title: The effect of scuba diving on airflow obstruction in divers with asthma.
abstract: BACKGROUND
  People with asthma are an under-represented group amongst scuba divers. Many may avoid or are advised against diving due to the potential risks, including bronchoconstriction, pulmonary barotrauma and arterial gas embolism. The aim of this study was to establish whether divers with asthma were more likely to experience reversible airways obstruction following typical scuba diving than divers without asthma.
  
  
  METHODS
  All divers with a history of asthma attending Operation Wallacea in Honduras were identified and peak expiratory flow rates (PEF) were measured pre and immediately post dive. All dives were boat dives in tropical sea water. Scuba dives were defined as those lasting between 40 and 55 minutes to a depth of between 10 and 18 metres. Of the 356 divers attending, 22 were identified as having asthma, of whom 19 were suitable for testing. They were classified by treatment regimen: five on no treatment, 11 on salbutamol only and three on regular preventative treatment. Twenty-four divers without a history of asthma acted as a control group.
  
  
  RESULTS
  Open-water scuba diving caused a small decrease in PEF in all populations (median decrease 4.4%, P < 0.001). Percentage decrease in PEF was significantly more in divers with asthma on regular preventative medication than in the control group (mean 9.3%, median decrease 6% vs. mean 3.1%, median 4.3% P = 0.039).
  
  
  CONCLUSIONS
  These findings support the view that asthmatics are more susceptible to airway changes following scuba diving. Differences to previous studies are likely due to environmental conditions, including dive depth.
authors.affiliation: Department of Medicine, Bishop Auckland Hospital, Durham, DL14 6AD, UK, E-mail: christopher.lawrence2@nhs.net.
authors.forename: Christopher H D
authors.initials: CH
authors.lastname: Lawrence
authors.affiliation: Department of Radiology, Newcastle Hospitals NHS Trust, Newcastle, UK.
authors.forename: Isobel Y D
authors.initials: IY
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000402:Airway Obstruction / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D016022:Case-Control Studies; D004242:Diving / Q000009:adverse effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010366:Peak Expiratory Flow Rate; D012623:Seawater; D013997:Time Factors; D055815:Young Adult
chemical_list: D018927:Anti-Asthmatic Agents
keywords: Lung function; diving research; respiratory