Cough can be either acute or chronic, defined in terms of 2-3 weeks. Less than 2 weeks duration = “acute,” because it includes a variety of viral illnesses. Over 2-weeks duration rules out the viruses, 3 weeks consolidates the paradigm & often mandates a chest x-ray (CXR). And even though the cough of lung cancer has to have its “Day #1,” no lawyer in the country could nab you for missing it that early.
A cough longer than 3-weeks’ duration that’s getting better can be called “acute” if it’s resolving. That’s why the most important question you can ever ask about a chief complaint is whether the symptom is, “Getting better, getting worse, or staying the same?” If it’s getting better, reassurance usually suffices [along with whatever symptomatic treatment you may enjoy]. You’d think the person wouldn’t present if they’re getting better, but people are funny.
KEY CLINICIAN GOAL — Structure your practice to avoid prescribing antibiotics as much as possible. After all, most illnesses are viral. Sadly, up to 90% of patients in studies may leave the office with an antibiotic Rx in hand!!!!!
Cough by definition originates in the respiratory tract, somewhere between the nostrils & alveoli. Diagnostic Step #1 is to determine whether it’s upper or lower. This is especially important, because Upper Respiratory Conditions don’t tend to kill, like lower ones might. Our limited differential is shown in the Table.
|Upper Respiratory Tract||Lower Respiratory Tract|
Two key symptom-complexes suffice to distinguish upper from lower:
1. Upper respiratory Symptoms:
- Rhinitis (Nasal Discharge, i.e. “runny nose” [or is it “running nose”?])
- Nasal Congestion (Stuffed Nose — air doesn’t seem to want to get in)
2. Dyspnea [usually just with exertion; but even worse if at rest]
If there’s dyspnea, the lower tract has to be involved (or major tracheal obstruction). Of course, you have to be sure you’re dealing with true dyspnea, i.e. exacerbated by exertion, and not merely fatigue, malaise, SOB during a coughing spell, or “I can’t breathe” through a clogged-up nose [see posting Acute SOB – 2].
One useless parameter you’ll have to evade is the insistent patient’s perception of where the cough is coming from. Patient slaps his chest & says, “The phlegm’s all here!” There’s no such thing — all cough originates from the airway segment between the epiglottis and carina (bottom of trachea/top of mainstem bronchi). That’s where our cough receptors are located !!! Patients with URI cough because of post-nasal drip. Conversely, debilitated bedridden persons may suffocate from pneumonia without any cough, because their mucociliary clearance is so compromised that it can’t sweep out the pus.
UPPER RESPIRATORY SYMPTOMS, but NO dyspnea, and NORMAL lung exam:
Here the differential of “acute cough” is limited to URI (the common cold), Sinusitis, and the beginning of Allergic Rhinitis. Of course, URI is the most common, and we could defer consideration of allergies until chronicity has been established. But why not help out sooner if we can?
I diagnose Allergic Rhinitis if I find any of the following 3 parameters:
- Sneezing is a very prominent symptom, especially if itchy eyes are too.
- There’s a history of similar episodes in the past that were prolonged [≥1 month]. We all get viral colds, but they don’t last a month.
- Exam is obvious for very pale/gray and boggy nasal mucosa, “allergic shiners” (darkened lower lids), or the “allergic salute” (horizontal crease across the tip of the nose).
Bacterial Sinusitis is tougher, because treatment involves antibiotics. True, patients love them [nobody seeks care to be told “You got a cold”], and a quick Rx certainly shortens the visit. But please, avoid the temptation.
It’s impossible to distinguish viral from bacterial sinusitis. The diagnosis is clinical; radiology is no help. My parameters:
1) Fever, with unilateral facial pressure & sinus tenderness. This constellation is not common, so you won’t find yourself overusing antibiotics. Patients with CNS symptoms get sent right to the ER (this is real rare).
2) Symptoms began as a URI or allergies, but changed & worsened 7-10 days into the illness.
3) My diagnostic threshold is lower for immunocompromised patients.
Green nasal discharge would only impress me if it persists throughout the day. But I’d also want to hear about significant facial pressure. The more unilateral, the more convincing [odds are that bacteria just happened to invade a single sinus].
The vast majority of patients with cough and upper respiratory symptoms don’t qualify for either allergies or bacterial infection. They have a URI. “It’s just a cold.” Should be reassuring, shouldn’t it? If that doesn’t sound empathetic enough, tell them it’s a “real bad cold.”
What if a patient has BOTH upper respiratory symptoms AND dyspnea? A few possibilities:
- They may have a URI that triggered asthma — you’ll hear wheezes, rhonchi, or a prolonged expiratory phase [see posting #___ on bronchospasm].
- They may have had a viral URI with secondary pneumonia — you’ll get a history of symptom exacerbation a few days into illness, the patient should be febrile, with signs of pneumonia [next posting].
- Their URI may have triggered CHF — there’ll be signs of, & risk factors for, the latter.
- They may not have true dyspnea, even though they think they’re SOB. If there are no objective signs suggesting lower respiratory tract involvement, or hypoxia, diagnose the URI and don’t worry.
NO upper respiratory symptoms, NO fever, and NO dyspnea
Only a cough. Here I rely on physical examination. Actually, I rarely use my exam to diagnose nasal disease, because normal findings are so variable, and we never know a given patient’s baseline. My focus is the lungs.
If lung exam and vital signs are normal, they don’t look ill, oxygen saturation is fine [if you have a machine], and all they’ve got is an Acute Cough, I diagnose viral Tracheitis. If they’re hoarse, I call it viral Laryngo-Tracheitis. There’s no such thing as true “croup” in anybody >3-years-old, because the trachea isn’t narrow enough to make you bark.
Acute Bronchitis can also present with just a cough, and a normal lung exam. But acute bronchitis is essentially always viral, so it doesn’t matter (we’ll discuss this point more next posting). However, if you want to be perfectly sure not to miss anything, call your diagnosis, “Laryngotracheobronchitis” [I’ve actually seen this entity in the literature!!!].
Foreign Body Aspiration — Hard to identify. Maybe suspect it when the cough began very abruptly while eating. Small children and the elderly with diminished swallowing capacity are at risk, but it can also happen to anyone who gobbles or eats fast.
But what do we do about it? If there’s respiratory distress or stridor (long high-pitched inspiratory “wheeze”), call 911 and send them to the ED. Do a Heimlich if there’s complete apnea. If they look OK, just have a cough and normal lung exam, find another diagnosis. A Foreign Body that’s worked its way to the lung doesn’t cause cough unless pneumonia develops. I certainly wouldn’t refer for bronchoscopy or pulmonary fluoroscopy without several episodes of pneumonia in the same location.
Pertussis (a specific form of bronchitis) is trickiest. The classic “catarrhal” prodrome of infancy is absent in older kids & adults. “Whoops” are infrequent.” Physical exam is unrevealing. Culture is insensitive. PCR is expensive, also loses sensitivity as duration increases, and lacks standardization except in state laboratories. The CDC & WHO case definition require a cough of at least 2 weeks duration, but treatment at that point is less effective at reducing both symptoms and transmission.
The clinical case definition is a “cough over 2-weeks duration, with either a ‘whoop’ [very rare beyond early childhood], coughing paroxysms, or post-tussive vomiting.” BUT, clinician beware — it’s very easy to convince yourself that your patient has “coughing paroxysms,” as a [subconscious?] excuse to prescribe azithromycin.
Laboratory diagnosis is important, especially for epidemiological reasons. You must use a small Dacron swab on a wire (NOT cotton or calcium-alginate], & have a cooperative patient. If PCR is available, & affordable, go for it. You need a second swab for culture, but only try if you have the right transport medium, a cold box <4° C, & a lab ready to process within 24 hours. See picture below before deciding if patient will be cooperative. Read this paragraph again, & you’ll see why I’ve never ordered the test. If I ever make 2 diagnoses close in time, I’ll contact the Health Dept. for help.
When it comes to Acute Cough of under 2-weeks duration, I put all my effort of Pertussis diagnosis into those adults & teens that are in contact with unimmunized children, especially infants under 6 months old. That’s who dies. I’m liberal giving antibiotics to such potential contacts if there’s any suggestion of significant paroxysms, since these patients are few. Most important — I insist that parents/guardians take their babies for care if they get a simple URI, & explain to the peds provider the possible [or proven] pertussis contact. Diagnostic tests are quite accurate during the prodromal “catarrhal” phase, when treatment is highly successful.
Another group who needs aggressive Pertussis consideration — health care workers! Especially those who work with infants. So we have a certain claim on an azithromycin Rx when we get sick [just like we also get flu vaccine at times of shortage; always felt a bit like cronyism].