>A: This issue has long prompted very spirited discussion among experts but very little consensus. The data available clearly support the use of surface oxygen for symptomatic individuals, but there is little to no data relevant to asymptomatic divers, and in our experience at DAN, there is no "one-size-fits-all" solution for the innumerable scenarios and events that can occur. Obviously, in-water recompression is not recommended as a viable plan outside of the military/commercial operations theater.
>DAN encourages each dive operator, scientific group or organization to work with local medical authorities to develop their own specific policies. There are problems and advantages to either approach. Based on our experience at DAN, neither the "wait and see" approach nor the "prophylactic oxygen" approach has been verified to alter any outcome. DAN is available for consultation through the Medical Information Line to any group or organization that wants to develop a policy. In an emergency, we can also provide you with contact information for local dive medicine experts. Our medical staff is always on call for emergencies to answer case-specific questions via the DAN Emergency Hotline: +1-919-684-9111. Please note: +1-919-684-9111 is for emergencies only. All other calls must go through the information line, +1-919-684-2948.
— Marty McCafferty, EMT-P, DMT-A
DAN medical information specialist
>A: Getting into a hot tub immediately after diving does alter decompression stress. As with many factors, the net response can be positive or negative, depending on the magnitude of the inert gas load and the heat stress. The hot tub or hot shower will warm the extremities and enhance peripheral circulation which might facilitate inert gas washout (or inert gas elimination).
>Large inert gas loads, however, can be problematic. Since the solubility of gas is inversely related to temperature, tissues will hold less in solution as they warm. Warming tissue with significant gas loads can promote bubble formation. Since the warming of the superficial tissues precedes the increase in blood flow, such bubbles can pose problems before the increased circulation can remove them.
>There is no simple formula to compute what constitutes a minor, significant or substantial peripheral inert gas load. The actual conditions vary as a function of the individual, thermal protection, physical activity and dive profile.
>My approach is to stack as many factors as possible in my favor to compensate for the Murphy effect we frequently see in decompression sickness. I encourage a simple rule of thumb: delayed gratification. Enjoy the thought of the hot tub or shower for a while instead of jumping in immediately. An interval of 15 to 30 minutes should help you avoid some of the risk, as will keeping more conservative dive profiles. Another compromise would be to employ a lower temperature in the hot tub or shower.
—Neal Pollock, Ph.D.>Q: On a recent dive trip, my husband had problems clearing his ears, and by the second day he complained of muffled hearing, a constant buzzing sound and trouble with his balance. We stopped diving, waited an appropriate surface interval and flew home to see an ear, nose and throat specialist. The doctor found excess mucus behind my husband's eardrum; it had hardened and turned black. He made an incision, removed the mucus and expressed amazement that my husband had experienced no problem flying. Can you tell me what happened and if my husband can dive again?
>A: These symptoms are consistent with middle-ear barotrauma, which is associated with the inability to equalize the middle-ear air space when diving. This is usually due to variable degrees of Eustachian tube dysfunction and most commonly caused by a problem like a recent cold, allergies or any type of irritation, which inflames the mucous membranes and causes swelling and mucus discharge.
>The pain, muffled hearing, buzzing sounds and difficulty with balance can all be caused by pressure and in this case appear to be from a fluid buildup in the middle-ear air space. The constant pressure exerted by the fluid on the inner ear is what produced your husband's symptoms. It seems the barotrauma was also sufficient to cause bleeding into the middle ear; this is why the mucus turned black. Bleeding indicates a fairly serious injury, so your husband was fortunate that he didn't rupture his eardrum or one of the internal membranes of the ear, which could result in decreased or a permanent loss of hearing.
>The small incision in the eardrum, or myringotomy, was necessary to drain the ear of excess mucus and provide an opening to ambient air, which can help dry out the middle ear. If the ear was full of blood and other tissue fluids during the flight, an increase in symptoms would not have necessarily occurred, since the lower pressure in the aircraft cabin would have been transmitted through the fluid-filled middle-ear chamber.
>Only time will tell if your husband can return to diving. Depending on the severity of the injury, your husband should wait at least six months and then return to his physician for a complete examination, including a hearing test (return sooner if there are infections or hearing or balance problems). If the specialist determines there is no permanent damage to your husband's Eustachian tubes or structures of the middle ear, chances are he can dive again.
>If your husband is cleared to resume diving by his physician, it's important to take steps to prevent this injury from happening again. The safest approach to preventing middle-ear or sinus barotrauma is to avoid any discomfort in these air spaces. Equalize before you feel pressure. If you feel pain, damage has already occurred. Be sure to make slow, steady descents, and equalize early and often as you go. If you cannot clear your ears, it's best to sit out the dive and not risk another injury.
—Joel Dovenbarger, BSN>Q: While diving about two months ago, I scraped my forearm against coral. Other than the initial cut and bleeding, I haven't experienced any significant pain. It wasn't fire coral, so I've had no burning or itching, and the swelling lasted only about 10 days. It still gets red once in a while, and I have some discoloration of my skin in that area. Is there anything I can do to speed the healing or to help return my skin to its normal color?
>A: Whenever you brush against coral, its outermost layer of fine sand-like grains will invade skin tissue where the surface has been broken. Unless you vigorously cleanse the area with soap and water to remove these tiny particles, they become embedded beneath the top layer of your skin. Because the sand-like granules are foreign bodies, it is possible that your body may work them out of your skin as small surface eruptions, possibly causing infection, redness and a rash. Your body's defenses will encapsulate the material, and eventually the discoloration should fade. So in answer to your question, there's probably nothing you can do to expedite healing; it is simply a matter of time.
—Joel Dovenbarger, BSN>Q: Is it safe to dive while breast-feeding an infant?
>A: Yes, it is safe. A mother's breast milk is not adversely affected by diving, and there is no risk of decompression sickness for the infant. Although nitrogen accumulates in all of the tissues and fluids of the mother's body, washout of inert gas occurs quickly after a safe dive. Insignificant amounts of nitrogen may be present in the mother's breast milk, but it is inert and poses no risk to the infant. However, because of the possible risk of bacterial growth on the skin under a suit, careful cleansing of the breast after diving and before feeding may help prevent systemic illness.
—Maida Taylor, MD MPH FACOG