ASTHMA AND SCUBA DIVING
Section snippets
THE PHYSICS AND PHYSIOLOGY OF DIVING
When a scuba diver descends in the water, the ambient pressure increases because of the weight of the water. In accordance with Boyle's Law, pressure and volume are inversely related at a constant temperature. As the diver descends, the surrounding ambient pressure increases and volume decreases. A volume of gas at the surface (1 atmosphere absolute = 1 ATA) will be compressed to half of its volume at 10 m of sea water (2 ATA). On ascent, surrounding pressure decreases and volume increases. A
RISKS OF DIVING FOR THE ASTHMATIC PATIENT
Lung structure and function in asthma are reviewed elsewhere.29, 39 One of the major concerns of asthmatic patients diving is the susceptibility to pulmonary barotrauma and AGE, even during a normal ascent. The risks for asthmatic individuals include (1) airway obstruction and (2) reduced exercise capacity.
As described previously, airway obstruction, airway closure, and gas trapping caused by asthma and other pulmonary diseases can precipitate pulmonary barotrauma during ascent. Liebow et al22
Prevalence of Asthmatic Individuals in the Diving Population
There are estimated to be between 2.5 and 3 million sport scuba divers in the United States.24 In analyzing dive accident statistics, the diving community has been criticized because asthmatic individuals have not been “allowed to dive.” Therefore, they are not represented in the accident data. We know, however, that asthmatic individuals are diving. Several studies have shown the general prevalence of asthmatic patients in the diving population is approximately 5% to 8%, which is similar to
INTERNATIONAL RECOMMENDATION FOR DIVING AND ASTHMA
As asthmatic individuals appear to be diving without an increase in accidents compared with nonasthmatic divers, the question now becomes which asthmatic patients can dive with a reasonable degree of safety? Three diving medical societies recently have published statements regarding asthmatic individuals and scuba diving.
EVALUATION OF THE ASTHMATIC PATIENT FOR DIVING
Asthma is a condition in which obstruction to the airways is variable. There is a large degree of heterogeneity among asthmatic patients, and the factors that precipitate attacks vary tremendously. Some asthmatic patients demonstrate normal pulmonary function tests (PFTs) between attacks whereas others show evidence of airway obstruction despite being asymptomatic. Currently, there are no data on the effects of diving on airway mechanics in asthmatic patients. Which test will best determine the
OUR RECOMMENDATIONS
We recommend the following:
- 1
Individuals with a past history of asthma but who are asymptomatic, on no medications, and who have normal PFTs (flow rates and static lung volumes) can be considered for diving. (Normal is defined as within 2 standard deviations of the mean.)
- 2
Individuals with current asthma who are well-controlled on medications (including inhaled steroids and β agonists), have well-defined triggers, and who have normal PFTs can be considered for diving. An appropriate exercise
SUMMARY
Asthma is no longer an absolute contraindication to diving. Individuals with normal airway function appear to be at low risk for idiopathic PBT. Proper screening with pulmonary function and exercise testing appear to be able to screen out those asthmatic patients who should not dive while identifying those who can be considered for diving. It is hoped that this change in perception will encourage more asthmatic individuals to seek medical advice prior to diving rather than not admit they have
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Cited by (10)
Diving and asthma: Literature review
2018, Revue de Pneumologie CliniqueClearance to Dive and Fitness for Work
2008, Physiology and Medicine of Hyperbaric Oxygen TherapyGas Embolism: Venous and Arterial Gas Embolism
2008, Physiology and Medicine of Hyperbaric Oxygen TherapyPulmonary function testing and extreme environments
2005, Clinics in Chest MedicineThe use of pulmonary function testing in piloting, air travel, mountain climbing, and diving
2001, Clinics in Chest MedicineCitation Excerpt :In addition, accidental aspiration of hypotonic fresh water or hypertonic sea water through the glottis into the tracheobronchial tree could trigger laryngospasm or bronchospasm in susceptible persons. Aerosolized sea water also has been proposed as a risk of diving97 because of the known potency of nebulized hypertonic saline to induce bronchospasm.79,80 Emotional stress also can trigger bronchial constriction in some patients.
Diving after sars-cov-2 (Covid-19) infection: Fitness to dive assessment and medical guidance
2020, Diving and Hyperbaric Medicine
Address reprint requests to Karen B. Van Hoesen, MD, Department of Emergency Medicine, UCSD Medical Center, San Diego, CA 92103–8676