Device and method for assisting a cough

The invention provides a device (11) for assisting a cough, based on an oscillation pressure. The oscillation pressure causes a periodic oscillation airflow in a lung system and the periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow. The device (10) comprises a controlling unit (11), and the controlling unit (11) comprises:

FIELD OF THE INVENTION

The invention relates to a device and a method for assisting a cough.

BACKGROUND OF THE INVENTION

In some medical conditions, such as, Chronic Obstructive Pulmonary Disease (COPD), Asthma, and Cystic Fibrosis (CF), an excessive volume of viscoelastic material, which is called lung mucus, may be built up in the lung of a patient. Excessive lung mucus is known to cause severe problems due to an increased chance of lung infections, declined lung function, reduced effect of inhaled medicine etc.

The removal of excessive lung mucus is therefore highly beneficial to the health status of a patient. Normally patients are instructed to cough in special ways (called directed cough) or breathe in special patterns (called Huffing), but both often do not result in the desired effect.

Currently, an oscillation device to assist a cough is provided for Cystic Fibrosis and Chronic Obstructive Pulmonary Disease patients in order to increase lung mucus clearance. The oscillation can be air oscillation pressure transmitted to a lung through a mouth for causing the airways of a lung to oscillate. The oscillation also can be mechanical oscillation pressure transmitted to a lung through the ribcage and muscles, like for example High Frequency Chest Wall Oscillations (HFCWO).

However, based on the current oscillation device, when oscillation is generated in the airways of a lung, a periodic oscillation airflow is generated, and the direction of the periodic oscillation airflow may be different from the direction of cough (exhalation) airflow during a cough, which may impede the cough.

SUMMARY OF THE INVENTION

An object of this invention is to provide a device for effectively assisting a cough.

The device for assisting a cough, based on oscillation pressure, comprises a controlling unit. The oscillation pressure causes a periodic oscillation airflow in a lung system and the periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow. The controlling unit comprises:a first determining unit for determining whether an inhalation of the lung system is complete, so as to control a valve which is to be closed for isolating the lung system from the external environment,a second determining unit for determining whether an internal air pressure in the lung system is larger than a pre-defined pressure threshold, anda detecting unit for detecting the start of the oscillation exhalation airflow, so as to control the valve which is to be opened for starting a cough.

The advantage is that the device of the invention can assist a cough more effectively.

The invention also provides a method corresponding to the device for assisting a cough.

The invention further provides a computer program used in the method of assisting a cough.

Detailed explanations and other aspects of the invention will be given below.

The same reference numerals are used to denote similar parts throughout the Figures.

DETAILED DESCRIPTION

FIG. 1schematically shows a device for assisting a cough according to an embodiment of the invention.

The device10is used for assisting a cough, based on an oscillation pressure. The device10comprises a controlling unit11, an oscillation unit12for oscillating a lung system to cause a periodic oscillation airflow in the lung system, and a valve13controlled by the controlling unit11, which valve is to be opened or closed for, respectively, connecting the lung system to the external environment through a mouth or isolating the lung system from the external environment.

The oscillation unit12may be integrated together with the controlling unit11and included in the device10. For example, the oscillation unit12is an air oscillation pressure unit. The air oscillation pressure provided by the oscillation unit12is transmitted to the lung system through a mouth for causing the airways of a lung system to oscillate.

Alternatively, the oscillation unit12may be separate from the device10, and not integral with the controlling unit11. For example, the oscillation unit12is a mechanical pressure oscillation unit. The mechanical oscillation pressure is transmitted to the lung system through the ribcage and muscles, like for example High Frequency Chest Wall Oscillations (HFCWO).

The oscillation unit12generates an oscillation pressure (shown as OP inFIG. 1) to oscillate the airways of the lung system, and the oscillation pressure causes a periodic oscillation airflow in the airways of the lung system. The periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow.

The controlling unit11comprises a first determining unit111for determining whether an inhalation of the lung system is complete, so as to control the valve which is to be closed for isolating the lung system from the external environment, a second determining unit112for determining whether an internal air pressure (shown as IAP inFIG. 1) in the lung system is larger than a pre-defined pressure threshold, and a detecting unit113for detecting the start of the oscillation exhalation airflow (shown as OEA inFIG. 1), so as to control the valve13which is to be opened for starting a cough.

The valve13may be integrated with the controlling unit11so as to be opened or closed based on the controlling action by the controlling unit11. If the valve13is controlled so as to be closed based on a closing signal (shown as CS inFIG. 1) from the first determining unit111, the lung system is isolated from the external environment and the external air cannot be inhaled into the lung system; if the valve13is controlled so as to be opened based on an opening signal (shown as OS inFIG. 1) from the detecting unit113, mucus and air (shown as A&M inFIG. 1) in the airways of the lung system can be coughed/exhaled to the external environment, and external air (shown as A inFIG. 1) can be inhaled into the airways of the lung system.

When the internal air pressure of the lung system is larger than the pre-defined pressure threshold, the lung system is ready to cough; if the detecting unit113detects the start of the oscillation exhalation airflow, the valve13is controlled so as to be opened; if the valve13is open, the lung system starts to cough when the oscillation exhalation airflow starts according to the periodic oscillation airflow. The pre-defined pressure threshold may be set by a user, and the pre-defined pressure threshold may be different for different people.

The first determining unit111may be intended to determine whether the inhalation of the lung system is complete when the velocity of an inhalation airflow (shown as VIA inFIG. 1) in the lung system is lower than a pre-defined velocity threshold. The oscillation exhalation airflow is synchronous with the exhalation airflow of the cough at least at the beginning of the cough. At the beginning of the cough, the cough causes a peak exhalation airflow in the airways of the lung system. The pre-defined velocity threshold may be set by a manufacturer of the device10or a user, and the velocity threshold can be zero or any other value near zero.

The inhalation airflow may comprise the inhalation airflow caused by the inhalation of the lung system only. Alternatively, the inhalation airflow may comprise the inhalation airflow caused by the inhalation of the lung system and the oscillating inhalation airflow caused by the oscillation pressure.

The first determining unit111may comprise a sensor for collecting the velocity of inhalation air in airways of the lung system, and the second determining unit may comprise a sensor for collecting the internal air pressure of the lung system. Alternatively, the sensor of the first determining unit111may be integrated together with the sensor of the second determining unit112.

FIG. 2is a diagram for illustrating a correlation between the velocity of an exhalation airflow of a cough and time. At the beginning of a cough, for example, at 0.03 seconds, the velocity of the exhalation airflow is almost 10 l/s (liter/second).

FIG. 3is a waveform for illustrating a correlation between the velocity of an oscillation airflow and time. The oscillation pressure causes a periodic oscillation airflow in the airways of the lung system, and the oscillation exhalation airflow of the oscillation airflow and the oscillation inhalation airflow of the oscillation airflow periodically change. In the first 0.05 s, the oscillation pressure causes an oscillation exhalation airflow (shown as OEA inFIG. 3) in the airways of the lung system, and in the next 0.03 s, the oscillation pressure causes an oscillation inhalation airflow (shown as OIA inFIG. 3) in the airways of the lung system. The period of the periodic oscillation airflow can be 0.1 s, 0.2 s, 0.3 s etc.

In an embodiment of the invention: firstly, the internal air pressure of the lung system is larger than the pre-defined pressure threshold, and the lung system is ready to cough; secondly, in a periodic oscillation airflow, an oscillation exhalation airflow starts; thirdly, the valve13is opened; fourthly, the lung system starts to cough and causes a peak exhalation airflow in the airways of the lung system at the beginning of the cough, for example, at 0.03 s, and, synchronously, in the periodic oscillation airflow, an oscillation exhalation airflow starts.

FIG. 4schematically shows a mechanical pressure oscillation (shown as MOP) applied to a lung system, and an air pressure (shown as AP) in the lung system is detected through a mouth according to an example of the invention.

FIG. 5schematically shows an air oscillation pressure (shown as AOP) applied to a lung system through a mouth, and an air pressure (AP) in the lung system is detected through the mouth according to another embodiment of the invention.

FIG. 6is a flow chart for illustrating a method of assisting a cough according to an embodiment of the invention. The method serves to assist a cough, based on an oscillation pressure, and the oscillation pressure causes a periodic oscillation airflow in the airways of a lung system. The periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow. The method comprises the following steps.

A step is carried out to determine62whether an inhalation of the lung system is complete, so as to control a valve13which is to be closed for isolating the lung system from the external environment. The determining step62is intended to determine whether the inhalation of the lung system is complete when the velocity of an inhalation airflow in the lung system is lower than a pre-defined velocity threshold.

A next step is carried out to determine63whether the internal air pressure in the lung system is larger than a pre-defined pressure threshold.

A following step is carried out to detect64the start of the oscillation exhalation airflow, so as to control the valve13which is to be opened for starting a cough. The oscillation exhalation airflow is synchronous with the exhalation airflow of the cough, at least at the beginning of the cough.

The method further comprises a step of generating61the oscillation pressure to oscillate the lung system so as to cause the periodic oscillation airflow in the airways of the lung system.

When the internal air pressure of the lung system is larger than the pre-defined pressure threshold, the lung system is ready to cough; in the periodic oscillation airflow, if an oscillation exhalation airflow starts, the valve13is controlled to open; if the valve13is open, the lung system starts to cough when an oscillation exhalation airflow starts according to the periodic oscillation airflow.

The determining step62may be intended to determine whether the inhalation of the lung system is complete when the velocity of an inhalation airflow in the lung system is lower than a pre-defined velocity threshold. The oscillation exhalation airflow is synchronous with the exhalation airflow of the cough, at least at the beginning of the cough

The inhalation airflow may comprise the inhalation airflow caused by the inhalation of the lung system only. Alternatively, the inhalation airflow may comprise the inhalation airflow caused by the inhalation of the lung system and the oscillating inhalation airflow caused by the oscillation pressure.

A computer program used in the method of assisting a cough, based on an oscillation pressure, wherein the oscillation pressure causes a periodic oscillation airflow in a lung system and the periodic oscillation airflow comprises an oscillation exhalation airflow and an oscillation inhalation airflow, the method comprising the steps of:

determining62whether an inhalation of the lung system is complete, so as to control a valve (13) which is to be closed for isolating the lung system from the external environment,

determining63whether an internal air pressure in the lung system is larger than a pre-defined pressure threshold, and

detecting the start of the oscillation exhalation airflow, so as to control the valve which is to be opened for starting a cough.

The computer program used in the method of assisting a cough, the method further comprising a step of generating the oscillation pressure to oscillate the lung system, so as to cause the periodic oscillation airflow in the airways of the lung system.

The oscillation frequency corresponding to the oscillation pressure may be in a range of 10-20 Hz.