Method for determining cardiac characteristics of subject
First Claim
1. A method for determining a desired physiological characteristic relating to the blood circulating action of the he art of a subject, said method comprising the steps of:
- (a) carrying out an incremental change in the volume (Δ
VL) of breathing gas in the subject'"'"'s lungs;
(b) measuring the corresponding change in pressure (Δ
PT) in an organ of the subject, other than a blood vessel, resulting from an incremental change in breathing gas volume in the subject'"'"'s lungs;
(c) determining the relationship between an incremental change in breathing gas volume (Δ
VL) and a resulting incremental change in pressure (Δ
PT) in the organ;
(d) measuring the change in pressure (Δ
PTH) in the organ caused by volumetric changes of the subject'"'"'s heart occurring from blood circulating action; and
(e) determining from the change in pressure (Δ
PTH) and the Δ
VL−
Δ
PT relationship, the amount of the volumetric change in the subject'"'"'s heart and the desired physiological characteristic.
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Accused Products
Abstract
A non-invasive method for determining the stroke volume of the heart, i.e. the volume of blood discharged per heart beat. A pressure transducer, is placed in a hollow organ, such as the lungs, stomach or bladder of a subject. During ventilation of, or breathing by, the subject, the incremental change in pressure in the hollow organ resulting from an incremental change in breathing gas volume in the subject'"'"'s lungs is obtained and a ratio between the two is established. The pressure change in the hollow organ caused by volumetric changes resulting from the contraction of the subject'"'"'s heart when discharging blood is also measured. The stroke volume of the subject'"'"'s heart is determined by applying the volume/pressure ratio to the pressure change resulting from the contraction of the heart.
60 Citations
31 Claims
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1. A method for determining a desired physiological characteristic relating to the blood circulating action of the he art of a subject, said method comprising the steps of:
-
(a) carrying out an incremental change in the volume (Δ
VL) of breathing gas in the subject'"'"'s lungs;
(b) measuring the corresponding change in pressure (Δ
PT) in an organ of the subject, other than a blood vessel, resulting from an incremental change in breathing gas volume in the subject'"'"'s lungs;
(c) determining the relationship between an incremental change in breathing gas volume (Δ
VL) and a resulting incremental change in pressure (Δ
PT) in the organ;
(d) measuring the change in pressure (Δ
PTH) in the organ caused by volumetric changes of the subject'"'"'s heart occurring from blood circulating action; and
(e) determining from the change in pressure (Δ
PTH) and the Δ
VL−
Δ
PT relationship, the amount of the volumetric change in the subject'"'"'s heart and the desired physiological characteristic.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method according to claim I wherein the volumetric change of the subject'"'"'s heart has temporal properties and wherein the method includes the step of measuring the temporal properties of the volumetric change to determine ejection time characteristics of the heart.
Specification