It was the oddest hangover Alex had ever had. He really didn’t think he had drunk that much, but he felt weird all night. Now, on his early-morning flight home after four days of diving in Mexico, things just kept getting worse. He drank as much water as he could and took acetaminophen, but nothing helped. And he still had two hours to go.

THE DIVER

Alex was a 25-year-old male diver in good health who exercised regularly and didn’t smoke. He had no known medical conditions. Certified when he was 20 years old, he typically made seven or eight dives a year while on vacation. He held advanced open water and enriched-air certifications.

THE DIVE

Alex and three college buddies were on a dive trip to Mexico. They enjoyed the warm water, drift diving and abundant sea life, and returned to the same resort each year. They also enjoyed the nightlife there. The group made seven dives in four days. On the first three days, Alex made six dives using a nitrox mix to a maximum depth of 90 feet of seawater. On the fourth day, he switched to air and dived to 85 feet for approximately 35 minutes, with a brief safety stop at 15 feet. That was the last dive of the trip.

THE ACCIDENT

After their last dive, Alex and his buddies met for lunch and started drinking. By late that afternoon, he felt achy—especially in his joints. He also noticed an unusual tingling in his left arm. The next morning Alex still felt the joint pain. He tried stretching and flexing, but the pain didn’t seem to change, regardless of the position he was in.

Alex had a flight to catch, so he finished packing and headed to the airport with his friends. Alex flew halfway home and then stayed the night with one of his buddies before catching a flight the next morning to get the rest of the way home.

While they traveled, Alex began to suspect the problem was related to his diving, but he didn’t say anything. When he got home he researched the symptoms online and called for a referral to a physician trained in diving medicine.

He was fortunate to live close to a hospital with a hyperbaric chamber. The physician treated him with U.S. Navy Recompression Treatment Table 5 in a monoplace chamber. Alex had complete resolution of his symptoms halfway through the two-and-a-half-hour treatment.

ANALYSIS

Decompression illness (DCI) is the blanket term for diving-related maladies. It includes arterial gas embolism (AGE) and decompression sickness (DCS). DCS can be further broken down into Type 1 and Type 2. Type 1 is the milder form of DCS, with mostly musculoskeletal symptoms ( joint pains) and skin symptoms like numbness, tingling and skin bends— that’s blotchy-looking skin that resembles a rash. Type 2 is more serious and presents as neurological symptoms, from paralysis to incontinence to death.

Every dive carries with it some level of risk of DCI—even when you follow the dive tables or your dive computer and make a safety stop on every dive. There is no obvious mistake in the way Alex and his friends dived. Four healthy young men did essentially the same dives using the same breathing gases, and only one had a problem. Diving in the Caribbean, where the air is warm and humid, can cause you to become dehydrated. Drinking alcohol after the dives can contribute to that as well. Dehydration is generally thought to predispose divers to decompression illness. It is likely that Alex’s body wasn’t functioning at 100 per- cent efficiency because of the alcohol, lack of sleep and general dehydration. The lessons to be learned have less to do with the dives themselves than Alex’s response to the symptoms.

Typically, DCI symptoms appear within a few hours, although it is possible they can be delayed as much as 24 hours.

Alex made a morning dive, and by late afternoon he first noticed the unusual symptoms. That is six to seven hours after the dive. The problem was, he didn’t report his symptoms. Had he told the dive staff that he was feeling unusual sensations they would have gotten him to breathe 100 percent oxygen and then taken him to a diving physician, who likely would have treated him on the spot.

The second problem was boarding a plane. And then, a day later, he took another flight. Typically, commercial airliners pressurize the cabin to the equivalent of about 8,000 feet. That’s low enough that no one passes out from lack of oxygen, but it’s still not the same as being pressurized to sea level.

For a diver with a nitrogen gas load, or who is already exhibiting symptoms, that only makes matters worse. There is less ambient pressure on the diver, causing even more nitrogen to come out of his body tissues, creating more or larger gas bubbles.

The guidelines for flying after diving are to wait at least 12 hours after a single no-decompression dive or 18 hours after multiple dives or dives over multiple days. Most divers expand this to 24 hours for an extra safety margin.

Divers should not fly with untreated symptoms, and should fly only when the diving physician clears them after treatment. The delay could have made it harder for the diving physician to treat his injuries and left Alex with residual symptoms for much longer. In this case, the symptoms were mild and the treatment was successful, no doubt aided by Alex’s age and general health. Not everyone will be that lucky.

LESSONS FOR LIFE

Symptoms of DCI: The sooner you recognize symptoms and report them, the better the chance for a positive treatment outcome.

Surface oxygen: Learn how to administer oxygen first aid in a diving accident and have 100 percent oxygen available wherever you are diving.

Flying after diving: Never fly with symptoms of DCI.

12 HOURS

For a single no-decompression dive, Divers Alert Network recommends a surface interval of at least 12 hours before flying.

18 HOURS

For multiple dives in one day, or multiple days of diving, DAN suggests a minimum surface interval of 18 hours before flying.

18+ HOURS

For decompression dives, DAN states there's insufficient evidence, but waiting far longer than 18 hours is suggested. The longer the better.

Read More Lessons for Life