TOC |
Pulm
Chronic Cough See: Chronic_cough.htm |
Common causes
of Chronic Cough: (Negative chest x-ray or Chest
CT scan)
Less common causes of cough: (less than 6% of all cases)
REF: the Virtual Hospital Home Page - U. of Iowa |
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| Ref: Bope: Conn's Current Therapy
2010
Cough is among the most common presenting complaints of outpatients in the United States. It serves as a protective reflex against foreign material and as a method to clear secretions from the airway. The cough center is located in the medulla, and the cough reflex is mediated by way of multiple nervous system pathways including the trigeminal, glossopharyngeal, vagus, and phrenic nerves. Angiotensin-converting enzyme (ACE) inhibitors increase cough reflex sensitivity and have been shown to decrease the risk of pneumonia in patients with cerebrovascular accidents.
Cough can be subcategorized into acute and chronic
cough, and post-upper respiratory infection
persistent cough. |
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| Acute
Cough
Acute cough may be defined as cough that has been present for less than 8 weeks. Because all causes of chronic coughs initially cause acute symptoms, patients with acute cough may actually have cough caused by one of the etiologies discussed later in this section; however, acute cough more commonly is the result of a less indolent process. Causes of Acute Cough < 8 weeks.
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| Postinfectious
Cough Postinfectious cough begins with an acute upper respiratory tract infection but persists following the resolution of the other acute symptoms. Postnasal drip syndrome may present following the common cold or sinusitis. Bronchospasm may lead to postinfectious cough either as a result of a single episode of postinfectious wheezing or an exacerbation of underlying asthma. Postinfectious cough may be the initial presentation of asthma. Causes of Postinfectious Cough
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| Causes of Chronic
Cough - Most non-smoker patients with problematic, persistent cough have multiple etiologies
Occasionally, chronic cough may be the result of:
* Habit cough and psychogenic cough |
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| Approach to Chronic
Cough Patients:
chronic_cough_approach.htm
All Patients Presenting With Cough
Patients With Postinfectious or Chronic Cough
Common Diagnostic Tests for Chronic Cough:
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Treatment of
Acute Cough
Treatment of Postinfectious Cough
Treatment of Chronic Cough
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Postnasal Drip Syndrome (PNDS),
either singly or in combination with other conditions, is the single most
common cause of chronic cough for which patients seek medical attention
(Grade II-2). The symptoms and signs of PNDS are nonspecific (Grade II-2);
therefore, a definitive diagnosis of PNDS-induced cough cannot be made from
history and physical examination alone. A favorable response to specific
therapy for PNDS, with resolution of cough, is a crucial step in confirming
that PNDS is present and is the etiology of cough. The combination of a
first-generation antihistamine and a decongestant is considered to be the
most consistently effective sole form of therapy in treating most patients
with PNDS-induced cough not due to sinusitis (Grade II-2). In most patients,
some improvement in cough will be seen within 1 week of initiation of therapy.
Newer-generation, relatively nonsedating antihistamines have been found
ineffective in treating acute cough associated with the common cold (Grade
I) and are not as effective as first-generation antihistamines in treating
PNDS secondary to nonallergic conditions. The first-generation antihistamines
should be used preferentially to treat PNDS-induced cough that is
nonhistamine-mediated (Grade I, II-2).
Asthma
is a common cause of chronic cough. A diagnosis of cough-variant
asthma is suggested by the presence of airway hyperresponsiveness,
and confirmed only when the cough resolves with asthma medications. The treatment
of cough-variant asthma is the same as for asthma presenting with other symptoms.
Inhaled medications prescribed for asthma may worsen the cough.
GERD
can cause cough by aspiration, but it most likely causes chronic cough
in patients with normal radiographs by a vagally mediated reflex
mechanism (Grade II, II-2). When GERD is the cause of chronic cough,
GI symptoms are often absent (Grade II-2). Twenty-four-hour esophageal
pH monitoring is the most sensitive and specific test for GERD. In interpreting
the test, it is important to assess the duration and frequency of reflux
episodes, and the temporal relationship between reflux and cough episodes.
Patients with normal standard reflux parameters may still have reflux as
a cause of cough if a temporal relationship exists (Grade II-2). When 24-h
esophageal pH monitoring cannot be done, an empiric trial of antireflux
medication is appropriate when GERD is suspected as a cause of cough. However,
if empiric treatment fails, GERD cannot be ruled out until objective studies
are conducted (Grade III) because the empiric therapy may not have been intensive
enough or medical therapy may have failed. Because minimum consistently effective
therapy for GERD-induced chronic cough is not known, initial treatment should
include diet and lifestyle changes in addition to drugs. Cough due to GERD
has been reported to resolve with medical therapy in 70 to 100% of patients;
mean time to recovery may take as long as 169 to 179 days (Grade II-2).
Antireflux surgery may be considered after intensive medical therapy has
been documented to have failed.
Chronic bronchitis
Cough is a principal feature of chronic bronchitis
(CB) and its treatment should chiefly be directed to reduction
of sputum production and airway inflammation ( eg, by smoking cessation and
removal of environmental irritants) (Grade II-2). While CB is among the most
frequent causes of chronic cough in the community, it is the cause in only
about 5% in series of patients who seek medical attention for cough.
Ipratropium can decrease sputum production and cough (Grade I).
Nonspecific cough suppressants should be avoided, and mucolytics are of uncertain
benefit. Although the effectiveness of systemic corticosteroids and
antibiotics on cough have not been specifically studied, they are likely
to be helpful in decreasing cough during exacerbations of COPD (Grade III).
Bronchiectasis
is a cause of chronic cough in a relatively small number of patients; the
diagnosis is established by clinical history, chest radiograph, high-resolution
CT scan of the thorax, and cough disappearance with specific therapy. Cough
associated with flares of the disease can be treated with a combination of
chest physiotherapy, drugs to stimulate mucociliary clearance, and systemic
antibiotics (Grade II-2). Inhaled antibiotics are recommended only in cystic
fibrosis (CF) patients with bronchiectasis (Grade I).
Postinfectious cough
is a diagnosis of exclusion; it should be considered when a patient complains
only of cough after a respiratory tract infection and has a normal chest
radiograph. Postinfectious cough ultimately resolves over time; oral
corticosteroids (Grade II-3), inhaled corticosteroids (Grade III), or ipratropium
bromide (Grade I) may attenuate the cough.
Bronchogenic carcinoma
Coughs that develop for the first time and last for months in susceptible
groups are suggestive of bronchogenic carcinoma.
Bronchogenic carcinoma is not a common
cause of chronic cough (Grade II-2), and is very unlikely in never-smokers
(Grade II-2). Present or prior cigarette smoking or occupational exposures
increase the risk. Chest radiographs, sputum cytology, and flexible bronchoscopy
are the most important initial tests for evaluating bronchogenic carcinoma
as a cause of chronic cough.
ACE-Inhibitors
Cough due to ACE-Inhibitors is
a class effect of these drugs and is not dose-related. The cough is typically
nonproductive and is associated with an irritating, tickling, or scratchy
sensation in the throat. ACEI-induced cough may appear hours to weeks or
months after ACEI is started (Grade II). Because no laboratory test predicts
who will have ACEI-induced cough, the diagnosis should be considered in any
patient who has a cough while taking an ACEI (Grade III). Cough due to ACEIs
will disappear or substantially improve within 4 weeks of discontinuing the
drug (Grade I); definitive treatment of ACEI-induced cough is discontinuation
of the drug.
Habit cough and psychogenic cough
are diagnoses of exclusion (Grade III). The character of the cough ( eg,
honking or barking) is not diagnostically helpful in adults (Grade II-2).
However, the pediatric literature suggests that honking and barking coughs
are consistent with psychogenic cough (Grade III). After exclusion of other
causes, psychological counseling and short-term antitussive therapy may be
appropriate for psychogenic cough (Grade III).
Chronic interstitial pulmonary disease
is an uncommon cause of cough; treatment of such cough is based on treatment
of the underlying condition. If this treatment fails to resolve the cough,
the cough may still be treatable with specific therapy for other comorbid
conditions. The most common causes of chronic cough should be investigated
before antitussives are prescribed (Grade III).
In children, asthma, upper and lower respiratory tract infections, and GERD are the most common causes of acute and chronic cough. Less common causes of cough in children are congenital anomalies, aspiration and environmental exposures. The approach to managing chronic cough in children is similar to the approach in adults (Grade III). Diagnostic testing may be limited because many children are unable to cooperate in testing, and positive tests do not necessarily establish diagnosis or predict a favorable response to specific therapy (Grade III). A chest radiograph should be obtained in nearly all children with chronic cough to rule out lower respiratory tract and cardiac pathology (Grade III). A sweat test for CF may be considered when no clear etiology for cough is established. The recommended diagnostic approach to cough in children is history, physical examination, and determination of a most likely etiology (Grade III).
The cause of chronic cough can be determined in most patients; specific therapy will be successful in the majority of patients when chronic cough is evaluated in a systematic manner. Guidelines and algorithms for evaluating acute and chronic cough in immunocompetent and immunocompromised adults, and children, with diagnostic caveats, are presented in the body of this report.
Pharmacologic treatment of cough is either
Antitussive therapy is indicated when cough serves no useful function such as clearing the airways. Specific antitussive therapy is directed at the etiology or mechanism causing cough ( eg, cigarette smoking, postnasal drip). Nonspecific antitussive therapy is directed at the symptom rather than the etiology or mechanism. Because of the high probability of being able to determine the causes of cough and prescribe specific treatment that can be successful, there is a limited role for nonspecific antitussive treatment (Grade II-2, II-3). It is indicated (Grade III) when specific therapy has not had a chance to work or will not work ( eg, inoperable lung cancer).
Protussive therapy is indicated when cough performs a useful function and needs to be encouraged ( eg, in bronchiectasis, CF). Although hypertonic saline, amiloride, and terbutaline by aerosol following chest physiotherapy have been shown to increase cough clearance (Grade I), or cough clearability in the case of amiloride, their clinical utility remains to be determined in future studies that assess short-term and long-term effects of these agents on the patient’s condition. Hypertonic saline in CF appears promising.