Pathogenesis and hemodynamic disorders
The development of a paroxysmal cough attack begins with the formation of a persistent focus of irritation in the CNS. Impulses from the receptor apparatus of the larynx enter the brain, where they directly affect the functioning of the respiratory and autonomic centers. A sharp decrease in the excitation threshold occurs: now any, even the most insignificant and non-specific irritation, is capable of triggering a severe attack of spasmodic cough.
The cough attack triggers a cascade of hemodynamic disorders:
- Pronounced spasm of the muscles of the larynx and bronchial tree occurs.
- Spasm of peripheral blood vessels develops reflexively.
- Blood stasis forms in the superior vena cava system.
- As a result, circulatory disorders of central origin progress, leading to systemic hypoxia.
Clinical manifestations
A classic paroxysmal cough attack follows a strict scenario. First, a series of short, jerky exhalations occurs, following one after another. Then a convulsive, deep breath takes place. This agonizing episode ends with the release of very viscous sputum or reflex vomiting.
It is extremely important to remember the features of the course in infants. In infancy, typical paroxysmal cough is completely absent. Instead, the disease manifests with the development of apnea (cessation of breathing), which poses a direct threat of asphyxia.
Pathological Anatomy
Macroscopic picture The mucous membrane of the upper respiratory tract appears markedly hyperemic (plethoric) and abundantly coated with viscous mucus. The lungs are in a state of emphysematous bloating, which in severe cases can lead to spontaneous pneumothorax. A typical marker of the disease, detected upon examination of the oral cavity, is the presence of characteristic tears and small ulcers on the lingual frenulum (the result of trauma against the teeth during coughing).
Microscopic picture
- Respiratory tract: the picture of serous inflammation predominates in the larynx, trachea, and bronchial tree.
- Pulmonary parenchyma: tissue edema, vascular plethora, foci of atelectasis, and compensatory hyperplasia of peribronchial lymph nodes are detected.
- Central nervous system: edema and small perivascular hemorrhages are recorded in the brain against the background of hypoxia.
Complications and outcome
The disease itself lasts a long time — from 1.5 to 3 months. The main structural complications of pertussis are associated not so much with the pathogen itself, but with the addition of a secondary infection. The overlay of bacterial flora leads to the development of severe panbronchitis and peribronchial pneumonia.
Currently, the outcome of the disease is predominantly favorable. The only serious exception is the risk of death in newborns from developing asphyxia during episodes of apnea.
Briefly: answers to topical questions
What microorganism is the etiological agent (pathogen) of pertussis?
The etiological agent of pertussis is the pertussis bacillus (Bordetella pertussis). It is a small, Gram-negative, non-motile bacterium with the following characteristics:
- Respiration type — obligate aerobe.
- Serotypes — has 4 main serological variants, significantly differing in virulence level.
- Resistance — possesses extremely low resistance in the external environment.
Historically, this microorganism was named the Bordet-Gengou bacillus in honor of the scientists who isolated it in 1906.
What specific changes in the clinical blood count are characteristic of the paroxysmal cough period in pertussis?
The clinical blood count in pertussis reveals lymphocytosis of infectious etiology. To determine this, a complete blood count with a leukocyte formula differential must be performed. Microscopy of smears evaluates the lymphoid lineage, which has the following features:
- Nucleus — very large, round or kidney-shaped, dense structure.
- Size — the nucleus occupies almost the entire cell.
Specific blood changes characteristic exclusively of the paroxysmal cough period are not described in the provided sources.
What extrapulmonary mechanical complications can occur due to severe coughing in pertussis, aside from tears of the lingual frenulum?
As a result of a sharp increase in intrathoracic and intra-abdominal pressure at the height of spasmodic coughing, the following mechanical complications may occur:
- Emphysema of the subcutaneous tissue and mediastinum.
- Umbilical hernia.
- Rectal prolapse.
Spontaneous pneumothorax also refers to mechanical complications.
The clinical picture of a classic attack can be remembered in three steps: «Series of exhalations → Convulsive inspiration → Viscous sputum/vomiting».
Class and exam questions
How does pertussis manifest in infants?
In infants, typical paroxysmal cough is absent. The disease presents as life-threatening episodes of apnea (cessation of breathing) and threatens the development of asphyxia.
What macroscopic sign in the oral cavity is considered typical for pertussis?
A typical sign is micro-tears and small ulcers on the lingual frenulum, which occur due to constant trauma during severe coughing fits.
Why do hypoxia and CNS damage develop in pertussis?
Laryngeal and bronchial spasm causes peripheral vascular spasm and stasis in the superior vena cava system. This disrupts central circulation, causing hypoxia, cerebral edema, and perivascular hemorrhages.
What else to study on this topic
- Morphological differences of serous inflammation in the trachea from diphtheritic inflammation
- Mechanisms of spontaneous pneumothorax formation against the background of emphysema during coughing
- Pathomorphology of peribronchial pneumonia as the main complication
- Features of the microscopic picture of perivascular hemorrhages in brain tissue
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