A review of asthma and scuba diving

[Asthma and scuba diving: Creation and evaluation of a website (For doctors, asthmatics and diving instructors)]

INTRODUCTION

Scuba diving has long been strictly contraindicated for asthmatics; this contraindication has been questioned in recent years. Our objective was to provide a website, evaluated by its users, for doctors, diving instructors and asthmatics.

MATERIALS AND METHODS

Creation of the site Asthme-Plongee.com based on a peer-reviewed literature review, then distribution of a questionnaire in summer 2018 to diving clubs, general practitioner groups, pulmonologists and FFESSM federal offices, and via social networks.

RESULTS

Our sample consisted of 413 assessors, including 264 health professionals (63.9%), 74 asthmatics (17.9%) and 92 diving instructors (22.3%), spread over the entire territory of France. The structure of the website, the clarity of the information written and its relevance were generally appreciated by the entire population with a median score of 8/10. The site was found useful: 72.9% of respondents thought they would visit it later.

CONCLUSION

Faced with a growing number of amateur divers, it seems essential to raise awareness of current recommendations and good diving practices.

[Diving and asthma: Literature review]

INTRODUCTION

Scuba diving has long been contraindicated for asthmatics. Recommendations are evolving towards authorisation under certain conditions. Our objective was to review the literature on the risks associated with scuba diving among asthmatics and about recommendations on this subject.

MATERIALS AND METHODS

We used the MEDLINE and LiSSa databases, until June 2018, in French, English or Spanish language, with the keywords "asthma AND diving" and "asthme plongée" respectively. References to the first degree were analyzed.

RESULTS

We have included 65 articles. Risk of bronchospasm is well documented, particularly in cold and/or deep water, or in the event of exposure to allergens (compressor without filter). Nonasthmatic 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.

CONCLUSION

A diver's examination should include a triple assessment: asthma control, number of exacerbations and treatment compliance. Homogenizing the recommendations would improve the framework for the practice of diving among asthmatics and allow larger studies in this population. Communicating the current recommendations remains important to divers, dive instructors and doctors in the context of the development of scuba diving.

Short- and long-term effects of diving on pulmonary function

The diving environment provides a challenge to the lung, including exposure to high ambient pressure, altered gas characteristics and cardiovascular effects on the pulmonary circulation. Several factors associated with diving affect pulmonary function acutely and can potentially cause prolonged effects that may accumulate gradually with repeated diving exposure. Evidence from experimental deep dives and longitudinal studies suggests long-term adverse effects of diving on the lungs in commercial deep divers, such as the development of small airways disease and accelerated loss of lung function. In addition, there is an accumulating body of evidence that diving with self-contained underwater breathing apparatus (scuba) may not be associated with deleterious effects on pulmonary function. Although changes in pulmonary function after single scuba dives have been found to be associated with immersion, ambient cold temperatures and decompression stress, changes in lung function were small and suggest a low likelihood of clinical significance. Recent evidence points to no accelerated loss of lung function in military or recreational scuba divers over time. Thus, the impact of diving on pulmonary function largely depends on factors associated with the individual diving exposure. However, in susceptible subjects clinically relevant worsening of lung function may occur even after single shallow-water scuba dives.

Risk factors for dive injury: a survey study

Scuba diving is a world sport, but it is not medically regulated. Study objectives sought to identify risk behaviors, preexisting medical conditions, compliance to dive guidelines, and injury patterns of recreational scuba divers. An Internet-based survey examined risk behaviors and diver safety practices. Responses from 682 of 770 (88.6%) divers revealed that 80.6% were certified; 51.7% of certified divers reported diving injuries versus 75.0% for noncertified divers (RR = 1.31; 95% CI: 1.16-1.48; P < 0.001); suspected decompression symptoms were witnessed by 52.6% of divers; 32.7% of certified divers reported medical problems including hypertension, asthma, diabetes, and epilepsy. No significant differences were observed in injuries among the certified divers based on dive frequency (P = 1.000), medical conditions (P = 0.750), smoking (P = 0.545), alcohol (P = 0.649), or illicit substances use (P = 0.230). Among certified divers, there was a positive association with fewer diving injuries but not with diving frequency, preexisting medical condition(s), smoking, alcohol, or illicit substance use.

Asthma and the diver

Self-contained underwater breathing apparatus (scuba) diving has grown in popularity, with nearly 9 million sport divers in the United States alone. Approximately 7% of the population has been diagnosed with asthma, which is similar to the percentage of divers admitting they have asthma. Numerous concerns exist regarding subjects with asthma who choose to participate in recreational diving. Among these concerns are pulmonary barotrauma, pneumomediastinum, pneumothorax, arterial gas embolism, ear barotrauma, sinus barotrauma, and dental barotrauma. Despite these concerns, a paucity of information exists linking asthma to increased risk of diving complications. However, it has long been the norm to discourage individuals with asthma from participating in recreational scuba diving. This article examines the currently available literature to allow for a more informed decision regarding the possible risks associated with diving and asthma. It examines the underlying physiological principles associated with diving, including Henry's law and Boyle's law, to provide a more intimate understanding on physiological changes occurring in the respiratory system under compressive stress. Finally, this article offers a framework for guiding the patient with asthma who is interested in scuba diving. Under the right circumstances, the patient with asthma can safely participate in recreational diving without apparent increased risk of an asthma-related event.

Pulmonary function testing and extreme environments

Millions of people worldwide engage in leisure or occupational activities in extreme environments. These environments entail health risks even for normal subjects. The presence of lung disease, or other conditions, further predisposes to illness or injury. Patients who have lung conditions should, but often do not, consult with their pulmonary clinicians before traveling. Normal subjects, including elderly or deconditioned adults, may be referred to pulmonologists for evaluation of risk prior to exposure. Other patients may present for consultations after complications occur. Pulmonary function testing before or after exposure can assist physicians counseling patients about the likelihood of complications.

Breathing at Depth: Physiologic and Clinical Aspects of Diving while Breathing Compressed Gas

When diving, human beings are exposed to hazards that are unique to the hyperbaric underwater environment and the physical behavior of gases at higher ambient pressure. Hypercapnia, hyperoxia, carbon monoxide intoxication, inert gas (predominantly nitrogen) narcosis, and decompression illness all may lead to impaired consciousness, with a high risk of drowning in this non-respirable environment. Proper physiologic function and adaptation of the respiratory system are of the utmost importance to minimize the risks associated with compressed gas diving. This article provides an introduction to the diving techniques, the physics, and the pertinent human physiology and pathophysiology associated with this extreme environment. The causes of the major medical problems encountered in diving are described, with an emphasis on the underlying respiratory physiology.