For Some Divers, Waiting Only 24 Hours before Flying Is Not Enough Time

Minhaj Qidwai from Frisco, TX, had gone diving while on a Bali vacation in May but failed to follow the standard rule about allowing 24 hours before flying. It was during the second, 13-hour leg of the flight, from South Korea to Dallas, when the symptoms of decompression illness (DCI) began to set in.

"My joints started hurting," Qidwai says. "My elbows, my knees -- everything started aching." He ended up crumpled on the floor at the Dallas-Fort Worth airport (DFW) before being diagnosed and rushed to the hyperbaric center. Fortunately, he made a successful recovery after five hours of recompression.

A few days later, another case of the bends caused a ruckus at DFW when a Denver-bound airplane had to make an emergency landing because diver Mike Altoos was experiencing DCI symptoms. Altoos, 26, was returning from a honeymoon in Cancun, but, as he told CBS Dallas/Fort Worth, "we were only about 20 minutes into the flight when my hands started tingling. I felt nauseous, dizzy, and had trouble breathing. I told the flight attendant, 'I need oxygen right away.'"

Altoos said he had made only three shallow dives, all between 15 and 30 feet deep, and took a 19-hour surface interval before getting on the plane. That he suffered DCI after such benign dives throws into disarray the famous research done by John S. Haldane in 1905, on which decompression theory is still based. Haldane found the body can withstand the pressure at 33 feet almost indefinitely without ill effect -- but he did his empirical research on goats at approximately sea level.

Another possibility is that Altoos suffered from an embolism or emphysema due to a fast breath-holding ascent, which caused air bubbles that then expanded in the reduced pressure of the aircraft cabin. Some on social media hypothesize that he might have misread a rented computer with depth-gauge calibrated in meters rather than feet and gone three times deeper than he believed.

DCI symptoms can be wide-ranging, from fatigue, skin rash, and joint aches to numbness and even complete paralysis. Unusual symptoms occurring within 48 hours after diving should be presumed to be DCI until proven otherwise. The onset of symptoms after 48 hours is unusual, unless an ascent to altitude provokes it. The pressure differences between being at depth and being at the 8,000-foot-altitude equivalent of a pressurized cabin can definitely exacerbate symptoms.

Qidwai and Altoos are not alone in underestimating the effects of flying after diving. Divers Alert Network recommends a minimum of 24 hours between your last dive and a flight. But Marguerite St. Leger-Dowse, a researcher at Diving Diseases Research Healthcare in Plymouth, England, wanted to answer this question: Is a 24-hour interval between diving and flying enough for the consecutive multi-dive diving days that many people typically do on a dive trip? So she and her colleagues conducted a study on the frequency and nature of symptoms in divers who had flown after consecutive multidive days.

Through an anonymous online survey, St. Leger- Dowse's team collected data including diver and diving demographics; signs and symptoms of DCI before, during, and after the flight home; details of the person's last two dives, and the length of his or her surface interval before diving. The 316 divers, with a male-female ratio of 69/31 percent and an age range from 17 to 75, recorded a total of 4,356 dives in the weeks preceding their flights. Fifty-four, or 17 percent of them, reported surface intervals of less than 24 hours.

Fifteen of the divers boarded their planes despite feeling DCI-related symptoms beforehand. Another 18 developed DCI-related symptoms -- nine of them during the flight, nine of them afterward. Of those 18 divers, 14 had waited more than 24 hours before flying. And of the 33 total divers who experienced symptoms before, during or after their flights, 11 subsequently sought help and were diagnosed and treated for DCI.

The divers' written comments in the online survey revealed a "lack of understanding of the consequences of altered pressure and gas environments during flight" by divers who had just finished an intense period of consecutive multi-dive days. St. Leger-Dowse's conclusion: Waiting only 24 hours after your last dive to fly home may not be enough time for some divers, particularly in the context of consecutive, multi-dive, multi-day diving.

The problem, of course, is that you don't know whether that applies to you until it's too late. So next time you make one of those types of dive trips, consider adding at least a day, even two, of sightseeing or relaxing on the ground before you board the plane home. Besides having some enjoyment, you'll have a decreased risk of experiencing DCS on that hours-long flight.

-- John Bantin