Acute cough (<3 weeks duration) is extremely common, but chronic cough , lasting more than 8 weeks, is also common. Cough continues to be one of the most frequent causes of consultations in primary care and pulmonology, as well as a common symptom in hospitalized patients. The causes vary and can be better defined depending on the duration of the cough.
For example, acute cough predominates in acute viral and bacterial infections of the upper and lower respiratory tract, but can also occur in exacerbations of preexisting conditions.
In chronic cough , such as cough related to cigarette smoking, the most prominent causes appear to be upper airway cough syndrome, bronchial asthma, nonasthmatic eosinophilic bronchitis, and gastroesophageal reflux disease (GERD). .
| Coughing can be a voluntary act or an unbearable reflex. It is an essential protective reflex intended to clear mucus, irritants, foreign particles and microorganisms from the larynx, trachea and bronchi, freeing the airways and preventing infections. |
After stimulation of receptors throughout the respiratory tract, a sudden inspiration occurs, and then tension of the chest and abdominal muscles against a closed glottis causes a sharp increase in intrathoracic pressures, up to 300 mm Hg. Then, suddenly, the glottis opens and rapid expiratory outflows and a characteristic noisy expiration, called a cough, occur.
The benefits of coughing , which often occur serially and can be quite forceful, are clear. Weak or ineffective cough is associated with serious lung infections. However, acute or chronic cough can be severe, violent, repetitive and associated with significant tissue injury, arising de novo or representing the aggravation of an underlying condition.
Interestingly, none of the prospective cough studies mentioned any harm and the author believes that the entire spectrum of cough-induced harm has not been previously studied, except in a single report updated through March 2004, focused on the quality of cough. life.
| Method |
From the systematic review of the literature emerges an overview of the myriad cough-induced harm forms that may be of practical value to clinicians in primary care, emergency medicine, and other disciplines. A review of the literature was carried out in all types of research models. The search is current as of November 2019.
| Results |
A wide spectrum of cough-induced complications and patient damage has been identified, with the possible involvement of many systems.
Cough-induced damage can be classified according to the “target organ” involved.
Thus, the varied adverse phenomena reported after coughing include those affecting the upper respiratory tract, the chest wall and thorax, the abdominal wall, the heart and aorta, the central nervous system, the eye, the gastrointestinal tract, the urogenital, emotional and psychological damage and other varied damages.
Most events appear to be rare and are described in a few case reports. However, some are considerably more common or have a special impact on patients.
Surprisingly, there are no prospective studies on any of the various cough-induced pathologies found. The only prevalence estimates found were not in studies of cough but of a specific complication associated with cough (e.g., syncope or headache precipitated by cough, spontaneous splenic rupture of a normal spleen, etc.).
It is noted that several complications induced by cough have served to discover the existence of an ignored disease. Because cough is common and the pathology induced by cough is not, since there are several complications of cough that constitute emergencies that should not be ignored or recognized late, it is important to consider several "red flags" in the patient with cough.
| Discussion |
Severe cough, strong enough to cause complications, was found in a variety of cough etiologies and could not be attributed to any specific underlying diagnosis. However, pertussis in adults (possibly due to the severity of the cough), chronic obstructive pulmonary disease (COPD) and asthma, (possibly due to its high prevalence) are mentioned repeatedly.
Despite the high prevalence of cough as a presenting symptom, both in outpatients and hospitalized patients, and the large number of studies of large series of patients dedicated to the etiology, no prospective study found cough-induced complications.
Therefore, the prevalence of most cough-induced pathologies remains unknown. Most are probably rare pathologies, limited to isolated case reports.
> Cough-induced rib fractures
Diagnostic criteria for this entity are well defined and include chest pain occurring after the onset of cough, radiographically documented rib fracture, and the absence of trauma, metastatic disease, or other explanation for the fracture.
Despite not having a prevalence estimate, a study from a healthcare center concluded that cough-induced fractures are a rare complication. In addition to the preceding cough, which may be acute or more often chronic, patients had pleuritic chest pain and tenderness of the chest wall.
Occasionally, hematomas or lung injury caused by the ends of the ribs are observed, which can cause pleural effusion, pneumothorax, hemothorax and even lung hernia. They predominate in women (73% in 1 series), but notably, a third of them do not have osteopenia/osteoporosis and cough fracture was even reported in a healthy 22-year-old man.
Chest x-ray has low sensitivity to detect these rib fractures (more than 33% remain undiagnosed). Typically 1-2 ribs are affected, often on the lateral aspect of the ribcage, with ribs 5-9 appearing especially vulnerable (particularly rib 6). This is because the middle of the rib is exposed to the greatest bending force during coughing. Even without rib fractures, after a vigorous cough there can be severe thoracic complications, including cartilage fracture, intercostal hernia of the lung, diaphragmatic rupture, spontaneous pneumothorax, pneumomediastinum, rupture of an intercostal artery, and hemothorax. In some cases, after a strong cough, the costal cartilage is fractured and not the ribs.
Painful cough often appears to be associated with poorly localized muscle pain, especially in the chest. This is mentioned indirectly, but with the exception of a report demonstrating a transient increase in positron emission tomography/computed tomography (PET/CT) uptake in many muscles after cough, and reports of elevations in serum creatine kinase ( CK). There is currently no solid information available.
> Hernias
The rapid increase in intra-abdominal pressure during coughing can worsen inguinal, umbilical, and abdominal hernias. Even a single intense coughing episode can be associated with the sudden onset of a hernia, although this is not common. However, the author could not find information on the prevalence of cough-induced hernias.
> Rupture of the spleen
Splenic rupture is usually seen after blunt abdominal trauma or, less commonly, as a complication of a previously diagnosed disease that causes splenic enlargement, such as acute Epstein-Barr virus or cytomegalovirus infection, or after Splenic infiltration in malignant hematological diseases.
However, rupture of a completely normal spleen can occur spontaneously.
In a systematic review of 613 of these cases, 12 were caused by cough and 4 were caused by vomiting. Severe cough or chronic cough can trigger this potentially catastrophic event. The patient presents with abdominal pain and hypotension or syncope, and emergency physicians should take this rare entity into consideration.
> Syncope due to cough
Several hundred cases of cough syncope have been published, characterized by loss of consciousness immediately after coughing, especially after prolonged episodes of violent coughing. These episodes usually last seconds, with rapid restoration of full consciousness. Cough syncope occurs more commonly in middle-aged, obese men, men with COPD, and smokers.
Syncope due to coughing (or sneezing) is classified as situational syncope along with syncope after stimulation of the gastrointestinal tract or urination, as a form of reflex (mediated by the nervous system), a syncope similar to. vasovagal.
Reflex syncope is the most common mechanism in any setting studied and even in specialized reference units, 56%-73% of syncope is due to this type of syncope, and only 4-7% of referred patients are affected. diagnose situational syncope.
The mechanism of cough syncope is not completely understood and appears to be complex. In any case, it is clear that coughing acutely increases intrathoracic pressure, with a decrease in venous return and cardiac output.
Blood pressure falls excessively while compensatory heart rate does not occur. Therefore, cerebral blood flow is temporarily reduced, with syncope. However, several conditions may coexist with cough syncope and should be considered, including sinus arrest or complete atrioventricular block, pericardial constriction, carotid artery stenosis, and posterior fossa pathology.
> Cough headache
Currently, the existence of cough headache is well defined and has been classified by the International Headache Society. Rapid increases in intrathoracic and intra-abdominal pressure during cough lead to increased central and intracranial venous pressure, triggering a sudden, sharp, stabbing, moderate to intense, short-lasting headache (1 second to 30 minutes). The location varies, but unilateral pain is common. Most patients are >40-50 years old and the prevalence is up to 1.2% in headache clinics.
Primary cough headache should be determined by neuroimaging (MRI because at least 40% of these patients have an underlying structural etiology, located primarily in the posterior fossa, often a type 1 Chiari malformation, which is herniation of the cerebellar tonsils through the foramen magnum.
These headaches secondary to cough differ in their mechanism; The headache is mediated by the transient increase in intracranial cerebrospinal fluid pressure, as a result of the obstruction, and the symptom can be reproduced by a modified Valsalva test.
> Myocardial injury
An important study based on data from Framingham examined the association of chronic cough with subsequent myocardial infarction in patients without any history of this pathology. Chronic productive or dry cough was found to be an independent predictor of myocardial infarction, with a significant relative risk.
Although no other studies were done, these data strongly confirm the results of a Finnish study and, furthermore, the risk correlates with the increased level of plasma fibrinogen, an acute phase reactant, and could be well explained by chronic cough associated lung inflammation, a new established risk factor for atherosclerosis.
Another intriguing type of post-cough myocardial injury is stress cardiomyopathy , which was reported in 2 women after particularly severe coughing episodes. Both developed chest pressure and dyspnea, elevated troponin levels, and significant abnormalities of left ventricular motion, with normal or near-normal coronaries. This type of cardiomyopathy is mainly attributed to excessive sympathetic stimulation, which can complicate rare cases of severe cough episodes.
> Focal neurological deficit
The development of a cough-induced focal neurological deficit is a rare but well-established complication. Several mechanisms may be involved, but the most important is cough-induced cervical artery dissection. This dissection occurs when the layers of the arterial wall separate and blood pools between them. Most patients do not have underlying tissue or vascular pathology; The average age of the patient is around 45 years and the dissection is spontaneous; It is often caused by a trivial trigger such as coughing, sneezing, diving, or childbirth.
Patients present with headache or neck pain and transient ischemic attack or cerebral infarction, in the territory of the carotid or vertebral artery, mainly due to thromboembolism. Substantial seasonal variation has been found, especially in the fall and winter months. The largest study of 982 patients revealed an infection in the previous week, up to 22%, with cough being a possible association, and common triggers in more than a third of patients.
There are few reports of coronary artery dissection and even aortic dissection following severe coughing, attesting to the forces generated. Rarely, cough can cause carotid thrombi that can embolize even without proven dissection.
Other mechanisms are cough-induced spinal cord compression, with anatomical changes, or hematoma in a patient with excessive anticoagulation, and arterial air embolism that complicates chronic lung disease, suggesting lung tissue injury.
> GERD and cough or cough and GERD
This controversy has now been resolved, and it appears that both sequences can occur; but chronic cough as the main symptom of GERD can occur even without concomitant gastrointestinal symptoms and is much more common. In 27.5% of 2,196 patients with prolonged cough, the etiology was determined and GERD was considered to be one of the main causes of chronic cough.
However, cough leading secondarily to GERD is also well established. An early report from the Mayo Clinic noted that 27 of 39 cough episodes studied by esophageal pH monitoring were related to reflux, gastroesophageal reflux followed by cough.
In a careful monitoring study of 128 consecutive patients with asthma, almost half of the coughs were associated with a reflux episode, 7 times more often than the opposite, but when the cough was what led to the reflux, it had a confirmation definitive.
This was confirmed in a study based on sound recordings of cough in 71 unselected patients with chronic cough, among whom, 56% had a positive probability that the symptom was associated with reflux preceded by cough. Therefore, chronic cough can actually engender episodes of esophageal reflux, and this association occurs quite frequently.
> Stress urinary incontinence in women
Stress urinary incontinence (SUI) is the rapid involuntary loss of urine with increased abdominal pressure associated with coughing, sneezing, laughing, or exercising.
In fact, a cough stress test is an inseparable part of the evaluation of women who may have SUI. This is a common disorder affecting 3.5% of women, and chronic cough is a putative risk factor for SUI, observed in 24%-53.8% of affected women.
In a recent study, 31 of 80 patients confirmed SUI (39%), although 25 men were included in this study. SUI reduces quality of life and negatively affects sexual intercourse, which is one of the most common (but often unmentioned) cough-induced complications, particularly when there is mixed urinary incontinence (SUI associated with urge incontinence).
> Quality of life and emotional problems
Another common problem related to cough, especially chronic cough, is its harmful effect on the patient’s life and emotions. Cough is experienced in different ways by different patients and its impact is multifactorial.
The deterioration in quality of life caused by chronic cough is well known. With greater emphasis placed on the patient’s point of view and the practice of patient-centered medicine, assessment tools have been developed, used and validated, such as the General Quality of Life Questionnaire and the Specific Quality of Life Questionnaire. for Cough or Leicester Cough Questionnaire, which have been the most studied and used.
These tools reveal that the more severe the cough, the more it is significantly associated with all subscales of depression, anxiety, stress (especially anxiety), and greater urinary incontinence. Therefore, as a baseline, a worse quality of life was found associated with cough, and the most important thing is that all the measures that improved cough also improved the quality of life of the patients.
Others also found prevalent anxiety, insomnia, frustration, and depression associated with chronic cough, although the effects on quality of life and emotional effects of cough syndromes of shorter duration have not been adequately studied.
| Conclusions |
In conclusion, a systematic review of the literature reveals that cough, very common in all settings, can be associated with an incredibly broad spectrum of pathologies that affect many systems. In the future, studies on the prevalence of cough-induced damage are needed, but even though cough complications are quite rare, rare adverse events are likely to be found associated with extremely common complaints.
On the other hand, several phenomena constitute true emergencies that can occur, either to primary care or hospital doctors of different disciplines, including emergency specialists. These physicians must be aware of the potential for cough to be violent enough to cause serious, even fatal, heterogeneous complications, the timely diagnosis of which is very important.
Therefore, under certain circumstances, acute or chronic cough, especially in patients experiencing violent and paroxysmal episodes, should be considered as a therapeutic target, regardless of the cause. Withdrawal should be considered, particularly for vulnerable patients (e.g., those treated with anticoagulants, suffering from portal hypertension, or who previously had complications associated with cough), or patients whose quality of life is greatly affected.
In this context, simple sound assessment may constitute a readily available and easy method to identify patients whose cough is more severe and whose risk of complications is higher, but again, this should be the subject of future studies.
