Colds and Flu: Variations on a Theme

    You wake up one morning with a scratchy tickle at the back of your throat. It’s nothing, you think, but by the evening you’re worried. What are you coming down with now? In all likelihood, it’s just a cold. The sore throat will persist for a few days, along with a runny nose and stuffy head. You may develop a cough. About a week after the scratchy throat began you begin to forget about the cold and by ten days it is a memory. Your body has met a small bit of protein-coated RNA called a virus, and defeated it. 

The difference between a cold symptoms and flu symptoms

    The next month another bit of protein-coated RNA called an orthomyxovirus finds its way into your nose. This time the story is very different. At noon, you are feeling well. By 4PM you have been felled. Getting up from your desk feels like climbing Mount Everest. You cannot get warm – even under a pile of blankets. Then come the muscle aches, as if you’d run a marathon. This time there is no hope of sticking to a routine – you have the flu. The worst of the symptoms fade after a week, but fatigue and lack of energy may persist for several more. Rest, time and patience eventually lead you back to health. Next year, you think, you will get that flu shot. 

The viruses that cause the problems

    The viruses that caused these two illnesses are superficially similar. They are little protein bags full of bits of RNA– technically not living things, but able to commandeer the machinery of living cells to reproduce themselves. Carried in droplets spewed into the air by coughs and sneezes of infected people, they are directly inhaled or carried into the nose and mouth on fingers from surfaces where those droplets landed. Specialized proteins on viral surfaces attach them to the cells in the upper airways. These proteins (H, or hemagglutinin and N, or neuraminidase) and their numbered subtypes (1, 2, or3) give flu viruses their unimaginative names. Swine flu virus becomes H1N1.   

    For reasons not yet understood, the body’s response to the attack of cold viruses is not as severe as it is to flu viruses. Once inside cells, flu viruses elicit a flood of proteins called interferons, which are the source of fever, muscle aches and profound fatigue. The viruses rapidly go about the business of making more of themselves, sending them out to infect more cells and generating a new wave of symptoms. In the meantime, white blood cells begin to produce antibodies that target viral surface proteins and prevent them from locking onto more cells. Eventually the tide of the battle turns and no more cells are infected. The rest of the illness -the recovery phase – involves cleanup of the remnants of the fight. 

Why flu shots don’t always work
    Flu shots use mixes of several different flu virus types to stimulate the body to make antibodies to those viral surface proteins in advance of “catching” the flu. If and when the virus invades, the antibodies are in place, ready to block the initial attachment to cells in the upper airways. Because the flu viruses that travel the world vary over time, each year’s flu vaccine is a composite of some of the currently circulating strains and may or may not be a good match to the virus that ultimately shows up.  

    Immunization is recommended for children (older than 6 months), the elderly, people in the health and teaching professions, those living in nursing homes and dormitories, and for all age groups who are at risk for flu complications, namely those with other respiratory problems, cardiac disease, diabetes and immune system impairments (including those induced by treatment of other diseases like cancer). Most adults in good health have the immune wherewithal to recover from flu and colds without complications or medical intervention. 

Complications of the flu

    The complications of the flu and of colds are similar. Both infections affect the upper airways, causing swelling and inflammation of the linings of the nose, throat and sinuses and blocking narrow passageways within. Earaches and pain in the forehead or the face develop but often resolve with simple measures like propping head up while sleeping, and taking an anti-inflammatory medication like aspirin or Advil. Unremitting pain, with or without fever, may indicate secondary bacterial infection of the ears or sinuses – the only reason for the prescription of an antibiotic during a cold. 

    Pneumonia is the most serious flu complication. Pneumonia means that the lungs’ spongy structures where carbon dioxide is exchanged for oxygen are swollen and filled with inflammatory debris. Reappearance of fever and fatigue after the flu has begun to improve may be the first sign of pneumonia. Other symptoms are chills, chest pain, shortness of breath, and dry or productive cough. Sometimes the pneumonia is caused by bacteria, but more often by the original virus or another. Pneumonia caused by bacteria, at least outside hospitals, is much less common. Prompt medical attention is in order because oxygen levels may be low. Medical attention should also be sought for other delayed symptoms like change in mental status, particularly in babies and the elderly. Occasionally diarrhea and vomiting are part of the flu and may produce dehydration.       

Why hydration is important

     Dehydration is also a result of fever, the metabolic equivalent of exercising in a warm environment. Dehydration stresses already inflamed airways. The easiest way to keep track of hydration status is to look at your urine – the darker the color, the drier you are. Aim for almost clear urine by drinking plenty of water.  

Managing fever

    Fever, while distressing, is part of the body’s defense against cold and flu viruses, which thrive in the relatively cooler temperatures of the upper airways. Some of the fever related discomfort can be relieved with a bath. Aspirin is not to be used in children with the flu because of a rare complication called Reyes syndrome, a liver failure. Tylenol is safe for them.

  What about anti-viral drugs for the flu

     Antiviral drugs (Tamiflu, Relenza. Symmetrel, and Flumadine) drugs are only effective if begun in the first 24-36 hours after symptoms begin. They lessen the duration of symptoms by about a day. Widespread use will produce increasing numbers of drug resistant strains of viruses.  

    New flu viruses appear regularly and prompt anxious comparisons to devastating epidemics of the past. Worrying about them doesn’t help. Taking care of what you can do for yourself and your contacts (see below) is your best option. 
                                                                      Useful actions to prevent colds and flu

  • Maintain good health habits throughout the year: adequate sleep and exercise, nutritious diet, no smoking, modest alcohol use.
  • Cover your nose and mouth with a disposable tissue when you cough or sneeze, with the crook of your elbow in the absence of a tissue.
  • Wash your hands with soap and water or an alcohol based cleanser after coughing or sneezing, before eating, and after being out in public.
  • Keep your hands away from your eyes, nose and mouth.
  • During flu outbreaks avoid crowded, closed environments when possible and wash hands when you come home.
  • Remember that your flu is infectious for up to 7 days and try to avoid infecting others.
  • Get a flu shot if you are in a high risk group.

The Air Connection: a Tour of the Lungs

Before birth the lungs are not inflated.  Oxygen and carbon dioxide enter and exit through the mother’s blood via the placenta. In the first 10 seconds after birth, a dramatic changeover begins, and from that point until the last breath is drawn the lungs connect us to this world.  The first gasping breath of a newborn baby signals the beginning of the body’s most vital  and most tenuous relationship with this world – that with air, or more correctly with the 21% of air that is oxygen.

Breathing is something we do without thinking, adjusting rate and depth of respiration to the demand for oxygen by the tissues.  Healthy hearts and lungs rise to the demand, increasing blood flow as needed.  In a sedentary person, exercising muscle has to be trained in order to be able to utilize the increased oxygen delivered.  Unhealthy lungs, however, fail to meet the increased demands of exertion, and may eventually fail to meet oxygen demands at rest. Then, breathing is always rapid and even speaking is laborious.

Decoding lung symptoms

A huge number of problems affect the airways, but only a limited number of symptoms result. They are: 1. shortness of breath, especially with exertion. 2.  cough – either dry and unproductive, or productive of sputum which is either clear, red and frothy, yellow or green, foul smelling, or bloody. 3. chest pain, often associated with the chest wall movement. 4.  wheezing.    In addition, lung tumors can cause a variety of peculiar symptoms outside the lungs – the most common is weight loss; the most exotic are peculiar neurological symptoms.

Because the lung is a living record of the air inhaled over time, a complete patient history is the first step in decoding symptoms. The second step is almost always an imaging study.  X-rays, CT and MRI scans are so good at revealing chest pathology that a skilled chest examination is a dying art. Technology also uncovers lung scars and nodules in patients who have no symptoms. Bronchoscopies and biopsies define abnormalities further. Often, but not always, such findings are benign, evidence of old encounters with fungus spores or of unknown cause. Autopsies also uncover unsuspected lung pathology like mild to moderate emphysema (see side bar) and evidence of long term exposure to pollution and smoke. Lungs of modern city dwellers are speckled with black particles from polluted air. Smokers’ lungs are black and shiny, as if smeared with tar. Smoking avoidance would be the single most effective way to improve many people’s respiratory problems, but a pristine lung at the end of a long life would still be a virtual impossibility.  Breathing is often very dirty work.

The bronchial tree – air’s roadway

The work of breathing begins with muscular contraction.  The diaphragm, a muscular sheet lying horizontally between the abdomen and the chest, contracts downward and expands the chest cavity. The short muscles between the ribs – the intercostals – assist by pulling the chest walls outward. Like a bellows, this chest expansion pulls air into the lungs by means of negative pressure. Air rushes from the nose into the trachea, down hollow tree-like branches called bronchi, into tinier branches called bronchioles, and finally into millions of tiny expandable sacs called alveoli. The bronchial tree is elastic, expanding on inhalation and collapsing back to baseline diameter on exhalation. In asthmatics, the fine muscles in these tubular walls respond irritably to allergens and constrict the passages. Inflammation from infection or inhalation of toxic substances and even rapid breathing of cold dry air can also trigger tightening of the bronchi, called bronchospasm.  Airflow resistance rises in bronchospasm, making the sufferers of asthma and bronchitis cough and wheeze.   Treatment of both conditions aims at dilating the airways by using drugs that relax the smooth muscle fiber and at reducing inflammation of the bronchial lining with steroids and antibiotics.

 The alveoli – where the work gets done

Air flow rushing down the bronchial tree dead ends in the alveoli, expanding them until they resemble very soft Styrofoam.  Fine capillaries course through the thin walls of the alveoli, picking up oxygen and delivering carbon dioxide for exhalation. Airborne particles settle out in the moist alveoli, though they only get that far by surviving the cough reflex and the cilia -the tiny hair-like projections that constantly sweep dust and foreign bodies up and out of the bronchial tree. Alveoli are also the site of pneumonia – infections with either bacteria or viruses that set up shop in thin alveolar fluid.  The organisms excite inflammation and increased secretions, which impair gas exchange and cause shortness of breath, fever and coughing. Patients with pneumonia look and feel terrible. Pneumonia can also involve the pleura, the lining over the lung, adding the misery of pleuritic pain with each breath, and causing fluid to accumulate between the lung and chest wall – a problem called a pleural effusion.

Fluid accumulation in the chest

Pleural effusions sometimes accompany heart failure. Less often, they are blood tinged accompaniments of pulmonary emboli – clots that reach the lung from leg and pelvic veins.  Small clots in the lung block oxygen exchange in their vicinity; large ones kill suddenly, with no warning, by blocking major blood vessels bringing blood to the lungs. Shortness of breath and coughing producing blood tinged sputum are warnings to be heeded, particularly if they occur after a prolonged period of bedrest or sitting without getting up – situations that promote clot formation in the legs.

Sputum- the stuff that gets coughed up

Blood-tinged sputum can be less serious a symptom, since it is a common result of a bloody nose above. But when associated with cough and weight loss, it is a telltale sign of lung cancer.  Yellow and green sputum usually indicate infection. If foul smelling, it may come from a lung abscess.  Pink frothy sputum is a sign of edema in the lungs, usually from heart failure, but also from altitude sickness, and is always accompanied by severe shortness of breath.

The last breath

At the end of life, breathing usually ceases not because the lungs fail, but because the drive to breathe that made the newborn gasp its first breath ceases. All those breaths in between are like footprints left behind. Use them well.

                                              

Addendum: Alveoli Gone Wrong

Over a lifetime, especially when chronic airway disease impedes airflow, the alveoli change. They merge making larger spaces with fewer capillaries for air exchange. When severe, even getting enough oxygen in at rest is difficult. This condition is called emphysema, most commonly a problem in chronic smokers, but also a genetic disease in rare people. Oxygen delivered by a mask helps the symptoms for a while, but the condition inevitably progresses.

If alveoli rupture, as they can in emphysema or in congenital conditions that produce enlarged pockets, they leak air into the chest cavity. Air builds up between the lung and the inner chest wall an emergency condition called a pneumothorax that is very painful and potentially life threatening, requiring insertion of a chest tube to drain the air and restore negative pressure to keep the lung inflated. Similarly, a penetrating wound in the chest wall sucks air into the chest cavity, collapsing the lung.  Covering the chest wound tightly to prevent air from entering can save a life.

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