Is there a new way to perform CPR?

DEAR DOCTOR K: I thought CPR involved chest compressions, breathing into a person's mouth and checking their pulse. But my daughter told me that the "new" CPR involves only chest compressions. Is this correct?

DEAR READER: That's right. Since 2008, the American Heart Association has recommended "hands only" cardiopulmonary resuscitation (CPR) if an adult suddenly collapses. Cardiac arrest is usually to blame when someone collapses and stops breathing. It occurs when the heart's electrical system malfunctions. The heart beats rapidly and chaotically -- or stops beating altogether. The person stops breathing and becomes unresponsive.

Can an alkaline diet help prevent cancer?

DEAR DOCTOR K: I've heard that an alkaline diet can help prevent cancer. Is this true?

DEAR READER: I wish it were, but it's not. So-called alkaline diets do not fend off cancer. That's because it's nearly impossible to change your body's pH by changing what you eat. Let me back up for a minute. Every day our bodies perform any number of intricate balancing acts. One of them is to make sure the body's fluids, tissues and cells don't get too acidic or, at the other extreme, too alkaline. As you may remember from high school chemistry, acidity and alkalinity are measured as pH.

Is there a nutritional difference between frozen and fresh produce?

DEAR DOCTOR K: I'm trying to eat more fruits and vegetables, but I don't have time to go to the grocery store every week. So I stock up on frozen produce. Am I missing out on any nutritional benefits by eating frozen instead of fresh?

DEAR READER: For taste, variety and quality of nutrients, recently picked local produce is the way to go. But if fresh produce is inconvenient or beyond your budget, frozen fruits and vegetables provide plenty of nutrition. Fresh fruits and vegetables are indeed more nutritious, but the difference between fresh and frozen produce may not be as stark as you think. Researchers at the University of California-Davis found that:

What is an astigmatism?

DEAR DOCTOR K: At my last visit, my eye doctor told me I have astigmatism. He told me what that means, but I still don't really understand what it is. Please explain it to me.

DEAR READER: Astigmatism means that the eye's cornea has an irregular shape, which causes vision problems. Astigmatism is very common; I am among the several billion people who have it. Fortunately, it's easy to correct. Let's start with a little eye anatomy. The cornea is the clear, dome-like window at the front of the eye.

What does neuropsychological testing involve?

DEAR DOCTOR K: My husband's doctor suspects that he has Alzheimer's disease and wants him to have neuropsychological testing. What will these tests involve?

DEAR READER: There is no single test that can diagnose Alzheimer's disease. In fact, a doctor cannot make the diagnosis with absolute confidence without studying the brain under the microscope, which is rarely done except in an autopsy. Alzheimer's disease is diagnosed presumptively by a combination of different types of evidence. The disease typically has a slowly progressive onset. Sudden confusion or speech problems, for example, are not caused by Alzheimer's.

Should I switch my atrial fibrillation medication?

DEAR DOCTOR K: I've been taking warfarin without any problems for years to treat atrial fibrillation. Now my doctor wants me to switch to a different medicine. Should I?

DEAR READER: Atrial fibrillation (aFib) is a rapid quivering in your heart's upper chambers, or atria. Instead of vigorously pumping blood down into the lower chambers (the ventricles), the quivering upper chambers let blood pool inside them. As blood sits, it can form clots. If a clot gets into the bloodstream and blocks a vessel supplying your brain, it can cause a stroke. Therefore, a person with aFib needs anticoagulant (anti-clotting) drugs.

Should I have a mammogram and a MRI if I’m at high risk for breast cancer?

DEAR DOCTOR K: I'm at high risk for breast cancer. Should I have screening mammograms, MRIs or both?

DEAR READER: Many factors can put a woman at high risk for breast cancer. The most common and important are these: (1) inheriting certain high-risk genes from one of your parents; (2) having a parent, sibling or child with breast cancer; and (3) having received radiation treatment to the chest (usually for some type of cancer) before age 30.

What is fibromyalgia?

DEAR DOCTOR K: My sister was just diagnosed with fibromyalgia. Can you tell me more about this condition?

DEAR READER: Fibromyalgia is a somewhat controversial condition, although less so than it was 20 years ago. It causes pain, aches and stiffness in muscles and joints throughout the body. Patients also feel unusually tired. The results of common blood tests, X-rays and other tests are usually normal for people with fibromyalgia, but depression and anxiety are also more common. Some doctors believe that the symptoms of fibromyalgia are explained by these psychological conditions.

What is the best way to treat blisters?

DEAR DOCTOR K: I wore a new pair of hiking boots on my vacation and now have several painful blisters on my feet. What's the best way to treat them?

DEAR READER: It sounds like you have friction blisters. A friction blister is a soft pocket of raised skin filled with clear fluid, caused by irritation from continuous rubbing or pressure. The irritation -- in your case caused by new hiking boots -- slightly damages the skin. The uppermost layer of skin separates from the layer beneath, and fluid accumulates in the space that's left.

What’s the difference between an essential tremor and Parkinson’s?

DEAR DOCTOR K: My father was recently diagnosed with essential tremor. Is this the same thing as Parkinson's disease? If not, what is the difference?

DEAR READER: Essential tremor is a brain condition that causes tremors: uncontrollable shaky movements of the hands, limbs, head or voice. It is usually mild and is very common, often running in families. It usually starts later in life, but when it runs in families it can start in young adulthood. In contrast, Parkinson's disease is a serious neurological condition that also causes a tremor.