Extravasation detector using microwave radiometry
First Claim
1. Apparatus for detecting extravasations in tissue injected with fluid from a fluid injector, comprising:
- a fluid temperature sensor for sensing the temperature of fluid present in a connector tube which transmits fluid to a patient, and generating a fluid temperature signal in response thereto;
a tissue temperature sensor for sensing the temperature of tissue proximate the site of injection and generating a tissue temperature signal in response thereto; and
a processor adaptable to periodically receive said tissue temperature signal and said fluid temperature signal, said processor having an alarm circuit for declaring the occurrence of an extravasation and a threshold calculation circuit for periodically calculating at least one threshold value as a function of said tissue temperature signal and said fluid temperature signal, said processor activating said alarm circuit as a function of said tissue temperature signal, said fluid temperature signal, and said at least one threshold value during the fluid injection.
1 Assignment
0 Petitions
Accused Products
Abstract
A microwave antenna senses the temperature of tissue into which a fluid is to be injected. The fluid is injected by a needle or other vascular entry device connected to a fluid injector by a connector tube. The fluid temperature is measured by a temperature sensor attached to the connector tube. An alarm processor determines whether an extravasation occurs by comparing a temperature discrimination function derived from tissue temperature taken at different times with a calculated threshold value. The threshold value is calculated from the tissue temperature and the fluid temperature. The threshold value is recalculated and updated continuously during the fluid injection.
-
Citations
59 Claims
-
1. Apparatus for detecting extravasations in tissue injected with fluid from a fluid injector, comprising:
-
a fluid temperature sensor for sensing the temperature of fluid present in a connector tube which transmits fluid to a patient, and generating a fluid temperature signal in response thereto; a tissue temperature sensor for sensing the temperature of tissue proximate the site of injection and generating a tissue temperature signal in response thereto; and a processor adaptable to periodically receive said tissue temperature signal and said fluid temperature signal, said processor having an alarm circuit for declaring the occurrence of an extravasation and a threshold calculation circuit for periodically calculating at least one threshold value as a function of said tissue temperature signal and said fluid temperature signal, said processor activating said alarm circuit as a function of said tissue temperature signal, said fluid temperature signal, and said at least one threshold value during the fluid injection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. A fluid temperature sensor for use with an extravasation detector having a fluid needle, a fluid connector tube having fluid, and a connector having an interior sidewall connecting said tube to said needle, said fluid temperature sensor comprising:
-
an electrical temperature transducer; and a thermally conductive insert adapted to extend through said connector and said interior sidewall, said thermally conductive insert adaptable to be in contact with said fluid in said connector tube to provide a temperature conductive path, and said thermally conductive insert coupled to said thermoelectric transducer. - View Dependent Claims (20, 21)
-
-
22. A fluid injection system comprising:
-
a fluid injector head capable of initiating and stopping fluid flow; a connector tube coupled to said fluid injector, said tube forming a path for transmitting fluid from said fluid injector to tissue containing a vessel into which fluid is intended to be injected; a fluid temperature sensor located on said connector tube, said temperature sensor producing a fluid temperature signal representing the temperature of said fluid in said connector tube; a tissue temperature sensor for generating a tissue temperature signal as a function of the temperature of said tissue; and an alarm circuit coupled to said tissue temperature sensor and said fluid temperature sensor, said alarm circuit having a temperature discrimination function circuit capable of calculating a temperature discrimination function from said tissue temperature, a threshold circuit capable of comparing at least a first threshold value with said temperature discrimination function, said threshold circuit calculating said first threshold value at different time intervals during said fluid flow. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
-
-
40. A method for detecting extravasations in tissue injected with fluid from a fluid injector, comprising the steps of:
-
periodically sensing the temperature of fluid present in a connector tube transmitting fluid to a patient, and generating a fluid temperature signal in response thereto; periodically sensing the temperature of tissue proximate the site of injection and generating a tissue temperature signal in response thereto; receiving the fluid temperature signal and the tissue temperature signal; storing a fluid temperature and a tissue temperature derived from the received signals; and declaring the occurrence of an extravasation as a function of said tissue temperature signal and said fluid temperature signal during the fluid injection. - View Dependent Claims (41, 42, 43)
-
-
44. A method of detecting an extravasation in fluid injected into a tissue by a fluid injector which generates fluid flow through a connector tube, the method comprising the steps of:
-
measuring a first tissue temperature; measuring a first fluid temperature; calculating a first threshold value as a function of said first tissue temperature and said first fluid temperature; measuring a second tissue temperature at a time after said step of measuring said first tissue temperature; calculating a temperature discrimination function from said first and second tissue temperatures; comparing said first threshold value with said temperature discrimination function; generating an alarm signal if said temperature discrimination function exceeds said threshold value; measuring a second fluid temperature and a third tissue temperature; calculating an updated temperature discrimination function from said third tissue temperature; calculating an updated first threshold value as a function of said second fluid temperature and said third tissue temperature; comparing said updated first threshold value with said updated temperature discrimination function; and generating an alarm signal if said updated temperature discrimination function exceeds said updated first threshold value. - View Dependent Claims (45, 46, 47)
-
-
48. Apparatus for detecting an extravasation in tissue injected with fluid from a fluid injector, the fluid transmitted through a connector tube, the apparatus comprising:
-
a tissue temperature sensor for sensing the temperature of the tissue proximate the injection and generating a tissue temperature signal in response thereto; a fluid temperature controller for controlling the temperature of the fluid; and a processor adaptable to receive said tissue temperature signal and a fluid temperature signal generated from the temperature of the fluid, said processor having an alarm circuit for declaring the occurrence of an extravasation as a function of said tissue temperature signal and said fluid temperature signal, said processor coupled to said fluid temperature controller to control said temperature of said fluid in said connector tube so that a minimum difference exists between said tissue temperature and said fluid temperature. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56, 57)
-
-
58. A method of detecting an extravasation in fluid injected into a tissue by a fluid injector which generates fluid flow through a connector tube, the method comprising the steps of:
-
measuring a tissue temperature; measuring a fluid temperature; controlling said fluid temperature so the difference between said tissue temperature and said fluid temperature is sufficient to permit extravasation detection; and declaring the occurrence of an extravasation as a function of said tissue temperature and said fluid temperature.
-
-
59. A method of detecting extravasations in tissue injected with fluid from a fluid injector, comprising the following steps:
-
periodically sensing the temperature of fluid present in a connector tube transmitting fluid to a patient, and generating a fluid temperature signal in response thereto; periodically sensing the temperature of tissue proximate the site of injection, and generating a tissue temperature signal in response thereto; receiving the fluid temperature signal and the tissue temperature signal; storing a fluid temperature and a tissue temperature derived from the received signals; determining the initial tissue and fluid temperatures; calculating at least one initial threshold value as a function of the initial tissue and fluid temperatures; calculating a temperature discrimination function based on the initial tissue temperature; and activating an alarm declaring the occurrence of an extravasation if the temperature discrimination function exceeds the at least one initial threshold value.
-
Specification