Asthma is an obstructive disease of the airway tract. It is caused by inflammation of the tract, which is driven by a certain trigger. The inflammation leads to a rapid swelling of the tract lining, and subsequent narrowing. 

This narrowing causes symptoms such as shortness of breath, a feeling of chest restriction and an audible wheeze. The wheeze is a high-pitched sound produced by air trying to leave the lungs through tight channels. 

Asthma is characterised by an acute attack - meaning that the restriction will come on suddenly. In the case of an attack, one should use their Ventolin inhaler (with appropriate technique - deep breaths and breath holding) as directed by their doctor. If the Ventolin does not relieve the wheeze after multiple uses, you will likely need to attend ED urgently. 

So, what are the common triggers? Let's list off a few - Cold air, Exercise, viruses, bacteria, smoke, dust, pets - all of these things can irritate the airways, and in asthmatics, this irritation can lead to an inappropriate, inflammatory cascade. 

What drives the inflammation? The inflammation is driven by IgE in most folks, however some people have non-IgE mediated asthma. IgE, or Immunoglobulin E, is a class of antibodies - something your body produces to fight infection. In the majority of asthmatics, an airway trigger will lead to a hyper-response from IgE - which will stir up a big pot of immune cells. Like a swollen knee after an injury, where there are numerous immune cells, there is inflammation - and where there is inflammation, there is swelling. 

Is it important for people with poorly-controlled asthma to take a "preventer" inhaler everyday, regardless of their symptoms. It is to minimise any low-grade inflammation that may be ongoing without you noticing a change in your breathing. This subtle inflammation can lead to airway remodelling, which makes you more prone to asthma attacks in the future. Some people won't require a preventer inhaler as their asthma is well-controlled on its own. 

What qualifies you as well-controlled? If you require your Ventolin inhaler less than twice a week - that's okay. If you're using it three times a week, or even worse, everyday - you need a preventer! If you are taking a preventer inhaler but still requiring a lot of Ventolin - you may need a different preventer, an additional preventer or your inhaler technique needs checking. Sometimes, tablets (such as theophylline) or injections (such as omalizumab) will be indicated.  

If you have an asthma attack and arrive to the shores of ED, we will likely begin back to back nebulisers (inhaler medications given via a mist-producing mask) to widen the airways. We can give supplemental oxygen via these masks at the same time. The medications are called bronchodilators, as they dilate the bronchi - duh!
At the same time, doctors will gain access to the veins with cannulation and give IV Hydrocortisone (a steroid to quickly reduce the inflammation - the driving factor). 
If these measures don't work, we have other tricks up our rolled-up sleeves - such as IV Magnesium. 
While we do these things, monitoring of the vital signs will continue and blood tests will be sent to monitor electrolytes amongst other things - particularly potassium which can be lowered by Ventolin. 

When you're feeling a bit better, we will measure your "peak flow" by asking you to blow really hard into a red canister thingy-ma-bob with a dial on the side. We have an expected number for your age and gender, and if you're below this number, you probably still have an element of airway obstruction. It gives a good idea too if it improves, because we're going in the right direction.

Asthma sufferers often have food allergies or are prone to hay fever - we nickname these types of issues "atopy" - which is medical jargon for a propensity for the immune system to overreact to a trigger. 

Let's list off a few common inhalers, why not?

Short-term relievers:
Ventolin (Salbutamol) - yeah, the blue one. 
Atrovent (Ipratropium Bromide). 

Preventers:
Seretide, Spiriva, Breo Ellipta, etc. These guys are combinations of two or three drugs, usually including a steroid component (Eg. Fluticasone).

Steroid inhalers on their own are usually brown - after using them it's important you rinse out your mouth, including a good gargle, so you don't develop oral thrush. Steroids suppress the immune system and even the immune cells of the tongue have a job to do!