Tourniquet apparatus for applying minimum effective pressure
First Claim
1. Tourniquet apparatus for maintaining the lowest constant pressure applied by a pressurizing cuff to a limb to stop blood flow past the cuff for the duration of a surgical procedure, comprising:
- a) a pressurizing cuff responsive to cuff pressure control means for substantially encircling and applying pressure to a limb;
b) distal flow sensing means for sensing the flow of blood past the pressurizing cuff;
c) cuff pressure control means for controlling the pressure applied by the pressurizing cuff to the limb in response to a cuff pressure control signal;
d) signal generating means responsive to the distal flow sensing means for generating a variable signal indicative of varying pressure to be applied by the cuff to the limb;
e) estimation means for producing an estimate of a pressure level to be applied by the cuff to the limb so that the sensed blood flow is below a threshold level near zero;
f) constant pressure means for producing a constant signal that is greater than the estimate and is indicative of a constant reference pressure to be applied by the cuff to the limb to stop blood flow past the cuff for the duration of a surgical procedure; and
g) selection means for selecting either the variable signal or the constant signal to be the cuff pressure control signal.
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Accused Products
Abstract
Tourniquet apparatus for use in intravenous regional anesthesia and limb surgery includes a pressurizing cuff for substantially encircling a limb and applying a varying pressure to an underlying vein in response to variations in a pressure control signal, applied venous pressure sensing means for producing an applied venous pressure signal representative of a pressure applied by the cuff to the underlying vein, venous pressure estimation means for producing a venous fluid pressure signal representative of the pressure of fluid in the vein distal to the cuff, and pressure control means responsive to the venous fluid pressure signal and applied venous pressure signal for generating a pressure control signal to maintain a predetermined relationship between the applied venous pressure signal and the venous fluid pressure signal. The apparatus automatically controls the introduction, retention and release of anesthetic fluid in the limb.
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Citations
5 Claims
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1. Tourniquet apparatus for maintaining the lowest constant pressure applied by a pressurizing cuff to a limb to stop blood flow past the cuff for the duration of a surgical procedure, comprising:
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a) a pressurizing cuff responsive to cuff pressure control means for substantially encircling and applying pressure to a limb; b) distal flow sensing means for sensing the flow of blood past the pressurizing cuff; c) cuff pressure control means for controlling the pressure applied by the pressurizing cuff to the limb in response to a cuff pressure control signal; d) signal generating means responsive to the distal flow sensing means for generating a variable signal indicative of varying pressure to be applied by the cuff to the limb; e) estimation means for producing an estimate of a pressure level to be applied by the cuff to the limb so that the sensed blood flow is below a threshold level near zero; f) constant pressure means for producing a constant signal that is greater than the estimate and is indicative of a constant reference pressure to be applied by the cuff to the limb to stop blood flow past the cuff for the duration of a surgical procedure; and g) selection means for selecting either the variable signal or the constant signal to be the cuff pressure control signal. - View Dependent Claims (2, 3, 4, 5)
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Specification