7/31/2019 GERD Chronic Cough

1/3

Gastroesophageal Reflux-related Chronic Cough

GERD is a very common problem. Surveys of the general population

have led to estimates that 10% of the adult population of the UnitedStates have daily heartburn and a third have intermittent symptoms;moreover, GERD has been shown to cause 10% to 40% of cases ofchronic cough. Cough in GERD is triggered by reflux of acid into thedistal esophagus and stimulation of an esophageal-tracheobronchialreflex. Cough is not dependent on aspiration into the larynx ortracheobronchial tree.

Proving the relationship of chronic cough to GERD can be difficult.The lack of typical symptoms of reflux and negative endoscopic andradiographic studies do not rule it out. The 24-hour esophageal pH

monitoring test has become the gold standard for diagnosis and hasboth a sensitivity and specificity approaching 90%. Correlation ofthe results of pH monitoring with response to therapy adds to thereliability of the test. If GERD is the sole cause of chronic cough,aggressive anti-reflux therapy should eliminate the cough in nearlyall cases. One study reported 100% success. Treatment involves theuse of dietary, mechanical and drug therapy. Drug therapy should beinitiated with proton pump inhibitors and prokinetic agents. H2-antagonist can be substituted for the proton pump inhibitor after 3months.

Terdapat afferent limb receptors reflex batuk pada gaster dan

esofagus bag bawah, maka GERD batuk kronikPenderita GERD termasuk dalam 3 penyebab utama batuk kronik,

dengan mekanisme :1. Iritasi esophagus dengan stimulasi esophageal-

tracheobronchial reflex2. Nocturnal aspiration cairan asam lambung

Mechanism of Cough

Cough is a protective reflex serving a normal physiologic function of

clearing excessive secretions and debris from the pulmonary tract.

The cough reflex has 3 components: an afferent sensory limb, acentral processing center, and an efferent limb.2

The trigeminal, glossopharyngeal, and vagus nerves supply theafferent pathways for cough receptors; the vagus, through its

pharyngeal, superior laryngeal, and pulmonary branches, supplies thelarge majority of these receptors.

Receptors are located throughout the airway from the pharynx to the

terminal bronchioles, with the greatest concentration located in thelarynx, carina, and the bifurcation of larger bronchi.6

Three types of receptors are predominant:7,8,9

Rapidly adapting receptors (RARs) that respond tomechanical stimuli, cigarette smoke, ammonia, acidic andalkaline solutions, hypotonic and hypertonic saline,

pulmonary congestion, pulmonary congestion, atelectasis,and bronchoconstriction

Slowly adapting receptors (SARs)

Nociceptors on C-fibers that respond to chemical stimuli aswell as inflammatory and immunological mediators such as

histamine, bradykinin, prostaglandins, substance P,capsaicin, and acidic pH

Afferent impulses are transmitted to the cough center of the brain,located in the nucleus tractus solitarius of the medulla of the

brainstem, which is connected to the central respiratory generator.

7/31/2019 GERD Chronic Cough

2/3

To complete the reflex arc, efferent impulses leave the medulla andtravel to the larynx and tracheobronchial tree via the vagus while the

phrenic and spinal motor nerves of C3 to S2 supply the intercostals

muscles, abdominal wall, diaphragm, and pelvic floor.6

This cough reflex has been shown to have neuroplasticity such that ahypersensitive response is elicited over time due to the cough itselfinducing chronic irritation and inflammation and tissue remodeling.8

Both peripheral (increase in sensitivity of cough receptors) andcentral (changes in central processing in the brainstem) sensitizationcan account for an exaggerated cough response that is common in

patients and further contributes to the maintenance of chronic

cough.9

Causes of Chronic Cough

The etiologies of chronic cough are numerous and may includepathology from the nose and nasopharynx to the distal bronchial tree.Obvious causes such as smoking and angiotensin-converting enzyme(ACE) inhibitor use can be easily ascertained from the history. Afterthis, the challenge for the clinician lies in how to efficiently andsystematically evaluate the patient without an overly exhaustiveworkup. Further compounding this is the fact that oftentimes morethan one condition is simultaneously present.

Prospective studies have shown that 3 conditions account for theetiologic cause of chronic cough in 92-100% of immunocompetent,nonsmoking patients with normal chest radiograph findings.10Inorder of frequency, they are as follows:

1. Upper airway cough syndrome (UACS), previously referredto as postnasal drip syndrome (PNDS)

2. Asthma

3. Gastroesophageal reflux disease (GERD)

These 3 conditions make up what is called the pathogenic triad of

chronic cough.

A fourth etiology that deserves mention is nonasthmatic eosinophilic

bronchitis (NAEB), which is relatively common, easy to diagnoseand treat, and should be considered early on in the diagnostic

evaluation.

Another way to categorize the etiologies is to draw a distinctionbetween cough due to eosinophilic airway diseases (asthma and

NAEB) and noneosinophilic chronic cough.11Eosinophilic airwaydiseases have airway inflammation due to eosinophils, which can be

diagnosed by raised induced sputum eosinophil counts and increasedexhaled nitric oxide levels. They are also associated with goodsteroid responsiveness.11

The physician who focuses on diagnosing and treating theseconditions will be extremely successful at treating chronic cough.

Gastroesophageal reflux disease

The following 2 mechanisms have been postulated for GERD-associated cough:13

Distal esophageal acid exposure that stimulates anesophageal-tracheobronchial cough reflex via the vagusnerve

Microaspiration of esophageal contents into thelaryngopharynx and tracheobronchial tree

http://emedicine.medscape.com/article/296301-overviewhttp://emedicine.medscape.com/article/176595-overviewhttp://emedicine.medscape.com/article/296301-overviewhttp://emedicine.medscape.com/article/176595-overview

7/31/2019 GERD Chronic Cough

3/3

The second entity refers to laryngopharyngeal reflux (LPR) orextraesophageal GERD, and it differs from traditional GERD in thatit does not manifest as heartburn and tends to occur when the patient

is upright as opposed to lying flat. This silent GERD can be presentin as many as 75% of patients with chronic cough.14Symptoms ofLPR include throat clearing, hoarseness, and globus sensation.Empiric treatment includes acid suppression and lifestyle and dietarymodifications.

http://emedicine.medscape.com/article/864864-overviewhttp://emedicine.medscape.com/article/864864-overview