Asthma
Dear Doctors,
I would like some advice on diving with a history of asthma. My situation is somewhat complicated so please bare with me.
While having a dive medical performed my lung function test was slightly below normal. I don't have the results of this test available. I have a history of asthma as a child, but would characterise this history as mild. I do not recall ever having an 'asthma attack', or ever being in severe difficulty breathing. My symptoms were never exercise induced and I was always physically active as a child. Nonetheless I recall using both preventative and reactive 'puffers', ventolin and becotide. My siblings symptoms were much worse which perhaps in part explains my diagnosis. This information was all made available to the GP performing the medical.
Given this infomation and my test results the GP referred me to a specialist for further testing. This specialist referred me for standard spirometry at the hospital's pathology laboratory. In this test my lung function was within the normal range. The specialist gave me a letter to that effect and cleared me to dive.
An opportunity to complete my open water course arose at short notice and using this specialist's report as my medical clearance to dive I completed the course with no complications.
In making this decision I took into account that I am very physically fit, especially aerobically (e.g. I regularly run 3km in around 11 minutes.), a strong swimmer, have not had any symptoms of asthma since ten years of age (I am 29) and have regularly snorkelled and surfed (and therefore occassionally inhaled salt water with no symptoms of asthma).
I was then interstate for a period and completed a number of dives, inlcuding one to a depth of 25m with no issues.
Once home I returned to the original GP with the specialists report and made him aware I had completed my open water course. The GP was unhappy that a bronchial provocation test was not perfomed by the specialist. I then underwent this test at different hospital's pathology lab. The test used mannitol. I have attached my results. The techinician informed me the results indicated I had asthma. Upon seeing my results the GP issued me with a not medically fit to dive certificate.
I have read the SPUMS Medical 2010, including appendix C and therefore understand that with treatment it is possible I could pass a bronchial provocation test in the future. I understand that completing a number of dives (around 8) with no issue does not mean that I am not at greater risk. Yet does it in any way temper the caution that you would usually associate with my results? Does talking into account my physical fitness and lack of asthma symptoms for 19 years further affect this risk?
Any advice would be greatly appreciated.
Cheers
There is little or no evidence that asthmatics are at increased risk when diving. The theory sounds compelling but has never been shown to be correct.
Your result may merely be a false-positive, and should be repeated in the first instance.
The main concern is that they are over-represented in diving fatality statistics (not causally linked) but agree that there is no direct link to asthmatics diving and injuries.
Regards Glen
There is little evidence available that a mannitol challenge is indicative of salt water inhalation tirggering asthma. Most asthmatics that dive and have problems usually have them on the surface - swimming back to the boat. The theoretical risks of trapped air and gas emoblism, surgical emphysema or pneumothorax are very very slim and I have yet to see a study that shows the risk higher in asthmatics than 'normal' divers.
The recommendation standard between the SPUMS and BSA asthma guidelines vary significantly.
If dive doctors were serious about determining which asthmatics should not dive they would do an exercise challenge. An ultrasonic saline or mannitol challenge does not logically duplicate what happens when diving.
A lot of the discussion centres around medico-legal issues and the 'theoretical risk' should something go wrong. I would recommend talking to a dive Doctor that does many dive medicals and making an informed decision yourself about the risks.
Although I tend to agree regarding the Mannitol testing I think Hypertonic Saline testing is a very indicative test of what can be experienced while diving. The triggers of aspirated salt water, cold and exercise all lead to possible exacerbation of asthma which leads to the reduced functional capacity of the person for exercise (and hence they get into trouble and drown). The gas trapping issue is very unlikely and I think that is no longer considered the reason to restrict asthmatics from diving.
SPUMS has recently developed a pathway for asthmatics (in the medical) using the currently available evidence in conjunction with respiratory physicians with diving experience and it gives a guide as to how 'asthmatics' can be investigated with respect to diving.
Regards Glen
Diving is a risky sport.
Diving with asthma has potential risks both to the diver and their buddy/rescuer if they get into difficulty. Salt water can trigger the reactive bronchioles (airways) of the susceptible patient. It is a fact that some people with a history of mild childhood asthma come to hospital in the back of an ambulance for certification of death in young adulthood....life-threatning asthma still occurs in 2012. We don't know why some people get these extreme attacks or who or when.Different diving medical specialist will offer different opinions on the risk with your history and normal lung function which is consistent with reversible airway reactivity.
You have an open water certificate. These can not be returned. Diving certificates are not regulated like driving liscences.However,there may be legal implications should the "not fit to dive" certificate came to light if an accident occurred.
On balance, I would recommend that you have a talk to your GP and be retested with mannitol after a course of prophylactic inhaled steroid +/- salbutamol.Should this resolve the issue (since the result was only a 17% reduction in FEV1/VC ratio and the cut off is 15%) and you still wish to dive you should consider this prior to any planned diving (commencing a couple of weeks prior).
Hope this helps,
Dr Susannah Sherlock
Hyperbaric Physician.
