Surgery – Diagnostic testing – Cardiovascular
Patent
1996-11-14
1998-11-10
Nasser, Robert L.
Surgery
Diagnostic testing
Cardiovascular
137504, 137517, A61B 0500
Patent
active
058336206
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant-rate deflator for a sphygmomanometer which reduces the air pressure in the pressurized chamber at a constant rate by gradually exhausting high pressure air in the chamber.
2. Description of the Background Art
In a cuff-type sphygmomanometer, the blood pressure is measured by identifying the pulsation phenomena (changes in the pulse pressure and the blood flow) caused during deflation of an inflated cuff. Therefore, a constant-rate deflator which gradually decreases the air pressure in the cuff depressing the arm, wrist, finger, and the like at a constant rate is used in the cuff-type sphygmomanometer.
Typical constant-rate deflators are proposed by Japanese Utility Model Application Laid-open No. 115507/1986, Japanese Patent Application Laid-open No. 193634/1986, and Japanese Patent Application Laid-open No. 193031/1991. These deflators are provided with a cylindrical tube in which the bottom is made from a flexible material such as rubber, with a slit being provided in a part thereof. To control the pressure decrease, the amount of opening of the slit is adjusted by providing a pressure from inside this cylindrical tube or from a side thereof by an indenter which is a component independent from the cylindrical tube.
Specifically, as shown in FIG. 6, a typical sphygmomanometer which is provided with a conventional constant-rate deflator has a high pressure chamber 50 directly joining with a cuff which depresses the arm, wrist, finger, and the like. This high pressure chamber 50 has a base plate 51 and an upper plate 52. Formed on a side of the base plate 51 is a lateral hole 51a, with steps, which is connected to an evacuation hole 60. A cylindrical ventilation valve 53 made of rubber is secured to this lateral hole 51a.
One or more slits 53a are provided at the circumferential surface on the bottom side of the cylindrical ventilation valve 53 along the longitudinal direction. These slits 53a are located in the high pressure chamber 50. On the other hand, an opening of the cylindrical ventilation valve 53 is positioned on the side of the ventilation hole 60 and secured by a securing ring 54.
Provided around the external circumference of the securing ring 54 is a male screw 54a which threadedly engages a female screw 60a formed around the internal circumference of the evacuation hole 60. The female screw 54b formed around the internal circumference is structured so as to be threadedly engaged by a male screw 55a which is formed around the external circumference of a head portion of an adjusting shaft 55. This adjusting shaft 55 has an evacuation hole 55b penetrating through the center thereof and a projection 55c having a size larger than the internal diameter of the cylindrical ventilation valve 53 at the tip.
The conventional constant-rate deflator with this configuration is operated as follows.
Specifically, the cylindrical ventilation valve 53 is placed in the lateral hole 51a which is formed on a side of the base plate 51 and secured by the securing ring screw 54. Then, the adjusting shaft 55 is threadedly engaged with the central female screw 54b of the securing ring screw 54, thereby causing the projection 55c at the tip to be inserted into the ventilation valve 53. Opening of the slit 53a provided in the ventilation valve 53 can be changed by changing the insertion distance of the projection 55c of the adjusting shaft 55 in this manner.
Here, the air in the high pressure chamber 50 is evacuated to the evacuation hole 55b of the adjusting shaft 55 through the slit 53a. At this instance, if the pressure of the high pressure chamber is high, the opening of the slit 53a of the ventilation valve 53 is decreased due to pressure at the external circumference, thereby decreasing the quantity of the exhaust gas and preventing the air to be evacuated in one stroke.
On the other hand, when the air pressure of the high pressure chamber 50 is low, the pressure to the slit 53a of the ventilation valve 53 at the exte
REFERENCES:
patent: 4332275 (1982-06-01), Brown
patent: 4497323 (1985-02-01), Matsuura et al.
patent: 4708166 (1987-11-01), Kobold
patent: 5220925 (1993-06-01), Hishida
patent: 5301713 (1994-04-01), Skoglund
Kasaya Masahiro
Murakami Tomomi
Nakahara Takanori
Tsuchiya Hidetaka
Citizen Watch Co. Ltd.
Nasser Robert L.
LandOfFree
Constant-rate deflator for sphygmomanometer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Constant-rate deflator for sphygmomanometer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Constant-rate deflator for sphygmomanometer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1511798