Гостра дихальна недостатність

Acute respiratory failure (ARF) is a syndrome, characterized by inability of the respiratory system to support effective and continuous gas exchange — oxygenation of blood and elimination of carbon dioxide to the environment. ARF is a medical emergency, potentially complicating most respiratory pathologies. The syndrome is globally widespread with increased mortality rate, high rate of intensive care unit admission and considerable inpatient costs. Most common causes of ARF include acute pneumonia, chronic obstructive lung disease, chronic cardiac insufficiency and acute respiratory distress syndrome. There are two main types of ARF: type I (hypoxemic) respiratory failure (when respiratory system is unable to supply enough oxygen to blood and tissues), and type 2 (hypercapnic) respiratory failure (when carbon dioxide accumulates in the body owing to insufficient alveolar ventilation). Acute hypercapnia usually develops as a consequence of affected central nervous system respiratory drive (e.g. structural lesions of respiratory center, drug toxicities), impaired chest bellows (e.g. myasthenia, thoracic trauma, neuromuscular blocking agents) or airway component (e.g. bronchospasm, chronic obstructive pulmonary disease exacerbation). Purely hypoxemic respiratory failure results from deficient alveolar component, when alveolar flooding (e.g. in pneumonia, acute respiratory distress syndrome, cardiogenic pulmonary edema) or atelectasis prevents oxygen from reaching pulmonary circulation. In severe ARF emergency measures of diagnosis and treatment should be implemented simultaneously in order to prevent progression of respiratory failure and development of further life-threatening complications. The diagnosis of ARF is commonly suspected based on clinical presentations, whereas confirmation of the diagnosis and differentiation between hypoxemic and hypercapnic respiratory failure is based mainly on arterial blood gas analysis and pulse oximetry saturation readings. Conventional anterior-posterior chest radiography and computed tomography scanning are the most commonly utilized imaging methods to detect underlying pulmonary di­seases. General principles of supportive care for ARF patients are similar irrespective of the underlying respiratory patho­logy. These include: 1) airways opening and protection (head tilt and chin lift, jaw thrust, oropharyngeal and nasopharyngeal airways, endotracheal intubation, laryngeal mask airway, eso­phageal-tracheal airway, percutaneous cricothyroidotomy, fiber-optic intubation); 2) oxygenation (oxygen supplementation through face mask or nasal cannula when patient is breathing spontaneously, administration of oxygen in gas mixture during mechanical ventilation); and 3) ventilator support (mouth-to-mouth, mouth-to-nose, mouth-to-face mask breathing, bag-valve-mask, mechanical ventilators). Improvement of current medical technologies and principles of respiratory support may result in overall trend of decrease in morbidity and mortality from ARF. However, the probability of favorable outcome in ARF patients also considerably depends on physicians’ ability to recognize the syndrome early and to introduce appropriate measures to support and restore respiratory system function. Based on present-day medical knowledge in the field of emergency and critical care, the article delineates main aspects of ARF pathogenesis, diagnosis and treatment. In particular, the paper describes key pathophysiologic principles of ARF deve­lopment depending on the type of respiratory system structural component involved in the pathologic process, criterions of ARF diagnosis and main principles of supportive care, inclu­ding measures of airway opening and modern methods (modes) of ventilatory support.