Apparatus for Independent Ventilation of Two Lungs With Selective Use of Positive End-Expiratory Pressures

This invention relates to apparatus for independent ventilation of two lungs with selective use of positive end-expiratory pressures.

Independent ventilation of two lungs with selective use of positive end-expiratory pressures consists in selection of inspiratory volumes and positive end-expiratory pressures for each of lungs in such a way that their ventilation will be adapted to their perfusion. This method of artificial ventilation ensures better, more effective gas exchange in the lungs during intensive care of patients with acute respiratory disease synchroms than in the case of non-controlled division of inspiratory volume between lungs and use of equal values of positive end-expiratory pressures for both lungs.

Known apparatus for independent ventilation of two lungs with selective use of positive expiratory pressures contains generally two synchronized respirators coupled with lungs by means of a double-lumen bronchial tube, through inspiratory and expiratory branches. Those branches are connected together in two inspiratory-expiratory pairs, each comprising inspiratory and an expiratory branch terminating in common point connected with the bronchial tube. One inspiratory-expiratory pair is connected with one of two conduits of this tube, while second pair with other conduit of bronchial tube.

Apparatus for independent ventilation of two lungs with selective use of positive end-expiratory pressures according to the invention connecting only one respirator with the double-lumen bronchial tube comprises two parallel inspiratory paths and two parallel expiratory paths. Each path is coupled with the double-lumen bronchial tube respectively through the inspiratory and expiratory branches. In one inspiratory path having common point with the expiratory path not provided with a positive end-expiratory pressure valve, a threshold inspiratory valve is placed, connected in series with a pneumatic unidirectional valve.

A pneumatic unidirectional valve is also situated in the inspiratory path having common point with the expiratory path provided with the positive end-expiratory pressure valve.

In both inspiratory paths coupled pneumatic resistors interconnected in parallel are placed.

In the another embodiment two threshold inspiratory valves are placed, in one inspiratory path one threshold inspiratory valve respectively. In each inspiratory path the inspiratory threshold inspiratory valve is connected in series with the pneumatic unidirectional valve. In both expiratory paths the positive end-expiratory pressure valves, are placed.

Moreover, in both inspiratory paths coupled pneumatic resistors interconnected in parallel, are placed in case of need.

The apparatus being the object of invention eliminates the necessity of use of two respirators for realization of independent ventilation of two lungs with the application of positive end-expiratory pressures. Such ventilation is realized using only one respirator.

Object of the invention will be explained in detail in example of preferred embodiment given in a drawing displaying the diagram of the apparatus for independent ventilation of two lungs with selective use of positive end-expiratory pressures.

This apparatus III connects a respirator I with lungs by means of a double-lumen bronchial tube II. The apparatus III contains two parallel inspiratory paths 1 and 2, as well as two parallel expiratory paths 3 and 4. The inspiratory and expiratory paths terminate in respectively in inspiratory 5 and 6 as well as in expiratory 7 and 8 branches, connected in inspiratory-expiratory pairs. In each pair the inspiratory branch 5 with the expiratory branch 7 and the inspiratory branch 6 with the expiratory branch 8 are interconnected. A common point of the inspiratory branch 5 and the expiratory branch 7 is coupled with one of two conduits of the double-lumen bronchial tube II, while a common point of the inspiratory branch 6 and the expiratory branch 8 is coupled with a second conduit of the bronchial tube II.

In the inspiratory paths 1 and 2 connected in parallel coupled pneumatic resistors 9 are placed. The pneumatic resistor in the inspiratory path 1 is connected in series with a pneumatic unidirectional valve 10 and the inspiratory branch 5, while the pneumatic resistor in the inspiratory path 2 is connected in series with a pneumatic unidirectional valve 11, a threshold inspiratory valve 12 and the inspiratory branch 6. In the inspiratory paths 1 and 2 pressure gauges 13 and 14 are placed. In expiratory paths 3 and 4 connected in parallel pneumatic unidirectional valves 15 and 16 are placed. The unidirectional valve 15 is connected in series with a volume meter 17, a positive end-the expiratory pressure valve /PEEP/ 18 and expiratory branch 7, while the unidirectional valve 16 is connected in series with a volume meter 19 and the expiratory branch 8.

A common input of the coupled pneumatic resistors 9 is connected with an inspiratory port .alpha. of the respirator while a common output of the volume meters 17 and 19 is connected with an expiratory port .beta. of the respirator.

The apparatus according to the invention operates as follows. In the inspiratory phase gas outflowing from the inspiratory port .alpha. of the respirator is divided between two inspiratory paths 1 and 2 and flows through the coupled pneumatic resistors 9 and the pneumatic unidirectional valves 10 and 11. Gas flowing through the inspiratory path 1 is directed by means of the inspiratory branch 5 and one of conduits of the bronchial tube to one lung, as during inspiratory phase the expiratory port .beta. of the respirator is closed. Gas flowing through the inspiratory path 2 and the threshold inspiratory valve 12 is directed by means of the inspiratory branch 6 and a second conduit of the bronchial tube II to the other lung. The increase of pressure in the inspiratory branches 5 and 6 during inspiratory phase is measured and indicated by the pressure gauges 13 and 14, respectively. During expiratory phase the inspiratory port .alpha. of the respirator is closed, while the expiratory port .beta. of the respirator is open, resulting in outflow of gases from the lungs. And so gas flows from the one lung through one of conduits of the bronchial tube II via expiratory branch 7, the positive end-expiratory pressure valve /PEEP/ 18, the pneumatic unidirectional valve 15, and the volume meter 17 down to the expiratory port .beta. of the respirator. On the other hand gas flows from the second lung through second conduit of the bronchial tube II via expiratory branch 8, pneumatic unidirectional valve 16 and the volume meter 19 down to the expiratory port .beta. of the respirator. The pneumatic unidirectional valves 10, 11, 15, 16 placed in definite places of examined system of connections of the apparatus according to the invention determinate the desired direction of a flow of gases, as described above, between the respirator and the lungs in individual phases of end-respiratory cycle /i.e. during inspiratory and expiratory phases/, enabling both the realization of independent ventilation of each lung and establishing positive end-expiratory pressure in one of the lungs only /by means of PEEP 18 valve/. The threshold inspiratory valve 12 placed in the inspiratory path 2 of the second lung divides ventilation between the lungs and compensate the change of gas flow rate during the inspiratory phase in inspiratory path 1, occuring after introduction of a positive end-expiratory pressure by means of PEEP valve 18, or during dynamic changes of the values of mechanical parameters of a patient respiratory system. The aim of the threshold valve 12 is also to pattern different inspiratory gas flows to each lung, which according to clinical findings, are optimal for gas exchange in the lungs in cases of acute respiratory failure of a patient. Thus a gas flow through the inspiratory path 1 has a decreasing pattern during an inspiratory phase, and a gas flow through the inspiratory path 2 has an increasing one. By means of coupled pneumatic resistors 9 the gas flow may be diminished in one inspiratory path, and at the same time increased in the other one.

In another embodiment the apparatus according to the invention is additionally provided with a positive end-expiratory pressure valve PEEP 20, used for setting the positive end-expiratory pressure in the expiratory branch 8 /and therefore in the lung coupled with this branch through the conduit of the bronchial tube/, and also provided with a threshold inspiratory valve 21, compensating the changes of gas flow rate during inspiratory phase in the inspiratory path 2.

The above embodiment apart from the possibility of providing an independent ventilation of each lung enables the application of a positive end-expiratory pressures independently to both lungs.