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Update From the Medical Journals: June 2009
June 30, 2009  By Mary Pickett, M.D.
Harvard Medical School What's the latest news in the medical journals this month? Find out what your doctor is reading. More Stroke Patients Can Receive Emergency Clot-Dissolving Treatment The most effective treatment for a stroke is to give the patient a clot-dissolving medicine (tissue-plasminogen activator, t-PA). This therapy is called thrombolysis. Now more people who are diagnosed with a stroke can receive thrombolysis, according to a new guideline that was issued jointly by the American Heart Association and the American Stroke Association. It was published online May 28 by the journal Stroke. Normally this treatment is only given within the first three hours of a stroke. That's when the benefits of the medicine seem to outweight the short-term risk for bleeding complications. Experts are now recommending clot-dissolving treatment for some people within 4 1/2 hours from the start of symptoms. Treatment with clot-dissolving medicine does not guarantee recovery. But it does offer hope to stroke victims. Past studies have shown that with thrombolysis treatment, a person who is having a stroke is 12% more likely to recover without a lasting disability compared with someone who does not receive the treatment. This is a small but significant chance for benefit. The new guideline still limits clot-dissolving treatment to three hours for people who have a higher risk for complications, such as people older than 80, people who are having a very severe stroke, those who have a history of both stroke and diabetes, and people who are taking strong blood-thinners. The sooner you receive stroke treatment, the greater the benefit. So if a person is showing signs of a stroke, get him or her to an emergency room as quickly as possible. Back to top Abnormal Heart Rhythms Are More Common In People Who Have Sleep Apnea A study published in the June 22 issue of the Archives of Internal Medicine reveals that heart rhythm disturbances are common among people who have interruptions in their breathing at night. This breathing problem is called "sleep apnea." The study shows that there is a stronger link between sleep apnea and heart troubles than many doctors thought. People who have severe sleep apnea have up to twice the risk for heart rhythm disturbance compared with people who have a mild sleep breathing disturbance or none at all. Sleep apnea occurs when a person briefly stops breathing during sleep. There are two kinds of sleep apnea: Obstructive sleep apnea and central sleep apnea. Both types result in low oxygen levels on and off throughout the night. With obstructive sleep apnea, your tongue and throat muscles become extremely relaxed during sleep. They collapse together and obstruct your airway. Air can't get into your lungs. You struggle against the closed airway in an effort to breathe. This causes a surge of adrenaline, which raises blood pressure. The drop in oxygen, the pressure changes that occur inside the chest as you try to breathe, the surge in adrenaline, and a high blood pressure surge can stress your heart muscle. This can lead to a dangerously fast rhythm called "ventricular tachycardia" (VT). VT is a life-threatening heart rhythm. This study, which tested 2,911 men over 65 with a sleep study and heart monitor, found that rhythm changes in the heart ventricle were about 50% more common for those with severe obstructive sleep apnea, relative to those with mild or no obstructive apnea during sleep. Central sleep apnea, on the other hand, occurs when you make no effort to breathe. Heart failure — the inefficient pumping by the heart — can lead to central sleep apnea. Even when heart failure is mild, it can cause you to hyperventilate because your lungs can become congested with fluid and getting oxygen requires extra effort. After you hyperventilate, your brain can stall your breathing on purpose, in an effort to correct your carbon dioxide level. It is twice as likely, according to this study, for people who have central sleep apnea to have an irregular heartbeat called atrial fibrillation. Experts in this study think it is likely that the atrial fibrillation — and the breathing change — both result from heart failure or another heart problem. This may be true whether or not a heart problem has been diagnosed. It's estimated that 12 to 18 million Americans have sleep apnea. Many people are unaware they have the condition. The most common way to treat both types of sleep apnea is with a "CPAP" (continuous positive airway pressure) mask and machine, which is worn at night to help keep the air passages open by blowing light air pressure. Back to top More News in Brief - H1N1 Influenza Is Now A Pandemic. In a statement to the press on June 11 about H1N1 flu strain (swine flu), the director of the World Health Organization announced that the scientific criteria for an influenza "pandemic" had been met. A pandemic is an outbreak of infection that occurs over a widespread area and affects many people. The WHO notes that most of the people who are infected with H1N1 influenza have only mild symptoms and recover completely. The agency predicts that the pandemic will be moderately severe in its early stages. Efforts to produce an effective vaccine are still ongoing. On June 22 the WHO reported that 52,160 known H1N1 influenza infections have occurred world-wide, and 231 deaths have resulted.
- People Who Sleep Less Are More Likely to Have High Blood Pressure. People who don't sleep enough seem more likely to develop high blood pressure, according to a study published June 8 in the journal Archives of Internal Medicine. The study included 578 adults who each wore movement sensors that recorded when they were at rest or active. The study participants slept an average of six hours per night. Only 1% of them averaged eight or more hours of sleep. The participants were followed for five years. Those people who slept less were more likely to be diagnosed with hypertension (high blood pressure) during the five years of follow up. The risk increased 37% for each hour of sleep that was "lacking" from a person's usual sleep schedule, compared with a group if people who received eight hours of sleep, or near to that.
- Maximum Tylenol Dose Should Be Lowered. Experts from the U.S. Food and Drug Administration (FDA) and invited experts have gathered June 29 and June 30 for an important meeting to reconsider safety concerns about acetaminophen (Tylenol). Preceding this meeting, the FDA released a report to the public that recommended limiting the maximum daily dose of acetaminophen to 3,250 milligrams. This is lower than the currently recommended dose. Many people take more than 3,250 milligrams of acetaminophen in a day. They take frequent doses or combine a variety of products that each contain acetaminophen. The drug is present in many over-the-counter pain and cold remedies and in many prescription pain medicines, such as Vicodin, Lorcet, Percocet, Tylenol with codeine, Darvocet, Fioricet, Norco and Midrin. Acetaminophen (Tylenol) is one of our safest medications when it is used appropriately, but it is dangerous to the liver when it is taken in excess.
- New Recommendations Give Targets for Weight Gain in Pregnancy. The Institute of Medicine updated recommendations for weight gain during pregnancy for the first time in almost 20 years. The new report appeared online on May 28. The report recommends that a woman's pre-pregnancy body mass index (BMI) should determine her range of weight gain . For a normal weight woman (BMI 18.5 to 24.9), between 25 and 35 pounds would be a healthy weight gain. If a woman is overweight (BMI 25 to 29.9), gaining between 15 and 25 pounds is recommended. Obese women with a starting BMI of 30 or more should limit weight gain to 11 to 20 pounds. Women with twins can gain more: 37 to 54 pounds for a normal-weight woman, 31 to 50 pounds for an overweight woman, 25 to 42 pounds for an obese woman. The report urges women to achieve a healthy weight (normal BMI) before getting pregnant, since this is healthiest for the mother and the baby. Babies born to women who are overweight have an increased risk for premature birth, and are at increased risk for becoming overweight themselves. The report also recommends breastfeeding, since this can help a mother lose weight after delivery.
- New Law Allows Government to Regulate Tobacco. On June 22, President Obama signed the Family Smoking Prevention and Tobacco Control Act. The government can now regulate how tobacco products are made, marketed and sold. The U.S. Food and Drug Administration (FDA) will be able to regulate the nicotine and chemical content of cigarettes, as well as the flavorings. The bill will require more obvious warning labels on cigarettes, and will limit the use of vending machines in order to prevent sales of cigarettes to children and teens. Confusing terms like "light," "low-tar," and "mild" will not be permitted on cigarette labels, since these terms can fool people into thinking that tobacco is not harmful. To protect children, advertisements and sponsorships will be banned near schools and playgrounds and at sports and entertainment events.
Back to top Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.
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