Definition of indications for carrying out invasive ventilation of the lungs at a koronavirusny infection has a number of features in comparison with other pathology. At an early stage of a course of a disease, in case of his lungs and medium-weight forms the need for IVL usually is absent and the sufficient level of oxygenation is reached by means of an oxygenotherapy, a high-line naznalny oxygenotherapy or noninvasive ventilation of the lungs. However, in case of progressing of a disease and development of respiratory insufficiency, the need for invasive ventilation of the lungs can become obvious.
For implementation of invasive ventilation of the lungs, as a rule, carry out a trachea intubation, and further carry out a tracheostomy if long IVL is planned.
Indications to an intubation at patients with COVID-19 following:
Anoxemia (SpO2 less than 92%), despite the carried-out high-line oxygenotherapy or noninvasive ventilation in a pron-position with oxygen concentration of 100%;
Exhaustion of forces of the patient against the background of high-line nasal oxygenation or NIVL in a pron-position with oxygen concentration of 100%;
Increase of movements of a thorax or participation of auxiliary respiratory muscles, despite an oxygenotherapy or NIVL in a pron-position with oxygen concentration of 100%;
Oppression of consciousness or excitement, hypoxemic encephalopathy;
Apnoea or its pathological forms;
Unstable hemodynamics at the patient.
Features of IVL at a koronavirusny infection
IVL serves for ensuring adequate gas exchange, a raspravleniye and stabilization of kollabirovanny alveoluses and also provides minimization of potential injury of lungs. The strategy of use of IVL at COVID-19 in general is based on the clinical recommendations devoted to treatment acute respiratory a distress syndrome of adult (ORDS), at the same time there are certain features connected with specific impact of a koronavirusny infection on pulmonary fabric. In particular, allocate two possible situations: malorekrutabelny lungs and rekrutabelny lungs.
In the presence of malorekrutabelny lungs the patient has centers of injury of alveoluses or the centers of consolidation on at a computer tomography. When carrying out IVL plateau pressure more than 30 cm w.g., static pliability of a respiratory system of 40 ml/cm w.g. is defined. above. In this situation the REER approximate values — 10–12 cm w.g.
If the patient has rekrutabelny lungs (as at ORDS), then specific drain injuries of alveoluses like opaque glass and consolidation, dorsal atelectases and also a picture of "a wet sponge" on KT take place. At respiratory monitoring during IVL plateau pressure more than 30 cm w.g., static pliability more than 40 ml/cm w.g. is defined. Approximate PEEP values for this situation — 12–20 cm w.g. depending on a rekrutabelnost of alveoluses and body mass index. In general, the rekrutabelnost of alveoluses and body mass index is higher, the REER is higher.
Carrying out safe IVL is possible as in the modes with management on pressure (PCV), and in the modes with management on the volume (VCV). But the IVL modes with management of an artificial breath on pressure are more usual for the majority of intensivist. When carrying out ventilation with control on volume it is desirable to use the descending form of an inspiratory stream which provides the best distribution of gas in lungs and smaller peak pressure in respiratory tracts. There are no convincing data on advantage any of the auxiliary modes of respiratory support in literature yet. It is necessary to seek to depart from use of the compulsory modes of respiratory support as soon as possible and if it allows a clinical situation, to pass to the modes of assisted ventilation.
A part of patients with PaO2/FiO2 is higher than 200 have some. at emergence of independent respiratory attempts after reversion of a mioplegiya it is recommended to switch over to completely auxiliary mode of ventilation (in the majority of fans it is called PSV) for improvement of distribution of gas, prevention of an atelektazirovaniye and an atrophy of a diaphragm. Here it is necessary to consider attentively behavior of the patient, a respiratory rhythm, lack of an asthma and participation in the act of breath of auxiliary muscles which can demonstrate that to the patient the level of support which is provided by this mode of ventilation suffices.
At patients with ORDS owing to COVID-19 when carrying out mechanical ventilation of the lungs it is sometimes expedient to apply not inversion of a ratio of a breath to an exhalation. It is necessary for more hypodispersion of respiratory mix in lungs and also decrease in negative influence of IVL on an afterload of a right ventricle. At the same time it must be kept in mind that routine use of an inverse ratio of a breath to an exhalation is not recommended and it is necessary to avoid an incomplete exhalation. By means of adjustment of frequency of ventilation provide achievement of a normocapnia.