Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
2002-02-28
2003-11-25
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S485000, C600S490000
Reexamination Certificate
active
06652466
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
This invention relates to a blood flow volume measurement method and a vital sign monitoring apparatus and in particular to a blood flow volume measurement method of measuring the blood flow volume ejected by cardiac contraction in vital sign monitoring apparatus and a vital sign monitoring apparatus.
2. Related Art
In medical facilities, variation in the hemodynamics of a patient in an operating room, an intensive care unit, an emergency treatment room, artificial dialysis treatment room, etc., needs to be monitored continuously as much as possible.
Hitherto, the variation in the hemodynamics of such a patient has been monitored mainly by monitoring the blood pressure directly.
In a living body, the cardiac output and the systemic vascular resistance are adjusted so that the blood pressure of the center is limited within a certain range. Therefore, to know the variation in the hemodynamics of a patient at an early stage, it is not enough to only monitor the blood pressure directly, and when change in the blood pressure is observed, the cause of the change in the blood pressure needs to be known. Then, in addition to change in the blood pressure, change in the cardiac output needs to be monitored.
As a method of measuring the change in the cardiac output to monitor the variation in the hemodynamics of a patient, methods are used as described below such as a thermo dilution method, a dye dilution method, and an ultrasound method.
First, the thermo dilution method will be discussed.
In the thermo dilution method a Swan-Ganz catheter is inserted through a jugular vein, a given amount of cooled saline or cooled glucose solution is poured to a central vein or a right atrial, and the cardiac output is measured from temperature change in a pulmonary artery.
Recently, another thermo dilution method of measuring the cardiac output from temperature change caused by blood warmed through a catheter has also been available; according to this method, the cardiac output can be measured automatically every given time.
Next, the dye dilution method will be discussed.
In the dye dilution method, a given amount of dye is poured through a vein, and the dye concentration is measured invasively or non-invasively in the part where the dye is uniformly diluted to a constant concentration, and the cardiac output is measured.
Next, the ultrasound method will be discussed.
The ultrasound method is a method of measuring the inner diameter of an arterial blood vessel such as a descending aorta and the blood flow velocity using ultrasound transesophageally, thereby the cardiac output is measured.
Aforementioned methods measuring cardiac output for monitoring the variation in the hemodynamics of a patient in the related arts involve the following problems:
The thermo dilution method involves a problem of intermittent measurement and incapability of continuous measurement. Inserting a catheter in the thermo dilution method is highly invasive for a patient and involves a possible danger of infection, etc.
Further, the thermo dilution method is a method requiring a skilled medical person for measurement and inserting a catheter.
Recently, a continuous measurement method has also been developed in the thermo dilution method, but the method requires insertion of a catheter and the above-described problem cannot be solved.
The dye dilution method also involves a problem of incapability of continuous measurement and requires a skilled medical person.
The ultrasound method imposes a burden of stress on a patient because a transducer is attached transesophageally.
Recently, a non-invasive measurement from the body surface has also been available as a kind of the ultrasound method, but continuous measurement is impossible.
Considering requirement for an advanced skill of medical person and an invasive procedure for a patient, the methods described above cannot continuously be conducted easily and it is difficult to monitor the variation in the hemodynamics of a patient continuously at all times by the methods.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a vital sign monitoring apparatus and a method of measuring the blood flow volume ejected by cardiac contraction in a vital sign monitoring apparatus capable of non-invensively monitoring the variation in the hemodynamics of a patient continuously at all times.
According to a first aspect of the present invention, there is provided a blood flow volume measurement method of measuring a blood flow volume ejected by cardiac contraction in a vital sign monitoring apparatus, the blood flow volume measurement method comprising the steps of calculating estimated systolic blood pressure and estimated diastolic blood pressure from information relevant to blood pressure successively measured based on the relationship between information relevant to blood pressure and systolic blood pressure and the relationship between information relevant to blood pressure and diastolic blood pressure, successively measuring a systolic duration and a diastolic duration, and calculating a blood flow volume ejected by cardiac contraction based on the estimated systolic blood pressure and the estimated diastolic blood pressure successively calculated and the systolic duration and the diastolic duration successively measured.
Since the estimated systolic blood pressure and the estimated diastolic blood pressure are thus calculated from the information relevant to blood pressure measured (non-invensively) successively, the variation in the hemodynamics of a patient can be monitored non-invensively continuously at all times. Further, a skilled medical person for inserting a catheter, etc., is not required.
According to a second aspect of the present invention, there is provided a blood flow volume measurement method of measuring a blood flow volume ejected by cardiac contraction in a vital sign monitoring apparatus, the blood flow volume measurement method comprising the steps of calculating estimated systolic blood pressure and estimated diastolic blood pressure from information relevant to blood pressure successively measured based on the relationship between information relevant to blood pressure and systolic blood pressure and the relationship between information relevant to blood pressure and diastolic blood pressure, calculating an estimated systolic duration and an estimated diastolic duration of an aorta from a systolic duration and a diastolic duration of a peripheral blood vessel successively measured based on the relationship between the systolic or diastolic duration in the aorta and the systolic or diastolic duration in the peripheral blood vessel, and calculating a blood flow volume ejected by cardiac contraction based on the estimated systolic blood pressure, the estimated diastolic blood pressure, the estimated systolic duration, and the estimated diastolic duration successively calculated.
The systolic or diastolic duration in the aorta is thus measured intermittently, whereby the estimated systolic blood pressure and the estimated diastolic blood pressure can be corrected, so that more accurate estimates can be provided.
According to a third aspect of the present invention, there is provided a blood flow volume measurement method of measuring a blood flow volume ejected by cardiac contraction in a vital sign monitoring apparatus, the blood flow volume measurement method comprising the first step of measuring a predetermined systolic pulse wave area in an aorta, measuring a systolic duration or a diastolic duration in the aorta, and measuring first blood flow volume based on the predetermined systolic pulse wave area and the systolic duration or the diastolic duration, the second step of calculating estimated systolic blood pressure and estimated diastolic blood pressure from information relevant to blood pressure successively measured based on the relationship between information relevant to blood pressure and systolic blood pressure and the relationship between information relevant to blood pressure
Hyogo Mitsushi
Ozawa Hideo
Sugo Yoshihiro
Hindenburg Max F.
Natnithithadha Navin
Nihon Kohden Corporation
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