The chronic respiratory disorder that affects asthmatics results in breathing difficulties (e.g. wheezing) in response to inflammation and narrowing of the bronchi (breathing tubes).
This guide explains why controlling the associated risks for asthma and scuba diving are relevant and important for determining whether someone with the condition is allowed to dive.
The exact cause will vary from one asthmatic to another. But, common triggers for attacks include:
It is fair to say that children and adults with asthma will find it difficult to breathe at certain times (e.g. during an attack).
But, people with severe asthma may be suffering with breathing problems for most of the time. Common asthma symptoms include:
During an actual attack, the symptoms may worsen for a short period of time. The deterioration may be sudden or it may be gradual (e.g. over several days). Severe asthma attacks often include:
Hence, it should be obvious why scuba diving health and safety guidelines exclude many divers with asthma (until the regulators accepted some recent changes).
New information released by the Diver Alert Network (DAN), U.S. Centers for Disease Control and Prevention, and the Asthma and Allergy Foundation of America shows:
Often, the outcome for a diver will be a reduction in exercise capacity. This adds to the existing reduced breathing capacity due to (both):
Moreover, a narrowing of the airways is also likely to trap gas inside the lungs during an ascent. It is crucial that any trapped gas does not expand faster than the diver can exhale it - albeit through narrowed airways.
If this happens, the resultant lung rupture may also cause an arterial gas embolism (AGE) or a pneumothorax (a collapsed lung).
Here's the important part:
There are two major concerns for asthmatics who want to scuba dive, being gas-trapping and a reduced capability of performing moderate exercise.
Most people will find it easy to stop and rest for a while to catch a breath on land. But, underwater divers may find this difficult to achieve. In fact, during diving activities and even on the surface, people with asthma will be at risk of:
Pro Tip: The South Pacific Underwater Medical Society (SPUMS) facilitates the study of underwater and hyperbaric medicine in Australia. They state that scuba diving may actually precipitate an asthma attack.
In fact, there are four (4) different categories of asthma. Doctors will base the treatment after making a diagnosis of which type you have.
Anyone diagnosed with this category should be experiencing the symptoms less than one time per week. Plus, the rate of airflow during exhalation should result in a less than 20% decrease of peak flow.
In fact, mild intermittent asthma sufferers should have only brief periods of exacerbation (increases in the severity of symptoms). The worsening should last no more than a few hours or for a few days.
Night time symptoms should occur less than twice per month. In addition, you should be asymptomatic and have 'normal' lung function between any acute attacks.
Note: Doctors prescribe albuterol or oral steroids (e.g. triamcinolone) to provide quick relief from bronchospasms when treating patients with mild intermittent asthma.
The peak flow should be close to normal, meaning the variation is less than 20%. But, asthmatic symptoms will be occurring more than one time per week. Patients will be experiencing a worsening in manifestation during sleep. It will be occurring more than two times per month.
Note: Standard treatment usually involves the use of short-acting bronchodilators for daytime use and long-acting bronchodilators for nocturnal use.
Generally, the symptoms will be more noticeable and they may also include bouts of coughing during exercise and at night. They may be occurring on a daily basis and interfering with normal sleeping patterns.
Note: Doctors usually prescribe daily medication (e.g. inhaled steroids) when treating patients diagnosed with the moderate persistent asthma category.
Patients diagnosed with this category of asthma will be experiencing continual symptoms. Plus, they may have less than 60% of normal peak flows.
Symptom worsening occurs on a regular basis, including at night. As a result, normal physical activity will become limited.
Note: Treatment includes oral steroids and long-acting bronchodilators. Patients may also be using short-acting bronchodilators to treat acute episodes.
The Undersea and Hyperbaric Medical Society (UHMS) is the primary source of scientific information for diving and hyperbaric medicine physiology worldwide.
Moreover, the medication used to treat asthma is also relevant for determining its severity and any associated risk for asthmatics in scuba diving.
Experts at UHMS suggest divers with "controlled" mild intermittent asthma, mild persistent asthma, or moderate persistent asthma, may take part in scuba diving activities.
The goal is to have the treatment regimen return pulmonary function test results back to normal, particularly after exercising.
In this case, patients with asthma may be able to scuba dive with relative safety. Thus, divers with asthma need to perform the strenuous exercises required in diving.
Any diver with a respiratory disorder should be aware that different countries will have 'conflicting' guidelines as to whether they allow people with asthma to dive.
For example, the United Kingdom allows people to scuba dive if their condition is under control and:
In contrast, Australia is one of the most conservative countries with regard to the Health and Safety Guidelines in Scuba.
As such, all divers need to pass a spirometer test (pulmonary function testing). The purpose is to rule out asthma prior to getting a scuba diver certification.
Pro Tip: Always keep the inhaler with you and be prepared to use it on a dive boat. It is also prudent to alert the dive operator about your use of an inhaler and how it may complicate your involvement and activities.
As a dive operator, it is reasonable to expect that divers with asthma will be under the care of a physician. As such, the doctor will be able to provide vital information about their condition, that it is under control, and there are no known complications.