Respiratory Illness: The "Itis's" Explained
It's the season for infectious respiratory illness. The sounds of blowing noses, coughing, sneezing, and hoarse voices are common-place. When I see patients with these complaints, I often feel the palpable anticipation as they wait for me to declare a diagnosis. Is it bronchitis? Laryngitis, perhaps? In reality, these "diagnoses" are more descriptive than anything else. This blog will explain the different "itis" diagnoses with respiratory tract infections.
The respiratory tract spans the entry portal of the mouth and nose to the terminus of the lung tissue. When mapped out, it looks like an upside down tree with tracts branching off, becoming increasingly smaller and more numeric. As air enters the mouth and nose, it circulates into the sinuses, past the back of the throat where the tonsils reside, past the larynx (voice box), down the main air tube in the neck (the trachea), into the large bronchi, into the smaller bronchioles, and, finally, into the tiny air pockets of the lungs (alveoli). In the lungs, oxygen enters the blood stream. There also, a respiratory byproduct, carbon dioxide, leaves the blood for the air in the lungs to be exhaled. It's an amazing and complex system.
This well-oiled machine can break down a bit when infection hits. Different viruses and bacteria have different predispositions for the various areas of the respiratory tract. Different symptoms occur with the different areas affected. And among the different areas potentially infected, different degrees of severity exist. Infection causes inflammation where it sets up shop. That is where the term "itis" comes in. From Greek terminology, this suffix connotes the presence of inflammation. Following are some examples, moving down the respiratory tree.
Rhinitis is synonymous with the common cold or a runny nose. When the mucous membranes in the nasal passages become inflamed, mucous is produced. The two usual culprits are allergens and the 250 or so strains of rhinovirus which cause the common cold. With rhinitis, the mucous produced can go forward (out the nose) or backward (down the throat). The color of the mucous does not dictate severity or whether it is caused by a bacterial infection. Rather, it is a measure of how long the mucous has been in the passage or how hydrated it is. Rhinitis caused by an infection is almost universally viral. Patience and hydration with plenty of fluids are the best medicine.
Sinusitis is a more smoldering infection of inflamed sinus tissue. Usually sinusitis comes atop a cold or allergies where sticky, boggy mucous membranes and a warm dark environment along with an immune system fighting something else off create the right environment for infection. Symptoms of sinusitis include mucous congestion and facial pain. Often the upper teeth hurt because the roots of these teeth extend to just beneath the floor of the sinuses. Treatment is geared at eradicating the bacterial infection with an antibiotic. Because the sinuses are more walled off from the body, treatment can be a bit more challenging than your typical respiratory infection.
The tonsils are actually lymph nodes that service the body's immune system. Given all the bacteria that enter our mouth and respiratory tract, the tonsils are often busy. These two sacks of lymph tissue sit in the back of the throat (the pharynx) and can be an easy target for infection - both viral and bacterial. Tonsilitis and pharyngitis occur when viral or bacterial infection cause inflammation of the tissue. Nasal drainage from rhinitis can also cause inflammation in this area. Symptoms include a sore throat and enlarged tonsils. Sometimes pus is noted on the tonsils.
Really, no symptom is specific to say whether a virus or a bacteria is causing the illness, but this distinction is important primarily because strep infection can cause serious consequences like rheumatic heart disease and post-strep kidney disease due to an immune cross-reaction. This bacterial infection should be treated promptly. Viral infections are treated symptomatically. While most viral infections resolve spontaneously, one such case, mononucleosis, lingers for week to months. Clinical findings such as lymph node enlargement in the back of the neck and an enlarged spleen can raise suspicion of mono and a blood test can confirm this. Other less common causes of chronic sore throats include HIV infection and chronic fatigue syndrome.
Laryngitis is inflammation of the vocal cords of the voice box, or larynx (pronounced "L-AIR-INKS"). Along with a cough, the predominant symptom is the loss of voice. Laryngitis is almost universally viral in nature when caused by infection. Supportive care includes voice rest, hydration, and control of the cough, which further perpetuates the inflammation.
The main airway, a single, rigid conduit in the neck is known as the trachea. Inflammation of the trachea is... you guessed it... tracheitis. Tracheitis is often lumped in with laryngitis. The most common syndrome involving tracheitis is croup. This illness affects children most commonly between the ages of 2 and 5. The classic symptoms involve cold symptoms along with a barky cough followed by stridor. Stridor is a characteristic whistling sound caused by air rushing in through the inflamed, pinched off air passage of the larynx and trachea. Unless the airway is seriously constricted, treatment is supportive. Taking the child into a bathroom with a running shower to create mist or the cold outside air can help to soothe the inflamed air passage. For severe cases, a mist of adrenaline (epinephrine) is used to relax the airway. The infection is self-limited lasting 5-9 days.
The most common illness involving a cough is bronchitis. The cough may be dry or mucous-producing. The inflammation occurs in the bronchial tree, the air passages between the trachea and the lungs. Symptoms include a cough which may be dry or productive. If the inflammation reaches the tiny airways, enough to cause significant restriction of air flow, wheezing can occur. Most all bronchitis infections are viral and last 5-9 days. Occasionally the cough can self-perpetuate itself and linger for weeks to months after the infection is gone. Antibiotics are often not necessary for bronchitis. Special conditions exist, however, in persons with asthma or other chronic underlying lung disease. In these cases, an antibiotic is commonly given to reduce inflammation and prevent secondary bacterial infection.
Perhaps the most serious "itis" of the respiratory tract is pneumonia (ironic, I know). This infection involves the tissue of the lungs. Progressing infection can fill the air pockets, preventing exchange of oxygen. Blood oxygen levels can lower to serious levels. Pneumonia can be viral or bacterial, but is mostly treated as bacterial with an antibiotic to cover all bases. While the color sputum (coughed up mucous) is not so concerning as yellow vs. green, rust colored sputum is concerning for pneumonia. The rust color comes from blood mixed within the sputum. Another complication of pneumonia is sepsis. This occurs when the infection of the lung tissue spreads to the nearby blood stream. Sepsis can become quickly fatal.
The language of respiratory tract infections can be confusing. Infections can span the extent of the airways from the nasal passages to the lungs, and each area takes on its own set of symptoms and its own degree of seriousness. If you are dealing with one of these all-to-common scourges, I hope that this primer helps identify the cause, give it a name, and lead to a more tolerable course.