DEAR DR. DONOHUE: My husband is an experienced scuba diver, and he is taking me on a scuba-diving vacation. In preparation for it I am taking scuba lessons. In the last lesson, the instructor rambled on and on about the lung damage that comes from improper breathing during a dive. I didn’t understand him and would appreciate if you would explain the problem. Thank you. – C.T.

ANSWER: I take it the topic was pulmonary barotraumas – lung damage that comes from the increased pressure in water.

On land, where there is 1 atmosphere of pressure, the normal lung capacity is 6 liters (6 quarts) of air. Upon diving into water, the pressure on the body and the lungs increases as the depth of the dive increases. At a depth of 33 feet (10 m), the pressure is twice that of the atmospheric pressure on land. The pressure compresses air in the lungs. Their volume is reduced to half (3 liters) their normal volume. At 100 feet (30 m), the water pressure is four times that of land pressure, and the air in the lungs is compressed to a volume of 1.5 liters.

If a diver takes a deep breath from the scuba tank, holds his or her breath and rises to surface, the compressed air in the lungs expands as the water pressure drops. Sudden expansion of the air can rupture alveoli – the lung air sacs – and cause big trouble.

This is a most important aspect of scuba diving, and you must understand it well. Have your husband or your instructor go over the matter until you have no doubts about it and about how to breathe properly.

The same concept applies to trauma to the eardrum upon diving and rising, so understanding the subject will help you prevent eardrum injury.

DEAR DR. DONOHUE: Running gives me blisters. How are they best handled? – R.M.

ANSWER: Blisters are best handled by not getting them.

They result when layers of skin are dragged across one another. Friction and moisture foster them. Keeping your feet dry is essential for blister prevention. Acrylic socks wick moisture away from the feet and maintain dryness. The friction part is something you have to grapple with on your own. Most of the time, friction comes from shoes that don’t fit or are too rigid. You can fashion moleskin cushions and place them on the parts of the feet that are blister-prone. You would also benefit by investing in a new pair of shoes that absorb the shock of feet striking ground and are flexible.

In treating a blister, try to keep its roof intact so it can act as a natural bandage. Puncture it with a sterile needle to drain the fluid. If it’s in a spot where it’s bound to be rubbed, cover it with a dressing such as DuoDerm. Otherwise, you can leave it exposed.

DEAR DR. DONOHUE: I happened to see my heels in a mirror. There is a black line across both of them. What is this? – H.J.

ANSWER: That goes by the name of “black heel.” If you prefer a more elegant name, use “talon noir,” French for “black heel.”

It happens in sports where there are a lot of starts and stops. Tennis is a good example. Those quick starts and stops bang the heel against the shoe and break tiny blood vessels beneath the skin surface. The broken vessels leave black deposits.

No treatment is needed. The lines disappear in time.

This can also happen on the palms of people who play racket sports or who lift weights.

DEAR DR. DONOHUE: My dad says that the best exercise for strong stomach muscles is to have someone throw a medicine ball against them. Do you agree? – D.K.

ANSWER: No, I don’t agree.

With all respect to your dad, that’s an excellent way to damage abdominal organs. It doesn’t encourage muscle growth.

DEAR DR. DONOHUE: Three years ago I was diagnosed with zoster herpes-2. I have your pamphlets on these infections, but I cannot match my symptoms with the ones you give. I never had blisters or rash of any kind. My only symptom is a mild burning pain at the end of my penis. It does not burn when I urinate.

Shortly before developing this problem, I met my sister-in-law in a store and she kissed me. (My wife, now dead, had been in a nursing home for four years, and I have had no intimacy since she entered the home.)

Do you have answers for me? – F.M.

ANSWER: There’s a bit of confusion that needs clearing up. Herpes zoster is shingles, an outbreak of painful blisters on the skin. It’s caused by activation of the chickenpox virus that lives in the body for life after a chickenpox infection. You do not have herpes zoster.

Herpes simplex-2 is the virus that causes the sexually transmitted genital infection. It produces an outbreak of tiny, often painful blisters in the genital region. The blisters might merge to form a sore. The herpes simplex virus is another virus that stays with people until death. You don’t sound to me like you have or ever had a herpes simplex-2 infection.

The kiss from your sister-in-law has no bearing on what you have. It definitely has no bearing on herpes simplex-2 or herpes zoster (shingles).

I can say with a high level of confidence what you don’t have, but I cannot say with an equal level of confidence what you do have.

You’re not going to make any headway with me guessing. You need to see your doctor.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.

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