20 September 2017

Bracing for the new thunderstorm asthma season

Allergies Respiratory

The spotlight has fallen on the management of asthma and allergic rhinitis as Victoria readies itself for another thunderstorm asthma season. A number of resources for healthcare professionals have been published ahead of the coming season, which starts on October 1.

The key message for GPs was to polish up asthma and hay fever management in at-risk patients, Dr Jonathan Burdon, the chair of National Asthma Council Australia, said. People at increased risk of flare-ups during a spring thunderstorm included those with seasonal allergic rhinitis. When the most extreme thunderstorm asthma event ever worldwide struck Melbourne and Geelong on 21 November last year, around 9,000 people presented to emergency departments with respiratory issues. The natural disaster claimed nine lives.

In past thunderstorm asthma events in Melbourne, Wagga Wagga and Newcastle, there have typically only been a handful of cases at each hospital.

But during the event last year, the ambulance service was completely overwhelmed and people were queuing up outside EDs, Dr Burdon said.

“With at least six episodes in Melbourne in 33 years, this is unlikely to be the last,” Melbourne researchers wrote in the MJA this week. (1)

Around 40% of people affected in Victoria last year were known asthmatics who had been prescribed regular medication but were not taking it, Dr Burdon, who is a respiratory physician, said.

“And you can see why it happens,” he said. When patients aren’t actively experiencing asthma symptoms, patients forget to take their Seretide, Symbicort or Serevent.

Patients should be reminded that adherence to asthma treatments lowered the odds of them experiencing severe asthma during a spring thunderstorm, he said.

The other main group affected by thunderstorm asthma – patients with allergic rhinitis – are recommended to take intranasal corticosteroids starting six weeks before the pollen season commences and continue throughout, even if they were already taking regular inhaled corticosteroids for asthma. This group should also have an up-to-date asthma action plan that included thunderstorm advice and advised them to increase their dose of both preventer and reliever when they had symptoms, even if they have not had asthma before.

“At a patient level, a key message should be to encourage identification of asthma in people with seasonal allergic rhinoconjunctivitis, along with education and the consideration of the prescription of inhaled corticosteroids to patients with both conditions, particularly for anyone who ‘sneezes or wheezes’,” the MJA authors wrote.

Thunderstorm asthma is thought to occur when perennial rye grass pollen grains are swept up by gusty winds. The pollen becomes heavy with humidity, ruptures due to osmotic shock, and releases a cloud of allergenic starch granules.

“[These are] small enough to penetrate into the lower respiratory tract and bring about a much more severe asthmatic response than would result from the inhalation of intact pollen grains,” the MJA article authors said.

The high concentrations of pollen, which reached 102-210 grains/m3 in Melbourne last year, also affected people with no history of hay fever or asthma.

“And that may be because they may have had asthma but it just hasn’t been diagnosed,” Dr Burdon said.

“If there is any history of wheezing during respiratory tract infections, even if you don’t have a diagnosis of asthma, that’s a prompt for you to go see your own doctor and discuss whether you should be taking any medication,” he said. National Asthma Council Australia is hosting education events for healthcare professionals over the coming month and has prepared online information sheets, which have been endorsed by the Australasian Society of Clinical Immunology and Allergy. (2)

References: 

1 MJA 2017, 18 September

2 https://assets.nationalasthma.org.au/resources/Allergic-Rhinitis-Asthma-HP.pdf

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