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Publication Number
US-9463113-B2
Publication Date
2016-10-11
Expiration Date
Abstract
Methods and systems for infusing a cooled infusate to a target location in a patient are described. A temperature of the blood and infusate admixture upstream of the catheter as well as at other locations along the catheter may be monitored and a feedback system utilized to control the volume, temperature, and/or infusion rate of the infusate so as to achieve a predetermined temperature at the target location. Control may also be based on the patient's native vessel flow rate. The system may monitor or calculate hematocrit upstream of the catheter and adjust infusion so as to provide sufficient oxygenation of the blood and infusate admixture. The system may also monitor reflux of the infusate past a distal end of the catheter and reduce infusion upon the detection of reflux.
Core Innovation
The invention relates to intravascular cooling by communicating with a source of an infusate and infusing the infusate through an insertion device placed in a blood vessel of a patient. The method controls at least one of an infusate temperature, an infusion rate, and a volume of infusate passed in a downstream direction based on a temperature of a blood and infusate mixture downstream relative to an infusate exit location while considering infusate temperature at and adjacent the exit location, temperature upstream and adjacent the exit location, and core body temperature of the patient.
The method receives signals from a plurality of temperature sensors, including at least one temperature sensor positioned downstream relative to the infusate exit location to measure the temperature of the blood and infusate mixture. The temperature sensors include a first sensor downstream relative to an infusate exit location, a second sensor adapted to measure the infusate temperature at and adjacent the exit location, a third sensor adapted to measure temperature outside the catheter upstream and adjacent the exit location, and a fourth sensor adapted to measure core body temperature.
In additional forms, the invention includes controlling a heat exchanger and/or an infusate pump based on the received sensor signals and controlling infusion parameters so they relate to downstream blood and infusate temperatures. The invention further calculates downstream dilution and hematocrit using a base whole body hematocrit and a dilution factor defined by an equation that depends on infusion rate and temperature relationships between the mixture downstream of the exit, the infusate at and adjacent the exit, temperature adjacent and upstream the exit, and the core body temperature.
The invention also supports coordinating infusate temperature by controlling flow from a first and a second pressurized reservoir at different temperatures through the insertion device, and includes an exterior-to-lumen sensing approach in which a sensor located away from the infusate exit location provides signals used for control, reflux detection, and calculations.
Claims Coverage
The provided set includes four independent claims. Across these independent claims, the core claim elements repeatedly include temperature-based downstream feedback control using multiple temperature sensors and controlling infusate temperature, infusion rate, and/or delivered volume relative to an infusate exit location, with additional independent coverage for hematocrit/dilution calculation, two-reservoir coordinated temperature control, and exterior-to-lumen sensing with reflux-based calculations.
Downstream temperature-based closed-loop infusion control with multiple catheter sensors
Communicating with a source of an infusate; controlling at least one of an infusate temperature, an infusion rate through an insertion device, and a volume of infusate passed through the insertion device in a downstream direction in accordance with a temperature of a blood and infusate mixture downstream relative to an infusate exit location while the insertion device is placed in a blood vessel of a patient; receiving signals from a plurality of temperature sensors with at least one downstream relative to the infusate exit location; measuring a temperature of the infusate and blood mixture; and measuring the temperature of the infusate at and adjacent the exit location, the temperature upstream and adjacent the exit location, and the core body temperature of the patient.
Downstream dilution and hematocrit calculation from multiple temperatures
Calculating at least one of a dilution of the blood and a hematocrit downstream the exit location using a base whole body hematocrit and the dilution of the blood based on an equation with a dilution factor defined from infusion rate and temperature relationships among the mixture downstream of the exit location, the infusate at and adjacent the exit location, temperature adjacent and upstream the exit location, and core body temperature.
Coordinated two-reservoir control to set infusate temperature
Controlling flow of infusate from a first pressurized reservoir of infusate at a first temperature through the insertion device; controlling flow of infusate from a second pressurized reservoir of infusate at a second temperature through the insertion device; and controlling the temperature of the infusate flowing through the insertion device via coordinated control of both flows.
Exterior-to-lumen sensing with reflux detection for flow and mixture calculations
Receiving signals from a sensor located exterior to an internal lumen of an insertion device positioned in a system filled with at least one of a fluid and gas flowing in a first direction, the signals indicative of at least one parameter of at least one of the fluid and gas to control at least one parameter of the infusate, an infusion rate of the infusate through the insertion device, and a volume of the infusate passing through the insertion device in accordance with the signals; and detecting reflux and calculating at least one of a native vessel flow rate, a dilution factor, a hematocrit of a mixture, and a temperature of the blood and infusate mixture in accordance with when reflux occurs.
Across the independent claims, the invention is characterized by controlling infusate temperature, infusion rate, and/or delivered volume based on downstream blood-and-infusate mixture temperature relative to the insertion-device exit using multiple temperature sensors, optionally including downstream dilution and hematocrit calculation and coordinated control using two pressurized reservoirs. A separate independent approach uses an exterior-to-lumen sensor positioned away from the exit location, together with reflux detection and calculation of native vessel flow rate, dilution factor, hematocrit, and mixture temperature.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Intravascular cooling by infusing cooled infusate through an insertion device in a patient blood vessel using downstream temperature sensor feedback control.
Using reflux detection to determine when reflux occurs and to calculate native vessel flow rate, dilution factor, hematocrit, and temperature based on that determination.
Using native vessel flow rate to infer or monitor downstream conditions and support infusion parameter decisions.
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