How Safe to Fly After Diving? At Last, Some Empirical Evidence

The study of data collected in DAN Europe's Diving Safety Laboratory (DSL) "Flying bubbles" project was concluded in 2013 and merited publication in Aviation Space and Environmental Medicine, in addition to Alert Diver EU in 2015.

For the first time empirical research was used to study what happens to divers when flying after diving. And the results are somewhat surprising.

To avoid DCS brought on by cabin depressurization, there have long been recommendations for a suitable surface interval before traveling by air, but these have been based solely on theory.

For commercial and military divers, the recommended wait times before boarding a commercial plane have varied from 2 to 24 hours. For sport divers, it's been a fixed interval of 24 or 48 hours, depending on whether it was after a single dive, a series of repetitive dives, or a decompression-stop dive.

Dr. Danilo Cialoni and Massimo Pieri of the DAN Diving Safety Laboratory team administered cardiac echo tests to divers during a flight after a dive trip. They involved DAN Europe Research, in particular Prof. Alessandro Marroni and Prof. Costantino Balestra. Airline safety rules were a challenge, and the cooperation of the airline was fundamental in getting electromagnetic interference certification in order to do the cardio echo tests in flight.

The research subjects flew between Milan (Italy) and the Maldives. The methodology involved several control phases, including tests during the outbound flight and after each dive during a week's dive trip. The subjects were divided into three categories: those who did not develop bubbles, those who occasionally developed bubbles, and those "bubble-prone" divers who developed bubbles after every dive.

Before departure from Male's airport, the researchers conducted more tests, and even more during the return flight to Milan, when they monitored all the divers by cardiac echo and Doppler tests in 30, 60 and 90-minute intervals after the aircraft reached cruising altitude.

The results indicated that some divers are more 'bubble-prone' than others. The majority of divers developed no bubbles during the return flight after a 24-hour interval between diving and flying. But, some did. The highest bubble levels were seen 30 minutes after reaching cruising altitude. For safety, these divers would need a longer surface interval before flying or even the preventative measure of breathing normobaric oxygen before flying.

So what does the study's outcome mean for divers? Prof. Marroni said, "We are headed straight toward a future where the individual component can influence the mathematic model, placing greater emphasis on the practical application of research in diving safety." In other words, the day may come when our dive computers can be programmed with data reflecting our own individual body processes.

But until then, there are no means by which an individual diver can determine how bubble-prone he might be without subjecting himself to the same rigorous test regime, which is impossible. So, for the time being, add a few more hours to your time between surfacing from the sea and lifting off into the atmosphere.

(Source: Diving and Hyperbaric Medicine. 2015 March;45(1):10-15)