Health

Asthma: what happens in your lungs, and why you shouldn't underestimate it

In the UK, children and young people have the highest death rate from asthma in Europe

The mainstay of ongoing asthma treatment remains inhalers

Dr Muiris Houston's face
Dr Muiris Houston
Mon Jan 15 2018 - 07:01

Asthma affects 470,000 people in the Republic; we have the fourth highest prevalence of asthma in the world. An estimated 75 per cent of hospital admissions for asthma are avoidable, and as many as 90 per cent of the deaths from asthma are preventable. What actually happens in the lungs during an asthma attack?

Primarily, a disease of the breathing tubes, when an asthma attack begins these airways narrow and begin to fill with inflammatory products. There is severe airway obstruction as a result of smooth muscle contracting and plugging of the airway by inflammatory cells and mucus. Patients have to work harder to breathe; they visibly use accessory muscles to reflect the added workload. And airway narrowing produces an audible wheeze.

Unlike some chronic diseases, there is no single test that can diagnose asthma. Common symptoms, such as shortness of breath, wheezing, and cough, are relatively nonspecific, and so doctors use some tests and clinical observation to reach an accurate diagnosis.

In a major review last autumn, the UK National Institute of Clinical Effectiveness (NICE) emphasised the importance of using objective tests to help confirm a diagnosis of asthma. Two tests in particular will help achieve more accurate diagnosis and therefore more effective treatment, it said.

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Spirometry tests assess how well someone’s lungs work by measuring how much air they inhale and exhale, and how quickly. It involves blowing hard and fast into a measuring device. A more recent addition is the fractional inhaled nitric oxide (FeNO) test: it measures the levels of nitric oxide in the breath. Increased levels signal lung inflammation.

Prof Mark Baker, director of the centre for guidelines at Nice, said: “We are recommending objective testing with spirometry and FeNO for most people with suspected asthma; a significant enhancement to current practice, which will take some time to implement, with additional infrastructure and training needed in primary care.”

A GP's experience can make the difference between life and death in a really bad exacerbation of asthma

Don’t expect to see FeNO testing in your local surgery just yet. Investment and training required to implement the new guidance will take time. And manufacturers are working on making the FeNO test more accessible, with the ultimate aim of having a self-testing device available for home use by people with asthma.

A recent US study concluded the FeNO test has moderate accuracy for patients aged five and older. “Asthma can sometimes be difficult to diagnose, and FeNO can be helpful to make therapeutic decisions more evidence based,” said lead investigator Dr M Hassan Murad of the Mayo Clinic. “Future research is needed to determine how FeNO can be used with other biomarkers with hopefully better accuracy that can provide a more definitive diagnosis.”

Meanwhile a recent editorial in the British Medical Journal warned of the dangers of an acute asthma attack in children. In the UK, children and young people have the highest death rate from asthma in Europe.

It says the mainstay of emergency treatment is short-acting antagonist drugs, such as Ventolin, given by nebuliser. Oxygen is also important, as is assessment using a pulse oximeter. A relatively inexpensive skin probe that tells the doctor how much the level of oxygen saturation has dropped, oximeters must be used in planning treatment in a severe asthma attack, the authors note.

But you cannot beat solid clinical assessment by an experienced GP or emergency physician. It is this experience and awareness that can make the difference between life and death in a really bad exacerbation of asthma.

The mainstay of ongoing treatment remains inhalers: “preventers” designed to stabilise the airways in advance of an asthma trigger, and “relievers” which are taken as soon as symptoms begin. The first “add-on therapy” to be tried is usually a leukotriene receptor antagonist (LRA) which blocks the action of naturally occurring chemicals in the lungs (leukotrienes) that cause inflammation in both the upper and lower airways.

Never underestimate the risk of an acute worsening of your asthma.