Cover Story
Sick of the Cold
What is it about cold weather that keeps us in harm’s way?
By Jeanne Mettner
Minnesotans are known for their ambivalence about cold weather. We blame it for our ailments—the toes that won’t thaw out, the ache in our back from shoveling snow, the seasonal bout with the flu, yet at the same time, we brag that it’s part of what makes us live long, work hard, and get above-average grades. Whether we’re better or worse for our weather may not be clear. But cold temperatures do affect our health in some very real ways.
In case you need the data to prove it, consider this: In 1999, Robert A. Kloner, M.D., Ph.D., a researcher at the Keck School of Medicine at the University of Southern California in Los Angeles, analyzed 12 years of data from Los Angeles and Los Angeles County where, obviously, the winters are much milder than here and found that 33 percent more coronary deaths occurred in December and January than from June through September. Kloner stood by his claim that winter is deadly in a 2004 editorial in Circulation, noting that nationwide data gathered over a longer period on deaths from both cardiac and noncardiac events supported his findings. Another study published in a 2004 British Medical Journal adds to the theory that the winter months are most lethal: Researchers from the London School of Hygiene and Tropical Medicine found elderly people in Britain were more likely to die between December and March, regardless of their socioeconomic status.
Even if it doesn’t kill us, cold weather brings with it a higher burden of illness. Here, we look at a few of the conditions that can be caused or exacerbated by a drop in temperature, discuss some new ways to treat them, and dispel some common misperceptions surrounding them.
Temps Dive, Viruses Thrive
For years, doctors believed close quarters alone were responsible for the increased incidence of influenza and other virus-borne illnesses during winter. Now, research is pointing a finger instead at the season’s low relative humidity and air temperatures. According to researchers at Mount Sinai School of Medicine in New York, cold and dry conditions favor transmission of flu virus. In 20 experiments in which the guinea pigs were exposed to flu viruses at relative humidity ranging from 20 percent to 80 percent, they found that transmission was most likely when relative humidity was between 20 percent and 35 percent and at 65 percent. Flu spread less well at around 50 percent and was blocked at humidity levels over 80 percent. In an article published October 19, 2007, in the online journal PLOS Pathogens, they explained that the virus-containing droplets can’t remain airborne when humidity is high. The researchers also found lower temperatures increased transmission. Animals kept at 5 degrees C (41 degrees F) were more likely to catch the flu than those kept at higher temperatures. At 30 degrees C (86 degrees F), no transmission was detected. They hypothesized that the cooler temperatures may lead to increased viscosity of the mucous layer in the nasal passages, making it harder to quickly shed the virus. Or that the cooler temperatures may make the virus more stable.
Other research has shown why the flu virus is more likely to survive and spread when temperatures fall. In 2008, a team at the National Institutes of Health found that flu viruses are coated in a fatty membrane that, at temperatures slightly above freezing, hardens to a gel that serves to protect and preserve the virus in the air. As temperatures approach 60 degrees F, the covering gradually thaws, causing the membrane to be less protective of the virus, which dries out and weakens. (Thus far, no data have demonstrated that H1N1 transmission is affected by cold temperatures.)
All this is interesting, says Mark Schleiss, M.D., director of the division of infectious diseases in the University of Minnesota’s department of pediatrics, but it doesn’t change protocols for care and prevention. “I don’t question the research, but I don’t know what the findings mean in terms of how to counsel patients,” he says. “If one gets into complicated algorithms involving certain amounts of humidity, certain degrees of temperature, that takes attention away from the most important pieces of advice, which advocate good hand washing, careful hygiene, and trying to avoid exposing others when you are ill.”
Not So Deadly Cold
Lorentz Wittmers, M.D., Ph.D., an associate professor in the department of physiology and pharmacology at the University of Minnesota, Duluth, has been known to pay his students to immerse themselves in cold water so he can study how it affects them. Ask the hypothermia expert what physicians should but may not know about the condition and he responds succinctly: “People can survive extreme cold for an extended period of time, and they can be warmed up if it’s done correctly—with few adverse outcomes.”
Duluth resident Janice Goodger could be considered a living testament to this dogma. Last December, Goodger injured herself when she fell outside her daughter’s house, where she was pet-sitting. For four hours, the then 64-year-old, who suffers from severe rheumatoid arthritis, lay on the driveway, waiting for help. By the time Goodger’s daughter returned home that evening, she found her mother unconscious. When paramedics arrived and began gingerly moving Goodger onto the gurney, the subtle movement caused her heart to stop. They immediately began chest compressions and continued to communicate with the St. Luke’s Hospital emergency department, where Goodger was being transported. At that point, Goodger’s body temperature was hovering around 70 degrees.
“When she arrived, I intubated her, got her on life support, and then took her from the ER to the OR, where our cardiac surgeon performed a bypass procedure,” recounts Chris Delp, M.D., an emergency physician at St. Luke’s. “Basically, they drained the blood out of her body, warmed it, and put it back in.” The gradual warming of her blood took approximately one hour.
When Delp left the hospital that night, he did not expect Goodger to live through the ordeal. He was concerned that her brain was too damaged to survive. But when he came in for his shift the next morning and paid her a visit, “she was off of the ventilator, bright, alert, chatting. It just shocked me.”
Most patients, especially elderly ones, who survive such extreme hypothermia experience cognitive deficits. Goodger is the exception: She has had no long-term cognitive effects from her cold spell—by her own estimations as well as those of clinicians and family members.
Wittmers is not surprised by the clinical outcome. He says physicians shouldn’t think it’s futile to treat patients who’ve experienced severe hypothermia. “There is a well-known saying that has been attributed to a large number of people: ‘You are not dead unless you are warm and dead,’” he says. “If you don’t rewarm a hypothermic patient, you risk having that patient wake up in the morgue.”
Frostbite Falls
Frostbite remains one of the most common presenting problems in Minnesota emergency departments during the winter. Severe frostbite blocks the flow of blood, causing damage to tissue and skin. In the most severe cases of frostbite—stages 3 and 4—the skin and tissue, typically the fingers and hands or toes and feet, are essentially frozen solid. “Physicians may see a lot of mild frostbite, but the severe cases are not often distinguished quickly enough and treated aggressively enough,” says George Edmonson, M.D., an interventional radiologist at St. Paul Radiology and Regions Hospital. “Worse yet, they think there is nothing at all they can do, and they just wait until the damage is demarcated so they can amputate.”
Edmonson has perfected a novel therapeutic approach that was developed two decades ago. Known as intra-arterial thrombolytic therapy, the procedure is currently performed on patients with severe frostbite who come to Regions. The idea behind the therapy is to counteract the clotting that the arteries initiate in response to rewarming the frozen tissue. Working in conjunction with burn surgeons, Edmonson first determines if the frostbite involves blocked arteries, which would indicate initiation of thrombolytic therapy. Using a catheter at either the top of the leg or arm, he can administer antithrombolytic agents (such as retaplase and tenecteplase) as well as vasodilators to dissolve the blood clots and relax the patient’s arteries. The result is increased circulation to the extremities, despite swelling and blistering. “If you can get the arteries reopened promptly and can keep them open for a few days while the arteries heal a bit, you can get blood back into the tissue and the muscles, and the nerves will not be destroyed,” Edmonson explains. “If you cannot get the arteries reopened, the patient will lose fingers and toes or an entire foot.”
Edmonson presented results of a study he did on the technique at the Society of Interventional Radiology’s scientific meeting in March 2008. He noted an 80 percent success rate with the therapy among patients ages 18 to 65 years who underwent treatment during a two-year period. Of the 24 patients in his study, 12 were infused with retaplase and 12 with tenecteplase.
Edmonson continues to explore why some patients do not benefit from the treatment. So far, he’s theorized that it may be because of a delay in seeking care, repeated frostbite, or other health problems. He notes that the people who get frostbite often have other serious problems in their lives including alcoholism, mental illness, or addiction to methamphetamine, a vasoconstricting drug. “They are the people in our society who seem to get the really severe frostbite because they are either incapacitated or don’t know enough to come out of the cold,” he says.
The Science Behind Cold Feet
Although rare, chilblains, or pernio, is another annoyance that can crop up during cold weather. A form of cold feet, pernio typically manifests as small, tender bluish or purplish bumps on the toes (and occasionally the fingers) in response to cold. Unlike frostbite, which can lead to tissue damage or death, pernio is a temporary phenomenon that may last for weeks but rarely causes ulceration or necrosis. “Basically, the blood vessels in the feet are clamping down in response to cold,” explains Spencer Holmes, M.D., a dermatologist at Park Nicollet Clinic and the University of Minnesota. “No one knows quite why it happens because it is quite uncommon. The person will be otherwise healthy but may complain that they get cold feet easily.”
Pernio is generally treated through self-care measures: insulating feet in cold weather, wearing boots that are roomy and warm, and avoiding outdoor activities when it’s really cold. “Basically, patients who have this condition just want to know what the bumps are and whether it’s serious,” says Holmes. “I tell them that it’s an unusual but well-described problem within the spectrum of cold sensitivity.”
Although emergency physicians and dermatologists see only a handful of cases each year, physicians still need to recognize that pernio is real—and uncomfortable.
Most cases are benign. However, Holmes notes that patients who do not respond to self-care measures should be referred to a rheumatologist or dermatologist, as pernio could indicate blood abnormalities such as the presence of cryoglobulins, proteins that become insoluble when exposed to cold, literally making the blood more viscous. Patients with cryoglobulinemia may have a viral infection or a specific type of autoimmune disease such as lupus or chronic leukemia or myeloma. If a patient’s medical history indicates symptoms associated with autoimmune disorders, a lab workup may be indicated to check for these and other conditions.
Cold Hands, Warm Heart
There’s more than meets the eye when it comes to Raynaud’s syndrome—a condition marked by cool, white fingers in response to cold temperatures. Most physicians are aware of what characterizes the syndrome, but many do not know that there are two very different subtypes: vasospastic and obstructive.
Up to 25 percent of the nation’s population may have vasospastic Raynaud’s, the milder form that affects people between the ages of 15 and 25 years, with 80 percent of cases affecting women. With this subtype, people have a hyperreaction to the body’s innate response of “warming up the core” in cold weather. As the fingers get cold, the digital arteries constrict, allowing little blood to enter the fingertips. But when the fingers warm up, the blood flow returns as normal. “We try to educate patients who have vasospastic Raynaud’s that it’s not a big deal, that it’s a relatively benign condition for the majority of people,” explains William Omlie, M.D., a peripheral vascular surgeon at Fairview Southdale Hospital. “The big concern that they have is that something is wrong with their arteries, and we can reassure them that there are no problems. It’s annoying, but if you protect your hands, you will almost never get a sore on your fingers.”
With obstructive Raynaud’s, however, the prognosis is not as bright. Occurring most commonly in adults 40 years of age and older, this subtype signals that something is wrong with the vessels themselves. The digital arteries constrict in the cold, but they do not improve when their fingers are warmed again. Obstructive Raynaud’s is often associated with autoimmune diseases such as Sjögren’s syndrome, lupus, and rheumatoid arthritis and is one of a constellation of symptoms known as CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia) that can signal scleroderma. Although it can be managed with calcium channel blockers, obstructive Raynaud’s is something that calls for continued monitoring, as it could be a sign of a more serious condition and could increase the risk of frostbite.
Determining which form of Raynaud’s a patient has involves a review of their medical history, demographic information, and perhaps some Doppler testing to measure blood pressure of the fingers both before and after exposure to cold. “Because there is a vessel problem and the cold weather keeps adding constriction to it, the patient with obstructive Raynaud’s can lose their fingertips or get ulcers that will stay for months,” Omlie says. “Suspecting this more serious form calls for additional lab tests, such as sedimentation rate (ESR), antinuclear antibody, and rheumatoid factor testing, to see what else is going on.”
Allergic to the Cold
Marcia Witt first realized she had a sensitivity to cold when she was in the grocery store shopping for produce. If she made her selections while the vegetable sprayers were activated, her hands would frequently become itchy, swollen, and riddled with hives. A year later, in 1999, while holding a cold soft drink between her legs as she drove her car, she developed a more serious reaction. “I ended up with hives the size of dinner plates on my thighs, and that’s when I said this was just not normal,” says Witt, an attorney in Minneapolis.
Soon after, a Twin Cities physician performed a standard ice cube test on Witt and diagnosed her as having cold urticaria—in effect, an allergy to the cold. (During the test, an ice cube is placed on the patient’s forearm for four minutes, then removed. The presence of hives at the location of the ice cube indicates cold urticaria.) Cold urticaria is rare. It affects less than 1 percent of the nation’s population. But as the 41-year-old Witt notes, simply charting its incidence signifies a step in the right direction. “At the time, people who did not know about it thought I was absolutely bonkers,” she recalls. “I was actually amazed that there was a doc who was willing to do this test and tell me I was not crazy.”
Gerald Volcheck, M.D., a specialist in allergic diseases and clinical immunology at Mayo Clinic, says the rarity of the condition still can leave some doctors scratching their heads. “Most cases of cold urticaria are idiopathic, but there are a couple of other diseases—cryoglobulinemia and viral infections—that can be associated with it,” he explains. “The most important thing to do as physicians is to know that it exists.”
Once a person is diagnosed as having cold urticaria, Volcheck says, he or she should be advised to avoid total body exposure to the cold to prevent more severe reactions. Witt wished she had received such counsel early on. Two years after her diagnosis, while swimming in a spring-fed creek in Austin, Texas, on a 90-degree day, she went into anaphylactic shock and was rushed to the hospital. Since then, Witt has been careful. She swims only in warm water on days when the ambient temperature is warm—and never alone. She also wears warm clothing on damp, chilly days, carries an epiPen (Witt also has an allergy to bee stings), and even lets a glass of milk warm up before drinking it. “I don’t think consuming cold liquids is going to put me into anaphylactic shock again, but it’s an irritation. And I just don’t want to be that uncomfortable, especially when there is something I can do to prevent it.”
Heeding Blood Pressure Hikes
Several studies have demonstrated seasonal variations in blood pressure. In one of the most recent investigations, the results of which were presented at the American Heart Association’s annual meeting in November 2007, a five-year analysis of the electronic health records of 444,000 adults with high blood pressure in the United States and its territories found that their blood pressure was less controlled in winter than in summer in all cities, from Anchorage, Alaska, to San Juan, Puerto Rico. The ostensible implication of this and other studies is that some patients may need their medications adjusted to ensure that their blood pressure is being appropriately managed in cold weather. But Gary Schwartz, M.D., a physician in Mayo Clinic’s division of nephrology and hypertension, says that’s not necessarily the wisest conclusion to draw from the data. “I cannot say that all of my patients’ blood pressure readings will go up in the winter; it’s just not that clear-cut,” he explains. “That’s not to say in a given patient there will be no seasonal change, but it would be hard to identify seasonal changes alone as the defining factor.”
Instead, Schwartz says providers must consider a number of other factors that may influence variability in blood pressure including activity level, compliance with medications, weight, sleep patterns, salt intake, and alcohol consumption. Says Schwartz: “Certainly, most of us in the Midwest recognize that we are less physically active in the winter than in the summer. The days are shorter, we don’t have our lawns and gardens anymore, and if we are not active outdoor sports goers, we decrease our physical activity. And unfortunately, our appetites do not correspond to that change in activity. We attend holiday parties and eat foods that are rich and salty. All of these behavior changes correspond with seasonal changes, and all of them will negatively affect blood pressure.” MM
Jeanne Mettner is a freelance writer in Minneapolis and a frequent contributor to Minnesota Medicine.