University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• For patients who have a history of asthma, are there any objective study or other means to differentiate those patients who should be excluded from participating in recreational scuba diving from those who may participate.

Clinical Bottom Lines

1. Study does not answer who is safe to dive.
2. Study does not answer my question directly.
3. Study is small in number and power.
4. Study was not prospective for ethical reasons.
5. Study could have had comparison with disease-free divers as an additional control group. 

Summary of Key Evidence

1. A total of 30 patients: 15 patients sequentially selected from an undersea medical clinic, who suffered from Pulmonary Barotrauma, were compared with 15 patients, sequentially selected from the clinic, who suffered from decompression illness type II, (no Pulmonary Barotrauma).
2. Comparison of the two groups revealed significant difference in pre-injury PFT's, with the Pulmonary Barotrauma group having decreased MEF 25% to 75%.
3. Comparison of the two groups shows that 2 members of the PBT group suffered from asthma.
4. Participation should be made by the individuals, with emphasis on risk reduction by strictly following the recreational diving guides and eliminating all other risk factors.

Additional Comments

• Biological Mechanism
  • Compressed air with regulator adjusts pressure for increasing depth pressure of diver.
    
  • Gas pressure increased 1 atmosphere q 10 meters.
    
  • Boyles Law: Volume vs. Pressure.
    
  • Dissolved nitrogen and helium at higher pressures.
    
  • Decompression sickness: Type I results in direct Pulmonary Barotrauma as a result of expanding gas that is trapped, Type II results in micro air embolism that cause infarction.
    
• Cost: Number needed to treat un-quantifiable by the study.  However PFTs are relatively inexpensive.  Decompression illness Type I is a very serious disease and is costly to treat in a hyperbaric chamber and may have long term effects.

Citation

1. Bove A. Pulmonary Barotrauma in divers: Can prospective pulmonary function testing identify those at risk?  Chest, 1997; 112(3):567-578.
2. Elliott DE.  Are asthmatics fit to dive?  Workshop, Undersea and Hyperbaric Medical Society, 1996, Kensington, MD.

CAT Author: Michael G. Anderson, MD

CAT Appraisers: <Reviewers>, MD

Date appraised: March 13, 2000