Process and devices for determining the instant of injection and the duration of injection in thermodilution measurements

• US 6,200,301 B1
• Filed: 08/31/1998
• Issued: 03/13/2001
• Est. Priority Date: 09/05/1997
• Status: Expired due to Fees

• Current Assignee: Pulsion Medical Systems AG
• Original Assignee: Pulsion Medical Systems AG
• Inventors: Pfeiffer, Ulrich, Joeken, Stefan, Seebauer, U.
• Primary Examiner(s): Kennedy, Sharon
• Assistant Examiner(s): Sirmons, Kevin C.
• Application Number:
  US09/144,276
• Time in Patent Office: 925 Days
• Field of Search: 604/503, 604/66, 604/20, 128/640, 128/691-692, 606/32
• US Class Current: 604/503
• CPC Class Codes: A61B 5/028 by thermo-dilution

Abstract

The present invention relates to a process and devices for determining the instant of injection and the duration of injection in thermodilution measurements in which an injectate fluid at a temperature deviating from the temperature of the blood of a patient is injected at a specific injection site into a blood vessel of the patient and the temperature of the blood is measured at a measuring site downstream of the injection site, the injectate fluid being used at approximately room temperature and, before entry into the blood vessel, passed by a temperature sensor which, before the measurement, has a temperature deviating from room temperature, the temperature determined by the temperature sensor being sensed continuously, the instant of the beginning of injection being determined from a change occurring in the sensed temperature and the instant of the end of injection being determined from a subsequently occurring change in direction of the temperature profile.

Claims

1. A process for determining an instant of injection and a duration of injection in thermodilution measurements, the process comprising the steps of:

providing an injectate fluid at a temperature deviating from a temperature of a blood of a patient and having a temperature at approximately room temperature;

providing a temperature sensor having a temperature deviation from room temperature;

injecting said injectate fluid at a specific injection site into a blood vessel of said patient;

passing said injectate fluid over said temperature sensor and reading continuously a temperature sensed by said temperature sensor;

measuring a temperature of the blood at a measuring site downstream of said injection site;

determining an instant of a beginning of injection from a change occurring in said temperature sensed by said temperature sensor; and

determining an instant of an end of injection from a subsequently occurring change in direction of said temperature sensed by said temperature sensor.

2. The process as claimed in claim 1, wherein the temperature of the temperature sensor deviates significantly from room temperature.

3. The process as claimed in claim 1, wherein the temperature of the temperature sensor deviates from room temperature by at least two degrees Celsius.

4. The process as claimed in claim 1, wherein the temperature sensor is brought to a temperature deviating from room temperature by supplying heat or by active or passive cooling from outside.

5. The process as claimed in claim 1, wherein the temperature sensor is brought to a temperature deviating from room temperature by contact with the body of the patient.

6. The process as claimed in claim 5, wherein the temperature sensor is brought to a temperature deviating from room temperature by thermal contact with the blood of the patient.

7. The process as claimed in claim 5, wherein the temperature sensor is brought to a temperature deviating from room temperature by thermal contact with the outer skin of the patient.