air before it reaches the lower airways. An extreme example of this is the very high level of asthma seen in winter athletes – between 15 per cent and 50 per cent depending on the sport. For contrast, about nine-to-10 per cent of the UK population have asthma.
They sound like a great idea, but real fires and wood-burning stoves generate lots of fine particles (i.e. pollution) which can trigger asthma as much as diesel particles can. Ensuring that the chimney is well-swept, and good ventilation in the room can help.
Environmental air pollution in general is worse in winter due to overcast weather ‘trapping’ pollution in the cold air nearer the ground, as well as the increase in car journeys and burning fossil fuels.
Certain allergies are worse in colder months due to increased exposure to the allergen. Most common of these is house dust-mite allergy. Dust-mite numbers increase during colder months, thought to be due to the increased use of central heating. We also spend more time indoors in contact with them in our soft furnishings (especially beds and bedding).
Antihistamines, and measures to reduce dust-mite load, may help. These include keeping the temperature even and low and wearing more clothes instead (but be aware of taking dusty jumpers out of storage!), steam cleaning soft furnishings, and considering anti-allergy bedding. Mould spores are also higher in colder weather so may necessitate antihistamines in patients with known allergy.
No joking – this is a dangerous time for asthma patients. They are inside with virus-ridden, perfume-soaked relatives. It is a time of stress. There are increased levels of wood smoke, and hot air / cooking fumes. The dust-covered decorations have been recovered from the dust-filled attic. The tree exudes a lovely pine scent guaranteed to irritate. And with all the bank holidays, they’ve run out of medication, and the GP surgeries and pharmacies are shut. The out-of-hours is miles away. The local emergency department has now been moved and isn’t so local anymore. And once there the hospitals are on a skeleton staff and the Christmas dinner is woeful.
So, take care and hopefully you can help prevent your asthma patients having Christmas dinner in hospital – though they may not thank you for it if it gets them away from the kids for a day or two!