Modern strategies of adaptation to the respiratory support as a way to reduce self-induced lung injury (SILI)

Abstract

Background. The success of respiratory support depends on the effectiveness of improving gas exchange, reducing lung damage, and adaptation of the respirator. Reduction of lung damage has previously been reported in the context of ventilator-associated injury: barotrauma in case of high plateau pressure and driving pressure, volume trauma in case of large tidal volume, atelectasis trauma due to the cyclic collapse of lungs on exhalation and opening on inspiration.
 Objective. To describe the features of lung damage during mechanical lung ventilation (MLV) and the possibility of its prevention.
 Materials and methods. Analysis of literature sources on this topic.
 Results and discussion. The main causes of “air hunger” breathing type and shortness of breath include hypoxia, acidosis, increased anatomical and functional dead space, psychomotor agitation and fear. Metabolic acidosis is compensated by hyperventilation and respiratory alkalosis, but it is treated by improving oxygenation. High-flow oxygenation helps to leach CO2 from the dead space. Psychomotor agitation and pain aggravate shortness of breath, so all components of these processes should be influenced by effective analgesia, providing the patient with a comfortable body position (especially obese people), ensuring the absence of hunger and thirst, creating conditions for night sleep and more. If all these measures are taken, but the patient’s agitation is maintained, sedation should be considered. Propofol and dexmedetomidine are increasingly used for short-term sedation. Approaches to sedation have been changing abroad in recent years. First, non-pharmacological methods are used and only then – pharmacological ones. First of all, it is recommended to achieve analgesia, and then – sedation. It is advisable to maintain moderate sedation (from 0 to -2 on the RASS scale) and avoid deep sedation (from -3 to -5 points on the RASS scale). Sedation should be stopped each morning for the wake-up test and the respirator quitting test. To improve the immediate consequences of treatment (duration of MLV and stay in the intensive care unit), it is advisable to minimize the use of benzodiazepines and prefer propofol or dexmedetomidine. The depth of sedation should be constantly monitored, however, even experienced physicians may not always be able to detect asynchrony and excessive sedation. Asynchrony is associated with the increased mortality and prolonged weaning. To assess the intensity of the patient’s respiratory effort, the index of rapid shallow breathing, the maximum vacuum in the airways and the pressure in 0.1 second after the start of the breathing attempt are used. If the latter exceeds 3.5 cm H2O, it indicates the excessive respiratory effort of the patient (Telias I. et al., 2020).
 Conclusions. 1. The term “self-induced lung injury” has become widely used in the practice of anesthesiologists. 2. The need for respiratory support is determined primarily by the patient’s breathing efforts. 3. The ability to timely identify and respond to asynchrony helps to avoid self-induced lung damage.