title: Flying after diving: should recommendations be reviewed? In-flight echocardiographic study in bubble-prone and bubble-resistant divers.
abstract: BACKGROUND
  Inert gas accumulated after multiple recreational dives can generate tissue supersaturation and bubble formation when ambient pressure decreases. We hypothesized that this could happen even if divers respected the currently recommended 24-hour pre-flight surface interval (PFSI).
  
  
  METHODS
  We performed transthoracic echocardiography (TTE) on a group of 56 healthy scuba divers (39 male, 17 female) as follows: first echo--during the outgoing flight, no recent dives; second echo--before boarding the return flight, after a multiday diving week in the tropics and a 24-hour PFSI; third echo--during the return flight at 30, 60 and 90 minutes after take-off. TTE was also done after every dive during the week's diving. Divers were divided into three groups according to their 'bubble-proneness': non-bubblers, occasional bubblers and consistent bubblers.
  
  
  RESULTS
  During the diving, 23 subjects never developed bubbles, 17 only occasionally and 16 subjects produced bubbles every day and after every dive. Bubbles on the return flight were observed in eight of the 56 divers (all from the 'bubblers' group). Two subjects who had the highest bubble scores during the diving were advised not to make the last dive (increasing their PFSI to approximately 36 hours), and did not demonstrate bubbles on the return flight.
  
  
  CONCLUSIONS
  Even though a 24-hour PFSI is recommended on the basis of clinical trials showing a low risk of decompression sickness (DCS), the presence of venous gas bubbles in-flight in eight of 56 divers leads us to suspect that in real-life situations DCS risk after such a PFSI is not zero.
authors.affiliation: DAN Europe Research Division, Contrada Padune 11, 64026 Roseto degli, Abruzzi (TE), Italy, Phone: +39(0)85-893-0333, Fax: +39-(0)85-893-0050, E-mail: dcialoni@daneurope.org.
authors.forename: Danilo
authors.initials: D
authors.lastname: Cialoni
authors.affiliation: DAN Europe Research Division, Roseto degli Abruzzi, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Pieri
authors.affiliation: DAN Europe Research Division, Roseto degli Abruzzi, Italy, Environmental, Occupational and Ageing Physiology Lab, Haute Ecole Paul Henri Spaak, Brussels, Belgium.
authors.forename: Costantino
authors.initials: C
authors.lastname: Balestra
authors.affiliation: DAN Europe Research Division, Roseto degli Abruzzi, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Marroni
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D003665:Decompression Sickness / Q000000981:diagnostic imaging / Q000209:etiology*; D004242:Diving / Q000009:adverse effects* / Q000502:physiology; D004452:Echocardiography / Q000379:methods; D004574:Electromagnetic Fields; D005260:Female; D019983:Guideline Adherence; D017408:Guidelines as Topic; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D018570:Risk Assessment; D013997:Time Factors
keywords: Doppler; altitude; bubbles; echocardiography; flying (and diving); recreational diving; remote locations; travel