초록 ▼

An apparatus for warming blood and other parental fluids as they are infused through a disposable flow system includes a pair of heating elements which heat the blood as it passes through a warming bag provided in the flow system. The heating elements are recurringly switched on and off with a duty

An apparatus for warming blood and other parental fluids as they are infused through a disposable flow system includes a pair of heating elements which heat the blood as it passes through a warming bag provided in the flow system. The heating elements are recurringly switched on and off with a duty cycle dependent on both the temperature of the blood at the output of the warming bag, and the temperature differential between the output and input of the bag to maintain the blood at a predetermined temperature independent of flow rate. A duty cycle alarm circuit senses current supplied to the heating elements and trips the main circuit breaker of the apparatus to terminate operation in the event current is continuously applied over a predetermined interval of time, and temperature range and door alarm circuits sound an alarm if the output temperature of the blood falls outside of a predetermined range or if the operator attempts to remove the warming bag from the apparatus while the apparatus is in operation.

대표청구항 ▼

Fluid warming apparatus for heating a refrigerated fluid such as blood to a predetermined nominal temperature prior to infusion at flow rates variable over a substantially predetermined range, said apparatus comprising, in combination: housing means defining a heating chamber for the fluid within th

Fluid warming apparatus for heating a refrigerated fluid such as blood to a predetermined nominal temperature prior to infusion at flow rates variable over a substantially predetermined range, said apparatus comprising, in combination: housing means defining a heating chamber for the fluid within the apparatus, the fluid having an input temperature and an output temperature within said chamber; at least one electric heater element operable from an applied electric current in thermal communication with the fluid in said heating chamber for heating the fluid as it passes through the apparatus; control circuit means responsive to said input and output temperatures of the fluid for generating a heater control signal dependent on both said output temperature and flow rate of the fluid; said control circuit means including first temperature sensing means for sensing the input temperature of the fluid and developing a first output signal indicative thereof, second temperature sensing means for sensing the output temperature of the fluid and developing a second output signal indicative thereof, a differential amplifier for developing from said first and second output signals a differential signal indicative of the differential between said input and output temperatures; said heater control signal being variable as a function of both said output temperature of the fluid and said differential signal; and switch circuit means electrically connected between said heating element and a source of electrical current, and responsive to said heater control signal for controlling the application of current to said heating element, for maintaining the fluid at the predetermined nominal temperature notwithstanding variations in the flow rate thereof.