"The above pressure profile may be repeated to replicate a second cough, or the device may adopt another profile in which the patient undergoes one (or more) cycle of regular breathing before undertaking another cough cycle.
"It is another advantage of a rotary proportional solenoid valve that the operational positions, i.e. the extremes of its reciprocating movement, can be varied. Thus, it can be arranged that the valve move further towards the inlet side of the pump than the outlet side of the pump, or vice versa. Also, it can be arranged that the valve dwells for a longer period of time at its operational position at the inlet side of the pump than at its operational position at the outlet side of the pump. In this way, the value of the negative pressure in the breathing tube will exceed the value of the positive pressure, and the average pressure over a cycle will be lower than atmospheric pressure. The average pressure could alternatively be greater than atmospheric if desired, and the average could change from cycle to cycle. For example, a cough programme could comprise a chosen number of regular breathing cycles (with gradual changes between positive and negative pressures) with an average pressure slightly higher than atmospheric, followed by a cough cycle during which the average pressure is lower than atmospheric pressure.
"The indicator is provided for the patient to synchronise his or her breathing with the device, the cough function being better simulated if the patient is trying to breathe out when the device switches from positive pressure to negative pressure.
"Desirably, the device has two outlets, one connected to the breathing tube, and another vented to exhaust. Desirably also, when the inlet side of the pump is connected to the breathing tube the outlet side of the pump is connected to exhaust, and vice versa. This minimises or avoids any pressure build-up, or vacuum build-up, within the device.
"Preferably, the output of the device is variable, i.e. the treatment device can be adjusted to vary the difference between the positive and negative pressures. Ideally, the pressure range may be varied between substantially zero and 60 cm of water (6,000 Pa). Preferably also the positive pressure can be adjusted independently of the negative pressure, i.e. the positive pressure can be adjusted from approximately 0 to 6,000 Pa and the negative pressure can be independently adjusted from approximately 0 to 6,000 Pa.
"Desirably, the period of the cycles of operation, and the individual stages within each cycle, are variable. Preferably, the inspiration period (i.e. positive pressure within the breathing tube) can be adjusted between around 0 and 7 seconds, and the exsufflation period (i.e. negative pressure within the breathing tube) can be adjusted (dependently or independently) between around 0 and 7 seconds. Ideally, both inspiration and exsufflation periods can be adjusted independently from zero to around 5 seconds.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
"The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:
"FIG. 1 shows a schematic representation of the treatment device of the present invention;
"FIG. 2 shows a perspective view of the valve of the device;
"FIG. 3 shows an end view of the valve;
"FIG. 4 shows a section along the line A-A of FIG. 3;
"FIG. 5 shows a side view of the valve;
"FIG. 6 shows a section along the line B-B of FIG. 5;
"FIG. 7 shows an exploded view of the valve;
"FIG. 8 shows an underside view of the valve; and
"FIG. 9 shows a detailed view of the valve member."
For the URL and additional information on this patent application, see: Davis,
Keywords for this news article include: Patents, Treatment, Respiratory Disease.
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