Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1997-06-12
2000-02-15
Lewis, Aaron J.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820423, A61M 1600
Patent
active
060240881
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a breath synchronization control unit for use in a gas feeder, which is capable of supplying a gas (an oxygen gas) in synchronization with the breath.
BACKGROUND ART
When patients suffering from a chronic respiratory decease are caused to inhale an oxygen gas, it is unsuitable to supply the oxygen gas continuously, because some resistance against the expiration of the patient is generated due to the pressure of oxygen gas supplied during the expiration, and there is a loss of oxygen gas not inhaled by the patient. For this reason, there has been developed such a technique that an oxygen gas is permitted to be supplied only upon the inhalation by detecting the breath timing of the patient.
For example, Japanese Patent Application Laid-open No. 270170/87 discloses the technique in which a breath sensor containing a pyroelectric element is disposed in a nose cannula attached to a nose of the patient to control the supply of oxygen gas in response to electric signals from the breath sensor. In this technique, the change in temperature in the nose cannula caused by the breath of the patient is detected by the pyroelectric element to generate corresponding electric signals. When the level of the electric signals exceeds a predetermined trigger level for the inhalation, the electromagnetic valve is opened to supply oxygen gas to the nose cannula. Also, when the level of the electric signal exceeds another trigger level for the Expiration, the electromagnetic valve is closed to interrupt the supply of oxygen gas.
In addition, Japanese Patent Application Laid-open No. 143082/88 discloses the technique further developed from the afore-mentioned technique, in which at least one electromagnetic valve is provided in a nose cannula to control the supply of oxygen gas by opening and closing operations thereof in response to electric signals generated from a breath sensor. In this technique, the supply of oxygen gas can be carried out with an excellent responsibility to the breath and the concentration of oxygen gas supplied can be kept stable.
Further, there is also known such an arrangement that a diaphragm-type high-sensitive pressure sensor is used as a sensor for detecting the breath, and a nose cannula and an oxygen source are coupled to each other through a three-way valve. When the pressure sensor detects the inhalation transmitted through the nose cannula, electric signals are generated to control the three-way valve. This arrangement enables the oxygen gas to be supplied through the nose cannula for a predetermined period of time.
On the other hand, there has been proposed an air pressure change detector comprising a strip-like piezoelectric element supported at one end thereof on a substrate which is accommodated in container having a vent hole at a position opposed to the piezoelectric element (Japanese Patent Laid-open No. 208827/92). In this air pressure change detector, an outside air is introduced into an interior of the container through the vent hole. When the pressure change in the outside air occurs, the pressure change is propagated to air in the container to cause the air to vibrate. The vibration of the air in turn induces the vibration of the piezoelectric element so that electric signals are generated therefrom, thereby enabling the detection of the change in air pressure. Especially, since the piezoelectric element is supported in a cantilever-like manner, the piezoelectric element is responsive to an extremely weak and low-frequency aerial vibration. By this arrangement, the air pressure change detector can detect an extremely small change in air pressure.
In the afore-mentioned techniques disclosed in Japanese Patent Laid-open Nos. 208827/92 and 143082/88, the breath sensor constituted by the pyroelectric element is disposed in the nose cannula and exposed to the expiration to accurately detect the temperature change occurring in association with the breath. However, since the pyroelectric element shows a low resistance to humidity or moistur
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patent: 4784130 (1988-11-01), Kenyon et al.
patent: 4827922 (1989-05-01), Champain et al.
patent: 5074299 (1991-12-01), Dietz
patent: 5134886 (1992-08-01), Ball
patent: 5367292 (1994-11-01), Szoke et al.
Hayakawa Eitaro
Ishikawa Shiro
Kanazawa Masayoshi
Murayama Yuki
Sato Takashi
Gunma Koike Co. Ltd.
Koike Medical Co., Ltd., Sumitomo Medical Mining Co., Ltd.
Lewis Aaron J.
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