New Modes of Ventilation Realized in the Servoventilator Chirana

Abstract

The servoventilator allows, apart from the standard modes, the application of several special modes of artificial lung ventilation (ALV) and the use of some new set-up features of the servoventilator. In his first part, the author describes and analyzes the so-called two-level ventilation 2-level+PS, which constitutes one of the progressive ventilation modes, at some other ventilators called as BiPAP, Bilevel, BiPAP-SIMV. This mode allows a patient to breathe in two pressure levels (Ppc/PEEP), whereas in the lower pressure level (PEEP) it allows the effective ventilatory support of spontaneous breathing by the pressure support (PS) mode. In this case, the mode is identical to the BiPAP-SIMV one. Further, the author describes a new mode of three-level ventilation (multilevel ventilation, MLV), in which patient breathes in three programmed levels of pressure that are PEEP, Phigh, and Ppc. This ventilation mode allows one to improve gas distribution in the non-homogenous injured lung. The further new mode that is implemented in the ventilator is so-called continuous flow ventilatory support (CFVS). It is unique in such a feature that catheter is introduced into the trachea of a spontaneously breathing patient, through which the gas flow from the ventilator flows and by washing out the dead space it decreases its volume and increases alveolar ventilation, without any need to intubate the patient or to perform relaxation. The patient is at his full consciousness. The author also describes the functionality of the new mode of intelligent ventilation regulation in pressure modes, a so-called minute ventilation servosystem that after the set-up of ventilatory parameters maintains the patient’s minute ventilation that is set by a doctor. Further, the author describes an adjustable Bias flow that is advantageous in such a feature that the negative inspiration peaks in the hyperventilating patient are eliminated and, thus, significantly relieves the work of an assistor. The ventilator also keeps at its disposal a monitor of mechanical properties of the lung, indicating the static compliance, airways resistance, inadvertent (auto) PEEPi and alveolar pressures. The Q/V and V/P loops are also naturally included. In conclusion, the author draws attention to the fact that the ventilator does not require compressed air for its operation and that it constitutes a step forward in the new modes of ALV. Key words: multilevel ventilation, lung mechanical properties, PEEPi, Cst, Bias flow, CFVS.