The high-line nasal cannula (HFNC) is usually used at treatment of hypoxemic respiratory insufficiency and is connected with бóльшим the number of days without connection to the ventilator and lower mortality in comparison with a standard oxygenotherapy or noninvasive ventilation.
Nevertheless, use of a high-line nasal cannula with a koronavirusny disease - 2019 (COVID-19) is difficult to therapy of patients in connection with the increased risk of distribution of microparticles (especially during fits of coughing), possible exhaustion of a reserve of oxygen and concern on the fact that it will hardly change natural process of viral pneumonia.
These factors led to appeals to refuse use of HFNC in favor of an early intubation. Though these doubts also are reasonable, they can have certain consequences at a present pandemic that is connected with growth of patients which needs an intensive care and possible development of the situation when there are not enough devices for carrying out IVL for all. Implementation of the hospital rules ordering carrying out an early intubation of patients with COVID-19 will accelerate exhaustion and other resources in intensive care units and an intensive care (ORIT), including sedative drugs and human resources. And, at last, reduction of the threshold of a possibility of carrying out an intubation and inclusion in ORIT hides true severity of a disease and distorts pandemic model.
The appearing data demonstrate that at patients with COVID-19 the atypical acute respiratory distress syndrome (ARDS) with rather well kept mechanics and komplaynsy lungs, despite a heavy anoxemia because of fraction of the shunt develops. It is also in addition known that the pronpozition can improve saturation by oxygen and reduce fraction of the shunt. Therefore a number of authors now supposes that in case of treatment of patients without the strengthened breath work use of a cannula of HFNC will be able to provide oxygen requirement, at the same time allowing patients to change position of the body without assistance, independently passing into a pronpozition (situation on a stomach). The problem of the additional generation of aerosol provoked by HFNC can be partially solved due to acceptance of the following measures: the surgical mask put on the patient for restriction of range of distribution of particles, the strengthened set of individual protection equipment for personnel, grouping of patients and also use of rooms with negative pressure.
In recently received report from Italy two phenotypical manifestations of the pneumonia caused by COVID-19 are described. Initially at many patients the heavy anoxemia in the absence of an asthma and preservation of a komplayens of lungs, with a small mass of lungs, a low ratio of ventilation / perfusion (V/Q) and a low rekrutiruyemost of lungs is shown (defined as a L-phenotype). Over time at some of these patients more classical phenotype of ORDS which is characterized by a low komplayens of lungs, high mass of lungs, the considerable shunt from right to left and a high rekrutiruyemost of lungs develops (defined as a H-phenotype). The alleged cause of emergence of an anoxemia in case of a L-phenotype consists in dysregulation of pulmonary perfusion and loss of hypoxemic vasoconstriction. It is known that dorsal departments of lungs are characterized by a large amount of pulmonary fabric and more developed vascular network that leads to lower local pulmonary resistance and weaker hypoxemic pulmonary vasoconstriction in view of the raised endothelial expression of nitrogen oxide. Pronpozition allows to reach more hypodispersion of pulmonary fabric between dorsal and ventral axes that results in more uniform alveolar architecture. Moreover, it also promotes more hypodispersion of pulmonary perfusion.
Saturation improvement by oxygen can also restore hypoxemic pulmonary vasoconstriction which is broken at lower levels of saturation by oxygen, further improving V/Q ratio. And, at last, the improved saturation by oxygen, perhaps, will prevent deterioration in an asthma, and redistribution of pulmonary fabric at independent acceptance of a pronpozition will change relationship between tension and deformation in a lung and intratorakalny forces, slowing down forming of a fluid lungs and progressing of a disease from L to a H-phenotype.
In addition to preservation of capacities of IVL in the conditions of load of resources, the described method of respiratory therapy can find important application in the countries with limited resources where more ORIT difficult technologies can be inaccessible.