Should Asthmatics Not Scuba Dive?
by Lawrence Martin, M.D.
drlarry437@gmail.com
This question is commonly asked in the diving community. Not surprisingly, there is no simple answer. In this chapter I will present background information on the question and offer some general recommendations. The final answer in all cases should rest with an informed patient, the patient’s physician and, for open water students, the scuba instructor.
Asthma is probably the most controversial medical condition affecting recreational divers. An estimated 10% to 15% of children have some history of recurrent wheezing, and an estimated 5% to 8% of adults are diagnosed as “asthmatic.” Added to these statistics are an estimated 3 million certified scuba divers in the U.S., with several hundred thousand newly certified every year, and it is no surprise that many current and would-be divers have some history of asthma.
Asthma is a disease of the airways. Patients prone to asthma can develop intermittent attacks of cough, wheezing, chest tightness, and/or shortness of breath. These symptoms are due to narrowing of the air tubes (bronchi) within the lungs. One major cause of the narrowing is excess mucous in the airways. Because symptoms occur episodically, and often unpredictably, there is no way to know when someone with an asthma history will have an “asthma attack.”
https://www.pedilung.com/pediatric-lung-diseases-disorders/diving-medicine/
Figure 1. Asthma can lead to narrowing of the bronchial or air tubes within the lungs. This narrowing may prevent exhalation of air on ascent and lead to barotrauma or arterial gas embolism. See Section F for discussion of these conditions.
A scuba diver breathes compressed air under water, so they must have unobstructed flow of air throughout both lungs in order to equalize air pressures. Unequal air pressures are the cause of all barotrauma, including ear and sinus squeeze, and air embolism. Since asthmatics may develop air flow obstruction in the lungs at any time, the question of when, if ever, asthmatics may safely dive is problematic. For reasons which I will discuss, there are many opinions and no uniform agreement. Quotes in the following table, taken from the medical literature, reflect this variety of opinion. Note that recommendations range from “never” to “not with a history of asthma over the previous five years” to “no diving within two days of wheezing.”
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Some recommendations and opinions from the medical literature about asthma and scuba diving
1970s — 1980s
“A history of bronchial asthma is disqualifying if there have been any attacks within 2 years, if medication is needed for control, or if bronchospasm has ever been associated with exertion or inhalation of cold air.” (Strauss 1979)
“Never — Once an asthmatic, always an asthmatic” (Linaweaver 1982)
“Absolute contraindications: [Asthma] attacks within the past 2 yr. Medication is required to prevent or treat episodes of dyspnea. Effort or cold induced asthma.” (Hickey 1984)
“Any patient with currently active bronchial asthma should be strictly forbidden to dive. Any patient with a history of childhood asthma, symptoms suggestive of asthma within the past year, suspicion of exercise or cold air induced asthma should be referred to a pulmonary medicine specialist for evaluation to include challenge testing.” (Davis 1986)
“No diving by individuals… who have had clinically significant bronchospasm within the last five years, whether or not they take medications and irrespective of the precipitating event.” (Neuman 1987)
“Divers using bronchodilators are disqualified. The bronchodilator itself leads to increased risk of arrhythmias.” (Millington 1988)
“Well-controlled, mild asthmatics should be allowed to dive during remissions, but be particularly advised about the risks of rapid ascent.” (Denison 1988)
1990s
“All individuals who have current active asthma are advised not to dive. Any individual who seems to have outgrown his asthma and has not had any bronchospasm, wheezing, or chest tightness and has not used any bronchodilator recently may be a candidate for diving if a complete battery of PFTs are normal.” (Neuman 1990)
“Never — Childhood asthma never goes away and continues to be a hazard to divers, even if apparently arrested and asymptomatic in adulthood.” (Greer 1990)
“…not to dive within 48 hours of wheezing is safe [reasonable].” (Farrell 1990)
“If the person ever has had bronchospasm associated with exercise or inhalation of cold air, diving is contraindicated.” (Harrison 1991)
“In principle, diving is absolutely contraindicated in those with air-trapping pulmonary lesions or bronchial asthma.” (Melamed 1992)
“…a conservative recommendation is that any asthmatic with frequent flare ups or continuous need for medication to control symptoms, should refrain from diving. Conversely, an adult who has “grown out” of asthma, or has been symptomatic for some time …with normal lung function, may participate in recreational diving. In all instances, of course, the potential risks should be explained to the diver.” (Martin 1992)
Not with: “History of asthma over the last 5 years, use of bronchodilators over the last 5 years, respiratory rhonchi or other abnormalities on auscultation.” (Edmonds 1992)
“Intending divers with a past history of asthma and asthma symptoms within the previous five years should be advised not to dive.” (Jenkins 1993)
“The recommendation that an asthmatic patient not dive should be determined by the history and severity of the disease.” (Neuman 1994)
2000s
“Bronchial hyper-responsiveness [is] a contraindication to scuba diving because it may promote pulmonary barotrauma.” (Badier 2000)
“Subjects with asthma should be advised not to dive if they have wheeze precipitated by exercise, cold, or emotion. Subjects with asthma may be permitted to dive if, with or without regular inhaled anti-inflammatory agents…they: are free of asthma symptoms; have normal spirometry (FEV1 >80% predicted and FEV1/VC ratio >70% predicted); and have a negative exercise test” (BTS Guidelines, 2003)
“There is some indication that asthmatics may be at increased risk of pulmonary barotrauma, but more research is necessary. Decisions regarding diving participation among asthmatics must be made on an individual basis involving the patient through informed, shared decision making.” (Koehle 2003)
“Although there is some indication that asthmatics may be at an increased risk of pulmonary barotrauma, the risk seems to be small. Thus, under the right circumstances, patients with asthma can safely participate in recreational diving without any apparent increased risk of an asthma-related event. Decisions on whether or not diving is hazardous must be made on an individual basis and be founded upon an informed decision shared by both patient and physician.” (Sade 2007)
“It has been agreed by the UKDMC that carefully selected asthmatics can probably safely scuba dive. These asthmatics have to demonstrate acceptable lung function on their normal medication, which can be optimised to achieve this. We accept the use of inhaled steroids, long acting beta 2 agonists & leukotriene antagonists. Patients should be managed in accordance with the accepted guidelines in their country of origin.” (UKDMC 2014)
“As a general overview, DAN statistics show that several divers with asthma have died. It is unclear, though, from examination of their accident reports whether asthma was actually the cause of death or merely an unrelated finding. Data from the British Sub Aqua Club (BSAC) indicate that few divers die with asthma or as a result of asthma.” (Dear 2014)
“…use of real world experience, registry data and surveys are the only means to gain insight into the risk incurred by diving with asthma or a history of asthma. To date, this approach has not identified an increased risk for divers with asthma or a history of asthma…Most sport divers limit dive depths to 130 feet (39.6 m), and avoid stressful environments…In advising any diver, prudence is always a key word to ensure the diver understands that avoidance of stressful diving should always be a first consideration.” (Adir 2016)
“Risk of bronchospasm is well documented, particularly in cold and/or deep water, or in the event of exposure to allergens (compressor without filter). Non-asthmatic atopic divers may be at greater risk of developing bronchial hyper-reactivity. Although the theoretical risk exists, epidemiological studies do not seem to show an over-risk of barotrauma, decompression sickness or arterial gas embolism in asthmatics. French, British, American, Spanish and Australian societies agreed on the exclusion of patients with moderate to severe persistent asthma, FEV1<80%, active asthma in the last 48hours, exercise/cold asthma and poor physical fitness.” (Muller 2018)
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WHY IS THERE A WIDE RANGE OF RECOMMENDATIONS ON ASTHMA AND DIVING?
There are three basic explanations, summarized below and then discussed in the following pages.
1. Asthma is a condition with a wide range of both frequency and severity of symptoms, such as wheeze and chest congestion. When used without precise definition or description, the term “asthma” may mean different things to different people.
2. Despite sound theoretical objections as to why asthmatics should not dive, there is no solid evidence that scuba-divers with a history of asthma have an increased accident rate.
3. There are differences in philosophy among physicians and scuba professionals about personal risk-taking.
1. Asthma is a condition with a wide range of frequency and severity of symptoms.
Some authors have recommended that anyone “with asthma” not go scuba diving. However, such a broad prohibition flies in the face of reality, since it includes a large group of people with a history of asthma who, in fact, dive often and without any problem.
On the other hand, any asthmatic who is constantly wheezing and coughing should obviously not go scuba diving. So, where should the line be drawn between remote history of asthma and active disease? It seems that most experts would draw the line at some arbitrary point, usually denoted by patient symptoms and need for medication (see quotes in table above). However, none of the guidelines for deciding who should not dive is established by any studies of which I am aware; they are all “best guess” recommendations that seem to make sense to the authors. Just realize that there are no hard data to support or refute any of the specific recommendations.
If there is a line to draw somewhere, and I believe there is, it should be based on individual evaluation as opposed to something as arbitrary as “5 years” or “2 days” without symptoms, or some specific test result. In contrast to many earlier blanket recommendations, the importance of individual assessment is becoming increasingly recognized; see quotes from 2000s.
To demonstrate variability of the label “asthma,” I have made up 10 different scenarios for “Joe,” a hypothetical 30-year-old man with a “history of asthma.”
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10 SCENARIOS FOR JOE, A 30-YEAR-OLD MAN WITH A “HISTORY OF ASTHMA,” RANKED FROM LEAST (1) TO MOST SEVERE (10)
1. Had asthma as child, grew out of it at age 12, no symptoms or trouble since. No symptoms when exercising.
2. Had asthma as child. No problems except very rarely, with heavy exertion, such as running in cold weather, he has noted a slight cough and shortness of breath. The last time for this symptom was about five years ago, and in the past it has always gone away without bronchodilator treatment.
3. No asthma as child. Three years ago he had to use an asthma inhaler. Occasionally feels “chest congestion” with a cold, but it always abates without any specific treatment. Last need for asthma medication was five years ago.
4. No asthma as a child. About once a year, with a cold, he has a little wheezing. Uses an asthma inhaler for a day or two at most, then recovers and feels fine. Exercises regularly with no difficulty.
5. No asthma as a child. About once a year gets a mild attack, and takes medication for a few days, including both prednisone tablets and an asthma inhaler. Between attacks he feels well.
6. Had asthma as a child. Grew out of it at age 10, then at age 25 asthma recurred. Now carries an asthma inhaler (albuterol) and uses it about once or twice a month. In the past five years he has had two bad asthma attacks, both requiring a week of steroid medication.
7. No asthma until age 22. Now uses a steroid inhaler regularly, but feels well controlled except for occasional exacerbations that also require oral prednisone. Lung function is normal when tested between attacks.
8. Uses prednisone tablets and an inhaler to control asthma symptoms. Doctor adjusts prednisone dose, sometimes to as low as only 5 mg a day, other times as high as 40 mg a day. Lung function is mildly abnormal when tested between attacks.
9. Has been hospitalized about once a year for past five years for a severe asthma attack. Has breathing machine (nebulizer) at home for inhalation of bronchodilator, which he requires regularly. Lung function shows modest impairment when tested between attacks.
10. Hospitalized several times a year for asthma. Lung function always abnormal when tested.
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Now, Joe signs up for a certification course, at which point he is asked to fill out a medical questionnaire. Below is a section of the PADI questionnaire relating to history of asthma and other lung conditions.
Joe checks the first condition, “Asthma, or wheezing with breathing, or wheezing with exercise.” Understandably, he is then asked to get a “medical clearance to dive.”
The consensus among dive medicine physicians would probably be to say “yes” to scenarios 1–3 (he may dive), and a clear “no” to scenarios 8–10 (he may not dive). Nos. 4–7 are problematic; most likely the percentage of diving physicians saying “no” would increase as we go from number 4 to 7. The worse the asthma, in terms of need for medication, symptoms, or degree of air flow obstruction, the riskier the diving (at least physicians perceive it this way). There can be no rule about diving that fits all asthmatics, except for the no-brainer that if you never dive you’ll never have a diving accident. Ultimately the dividing “line” for diving vs. no diving should be based on an evaluation of the individual, and not on any arbitrary and unproven criteria.
Of course, if Joe wanted to avoid a medical evaluation, he could just omit checking off asthma on the questionnaire. No doubt some (?many) asthmatics do this, knowing full well they will be referred for medical clearance if they check a history of asthma. Omitting the history is of course not recommended, for obvious reasons, not least of which is the other part of the PADI questionnaire, which states:
The information I have provided about my medical history is accurate to the best of my knowledge. I agree to accept responsibility for omissions regarding my failure to disclose any existing or past health condition.
2. Air trapping can lead to fatal air embolism, yet many asthmatics do dive, and without any definite evidence for increased accident rate.
The major theoretical concern is an increased risk of air embolism. This can occur if an area of the lungs traps air under water. It is possible that mucous in the airways may allow air to pass by as the diver descends, but then trap the air on ascent. On ascent the trapped air will expand and could rupture the lungs, putting air bubbles into the circulation. The result can be a non-fatal or fatal stroke. Other theoretical asthma-related problems, all of which may lead to drowning, include:
- the possibility of asthma exacerbation from physical exertion, inhalation of hypertonic saline (seawater), or from breathing dry, compressed air (Edmunds 1991);
- pollen contamination of the air tank that may exacerbate allergic asthma (Coop 2016);
- increased work of breathing, due to increased air density at depth;
- increased risk of heart rhythm disturbance in people using a bronchodilator (the most common type of asthma medication);
- bronchodilator-induced dilation of blood vessels in the lungs may allow venous bubbles to enter the arterial circulation as gas emboli (Edmunds 1992, Jenkins 1993);
- increased risk to diving companions if the asthmatic gets into trouble.
Despite all these theoretical objections, many asthmatics do dive, and without mishap. Information in this area is based mainly on surveys of active divers and retrospective compilation of accident data. A comprehensive review published in 2003 found 15 studies identified as relevant to the area of diving and asthma. Three were surveys of divers with asthma, four were case series, and eight were investigations of the effect of diving on lung function (Koehle, et. al., 2003). The review showed:
“…a high prevalence of asthma among recreational SCUBA divers, similar to the prevalence of asthma among the general population. There was some weak evidence for an increase in rates of decompression illness among dives with asthma. In healthy participants, wet hyperbaric chamber and open-water diving led to a decreased in forced vital capacity, forced expired volume over 1.0 second and mid-expiratory flow rates. In participants with asymptomatic respiratory atopy (allergy), diving caused a decrease in airway conductivity. There is some indication that asthmatics may be at increased risk of pulmonary barotauma… Decisions regarding diving participation among asthmatics must be made on an individual basis involving the patient through informed, shared decision making.”
Another review of the issue, also published in 2003, by the British Thoracic Society, included an algorithm for medical evaluation. Included in the BTS summary recommendation:
“Subjects with asthma should be advised not to dive if they have wheeze precipitated by exercise, cold, or emotion. Subjects with asthma may be permitted to dive if, with or without regular inhaled anti-inflammatory agents…they: are free of asthma symptoms; have normal spirometry (FEV-1 >80% predicted and FEV-1/VC ratio >70% predicted); and have a negative exercise test.” (BTS Guidelines, 2003)
Spirometry is a basic pulmonary function test that can done in about half an hour and is available in all acute care hospitals and many outpatient clinics. The graphic below shows a subject having a spirometry test. He takes in a deep breath, blows out as hard and fast as possible, then inhales deeply. Often the maneuver is repeated several times to get the best effort. The results are shown in graphic form on the screen, and are quantified by values such as FEV-1 and FVC. FEV-1 is a measure of how much air you can blow out in 1 second (Forced Expiratory Volume). FEV-1/VC is a ratio of the FEV-1 over the Vital Capacity, the total amount of air you can blow out after a maximal inhalation.
https://www.shutterstock.com/search/spirometry
Figure 2: Subject undergoing test of spirometry
Spirometry and exercise testing, if normal, can help assure normal lung function when tested. But it’s never been shown that this testing, expensive to the individual (if not covered by insurance) and time consuming (has to be scheduled, results reviewed by physician, etc.) is any better than just a history of symptoms and medication usage. Or, that a slightly abnormal spirometry puts the diver at greater risk than a normal test result. This is not a criticism of testing-based recommendations, just a reminder that we don’t have studies to prove the predictability of these guidelines.
Another set of guidelines came out of the UK, from the Diving Medical Commission.
“It has been agreed by the UKDMC that carefully selected asthmatics can probably safely scuba dive. These asthmatics have to demonstrate acceptable lung function on their normal medication, which can be optimised to achieve this. We accept the use of inhaled steroids, long acting beta 2 agonists & leukotriene antagonists. Patients should be managed in accordance with the accepted guidelines in their country of origin.” (UKDMC 2014)
Note the difference between UKDMC and the BTS recommendations. The former just asks for “acceptable lung function,” and doesn’t require an exercise test.
Divers Alert Network (DAN) weighed in on the subject in 2014, noting:
“…One consistent theme from all the medical agencies involved was the lack of good information about asthma and diving…The best source to help you decide on the issue of diving and asthma for yourself is your physician.” (Dear 2014)
A 2016 review of the subject, in the European Respiratory Review, came to the following conclusion:
“While there is a strong theoretical risk of a serious complication from diving with asthma, real world experience has shown that adverse events related to asthma and diving are rare. Because is it highly unlikely that a randomised clinical trial could be conducted to answer this question, use of real world experience, registry data and surveys are the only means to gain insight into the risk incurred by diving with asthma or a history of asthma. To date, this approach has not identified an increased risk for divers with asthma or a history of asthma…Most sport divers limit dive depths to 130 feet (39.6 m), and avoid stressful environments…In advising any diver, prudence is always a key word to ensure the diver understands that avoidance of stressful diving should always be a first consideration. This approach to divers with asthma or a history of asthma should minimise any adverse events related to diving with asthma. In general, the effects of the various changes induced by asthma are minimal in usual sport diving exposure, in spite of the strong theoretical risk derived from physiological studies, which are usually carried out at high workloads.”
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Divers Alert Network (DAN) keeps records on recreational scuba diving deaths worldwide, using information reported to it, and records of the United States Coast Guard and local law enforcement agencies. Below is a table of data extracted from DAN’s last 3 comprehensive reports on deaths from recreational scuba diving (DAN Annual Reports, 2016, 2017 and 2018).
2016 DAN Report: 146 deaths for 2014, 69 investigated, 1 with mention of “asthma”
2017 DAN Report: 127 deaths for 2015, 67 investigated, 1 with mention of “asthma”
2018 DAN Report: 169 deaths for 2016, 94 investigated, none with mention of “asthma.”
For the years 2014–2016, DAN recorded 442 deaths. DAN actively investigates all recreational scuba diving deaths that occur in the US or Canada, or involve US or Canadian citizens overseas; this number totaled 229 for the three years.
For the year 2014, the 2016 DAN Report mentions asthma in the medical history of one deceased diver, but there was no mention of how that diver died (DAN 2016, p. 12).
For 2015, the 2017 DAN Report mentions asthma for only one diver, a 51-year-old man who died from rapid gas depletion followed by repaid ascent. The previous day, while doing a checkout dive, he had reported “asthma issues” (DAN 2017, p. 14). It is not stated if underlying asthma played a role in this diver’s demise. Certainly, in retrospect, having “asthma issues” on a checkout dive suggests he was not ready to continue with an open water dive.
For the year 2016, the 2018 DAN Report does not mention asthma in any of the fatalities.
DAN makes clear in these reports that the medical history of many of the divers was lacking, so it is possible that asthma was a factor in other deaths. Still, it seems to be much less of a problem than other pre-existing conditions noted more frequently in the DAN reports, including hypertension, diabetes, and heart disease,
In addition to pre-existing medical conditions as noted above, other causative factors were morbid obesity, diver error (e.g., cave diving with insufficient air to return), unexpected environment (e.g., strong and unforeseen currents), and equipment malfunction. Whatever the reasons, some deaths among the millions of scuba divers is an accepted reality. No one seeks to ban the sport because of these deaths, only to make it safer for all participants.
So there you have it. You can review decades of articles and a mountain of statistics, but still come away without an easy answer to the question, Should asthmatics not scuba dive? The risks are known, but there is no solid evidence that they impact the vast majority of divers “with asthma.” In the end, the decision should be up to the individual in consultation with his or her physician.
3. Differing opinions may be based on differences in personal philosophy.
This is the third explanation for varying opinion about asthma and scuba diving. I mentioned this reason in discussing the 10 asthma scenarios for Joe, our hypothetical diver “with asthma.” For scenarios in the middle group (4–7), the difference between saying “yes” and “no” to scuba diving may be attributable to philosophical differences over “taking risks.”
Recreational scuba diving is an inherently risky activity for anyone. Physicians believe that any condition characterized as “asthma” might well add some extra measure to the sport’s inherent risk. But how much extra risk? No one knows, of course. Surely the answer must largely depend on the vagaries of a particular diver’s asthma. But even if some precise measurement of extra risk were known, there is no agreement over what would constitute unacceptable additional risk for scuba diving.
We know active asthma, where the airways are unstable, can be dangerous. The problem is the broad brush often applied to divers “with asthma.” Even if we had good statistics of deaths or accidents in people with a history of asthma, that wouldn’t answer the question. Instead, there would likely be more questions about the statistics. For example, Why did these particular divers get into trouble, and not all the other asthmatics who also dive? Was their asthma worse? Their dive profiles more extreme? Was there some pattern of behavior that could be identified and perhaps changed?’
Interpretation of statistics can be subjective, so even as more studies accumulate the issue will likely remain unsettled and argued. At the 1995 meeting of the Undersea and Hyperbaric Medical Society, two eminent dive medicine physicians took opposite sides of the debate, “Should asthmatics not dive?” Both physicians knew all the literature to that point, and had experience treating dive accident victims. With similar knowledge and backgrounds the two physicians eloquently argued two different ways.
Future debates might focus on the methodology of the studies or the validity of the statistics, but the real argument is likely to be over something more subtle: philosophical differences in personal risk taking. Simply put, any given study on the subject may be interpreted in different ways, depending on inherent biases. As a result, for people with mild and non-limiting asthma, the answer to the question “Should asthmatics not dive?” might largely depend on who you ask.
WHAT ARE SPECIFIC RECOMMENDATIONS?
My recommendations are presented here for the recreational scuba diver and would-be diver. These recommendations, based on both the theoretical risk of arterial gas embolism and the information at hand, are not to be construed as specific for any given individual. If you have asthma, consider your situation unique to you; consult with your physician.
“ACTIVE” ASTHMA
There are many ways to classify asthma, and the 10 scenarios listed for the 30-year-old man shows the wide spectrum for the condition. The latest “official classification” for patients with active asthma categorizes them as “mild intermittent,” “mild persistent,” moderate persistent,” and “severe persistent.” I mention these categories because you’re apt to come across them if you read on the subject, but in clinical practice most patients are not labeled this way. Symptoms can vary from week to week, and month to month, and what may be mild one week can become severe another week, etc.
If asthma is “active,” requiring daily or frequent medication to control symptoms I would advise against diving altogether. This is particularly true for any prednisone-dependent asthmatic. Prednisone is a corticosteroid in pill form, widely used to treat asthma symptoms. Prednisone-dependent asthma suggests a significant degree of symptoms and/or impairment, and should probably disqualify for diving.
On the other hand, an asthmatic who is well-controlled on an inhaled steroid (e.g., beclomethasone, flunisolide, triamcinolone) is likely using the drug not to treat symptoms but to prevent them, and may be able to dive safely.
I would also classify as “active” any asthmatic with a demonstrably abnormal: lung function test (spirometry); physical examination (wheezing); or chest x-ray. “Demonstrably abnormal” means there is no doubt as to the abnormality. This is an important qualification because sometimes changes are noted on tests which don’t really reflect any significant abnormality, but instead only a normal variation. If there is any doubt or question about an abnormality, the patient should be referred to a specialist familiar with the question about asthma and diving.
For anyone classified as having “active asthma” the theoretical risks seem too great for what amounts to a purely recreational activity. Although some asthmatics do use a bronchodilator inhaler just before a dive (Lin 1987, Farrell 1990, Corson 1992) this practice is certainly not recommended by physicians. Thus there is an admitted paradox. “Active” asthmatics do engage in a theoretically risky recreational activity without apparent mishap, but physicians (myself included) are not willing to condone it. Nor are we willing to provide sanction for “active” asthmatics to begin scuba diving as a new activity.
At some point it must be acknowledged that diving is different from swimming or jogging; any asthma exacerbation under water could lead to panic and drowning. I would advise people in this group to go snorkeling instead, or take up some other water sport such as swimming, sailing or windsurfing.
“CHILDHOOD-ONLY” ASTHMA
If someone had childhood asthma, and as an adult has had no asthma symptoms or required asthma medication, and is otherwise in good physical condition, there should be no medical restriction to scuba diving. I would not require an examination for people in this group, but if one is done it should reveal no wheezing. A breathing test and chest x-ray, if done, should be normal. While this recommendation for childhood-only asthma appears to reflect a consensus among diving-trained physicians it should be pointed out that some experts, at least in the past, felt even remote asthma poses an unacceptable risk for diving-related barotrauma (Linaweaver 1982, Greer 1990).
“INACTIVE” ASTHMA
The person in between the “childhood only” and “active asthma” groups presents the most difficult problem: the asthmatic who wheezes infrequently, or uses a bronchodilator or steroid medication occasionally, or who feels normal and well-controlled with routine inhaled medication (i.e., not for treatment of acute symptoms). This might include the asthmatic with exercise-induced asthma who has learned to prevent symptoms with inhalation medication. On theoretical grounds, this person should probably not take up scuba diving, although there are no compelling data to support this position. Patients with inactive asthma who wish to dive should have a physical exam, chest x-ray and a test of vital capacity (spirometry). As explained above, these tests should show no demonstrable abnormality.
Some physicians recommend specialized pulmonary function tests, including exercise tests and something called “inhalation challenge” or “bronchoprovocation test,” which involves inhaling an asthma-provoking drug in the pulmonary function lab, such as carbachol or mannitol. (Badier 2000; Ustrup 2019). Only people susceptible to asthma attacks react to the inhaled drugs; the rest of the population does not. The idea with both exercise and bronchoprovocation testing is to induce a potential asthmatic to have an attack under stressful or abnormal conditions; if an attack occurs under stressful conditions in the lab, diving would then be considered too risky an activity.
That is the theory, but I don’t believe these asthma-provoking tests are particularly useful for answering the question about diving. Simulation of what may happen in the water cannot be had by exercising someone on a treadmill or having them inhale a noxious agent in the lab. There are no studies showing that these “stress” tests are any more useful in answering the asthma question than are the basic tools available to all doctors: a test of vital capacity (spirometry), a careful history and a good physical examination. (Still, since the issue is unsettled either way, some doctors may choose to rely upon exercise and inhalation tests to reach a decision.)
WHAT IS THE INFORMED CONSENT APPROACH?
For the inactive asthmatic who wishes to take up scuba diving, I recommend an “informed consent” approach. He or she should receive an explanation of the theoretical risks. I have already explained that many people with “inactive asthma” do dive, but that doesn’t mean it is safe. The would-be diver needs to understand that air flow obstruction might increase the risk of barotrauma, and that stressful conditions (cold water, strenuous activity) could trigger an asthma exacerbation. Particularly, the potential diver should understand that open water conditions are very different from the swimming pool (where scuba training initially takes place), and may lead to problems not encountered in the more benign pool environment (Martindale 1990).
Ultimately, the decision should be left up to the individual. How is this done? After the risks are explained, he or she must re-affirm their wish to dive. Then, if a note is required by the training agency, the examining physician should not sign or offer any statement that diving “is safe” for the individual, but instead write a brief note summarizing the patient’s condition. The note should state that the patient’s asthma history is not a prohibition to diving and that the potential diver understands the risks. Diving is inherently a risky activity anyway, so this type of informed consent makes sense. As example only, I offer the type of note shown below.
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TO: XYZ SCUBA TRAINING AGENCY
I have examined patient John/Jane Doe on June 15, 20 — . He/she has a history of inactive asthma, and requires no medication to treat symptoms. His/her lung exam, chest x-ray and breathing test (spirometry) are normal. I see no reason why he/she cannot engage in scuba diving. We have discussed the risks inherent to all scuba divers. He/she understands that any tendency to an asthma attack on or under the water might increase those risks, particularly for fatal air embolism.
He/she has chosen to continue with dive training, and I see no medical reason to prohibit him/her from scuba diving at this time.
[Signed, Dr. — — — — — -]
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It is important to emphasize that the physician should never approve an asthmatic for “shallow water diving only.” Barotrauma is actually more apt to occur closer to the surface than in deeper water. This is because the greatest pressure changes occur near the surface. From 33 feet depth to the surface, ambient pressure decreases 100%, whereas from 66 to 33 feet the pressure decreases only 50%.
If a note is not required for the training agency, the patient might still be asked to sign such a statement to keep in the medical file. This will indicate that the physician and the patient discussed the issues, and that an informed decision was made by the patient.
Some people have criticized this approach, on the grounds that individuals referred to a doctor deserve a medical decision on whether they should or should not dive. One doctor stated, “Either you are going to take responsibility for the situation or you are not. To try and leave the decision up to the individual or agency is not only inappropriate but not serving the patient very well.”
I believe the “either-or” criticism reflects an outdated, paternalistic attitude, one that the practice of medicine has moved away from over the years. In fact, if a patient with inactive or childhood-only asthma is clueless as to the risks, seems unable to accept his or her own responsibility for diving, and has a “You’re-the-doctor-tell-me-what-to-do” attitude, I would not be able to write the kind of letter shown above. Such a patient would simply not receive my sanction for scuba diving.
In summary, a patient with inactive asthma, who wishes to scuba dive, should be approached with an open mind. The theoretical risks should be explained. A physical exam, detailed medical history, and perhaps a chest x-ray and simple test of lung function (spirometry) may be all that are needed to reach a reasonable assessment; the exam and basic tests should be normal.
I realize the safest approach (for doctor and patient) might be to “just say no.” However, such a dogmatic response might lead some people to seek a more favorable second opinion, or to file a new medical questionnaire with a different dive shop and omit the asthma history.
WHAT ABOUT MEDICO-LEGAL CONCERNS?
Underlying any evaluation for diving fitness is concern about legal liability. The agency and scuba instructor are wary of being sued if one of their trainees has a mishap. The trainee signs a waiver, but pieces of paper don’t always eliminate the possibility of lawsuit.
Doctors, of course, are always concerned about malpractice suits and protect themselves with malpractice insurance. But nobody wants to be sued; it is painful even when you are insured and have done nothing wrong. Doctors win about 80% of all malpractice cases that come to trial, but each “won” case still leaves a trail of stress, lost work time, and a demoralized feeling.
Even when a doctor is named in a lawsuit from which he or she is eventually dropped (50 out of every 100 initial claims are dropped with no further action), the whole process takes from one to three years and costs thousands of dollars. Until the suit is dropped against the doctor, he or she must report the existence and nature of the lawsuit on every professional application, such as for hospital staff privileges, renewal of existing privileges, licensure renewal, etc. For the sloppy lawyer who files a meritless lawsuit, there is no penalty.
Understandably, some doctors figure it is not worth “taking a chance” on a lawsuit by passing judgment on a patient for scuba diving. Other doctors feel that “just saying no” is the safest route, since that stance surely eliminates any legal risk. This is unfortunate, because the risk in most cases should be with an informed diver, not with the training agency or the doctor.
Surely, if the training agency lies to the trainee, or the doctor gives false assurances, that might be actionable. Such is rarely, if ever, the case. Agencies are explicit in explaining to trainees the potential hazards of scuba diving, and all trainees sign informed consent waivers of one sort or another. Physicians certainly have nothing to gain monetarily or otherwise by inducing someone to dive.
This is not to say that concern about liability is misplaced. Even if the doctor does his or her best to fully inform about the risks, an accident is an accident, and an enterprising lawyer will look for someone to blame (except the diver, of course). So medico-legal concerns are real and something we all have to live with. For the doctor, there are three options: stay out of the arena altogether; say “no” without performing a thorough evaluation; or evaluate and fully inform the patient about the potential risks (preferably in a face to face meeting, with clear documentation about the communication). For the potential diver, I believe there is only one option: become fully informed about the risks of diving, not dive when ill or unfit, and strive to make every dive as safe as possible.
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