by Carlos Salvarezza

Definition

Coughing is the removal, by cough, of all material contained within the respiratory system. The normal individual does not expectorate, despite a daily production of secretions in the tracheobronchial tree of about 100 to 150ml. The bronchial secretion is made up of mucin (mucus), water, a small amount of protein, some desquamation cells and macrophages.

Usually, under normal health conditions, this volume of respiratory secretions is mobilized by the cilia of the cells of the bronchial mucosa and the trachea to the glottis and pharynx, being swallowed unconsciously. Only when this physiological amount is exceeded or the bronchial secretion is qualitatively altered, does cough and expectoration appear. The sputum description is important and should be done in terms of color, consistency, quantity, odor, or the presence of blood, pus, or other materials; in such a way that, in a specific clinical context, this helps establish a causal diagnosis of expectoration and establish astudyriate treatment if required.

Pathophysiology. Classification and types of expectoration

In healthy people, the mucous glands of the respiratory tract and the goblet cells of the bronchial epithelium produce around 100ml daily of seromucous secretion separated into 2 superimposed layers: the deep one, the sun, in which the cilia beat, and the superficial one, the gel on which the aspirated particles are deposited.

Taken together, normal cilia and mucus constitute the "mucociliary elevator system" responsible for the clearance of the respiratory tree. The 100ml of secretion are swallowed daily in an insensitive way by a normal person; consequently any elimination of secretions from the respiratory system is abnormal and this symptom is called expectoration. The following characteristics of expectoration should be considered:

1. Quantity: It is dependent on the underlying pathology, as well as the strength of the patient's cough. In the initial stages of an inflammatory process, expectoration is generally scant to increase in periods of state and decline. Very abundant expectoration (sometimes more than 300ml / day) usually indicates the existence of cavities that drain into a bronchus in suppurative processes of the lung or bronchiectasis. This amount of sputum can sometimes not be observed if the patient swallows the sputum (frequent in the female sex), if there is bronchoplegia or obstruction of the drainage bronchus.
2. Viscosity or consistency: This characteristic depends on the amount of water, mucus and debris. Examples:
   1. Fluids: as in acute lung edema
   2. Adherent: with fibrinous molds as in asthmatic flare-ups
   3. Necrotic: as in lung abscesses or necrotic tumors.
3. Odor: if it is fetid and putrid, consider anaerobic infection typical of suppurative processes of the lung or lung abscesses.
4. Color:
   1. Colorless-transparent, mucous expectoration
   2. Greenish-yellow, mucopurulent expectoration typical of bacterial infectious processes of the airway
   3. Rusty, brick-colored expectoration typical of pneumococcal pneumonia
   4. Red, due to the presence of blood in the sputum, with different tints, in the different causes of hemoptysis
   5. Black, in pulmonary anthracosis, typical of heavy smokers or carriers of pneumoconiosis.

According to its macroscopic appearance, expectoration can be classified as follows:

• Mucosa: The sputum, colorless and transparent, can be of different consistency; from very fluid to highly viscous and dense, difficult to remove. It is the result of the exaggerated secretion of goblet cells and mucous glands; Thus they are observed in an initial period of acute tracheobronchitis and is the most characteristic of uncomplicated chronic bronchitis.
• Serosa: It appears as a clear, foamy liquid, slightly yellowish or pale pink, sometimes very abundant. In general, it results from transudation at the alveolar level, and hence its foamy character and its origin in an alveolar edema typical of acute lung edema or bronchioloalveolar carcinoma. Coughing up large amounts of "egg white" sputum is seen in 50% of bronchioloalveolar carcinomas.
• Mucopurulent and purulent:It is characterized by being fluid, opaque, yellow or greenish. It is made up of the elements of pus produced by the peroxidase action of neutrophils on the tracheobronchial secretion before being expectorated. Mucopurulent expectoration varies in its content of pus and mucus and the way in which these components appear mixed; the pus can appear in the form of striae or even of globules. A characteristic aspect is that of the expectoration called "nummular" originated by the tubercular caverns and that can also be observed in suppurations of the lungs, in bronchiectasis and in infected lung tumors. Its characteristic shape is that of a circular (coin-shaped) or oval conglomerate that flattens on the bottom of the container, clearly separated from the rest of the liquid mass of the sputum. The amount of expectoration depends on the nature of the pathological process and the evolutionary period in which it is found: it is absent at the beginning of acute infectious processes and abundant in the periods of state and resolution of acute bronchitis or pneumonia. In contrast, in chronic bronchitis and tuberculosis it is eliminated in large quantities, as well as in bronchiectasis.
• Bloody: It is called "hemoptoic sputum" and constitutes a minimal form of hemoptysis that will be treated later.

Other macroscopic characteristics of expectoration are more specific for certain pathologies:

• Fibrinous clots, bronchial coils and Dittrich plugs: they are evidence of highly viscous and desiccated bronchial secretions.
• The classic creole (pearl sputum) bodies are characteristic of bronchial asthma during the crisis resolution period; they show Leyden crystals, products of the major basic protein released by eosinophils
• Hydratid debris, such as scolex or teeth (hydatidosis)
• Actinomyces grains (actinomycosis)
• Foreign bodies or food debris from previously aspirated materials or from esophagobronchial fistulas;
• Tissue fragments with necrotic remains: typical of excavated carvomit

If the amount of the expectoration exceeds 300ml of pus or fluid of any other nature, the symptom is called vomica. This is characterized by the sudden irruption into the bronchial lumen of a purulent collection until then closed; when it is very abundant, it occurs in the midst of intense coughing and suffocation, and the liquid is expelled in large puffs, sometimes flowing, also through the nose.

In pulmonary suppurations, vomica is a very frequent symptom and the material, depending on the responsible germ, presents very precise characteristics of color and fetidity. The hydatid cyst can also cause vomiting. If it is not complicated, the vomica can be of a clear, crystalline liquid, such as rock crystal, in which fragments of its germinative membrane can sometimes be found: it is then called hydatidoptosis. If, on the other hand, the cyst has become complicated, the vomica presents characteristics similar to those of pulmonary suppurations.

Vomics (Vómica) of pleural, mediastinal or extrathoracic origin, relatively frequent in other times and originating from pleural empyemas, suppurative mediastinitis or amoebic liver abscesses, are currently exceptional, since none of these processes reaches the evolutionary period of softening necessary to produce them.

Whatever the material removed, it must undergo a thorough bacteriological, mycological and cytological examination; it is necessary to respect the techniques for collecting the material under study.

Interrogation and physical examination of the patient

Since expectoration is always accompanied by the cough symptom, the same procedures developed for cough must be followed in the history and physical examination of these patients, with special emphasis on questioning and "observation" of the different types, if possible. expectoration that will guide the etiology and the diagnostic procedure to follow.

Study methodology

The diagnostic methodology of expectoration will depend on the radiological clinical context of the patient. The expectoration of a few days of evolution associated with an acute respiratory infectious process, generally, does not require any complementary procedure.

For expectoration that persists and that is associated with a presumptively infectious process, such as exacerbation of COPD, exacerbated bronchiectasis, acute bronchopneumopathies refractory to treatment, clinical-radiological suspicion of TB, etc., it is essential to carry out a bacteriological examination of sputum; In the case of investigating common germs, one sputum sample is sufficient, and for the investigation of the Koch bacillus, 3 samples are required on successive days to increase the diagnostic yield (serial sputum). For the sputum sample to be of good quality, in order to achieve an adequate bacteriological result, certain requirements must be met. The patient should extract the sample preferably in the morning, fasting, expectorating as deep as possible. You must be without antibiotics for at least the previous 48-72hs. The sample should be sent promptly to the laboratory and processed within 2 hours preferably. Sputum must have more than 25 leukocytes and less than 10 flat epithelial cells per high-magnification field to be suitable for study, otherwise it is contaminated with oral secretions or saliva. Once the sputum sample is obtained, its direct examination is done in a smear under a microscope with Gram staining to distinguish between Gram (+) or (-) germs, which defines valuable information about the most appropriate antibiotics at first. In the case of suspected pulmonary tuberculosis, a Ziehl Nielsen stain will be done to investigate acid-resistant bacilli, characteristic of mycobacteria. After the direct exam,

In cases of expectoration associated with the clinical-radiological suspicion of pulmonary neoplasia, sputum samples can be sent for cytological study to the Pathological Anatomy laboratory (in the same way as when tuberculous etiology is suspected), sending 3 samples on successive days (sputum serial cytology for neoplastic cells). This is a non-invasive method that can sometimes have a high diagnostic yield (especially in bronchioloalveolar carcinoma where there is a large elimination of desquamated neoplastic cells in the sputum).

All the remaining causes of expectoration will be analyzed individually taking into account the clinical-imaging context of the patient to decide the most appropriate diagnostic procedure in order to arrive at the etiological diagnosis of the same.