Asthma
Asthma is a condition of the airways, caused by chronic inflammation and hypersensitivity to certain triggers. When an individual is exposed to a trigger, the muscle in the walls of the small airways contracts. This narrowing causes wheezing as air struggles to get out of the lungs. Some air will be trapped in the alveoli and bronchioles, the smallest parts of the lungs where gases are exchanged. Inhalers such as Salbutamol (Ventolin) help to relax the muscle walls and open up the airways. Long term use of steroid inhalers prevent this narrowing from occurring by reducing the level of chronic inflammation.
Can I dive with asthma?
Diving is not advisable if your asthma is triggered by exercise or cold air. Diving often requires you to exert yourself (swimming against currents is hard work!). Even when diving in exotic places, air from a tank is cold and dry, which can be irritating to the lungs. Small amounts of sea water that may enter the lungs through the breathing apparatus can also trigger asthma attacks.
Any wheeze whilst diving is bad news. The airways can become narrowed underwater, trapping air inside the lungs. This air expands as you come to the surface due to the pressure change, which can burst your lung (called barotrauma) and this can introduce air into your bloodstream (air embolism).
If you have allergy induced asthma then diving may be possible, depending on how well your symptoms are controlled. Some people may have been diagnosed with asthma in childhood, with few symptoms since.
In any case, it is a condition you will always need to discuss with a doctor before diving.
What does the doctor need to know?
The first step is to discuss your fitness to dive with one of our doctors. You can do this using our telephone consultation service.
There are some key questions we will ask during this initial telephone consultation:
- When was the last time you were on asthma medication?
- What asthma medication were you on?
- Have you ever been hospitalised because of your asthma?
- Have you ever been in intensive care for your asthma?
- Have you ever required oral steroids for your asthma?
- Do you dive already? If so, how many dives and have there been any problems?
- Do you have any other chest problems?
- Do you undertake regular cardiovascular exercise (where you raise your heart rate) and if so, does your chest ever feel tight or do you get any wheezing (whistling noises)? In particular, do you have any trouble when you exercise in cold environments (for example, going for a run on a cold day)?
The doctor will be able to advise you on the next steps during this consultation – usually you will need to ask your GP for a summary of your records, and you will need to complete a ‘peak flow’ diary for 2 weeks. This is to assess your suitability for an asthma stress test, which is the best tool we have to test whether diving will trigger your asthma.
What is peak flow?
Peak flow (otherwise known as peak expiratory flow or peak expiratory flow rate – PEF/PEFR) is a quick way to measure how fast you can blow air out of your lungs. It is a measure of how open the airways are, so during an asthma attack it is significantly reduced. In healthy lungs the measurement will not vary. People with asthma will usually see variation in their peak flow measurements, and so this variation is a good marker of how well an individual’s asthma is controlled.
As part of our assessment we will look at your peak flow diary, kept over 2 weeks, for signs of variation. If your GP or asthma nurse has not given you a peak flow meter, you can buy one online for around £10. You can record your readings (morning and evening) on a chart, which can be downloaded here.
What is an Asthma Stress Test?
Based on your peak flow diary, your GP summary and the information you give to our doctor, we can decide whether or not it is safe to carry out an asthma stress test. This test attempts to recreate the conditions you might experience underwater whilst breathing compressed air (for example swimming against a current). You will breathe air from a SCUBA tank whilst pedalling on an exercise bike, and a series of lung function tests will be performed before and after to detect any changes. This is a way to detect whether your asthma might be triggered by diving.
After the test you can see one of our doctors for a sports diver medical, at which point they will discuss any other medical problems, examine you and discuss the result of the asthma stress test.
How do I book an Asthma Stress Test and Sports Diver Medical?
We can only book your stress test once we are sure it is safe to proceed. For this reason, we require your peak flow diary and GP summary first. Our doctors will advise you when you can book the asthma stress test and medical during a telephone consultation.
Please note you may need more than one telephone consultation as part of this process, prior to your face to face medical. We have found this to be the safest and most time efficient way to assess fitness to dive for asthmatic patients.
What do I need to do before an Asthma Stress Test?
For an asthma stress test at our facility you will need to bring the following:
- Your current asthmatic medication
- Suitable clothing and footwear for cycling
- Prior to the test, you should continue your preventative medication but should not use a salbutamol inhaler for 48 hours before the test.
- You should avoid caffeine and chocolate on the morning of your test, but do have something to eat before the stress test. If you drink caffeine before the test then unfortunately the test will have to be cancelled!
If you are not able to do this please let us know well beforehand. If you cannot stop your medication for 48 hours you may not be fit to undertake the test, so please discuss this with our doctors during your telephone consultation.
On the day you will be required to sign a declaration to say you have fulfilled these criteria and consent to the test. There is a small risk that we could induce an asthma attack. There will be a doctor present at all times.
I have been told I can dive by my doctor. What do I need to do to keep safe whilst diving?
Asthma can deteriorate when you become unwell with a cough or cold, or become exposed to new triggers. If you experience wheeze or shortness of breath then you should not dive, and you should discuss your symptoms with a diving doctor before returning to diving.
If your symptoms are stable, then simple peak flow measurements will give an indication of the control of your asthma. You should do twice daily (morning and evening) peak flow readings during the diving season. If your peak flow drops more than 10% below your predicted reading then you should not dive until this recovers to normal and you feel well.