Ask the Doctors: No evidence electric blanket will impact AFib

Hello, dear readers, and welcome to our first regular letters column of spring. With the longer days and the gradually warming weather, many of us are spending more time outdoors. Whether it's with sunscreen or protective clothing (or, better yet, with both), please remember to gear up against the UV rays. And now, onward to the mail.

— We recently wrote about atrial fibrillation, an irregular and often abnormally rapid heart rhythm in which the upper chambers of the heart fail to sync up with the lower chambers. The topic prompted a question from a reader living with that condition. "Is there any research that shows that atrial fibrillation is adversely impacted by sleeping with an electric blanket?" they asked. The short answer is no, there is no scientific evidence that using an electric blanket will have an effect on atrial fibrillation. However, becoming overheated can stress the heart, which might conceivably trigger an episode. If you do use an electric blanket, be sure to use it on a safe and appropriate setting. Alternatively, you might consider using it just to preheat the bed.

— In answering a question about valley fever, a potentially serious infection caused by the fungus Coccidioides, we shared recent findings that drought is contributing to its spread. A reader wrote to say she found this confusing. "How can this be, when fungi thrive in moist environments?" Coccidioides is found in the soil of certain arid regions, including throughout the southwestern United States. It grows during cycles of rainfall, which, as you point out, provides the moist environment fungi need to reproduce. However, the spores of Coccidioides are able to withstand dry conditions. They lie dormant in the soil, then spread easily in hot, dry and windy conditions. If inhaled into the moist environment of the lungs or somehow entrapped in flesh, infection is possible.

— A column about resistant starch, which is a carbohydrate that resists digestion, is getting a lot of mail. Because resistant starches skip the small intestine, they both contribute to glucose control and help feed the gut microbiome. Some high-carb foods, such as potatoes and pastas, develop resistant starch when cooled after cooking. This led a reader to ask for more specifics. "Do high-carb foods that are reheated after being chilled still maintain their benefits?" they asked. "Sounds like a great new benefit from leftovers!" Researchers have looked into that question and found that, for the most part, yes, the resistant starch persists, even after reheating. As the reader suspected, there is indeed a decrease in resistant starch upon reheating. However, the net result is a significant gain in the percentage of resistant starch.

Thank you, as always, for taking the time to write. We love hearing from you. The most recent batch of mail included some very kind thoughts and encouragement, which we appreciate. For newer readers, a reminder: We are not able to give a diagnosis, offer a second opinion, look at personal medical information or photographs or comment on specific treatment plans.

Dear Doctors:

I want to start checking my blood pressure to see if the high readings my doctor gets are accurate. I read you should always sit still before getting a reading. Is that true? That never happens at my doctor's office.

Blood pressure has been central to several columns in recent months. It's an important metric when it comes to general health, so we will risk repeating ourselves a bit in this new discussion.

Blood pressure readings measure the force that circulating blood exerts on the walls of the arteries. The two numbers, expressed as a fraction, show the degree and the range of the force. The top number is systolic pressure. That's blood pressure as the heart contracts. The bottom number, known as diastolic pressure, reflects blood pressure while the heart is at rest.

Blood pressure varies throughout the day. Readings are affected by activity, physical fitness, illness, stress, emotion, salt intake and even time of day. Getting an accurate picture of your blood pressure profile requires both proper technique and multiple readings. To aid in that, you need a good

Dear Reader:

monitor. A list of at-home monitors that meet the American Heart Association's criteria is available at validateBP.org. Your doctor can also advise you on a choice.

When taking blood pressure, make sure it has been at least 30 minutes since you used tobacco or caffeine or engaged in exercise. Empty your bladder, as that can affect readings. Sit upright, your back supported, with both feet flat on the floor. The arm on which you place the cuff should be relaxed and supported at the level of your heart. The cuff itself should be firmly in place, but not tight. You should be able to slip a fingertip beneath the top of the cuff. The bottom of the cuff sits directly above the bend of the inner elbow, with the air tubes centered.

Begin by taking about five minutes to sit quietly. Let it be a meditative pause. Don't chat or watch TV or read your phone while you wait. Most devices are automated and digital. When you're ready, press the start button. The cuff will inflate, pause for a moment, then gradually deflate. Be sure to stay relaxed and breathe normally as the machine goes through its cycle. The final reading is displayed on the monitor in the familiar fraction format.

As we mentioned, blood pressure is not a constant. Don't panic if you get an occasional high reading. For the most accurate blood pressure profile, you need multiple readings. It is recommended these be taken at the same time each day, perhaps twice in the morning and twice in the afternoon. Over the course of a week, with multiple readings, you'll get a fuller picture than a single reading can offer.

At this time, 120/80 falls into the normal range. Blood pressure higher than 130/80 enters the realm of hypertension. If your readings prove consistently high, it's a good idea to review the results with your doctor.

Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.