I appreciate that this question has been asked and answered numerous times over the many iterations of this board. However, those threads often were incomplete, fragmented and lacking in research references. Plus, the topic hasn't been updated here in a quite a while. The following is an endeavor to do so. It's is an updated version of a piece that appeared in my "Dive Workshop" column in Rodale's Scuba Diving
"Can I Dive With Asthma?
Asthma is a chronic but often largely controllable obstructive pulmonary disease that affects about eight to 10 percent of children and five to eight percent of adults in the U.S. Signs and symptoms include shortness of breath, wheezing, tightness in the chest and lasting cough. The potential adverse impact of a severe attack under water is obvious, and could be fatal. Arterial gas embolism (AGE) as a result of air trapping from the constriction and plugging characteristic of this disease has also been a frequent, but as yet inconclusive, concern. However, while much yet needs to be explored, there is recent research (e.g., 1, 2 & 3 below) supporting the position that divers with asthma can under certain circumstances dive without undue risk of precipitating an asthmatic event or pulmonary barotrauma.
Asthma is a chronic irritation and hypersensitivity of the respiratory tract, and attacks can be triggered as a reaction to a variety of conditions including stress, cold or exercise, and allergens such certain medications, pollens and foods. The asthmatic’s body reacts to these triggers, in varying order and severity, by constriction of smooth muscle in the bronchi and bronchioles, inflammation of the airway and increased mucous production. Attacks tend to be recurrent rather than continuous, and there is often much that can be done medically to reverse breathing difficulties when they do occur. In addition, since many of the precipitants of an attack are known, they can be avoided or controlled.
Diving with Asthma
Until the mid-1990s, asthma was largely considered an absolute contraindication to diving. However, thinking in the medical and professional dive community has rather radically altered since then, and those with asthma can now be certified under certain circumstances. Although they differ somewhat, the YMCA (YScuba’s diving program closed back in mid-2008, but essentially the same program is now offered by Scuba Educators International (SEI Diving), British Sub Aqua Club (BASC) and Undersea and Hyperbaric Medicine Society (UHMS) each offer protocols guiding medical clearance to dive with asthma.
For example, the YMCA criteria included a requirement that all asthmatics have normal resting and exercise pulmonary function tests with no degradation after exercise. The criteria allow those taking routine preventative medications to be evaluated while continuing their treatment. Also required is the ability to exercise and tolerate stress without becoming symptomatic while on maintenance medications, and the absence of a need for “rescue” inhalers during times of stress or exertion.
If you suffer from asthma, it’s clearly unwise to deny or minimize this condition to yourself, or hide it from your instructor or the operators with whom you dive. Scuba can involve some of the asthma triggers discussed above, such as cold and exercise, not mention hyperdry scuba cylinder gas. If you have asthma and want to dive, or are already diving without medical clearance, it is critical that you consult a physician to obtain an appropriate pulmonary workup and permission to dive.
Finally, the issue of being a reliable dive partner must be considered. A diver with asthma should always inform his buddy of his medical status."
(1) Sports Med. 2003;33(2):109-16.
Asthma and recreational SCUBA diving: a systematic review.
Koehle M, Lloyd-Smith R, McKenzie D, Taunton J.
Allan McGavin Sports Medicine Centre, Department of Family Practice and the School of Human Kinetics, University of British Columbia, Vancouver, British Columbia, Canada. email@example.com
Asthma has traditionally been a contraindication to recreational self-contained underwater breathing apparatus (SCUBA) diving, although large numbers of patients with asthma partake in diving. The purpose of this paper is to review all the research relevant to the issue of the safety of asthma in divers. MEDLINE and MDConsult were searched for papers between 1980-2002. Keywords used for the search were 'asthma', 'SCUBA' and 'diving'. Additional references were reviewed from the bibliographies of received articles. A total of fifteen studies were identified as relevant to the area. These included three surveys of divers with asthma, four case series and eight mechanistic investigations of the effect of diving on pulmonary function. The survey data 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 divers with asthma. In healthy participants, wet hyperbaric chamber and open-water diving led to a decrease in forced vital capacity, forced expired volume over 1.0 second and mid-expiratory flow rates. In participants with asymptomatic respiratory atopy, diving caused a decrease in airway conductivity. 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.
2. “Int J Sports Med. 2005 Sep;26(7):607-10.
Demographics and respiratory illness prevalence of sport scuba divers.
Tetzlaff K, Muth CM.
Medical Clinic and Polyclinic, Department of Sports Medicine, University of Tubingen, Germany. Kay.Tetzlaff@bc.boehringer-ingelheim.com
This study aimed to establish epidemiological data on diving habits and outcome of subjects with respiratory diseases who are considered at increased risk for diving injuries. We conducted a cross-sectional demographics and prevalence study by distribution of an anonymous questionnaire with an issue of a widespread sport diving magazine. The questionnaire was designed to obtain medical and diving history data with an emphasis on respiratory diseases and complaints. The investigational population comprised sport scuba divers of any age and gender from Austria, Germany, and Switzerland. Two hundred and twenty-six male and 96 female divers sent completed questionnaires. Of the respondents 8.7 % indicated that they currently have asthma. Two thirds of asthmatics complained about regular dyspnoea. However, only 42.4 % used drugs relieving or controlling their symptoms regularly and 27.3 % used them in a prophylactic manner before diving. Five percent and 4.7 % of all divers reported a history of respiratory disease other than asthma or dyspnoea respectively. The divers with respiratory illness or complaints had logged a total of 17,386 dives. There were no cases of serious diving injuries. Despite the well-known limitations of postal surveys assessing self reported data, this study indicates that there is a population of subjects diving uneventfully with respiratory diseases that are considered medical contraindications to diving. These subjects deserve particular guidance on related risks and disease management.
3. Harefuah. 2007 Apr;146(4):286-90, 317.
Asthma and scuba diving: can asthmatic patients dive?
Department of Medicine 'T', Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel. firstname.lastname@example.org
Self-contained underwater breathing apparatus (scuba) diving has grown in popularity, with millions of divers enjoying the sport worldwide. This activity presents unique physical and physiological challenges to the respiratory system, raising numerous concerns about individuals with asthma who choose to dive. Asthma had traditionally been a contraindication to recreational diving, although this caveat has been ignored by large numbers of such patients. Herein we review the currently available literature to provide evidence-based evaluation of the risks associated with diving that are posed to asthmatics. 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."
This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.